WO2025213421A1 - Encoding method, decoding method, bitstream, encoder, decoder, and storage medium - Google Patents

Abstract

The present application discloses an encoding method, a decoding method, a bitstream, an encoder, a decoder, and a storage medium. The decoding method comprises: determining prediction mode identification information of a current block; when the prediction mode identification information indicates that the current block performs inter prediction in a transform domain, on the basis of a reference block of the current block, determining a transform coefficient predicted value of the current block; decoding a bitstream to determine a transform coefficient residual value of the current block; and on the basis of the transform coefficient predicted value of the current block and the transform coefficient residual value of the current block, determining a transform coefficient of the current block. In this way, time complexity is reduced, and the attribute encoding and decoding efficiency of a point cloud is improved.

Description

Coding and decoding method, code stream, encoder, decoder and storage medium Technical Field

The embodiments of the present application relate to the field of video coding and decoding technology, and in particular to a coding and decoding method, a bit stream, an encoder, a decoder, and a storage medium.

Background Art

In the Geometry-based Point Cloud Compression (G-PCC) codec framework, the geometric and attribute information of a point cloud are encoded separately. G-PCC attribute encoding can include Predicting Transform (PT), Lifting Transform (LT), and Region Adaptive Hierarchical Transform (RAHT).

During the RAHT transform, attribute information is adaptively transformed from the bottom up based on the octree's construction hierarchy. Due to the suboptimal nature of existing technical solutions, the time complexity of transforming the reference image at both the encoder and decoder ends increases, increasing the complexity of the RAHT attribute transform encoding and decoding, and reducing attribute coding efficiency.

Summary of the Invention

The embodiments of the present application provide a coding and decoding method, a code stream, an encoder, a decoder, and a storage medium, which can reduce time complexity, improve the efficiency of attribute coding and decoding of point clouds, and thereby improve the coding and decoding performance of point clouds.

The technical solution of the embodiment of the present application can be implemented as follows:

In a first aspect, an embodiment of the present application provides a decoding method, applied to a decoder, the method comprising:

Determining prediction mode identification information of the current block;

When the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, determining a transform coefficient prediction value of the current block according to a reference block of the current block;

Decode the code stream and determine the residual value of the transform coefficient of the current block;

The transform coefficient of the current block is determined according to the transform coefficient prediction value of the current block and the transform coefficient residual value of the current block.

In a second aspect, an embodiment of the present application provides an encoding method, applied to an encoder, the method comprising:

Determining prediction mode identification information of the current block;

When the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, determining a transform coefficient prediction value of the current block according to a reference block of the current block;

Determining a transform coefficient residual value of the current block according to a transform coefficient prediction value of the current block;

The transform coefficient residual value of the current block is coded, and the obtained coded bits are written into the bitstream.

In a third aspect, an embodiment of the present application provides a code stream, which is generated by bit encoding based on information to be encoded; wherein the information to be encoded includes at least one of the following: a low-frequency coefficient value of a root node and a high-frequency coefficient residual value of a current block.

In a fourth aspect, an embodiment of the present application provides an encoder, comprising a first determining unit, a first predicting unit, and an encoding unit, wherein:

A first determining unit configured to determine prediction mode identification information of a current block;

A first prediction unit is configured to determine a transform coefficient prediction value of the current block according to a reference block of the current block when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain;

The first determining unit is further configured to determine a transform coefficient residual value of the current block according to the transform coefficient prediction value of the current block;

The encoding unit is configured to perform encoding processing on the transform coefficient residual value of the current block and write the obtained encoding bits into the bit stream.

In a fifth aspect, an embodiment of the present application provides an encoder, comprising a first memory and a first processor; wherein,

a first memory for storing a computer program capable of running on the first processor;

The first processor is configured to execute the method according to the second aspect when running a computer program.

In a sixth aspect, an embodiment of the present application provides a decoder, comprising a second determination unit, a second prediction unit, and a decoding unit, wherein:

A second determining unit configured to determine prediction mode identification information of a current block;

The second prediction unit is configured to, when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, predict the current block according to the parameters of the current block. Consider the block and determine the predicted value of the transform coefficient of the current block;

a decoding unit configured to decode the bitstream and determine a transform coefficient residual value of a current block;

The second determining unit is further configured to determine the transform coefficient of the current block according to the transform coefficient prediction value of the current block and the transform coefficient residual value of the current block.

In a seventh aspect, an embodiment of the present application provides a decoder, the decoder comprising a second memory and a second processor; wherein,

a second memory for storing a computer program capable of running on the second processor;

The second processor is configured to execute the method according to the first aspect when running a computer program.

In an eighth aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method as described in the first aspect or the method as described in the second aspect.

In a ninth aspect, an embodiment of the present application provides a computer program product, comprising a computer program or instructions, which, when executed by a processor, implements the method described in the first aspect, or implements the method described in the second aspect.

The embodiments of the present application provide a coding and decoding method, a code stream, an encoder, a decoder, and a storage medium. At the encoding end, the prediction mode identification information of the current block is determined; when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, the transform coefficient prediction value of the current block is determined based on the reference block of the current block; the transform coefficient residual value of the current block is determined based on the transform coefficient prediction value of the current block; the transform coefficient residual value of the current block is encoded, and the obtained coded bits are written into the code stream. At the decoding end, the prediction mode identification information of the current block is determined; when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, the transform coefficient prediction value of the current block is determined based on the reference block of the current block; the code stream is decoded to determine the transform coefficient residual value of the current block; and the transform coefficient of the current block is determined based on the transform coefficient prediction value of the current block and the transform coefficient residual value of the current block. In this way, whether at the encoding end or the decoding end, when the current block performs inter-frame prediction in the transform domain, the transform coefficient prediction value of the current block can be determined based on the reference block of the current block. Among them, the reference block can be transformed based on the slices divided by the reference point cloud, rather than based on the entire frame of the reference point cloud, which reduces the time complexity; and the transformation coefficients of the reference block can be stored in the memory module, so that when the transformation coefficients of the reference block are needed, they can be directly obtained from the memory module, further reducing the time complexity, thereby improving the attribute encoding and decoding efficiency of the point cloud, and thus improving the encoding and decoding performance of the point cloud.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1A is a schematic diagram of a three-dimensional point cloud image;

FIG1B is a partially enlarged view of a three-dimensional point cloud image;

FIG2A is a schematic diagram of six viewing angles of a point cloud image;

FIG2B is a schematic diagram of a data storage format corresponding to a point cloud image;

FIG3 is a schematic diagram of a network architecture for point cloud encoding and decoding;

FIG4 is a schematic diagram of a composition framework of a G-PCC encoder;

FIG5 is a schematic diagram of a composition framework of a G-PCC decoder;

FIG6 is a schematic diagram of a RAHT transformation structure;

FIG7 is a schematic diagram of a RAHT transformation process along the x, y, and z directions;

FIG8A is a schematic diagram of a RAHT forward transformation process;

FIG8B is a schematic diagram of a RAHT inverse transformation process;

FIG9 is a schematic diagram of the structure of a RAHT attribute inter-frame prediction coding;

Figure 10 is a schematic diagram of the hierarchical structure of a point cloud attribute RAHT;

FIG11 is a schematic diagram of a framework of RAHT inter-frame prediction transformation applied to the encoding end;

FIG12 is a schematic diagram of a framework of RAHT inter-frame prediction transformation applied to a decoding end;

FIG13 is a schematic diagram of the logical structure of a RAHT inter-frame prediction transformation;

FIG14 is a flowchart diagram 1 of a decoding method provided in an embodiment of the present application;

FIG15 is a schematic diagram of the logical structure of an inter-frame prediction transformation provided by an embodiment of the present application;

FIG16 is a second flow chart of a decoding method provided in an embodiment of the present application;

FIG17 is a third flow chart of a decoding method provided in an embodiment of the present application;

FIG18 is a fourth flow chart of a decoding method provided in an embodiment of the present application;

FIG19 is a schematic diagram of a flow chart of an encoding method provided in an embodiment of the present application;

FIG20 is a schematic diagram of a framework of inter-frame prediction transformation applied to a decoding end provided by an embodiment of the present application;

FIG21 is a schematic diagram of a framework of inter-frame prediction transformation applied to an encoding end according to an embodiment of the present application;

FIG22 is a schematic diagram of the structure of an encoder provided in an embodiment of the present application;

FIG23 is a schematic diagram of a specific hardware structure of an encoder provided in an embodiment of the present application;

FIG24 is a schematic diagram of the structure of a decoder provided in an embodiment of the present application;

FIG25 is a schematic diagram of a specific hardware structure of a decoder provided in an embodiment of the present application;

FIG26 is a schematic diagram of the composition structure of a coding and decoding system provided in an embodiment of the present application.

DETAILED DESCRIPTION

In order to enable a more detailed understanding of the features and technical contents of the embodiments of the present application, the implementation of the embodiments of the present application is described in detail below with reference to the accompanying drawings. The attached drawings are for reference only and are not used to limit the embodiments of the present application.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein are for the purpose of describing the embodiments of this application only and are not intended to limit this application.

In the following description, reference is made to “some embodiments”, which describes a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

It should also be pointed out that the terms "first\second\third" involved in the embodiments of the present application are only used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described here can be implemented in an order other than that illustrated or described here.

Point Cloud is a three-dimensional representation of the surface of an object. Point Cloud (data) on the surface of an object can be collected through acquisition equipment such as photoelectric radar, lidar, laser scanner, and multi-view camera.

A point cloud is a set of irregularly distributed discrete points in three-dimensional space that represent the spatial structure and surface properties of a three-dimensional object or scene. These points contain geometric information representing spatial location and attribute information representing the point cloud's appearance and texture. Figure 1A shows a 3D point cloud image, and Figure 1B shows a zoomed-in view of a 3D point cloud image. It can be seen that the point cloud surface is composed of densely distributed points.

Two-dimensional images contain information at every pixel and are distributed regularly, so there's no need to record their location information. However, the distribution of points in a point cloud in three-dimensional space is random and irregular, so recording the spatial location of each point is necessary to fully represent the point cloud. Similar to two-dimensional images, each location in the acquisition process has corresponding attribute information, typically including color and reflectance. Color information reflects the color of an object and is typically represented in RGB; reflectance information reflects the surface texture of an object and is typically represented in reflectance. Point cloud data typically consists of geometric information (x, y, z) representing the three-dimensional spatial location, as well as attribute information such as color (r, g, b) and reflectance. For example, reflectance information can be one-dimensional reflectance (r); color information can be in any color space, or it can be three-dimensional color information, such as RGB. Here, R represents red (red), G represents green (green), and B represents blue (blue). For another example, the color information may be luminance and chrominance (YCbCr, YUV) information, where Y represents brightness (Luma), Cb (U) represents blue color difference, and Cr (V) represents red color difference.

For example, a point cloud obtained using laser measurement principles may include both 3D coordinate information and reflectivity information for each point. For another example, a point cloud obtained using photogrammetry principles may include both 3D coordinate information and 3D color information for each point. For another example, a point cloud obtained using a combination of laser measurement and photogrammetry principles may include both 3D coordinate information, reflectivity information, and 3D color information for each point.

Figures 2A and 2B show a point cloud image and its corresponding data storage format. Figure 2A provides six viewing angles of the point cloud image, while Figure 2B consists of a file header and data. The header includes the data format, data representation type, the total number of points in the point cloud, and the content represented by the point cloud. For example, the point cloud is in ".ply" format, represented by ASCII code, with a total of 207,242 points. Each point has 3D coordinate information (x, y, z) and 3D color information (r, g, b).

Point clouds can be divided into the following categories according to the acquisition method:

Static point cloud: the object is stationary and the device that acquires the point cloud is also stationary;

Dynamic point cloud: The object is moving, but the device that obtains the point cloud is stationary;

Dynamic point cloud acquisition: The device used to acquire the point cloud is in motion.

For example, point clouds can be divided into two categories according to their usage:

Category 1: Machine perception point cloud, which can be used in scenarios such as autonomous navigation systems, real-time inspection systems, geographic information systems, visual sorting robots, and disaster relief robots;

Category 2: Human eye perception point cloud, which can be used in point cloud application scenarios such as digital cultural heritage, free viewpoint broadcasting, 3D immersive communication, and 3D immersive interaction.

Point clouds can flexibly and conveniently express the spatial structure and surface properties of three-dimensional objects or scenes. Moreover, since point clouds are obtained by directly sampling real objects, they can provide a strong sense of reality while ensuring accuracy. Therefore, they are widely used, including virtual reality games, computer-aided design, geographic information systems, automatic navigation systems, digital cultural heritage, free viewpoint broadcasting, three-dimensional immersive remote presentation, and three-dimensional reconstruction of biological tissues and organs.

The main ways to collect point clouds are: computer generation, 3D laser scanning, 3D photogrammetry, etc. Computers can generate virtual three-dimensional 3D laser scanning can generate point clouds of static, real-world 3D objects or scenes, generating millions of point clouds per second. 3D photogrammetry can generate point clouds of dynamic, real-world 3D objects or scenes, generating tens of millions of point clouds per second. These point cloud acquisition technologies reduce the cost and time required to acquire point cloud data, while improving data accuracy and further promoting the practical application of point clouds. The increasing industrialization of point cloud data acquisition methods has made it possible to acquire large amounts of point cloud data. However, as application demand grows, processing massive amounts of 3D point cloud data has encountered bottlenecks in storage space and transmission bandwidth.

For example, taking a point cloud video with a frame rate of 30 frames per second (fps), each frame of the point cloud has 700,000 points, and each point contains coordinate information xyz (float) and color information RGB (uchar). Therefore, the data volume of a 10-second point cloud video is approximately 0.7 million × (4 Byte × 3 + 1 Byte × 3) × 30fps × 10s = 3.15GB, where 1 Byte is 10 bits. Correspondingly, a 1280 × 720 two-dimensional video with a YUV sampling format of 4:2:0 and a frame rate of 30fps has a data volume of approximately 1280 × 720 × 12 bits × 30fps × 10s ≈ 0.39GB for 10 seconds, and a two-view three-dimensional video of 10 seconds has a data volume of approximately 0.39 × 2 = 0.78GB. This shows that the data volume of a point cloud video far exceeds that of a two-dimensional video or a three-dimensional video of the same length. Therefore, in order to better realize data management, save server storage space, and reduce the transmission traffic and transmission time between the server and the client, point cloud compression has become a key issue in promoting the development of the point cloud industry.

That is to say, since the point cloud is a collection of massive points, storing the point cloud not only consumes a lot of memory, but is also not conducive to transmission. There is also not enough bandwidth to support direct transmission of the point cloud at the network layer without compression. Therefore, the point cloud needs to be compressed.

Currently, point cloud coding frameworks that can compress point clouds can include the Geometry-based Point Cloud Compression (G-PCC) codec framework or the Video-based Point Cloud Compression (V-PCC) codec framework provided by the Moving Picture Experts Group (MPEG), or the AVS-PCC codec framework provided by AVS. The G-PCC codec framework can be used to compress the first type of static point clouds and the third type of dynamically acquired point clouds, and can be based on the Point Cloud Compression Test Platform (Test Model Compression 13, TMC13). The V-PCC codec framework can be used to compress the second type of dynamic point clouds, and can be based on the Point Cloud Compression Test Platform (Test Model Compression 2, TMC2). Therefore, the G-PCC codec framework is also called the Point Cloud Codec TMC13, and the V-PCC codec framework is also called the Point Cloud Codec TMC2.

An embodiment of the present application provides a network architecture of a point cloud encoding and decoding system including a decoding method and an encoding method. FIG3 is a schematic diagram of a network architecture of a point cloud encoding and decoding system provided by an embodiment of the present application. As shown in FIG3 , the network architecture includes one or more electronic devices 13 to 1N and a communication network 01, wherein the electronic devices 13 to 1N can perform video interaction through the communication network 01. During the implementation process, the electronic device can be various types of devices with point cloud encoding and decoding functions. For example, the electronic device can include a mobile phone, a tablet computer, a personal computer, a personal digital assistant, a navigator, a digital phone, a video phone, a television, a sensor device, a server, etc., which is not limited by the embodiment of the present application. Among them, the decoder or encoder in the embodiment of the present application can be the above-mentioned electronic device.

Among them, the electronic device in the embodiment of the present application has a point cloud encoding and decoding function, generally including a point cloud encoder (ie, encoder) and a point cloud decoder (ie, decoder).

The following describes the related technologies using the G-PCC encoding and decoding framework as an example.

As you can understand, in the point cloud G-PCC codec framework, the input point cloud is first divided into multiple slices through slice partitioning. In each slice, the geometric information of the point cloud and the attribute information corresponding to each point are encoded separately.

Figure 4 is a schematic diagram of the composition framework of a G-PCC encoder. As shown in Figure 4, the G-PCC encoder is applied to a point cloud encoder. In the G-PCC encoding framework, the input point cloud is sliced, and then the slices are independently encoded. Within the slice, the geometric information of the point cloud and the attribute information corresponding to the points in the point cloud are encoded separately. The G-PCC encoder first encodes the geometric information. The encoder performs coordinate transformation on the geometric information so that the entire point cloud is contained in a bounding box; then quantization is performed. This quantization step mainly serves a scaling purpose. Due to quantization rounding, the geometric information of some points is the same. The decision to remove duplicate points is made based on parameters. This process of quantization and removing duplicate points is also called voxelization. Next, the bounding box is partitioned based on an octree. Depending on the depth of the octree partitioning level, the encoding of geometric information is divided into two frameworks: octree-based and triangle facet-based.

In the octree-based geometry information coding framework, the bounding box is divided into eight equal parts, and the placeholder bits of each sub-cube are recorded (where 1 indicates a non-empty sub-cube and 0 indicates an empty sub-cube). The non-empty sub-cubes are further divided into eight equal parts, usually stopping when the resulting leaf node is a 1×1×1 unit cube. During this process, the placeholder bits are intra-predicted using the spatial correlation between the node and its surrounding nodes. Finally, CABAC encoding based on the context model is performed to generate a binary geometry bit stream, also known as the geometry code stream.

In the triangle facet-based geometric information coding framework, octree partitioning is also performed first. However, the difference is that the octree-based geometric information coding method does not need to divide the point cloud into unit cubes with a side length of 1×1×1. Instead, the partitioning stops when the block side length is W. Based on the surface formed by the distribution of the point cloud in each block, the surface and the twelve edges of the block are obtained. Finally, the vertex coordinates of each block are encoded in sequence to generate a binary geometric bit stream, namely the geometric code stream.

After completing the geometric information encoding, the G-PCC encoder reconstructs the geometric information and uses the reconstructed geometric information to encode the attribute information of the point cloud. At present, the attribute encoding of the point cloud mainly encodes the color information of the point in the point cloud. First, the encoder can perform color space conversion on the color information of the point. For example, when the color information of the point in the input point cloud is represented by the RGB color space, the encoder can convert the color information from the RGB color space to the YUV color space. Then, the point cloud is re-colored using the reconstructed geometric information. Color is encoded so that the unencoded attribute information corresponds to the reconstructed geometric information. In color information encoding, there are two main transformation methods. One method is to rely on the distance-based lifting transform based on the level of detail (LOD) division, and the other is to directly perform the region adaptive hierarchical transform (RAHT). Both methods transform the color information from the spatial domain to the frequency domain to obtain high-frequency coefficients and low-frequency coefficients. Finally, the coefficients are quantized and arithmetic encoded on the quantized coefficients to generate a binary attribute bit stream, namely the attribute code stream.

Figure 5 is a schematic diagram of the composition framework of a G-PCC decoder. As shown in Figure 5, the G-PCC decoder is applied to a point cloud decoder. In the G-PCC decoding framework, after obtaining the binary code stream, the geometric bit stream and attribute bit stream in the binary code stream are decoded independently. When decoding the geometric bit stream, the geometric information of the point cloud is obtained through arithmetic decoding-synthetic octree-surface fitting-reconstructed geometry-inverse coordinate transformation; when decoding the attribute bit stream, the attribute information of the point cloud is obtained through arithmetic decoding-inverse quantization-LOD-based inverse lifting or RAHT-based inverse transformation-inverse color conversion. The original slice can be restored based on the geometric information and attribute information; then, after merging the slices, the three-dimensional image model of the input point cloud can be restored.

It should be noted that, as shown in Figure 4 or Figure 5, the current G-PCC geometry codec can be divided into octree-based geometry codec and prediction tree-based geometry codec. Currently, G-PCC attribute codec includes three attribute encoding methods: Predicting Transform (PT), Lifting Transform (LT), and Region Adaptive Hierarchical Transform (RAHT). Among them, the first two predictively encode the point cloud based on the LOD generation order, while RAHT adaptively transforms attribute information from bottom to top based on the octree construction hierarchy.

The following describes the point cloud attribute encoding method in detail using region-adaptive hierarchical transformation as an example.

The Regional Adaptive Hierarchical Transform (RAHT) is a Haar wavelet transform that transforms point cloud attribute information from the spatial domain to the frequency domain, further reducing the correlation between point cloud attributes. Its main concept is to transform the nodes in each layer in the X, Y, and Z dimensions in a bottom-up manner according to the octree structure (as shown in Figure 7), and iterate until the root node of the octree. As shown in Figure 6, the basic idea is to perform a wavelet transform based on the hierarchical structure of the octree, associate attribute information with the octree nodes, and recursively transform the attributes of occupied nodes under the same parent node in a bottom-up manner, transforming the nodes in each layer in the X, Y, and Z dimensions until the root node of the octree is reached. During the hierarchical transformation process, the low-pass/low-frequency (DC) coefficients obtained after the transformation of the nodes in the same layer are passed to the nodes in the previous layer for further transformation, while all high-pass/high-frequency (AC) coefficients can be encoded using an arithmetic coder.

During the transformation process, the DC coefficients (direct current components) of the transformed nodes at the same layer are passed to the previous layer for further transformation, while the AC coefficients (alternating current components) of each layer are quantized and encoded. The main transformation processes are described below.

Figure 8A illustrates a RAHT forward transform process, and Figure 8B illustrates an inverse RAHT transform process. For the RAHT transform and inverse transform processes, assume that g′ _L,2x,y,z and g′ _L,2x+1,y,z are two attribute DC coefficients of neighboring nodes in the L layer. After linear transformation, the information in the L-1 layer consists of the AC coefficients f′ _L-1,x,y,z and the DC coefficients g′ _L-1,x,y,z . f′ _L-1,x,y,z is no longer transformed and is directly quantized. g′ _L-1,x,y,z continues to search for neighboring nodes for transformation. If no neighboring nodes are found, the transform is passed directly to the L-2 layer. This means that the RAHT transform is only effective for nodes with neighboring nodes; nodes without neighboring nodes are directly passed to the previous layer. In the above transformation process, the weights (the number of non-empty child nodes in the node) corresponding to g′ _L,2x,y,z and g′ _{L,2x+1,y ,z are w′ L,2x,y,z} and w′ _L,2x+1,y,z (abbreviated as w′ ₀ and w′ ₁ ) respectively, and the weight of g′ _L-1,x,y,z is w′ _L-1,x,y,z . The general transformation formula is:

Among them, T _w0,w1 is the transformation matrix:

The transformation matrix will be updated as the weights corresponding to each point change adaptively. The above process will be iterated and updated continuously according to the partitioning structure of the octree until the root node of the octree is reached.

In a specific implementation, for region-adaptive hierarchical inter-frame prediction transform coding, the process of G-PCC attribute inter-frame prediction coding is similar to the process of intra-frame prediction coding, which is described as follows:

First, a RAHT attribute transform coding structure is constructed based on geometric information. This involves performing transforms at the voxel level until the root node is reached, completing the hierarchical transform coding of the entire attribute. This approach results in both intra-frame and inter-frame coding structures. The inter-frame coding structure for the RAHT attribute can be seen in Figure 9.

As shown in FIG9 , the geometric information of the current node to be coded is first used to obtain the co-located predicted node of the node to be coded in the reference image, and then the geometric information and attribute information of the reference node are used to obtain the predicted attribute of the current node to be coded.

Secondly, the attribute prediction value of the current node to be encoded is obtained according to the following two different methods:

① The inter-frame prediction node of the current node is valid: that is, if the same-position node exists, the attribute of the predicted node is directly used as the attribute prediction value of the current node to be encoded;

② The inter-frame prediction node of the current node is invalid: that is, the co-located node does not exist, and the attribute prediction value of the adjacent node in the frame is used as the node to be encoded. The predicted value of the attribute of the code node.

Finally, the attribute prediction value is used to predict the attribute of the current node to be encoded, thereby completing the predictive coding of the entire attribute.

In another specific implementation, the hierarchical structure of the RAHT inter-frame transform may include:

a. A point cloud can be a frame (or "an image"), and a frame (or "an image") can be divided into multiple slices.

b. For the point cloud to be decoded, it is decoded independently according to the slice.

c. A slice is a unit of RAHT transformation/inverse transformation, and a slice performs one RAHT transformation/inverse transformation.

d. A RAHT transform/inverse transform can include many transform layers.

e. Each transform layer may include multiple RAHT transform blocks. Both intra-frame prediction and inter-frame prediction are for transform blocks.

For example, Figure 10 illustrates a hierarchical structure of a point cloud attribute RAHT. As shown in Figure 10, a point cloud can be divided into multiple slices, such as slice 1 and slice 2. For each slice, taking slice 1 as an example, slice 1 can undergo a RAHT transform/inverse transform, for example, to obtain RAHT transform layer 1. RAHT transform layer 1 can include multiple RAHT transform blocks, such as RAHT transform block 1 and RAHT transform block 2.

In a specific implementation, Figure 11 is a schematic diagram of a framework for RAHT inter-frame prediction transform applied to the encoding end. As shown in Figure 11, the geometric information of the point cloud to be encoded is subjected to a point cloud geometric octree decomposition, and the attribute information of the point cloud to be encoded is subjected to a RAHT transform to determine the transform coefficients of the point cloud to be encoded. The transform coefficient prediction value of the point cloud to be encoded is determined based on RAHT inter-frame prediction or RAHT intra-frame prediction. The transform coefficient residual value is obtained by subtracting the transform coefficient of the point cloud to be encoded from the transform coefficient prediction value. The transform coefficient residual value is then quantized to obtain the quantized transform coefficient residual value. On the one hand, the quantized transform coefficient residual value can be encoded and written into the attribute code stream. On the other hand, the quantized transform coefficient residual value can be dequantized to obtain the reconstructed transform coefficient residual value. The reconstructed transform coefficient residual value is then added to the transform coefficient prediction value to obtain the reconstructed transform coefficient. The reconstructed transform coefficient is then subjected to a RAHT inverse transform to obtain the reconstructed point cloud attributes. In addition, during the RAHT inter-frame prediction process, the encoding end also involves octree decomposition of the geometric information of the reference point cloud and RAHT transformation of the attribute information of the reference point cloud.

In another specific implementation, Figure 12 is a schematic diagram of a framework for RAHT inter-frame prediction transformation applied to the decoding end. As shown in Figure 12, the geometric information of the point cloud to be decoded is subjected to a point cloud geometric octree decomposition, and the attribute code stream is parsed to obtain the quantized transform coefficient residual value. The quantized transform coefficient residual value is then dequantized to obtain the transform coefficient residual value of the point cloud to be decoded. The transform coefficient prediction value of the point cloud to be decoded is determined based on RAHT inter-frame prediction or RAHT intra-frame prediction. The transform coefficient of the point cloud to be decoded is then added to the transform coefficient prediction value. Finally, the transform coefficient is subjected to a RAHT inverse transform to reconstruct the point cloud attributes. In addition, during the RAHT inter-frame prediction process, the decoding end also involves the octree decomposition of the geometric information of the reference point cloud and the RAHT transform of the attribute information of the reference point cloud.

That is, when performing regional adaptive layered inter-frame prediction transform coding, the related technology needs to re-perform a RAHT transform operation on the reference point cloud at the encoding and decoding ends, which greatly increases the time complexity and brings high algorithmic complexity. In addition, as shown in Figure 13, when decoding the current point cloud, when the reference point cloud is used as a reference frame, the reference frame is regarded as a slice and only performs a single RAHT transform (i.e., only one RAHT transform layer) as a reference. The information of different RAHT transform layers of the reference image is not retained, which increases the complexity of RAHT attribute transform encoding and decoding and reduces the attribute coding efficiency.

Based on this, an embodiment of the present application provides an encoding method, which determines the prediction mode identification information of the current block; when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, the transform coefficient prediction value of the current block is determined based on the reference block of the current block; based on the transform coefficient prediction value of the current block, the transform coefficient residual value of the current block is determined; the transform coefficient residual value of the current block is encoded, and the obtained encoded bits are written into the code stream. An embodiment of the present application also provides a decoding method, which determines the prediction mode identification information of the current block; when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, the transform coefficient prediction value of the current block is determined based on the reference block of the current block; the code stream is decoded to determine the transform coefficient residual value of the current block; and the transform coefficient of the current block is determined based on the transform coefficient prediction value of the current block and the transform coefficient residual value of the current block.

In this way, whether at the encoding or decoding end, when the current block is subjected to inter-frame prediction in the transform domain, the transform coefficient prediction value of the current block can be determined based on the reference block of the current block. Among them, the reference block can be transformed based on the slices divided by the reference point cloud, rather than the entire frame of the reference point cloud, which reduces the time complexity; and the transform coefficients of the reference block can be stored in the memory module, so that when the transform coefficients of the reference block are needed, they can be directly obtained from the memory module, further reducing the time complexity, thereby improving the attribute encoding and decoding efficiency of the point cloud, and thus improving the encoding and decoding performance of the point cloud.

The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

In one embodiment of the present application, FIG14 is a flowchart diagram of a decoding method provided by the embodiment of the present application. As shown in FIG14 , the method may include:

S1401: Determine prediction mode identification information of the current block.

It should be noted that the decoding method of the embodiment of the present application is applied to the decoder, and the decoding method specifically refers to a transform domain prediction method of point cloud attributes. The transform domain prediction of the current block may include inter-frame prediction in the transform domain and Intra-frame prediction in the transform domain: When the current block is subjected to inter-frame prediction in the transform domain, the temporal complexity can be reduced.

It should also be noted that, in the embodiment of the present application, the current block may be a transformed block to be decoded in the current point cloud.

In an embodiment of the present application, mode indication information (or mode flags) in the form of some syntax elements can be written into the bitstream. In this way, by parsing the values of the syntax elements in the bitstream, the prediction mode identification information of the current block can be determined. For example, the first syntax element can be used to indicate the prediction mode identification information of the current block. In this way, by decoding the bitstream, the value of the first syntax element is determined; based on the value of the first syntax element, the prediction mode identification information of the current block can be determined.

In an embodiment of the present application, if the value of the first syntax element is a first value, it is determined that the current block performs inter-frame prediction in the transform domain; if the value of the first syntax element is a second value, it is determined that the current block performs intra-frame prediction in the transform domain. The first value and the second value are different. For example, the first value can be 1 and the second value can be 0; or the first value can be true and the second value can be false.

Considering the bit overhead in the bitstream, embodiments of the present application may also not write the first syntax element into the bitstream. In some embodiments, for the prediction mode identification information of the current block, the method may further include: if there is a reference block in the reference point cloud that satisfies a preset inter-frame condition with the current block, determining that the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain; if there is no reference block in the reference point cloud that satisfies the preset inter-frame condition with the current block, determining that the prediction mode identification information indicates that the current block performs intra-frame prediction in the transform domain.

That is to say, in the embodiment of the present application, the prediction mode identification information of the current block can be determined by the first syntax element in the code stream, or it can be determined based on whether the current block finds an inter-frame reference block in the reference point cloud as a judgment condition for the prediction mode identification information, or it can be other judgment conditions, which are not specifically limited here.

For example, when the prediction mode identification information is determined based on whether the current block finds an inter-frame reference block in the reference point cloud, if the current block can find a reference block that meets the preset inter-frame condition in the reference point cloud, then it can be determined that the current block performs inter-frame prediction in the transform domain; if the current block cannot find a reference block that meets the preset inter-frame condition in the reference point cloud, then it can be determined that the current block performs intra-frame prediction in the transform domain. Here, the reference point cloud is the reference frame of the current point cloud where the current block is located.

S1402 : When the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, determine a transform coefficient prediction value of the current block according to a reference block of the current block.

In the embodiment of the present application, if the current block performs inter-frame prediction in the transform domain, a reference block of the current block is first determined, and then a transform coefficient prediction value of the current block is determined based on the reference block of the current block.

In some embodiments, the method may include: determining a reference block of the current block based on the slice identification information in the reference point cloud.

It should be noted that, in the embodiment of the present application, the reference point cloud is divided into slices to obtain at least one slice of the reference point cloud, and the at least one slice includes the reference slice where the reference block is located.

It should also be noted that, in the embodiment of the present application, the slice ID (sliceID) here can be used to indicate a reference slice. Thus, the reference block of the current block can be determined from the reference slice indicated by the slice ID information.

That is to say, in the embodiment of the present application, for the reference block of the current block, the transformation operation is performed based on the slice divided by the reference point cloud, rather than the transformation operation based on the entire frame where the reference point cloud is located. As shown in Figure 15, the reference point cloud can be divided into at least two slices, such as slice1-ref1 and slice2-ref2. For slice1-ref1, a RAHT transformation layer ref-1 can be obtained, and the RAHT transformation layer ref-1 can include RAHT transformation block ref1-1, RAHT transformation block ref1-2, etc.; for slice2-ref2, a RAHT transformation layer ref-2 can be obtained, and the RAHT transformation layer ref-2 can include RAHT transformation block ref2-1, RAHT transformation block ref2-2, etc. In this way, by avoiding RAHT transformation of the entire frame where the reference point cloud is located, the time complexity can be reduced; and the slice-level transformation coefficients can be retained. Since the RAHT transform of the current point cloud is based on the inter-frame prediction at the slice level, the accuracy of the inter-frame prediction can be improved by using the slice-level transformation coefficients as a reference; at the same time, certain slices of the reference point cloud can be adaptively selected for inter-frame prediction, and certain slices are not used for inter-frame prediction, thereby improving the flexibility of the prediction and saving memory.

In some embodiments, for determining the reference block of the current block, the method may further include: if the candidate reference block existing in the reference point cloud and the current block meet a preset inter-frame condition, determining the candidate reference block as the reference block of the current block.

In the embodiment of the present application, if an inter-frame reference block can be found in the reference point cloud for the current block, that is, a candidate reference block that satisfies a preset inter-frame condition with the current block, then the current block is subjected to transform-domain inter-frame prediction, and the found candidate reference block is used as the reference block for the current block. Whether the found candidate reference block satisfies the preset inter-frame condition with the current block can be determined through the following possible implementations.

In one possible implementation, the candidate reference block existing in the reference point cloud and the current block meet the preset inter-frame conditions, which may include: the coordinate information of the candidate reference block is the same as the coordinate information of the current block, and the slice identification information where the candidate reference block is located is the same as the slice identification information where the current block is located, and the transformation layer information where the candidate reference block is located is the same as the current layer information where the current block is located.

In another possible implementation, the candidate reference block existing in the reference point cloud and the current block meet the preset inter-frame conditions, which may include: the coordinate information of the parent transform block of the candidate reference block is the same as the coordinate information of the parent transform block of the current block, and the slice identification information where the candidate reference block is located is the same as the slice identification information where the current block is located, and the transform layer information where the candidate reference block is located is the same as the current layer information where the current block is located.

In the embodiment of the present application, the coordinate information may include geometric position (x, y, z) information and Morton code information. In addition, in the embodiment of the present application, the absolute coordinates of the candidate reference block can be determined based on the coordinate information of the candidate reference block and the slice identification information where the candidate reference block is located. Information, and the absolute coordinate information of the parent transform block of the candidate reference block can be determined according to the coordinate information of the parent transform block of the candidate reference block and the slice identification information where the candidate reference block is located.

In another possible implementation, the candidate reference block in the reference point cloud and the current block meet a preset inter-frame condition, which may include: the absolute coordinate information of the candidate reference block is the same as the absolute coordinate information of the current block and the transformation layer information of the candidate reference block is the same as the current layer information of the current block.

In another possible implementation, the candidate reference block in the reference point cloud and the current block meet a preset inter-frame condition, which may include: the absolute coordinate information of the parent transform block of the candidate reference block is the same as the absolute coordinate information of the parent transform block of the current block and the transform layer information where the candidate reference block is located is the same as the current layer information where the current block is located.

In an embodiment of the present application, the absolute coordinate information of the candidate reference block may be determined based on the coordinate information of the candidate reference block and the slice identification information (sliceID) where the candidate reference block is located.

In some embodiments, for the absolute coordinate information of the candidate reference block, the method may include: determining the coordinate information of the candidate reference block; and determining the absolute coordinate information of the candidate reference block based on the coordinate information of the candidate reference block and coordinate offset information of the slice identification information where the candidate reference block is located relative to the origin. Specifically, the absolute coordinate information of the candidate reference block may be obtained by adding the coordinate information of the candidate reference block to the coordinate offset information of the slice identification information where the candidate reference block is located relative to the origin.

It should also be noted that for the candidate reference block and the current block to meet the preset inter-frame conditions, the preset inter-frame conditions here can be the several possible implementation methods mentioned above, or other conditions that can be used to find inter-frame reference blocks. No limitation is made here.

In this way, for the reference block found in the reference point cloud, it may specifically include: the coordinate information of the reference block is the same as the coordinate information of the current block, and the slice identification information of the reference block is the same as the slice identification information of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block; or, the coordinate information of the parent transformation block of the reference block is the same as the coordinate information of the parent transformation block of the current block, and the slice identification information of the reference block is the same as the slice identification information of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block; or, the absolute coordinate information of the reference block is the same as the absolute coordinate information of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block; or, the absolute coordinate information of the parent transformation block of the reference block is the same as the absolute coordinate information of the parent transformation block of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block, etc., without any limitation here.

It should also be noted that, in the embodiment of the present application, for the absolute coordinate information of the reference block, the coordinate information of the reference block can be determined, and then jointly determined based on the coordinate information of the reference block and the coordinate offset information of the slice identification information where the reference block is located relative to the origin; for the absolute coordinate information of the parent transformation block of the reference block, the coordinate information of the parent transformation block of the reference block can be determined, and then jointly determined based on the coordinate information of the parent transformation block of the reference block and the coordinate offset information of the slice identification information where the reference block is located relative to the origin.

It can be understood that after determining the reference block of the current block, determining the transformation coefficient prediction value of the current block according to the reference block of the current block may specifically include: determining the transformation coefficient prediction value of the current block according to the transformation coefficient of the reference block.

In a specific embodiment, when the current block performs inter-frame prediction in the transform domain, referring to FIG16 , the method may include:

S1601 : Determine attribute information of a reference slice based on the reference slice indicated by the slice identification information.

S1602: Perform region-adaptive hierarchical transformation on attribute information of a reference slice to determine transformation coefficients of at least one transformation layer.

S1603 : Determine a transform coefficient of a reference block from transform coefficients of at least one transform layer.

S1604: Determine a predicted value of the transform coefficient of the current block according to the transform coefficient of the reference block.

In an embodiment of the present application, in order to reduce time complexity, when determining the transform coefficients of the reference block, the RAHT transform can be performed on the slices (i.e., reference slices) divided based on the reference point cloud, rather than on the entire frame of the reference point cloud. In this way, the transform coefficients at the slice level can be retained. Since the RAHT transform of the current point cloud is based on the inter-frame prediction performed at the slice level, the transform coefficient prediction value of the current block can be obtained more accurately by using the transform coefficients at the slice level as a reference, thereby improving the accuracy of the inter-frame prediction. At the same time, certain slices of the reference point cloud can be adaptively selected for inter-frame prediction, while certain slices are not used for inter-frame prediction, thereby improving the flexibility of the prediction and saving memory.

That is, in the embodiment of the present application, the transform coefficients of the reference block can be determined by performing a RAHT transform on the slices (i.e., reference slices) divided by the reference point cloud. Specifically, by performing a RAHT transform on the attribute information of the reference slice, the transform coefficients of at least one transform layer can be determined. Each transform layer can include at least one transform block, from which the transform coefficients of the reference block are obtained; and then the transform coefficients of the reference block are used as the transform coefficient prediction values of the current block.

In another specific embodiment, for the transform coefficients of the reference block, the method may include: decoding the code stream to determine the transform coefficient residual value of the reference block; and determining the transform coefficient of the reference block based on the transform coefficient prediction value of the reference block and the transform coefficient residual value of the reference block.

In an embodiment of the present application, when the transform coefficients of the reference block need to be predicted, the code stream can be decoded to determine the quantization coefficient residual values of the reference block; the quantization coefficient residual values of the reference block are inversely quantized to determine the transform coefficient residual values of the reference block; and then the transform coefficients of the reference block are determined based on the transform coefficient prediction values of the reference block and the transform coefficient residual values of the reference block.

In yet another specific embodiment, for the transform coefficients of the reference block, the method may include: decoding a code stream to determine the transform coefficients of the reference block.

In the embodiment of the present application, when the transform coefficients of the reference block do not need to be predicted, the reference block can be determined by decoding the code stream. The quantization coefficients of the reference block are inversely quantized to determine the transformation coefficients of the reference block.

It should be noted that after obtaining the transform coefficients of the reference block, they can be stored in a memory module. In a specific embodiment, the method may further include: determining storage information of the reference block; and storing the storage information of the reference block in the memory module. The storage information of the reference block may include at least one of the following: the transform coefficients of the reference block, the coordinate information of the reference block, the slice identification information where the reference block is located, and the transform layer information where the reference block is located.

It should also be noted that after the storage information of the reference block is saved in the memory module, in some embodiments, when performing inter-frame prediction in the transform domain on the current block, referring to FIG. 17 , the method may include:

S1701, determining the transformation coefficient of the reference block according to the storage information corresponding to the reference block in the memory module.

S1702: Determine a predicted value of the transform coefficient of the current block according to the transform coefficient of the reference block.

It should be noted that, in an embodiment of the present application, the storage information corresponding to the reference block can be pre-stored in the memory module. As shown in Figure 15, based on the multiple slices divided by the reference point cloud, the memory module can retain information on multiple RAHT transformation layers of the reference point cloud. In this way, after determining the reference block of the current block, the transformation coefficients of the reference block can be quickly obtained from the memory module according to the sliceID where the reference block is located, and then the transformation coefficients of the reference block are used as the transformation coefficient prediction values of the current block, thereby further reducing the time complexity and making the inter-frame prediction more accurate.

In some embodiments, the storage information corresponding to the reference block in the memory module may include at least one of the following: the transformation coefficient of the reference block, the coordinate information of the reference block, the slice identification information where the reference block is located, the transformation layer information where the reference block is located, and the absolute coordinate information of the reference block.

It should also be noted that, in embodiments of the present application, the absolute coordinate information of the reference block can be determined based on the coordinate information of the reference block and the slice ID information where the reference block is located. In some embodiments, for the absolute coordinate information of the reference block, the method may include: determining the coordinate information of the reference block; and determining the absolute coordinate information of the reference block based on the coordinate information of the reference block and the coordinate offset information of the slice ID where the reference block is located relative to the origin. Specifically, the absolute coordinate information of the reference block can be obtained by adding the coordinate information of the reference block to the coordinate offset information of the slice ID where the reference block is located relative to the origin.

It should also be noted that, in the embodiment of the present application, the coordinate information may include geometric position (x, y, z) information and Morton code information. Taking the reference block as an example, the coordinate information of the reference block refers to the position information of the reference block when the RAHT transform is performed, and the absolute coordinate information of the reference block refers to the absolute position information of the reference block in the reference frame.

In this way, if the current block performs inter-frame prediction in the transform domain, after finding a reference block that meets the preset inter-frame condition in the reference frame, the transform coefficient prediction value of the current block can be determined based on the transform coefficient of the reference block.

In some embodiments, when the prediction mode identification information indicates that the current block performs transform domain intra prediction, after step S1401, referring to FIG18 , the method may further include:

S1801, when the prediction mode identification information indicates that the current block performs intra-frame prediction in the transform domain, determine the transform coefficient prediction values of the neighboring blocks of the current block, the transform coefficient prediction values of the parent transform block of the current block, and the transform coefficient prediction values of the neighboring blocks of the parent transform block.

S1802 , performing a weighted operation on the transform coefficient prediction values of the neighboring blocks of the current block, the transform coefficient prediction value of the parent transform block of the current block, and the transform coefficient prediction values of the neighboring blocks of the parent transform block to determine the transform coefficient prediction value of the current block.

That is, if no candidate reference block that meets the preset inter-frame condition can be found in the reference point cloud, the current block is determined to be intra-predicted in the transform domain, and the resulting intra-prediction value can be used as the transform coefficient prediction value of the current block. The intra-prediction value can be obtained by weighted calculation of the transform coefficient prediction values of the neighboring blocks of the current block, the parent transform block of the current block, and the neighboring blocks of the parent transform block.

It should also be noted that in the embodiments of the present application, transform coefficients may include low-frequency coefficients and high-frequency coefficients. The low-frequency coefficients may also be referred to as direct current coefficients or DC coefficients, and the high-frequency coefficients may also be referred to as alternating current coefficients or AC coefficients. It should be noted that the transform coefficient prediction values herein primarily refer to the high-frequency coefficient prediction values of the current block.

S1403: Decode the code stream to determine the transform coefficient residual value of the current block.

S1404 , determining the transform coefficient of the current block according to the transform coefficient prediction value of the current block and the transform coefficient residual value of the current block.

In the embodiment of the present application, steps S1401-S1402 and step S1403 are not executed in any particular order. For example, steps S1401-S1402 may be executed first, followed by step S1403; or, step S1403 may be executed first, followed by steps S1401-S1402; or, both steps may be executed simultaneously, without limitation.

In an embodiment of the present application, decoding the code stream and determining the transform coefficient residual value of the current block may include: decoding the code stream and determining the quantization coefficient residual value of the current block; and dequantizing the quantization coefficient residual value to determine the transform coefficient residual value of the current block.

In an embodiment of the present application, the transform coefficient of the current block is obtained by performing an addition operation on the transform coefficient prediction value of the current block and the transform coefficient residual value of the current block.

It can be understood that in the embodiment of the present application, the method further includes: determining the storage information of the current block; and saving the storage information of the current block into the memory module.

Furthermore, in some embodiments, the method further includes: when the current point cloud where the current block is located meets the conditions for being used as a reference point cloud, saving the storage information of the current block to the memory module. That is, in the embodiment of the present application, if the frame where the current point cloud is located may be used as a reference frame for subsequent frames, then the storage information of the current block can be saved to the memory module; thereby, in the subsequent inter-frame conversion in the transform domain, During prediction, the relevant information of the required reference blocks can be obtained from the memory module.

It can also be understood that in an embodiment of the present application, the storage information of the current block may include at least one of the following: the transformation coefficient of the current block, the coordinate information of the current block, the slice identification information where the current block is located, the current layer information where the current block is located, and the absolute coordinate information of the current block.

In some embodiments, for the absolute coordinate information of the current block, the method may include: determining the coordinate information of the current block; determining the absolute coordinate information of the current block based on the coordinate information of the current block and the coordinate offset information of the slice identification information where the current block is located relative to the origin.

That is to say, in an embodiment of the present application, the absolute coordinate information of the current block can be obtained by performing an addition operation based on the coordinate information of the current block and the coordinate offset information of the slice identification information where the current block is located relative to the origin. In this way, when searching for a reference block, the reference block of the current block can be determined based on the fact that the absolute coordinate information of the candidate reference block is the same as the absolute coordinate information of the current block and the transformation layer information where the candidate reference block is located is the same as the current layer information where the current block is located, or the reference block of the current block can be determined based on the fact that the absolute coordinate information of the parent transformation block of the candidate reference block is the same as the absolute coordinate information of the parent transformation block of the current block and the transformation layer information where the candidate reference block is located is the same as the current layer information where the current block is located, and so on. No limitation is made here.

In a specific embodiment, decoding a bitstream and determining a transform coefficient residual value of a current block may include: decoding the bitstream and determining a high-frequency coefficient residual value of the current block. Accordingly, determining the transform coefficient of the current block based on a transform coefficient prediction value of the current block and a transform coefficient residual value of the current block may include: determining the high-frequency coefficient value of the current block based on the high-frequency coefficient prediction value of the current block and the high-frequency coefficient residual value of the current block. Specifically, the high-frequency coefficient value of the current block may be determined by adding the high-frequency coefficient prediction value of the current block and the high-frequency coefficient residual value of the current block.

In some embodiments, the method may further include: determining geometric information of the current slice; performing octree decomposition on the geometric information of the current slice to determine at least one transformation layer; wherein the at least one transformation layer includes the current layer where the current block is located.

In the embodiment of the present application, the slice identification information (sliceID) of the current block can be used to indicate the current slice. The current slice is determined by the slice division of the current point cloud. For the current slice, the geometric information of the current slice is decomposed into an octree and transformed based on the hierarchical structure of the octree. Specifically, the RAHT inverse transformation is performed from top to bottom on the root node of the octree, and the RAHT inverse transformation is performed on the nodes in each layer from the three dimensions of x, y, and z until the inverse transformation reaches the leaf node of the octree.

In some embodiments, the method further includes: when the current layer is the L-1th layer in at least one transformation layer, performing a region-adaptive hierarchical inverse transformation on the transformation coefficients of the current block in the L-1th layer to determine the reconstruction attribute information of the nodes in the Lth layer; wherein L is a positive integer.

In some embodiments, the method further includes decoding the bitstream to determine the low-frequency coefficient value of the root node. In other words, the low-frequency coefficient value of the root node and the residual value of the high-frequency coefficient of each layer are written into the bitstream so that the decoding end can perform region-adaptive layered inverse transform.

In an embodiment of the present application, a regional adaptive hierarchical inverse transform is performed on the transform coefficients of the current block in the L-1 layer to determine the reconstruction attribute information of the nodes in the L layer. Specifically, it may include: when the current layer is the first transform layer, performing a regional adaptive hierarchical inverse transform based on the low-frequency coefficient value of the root node and the high-frequency coefficient value of the current block in the first layer to determine the reconstruction attribute information of the nodes in the second transform layer; when the current layer is not the first transform layer, determining the DC coefficient value of the current block in the current layer, performing a regional adaptive hierarchical inverse transform based on the DC coefficient value of the current block in the current layer and the AC coefficient value of the current block in the current layer to determine the reconstruction attribute information of the nodes in the next layer.

That is to say, in an embodiment of the present application, the attribute information of the current slice can be subjected to RAHT inverse transformation in a top-down manner along the octree decomposition, and the nodes in each layer are subjected to RAHT inverse transformation from the three dimensions of x, y, and z respectively, until the leaf nodes of the octree are transformed. In the process of hierarchical transformation, the DC coefficient and AC coefficient of the node in the same layer (L-1 layer) are subjected to RAHT inverse transformation to obtain the DC coefficient of the next layer (L layer), that is, the attribute information of each layer is obtained. Among them, the transformation matrix will be updated as the weights corresponding to each point change adaptively. The above process will be continuously iterated and updated according to the division structure of the octree until the leaf nodes of the octree.

For example, assuming that g′ _L-1,2x,y,z is the attribute DC coefficient in the L-1 layer, and f′ _L-1,2x,y,z is the attribute AC coefficient in the L-1 layer, then for the attribute DC coefficient in the L-1 layer, the calculation formula for the RAHT inverse transform is:

Based on the inverse RAHT transform, the reconstruction attribute information of the current slice can be determined.

The embodiment of the present application provides a decoding method, specifically a decoding scheme for fast inter-frame attribute transformation of point clouds. Determine the prediction mode identification information of the current block; when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, determine the transform coefficient prediction value of the current block based on the reference block of the current block; decode the code stream to determine the transform coefficient residual value of the current block; determine the transform coefficient of the current block based on the transform coefficient prediction value of the current block and the transform coefficient residual value of the current block. That is, when the current block performs inter-frame prediction in the transform domain, the transform coefficient prediction value of the current block can be determined based on the reference block of the current block. Among them, the reference block can be transformed based on the slices divided by the reference point cloud, rather than based on the entire frame of the reference point cloud, which reduces the time complexity; and the transform coefficient of the reference block can be stored in the memory module, so that when the transform coefficient of the reference block is needed, it can be directly obtained from the memory module, further reducing the time complexity, thereby improving the attribute encoding and decoding efficiency of the point cloud, and thus improving the encoding and decoding performance of the point cloud.

In one embodiment of the present application, FIG19 is a flow chart of an encoding method provided by the embodiment of the present application. As shown in FIG19 , the method may include:

S1901, determine prediction mode identification information of the current block.

It should be noted that the encoding method in the embodiments of the present application is applied to an encoder and specifically refers to a transform domain prediction method for point cloud attributes. The transform domain prediction of the current block may include inter-frame prediction and intra-frame prediction in the transform domain. When the transform domain inter-frame prediction is performed on the current block, time complexity can be reduced.

It should also be noted that, in the embodiment of the present application, the current block may be a transformed block to be encoded in the current point cloud.

In an embodiment of the present application, mode indication information (or mode flags) in the form of some syntax elements can be written into the bitstream. Thus, by parsing the values of the syntax elements in the bitstream, the prediction mode identification information for the current block can be determined. For example, the first syntax element can be used to indicate the prediction mode identification information for the current block. Thus, the value of the first syntax element is determined; the value of the first syntax element is encoded, and the resulting encoded bits are written into the bitstream.

In an embodiment of the present application, if the current block performs inter-frame prediction in the transform domain, the value of the first syntax element is determined to be a first value; if the current block performs intra-frame prediction in the transform domain, the value of the first syntax element is determined to be a second value. The first value and the second value are different. For example, the first value can be 1 and the second value can be 0; or the first value can be true and the second value can be false.

Considering the bit overhead in the bitstream, embodiments of the present application may also not write the first syntax element into the bitstream. In some embodiments, for the prediction mode identification information of the current block, the method may further include: if there is a reference block in the reference point cloud that satisfies a preset inter-frame condition with the current block, determining that the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain; if there is no reference block in the reference point cloud that satisfies the preset inter-frame condition with the current block, determining that the prediction mode identification information indicates that the current block performs intra-frame prediction in the transform domain.

That is to say, in the embodiment of the present application, the prediction mode identification information of the current block can be determined by the first syntax element in the code stream, or it can be determined based on whether the current block finds an inter-frame reference block in the reference point cloud as a judgment condition for the prediction mode identification information, or it can be other judgment conditions, which are not specifically limited here.

For example, when the prediction mode identification information is determined based on whether the current block finds an inter-frame reference block in the reference point cloud, if the current block can find a reference block that meets the preset inter-frame condition in the reference point cloud, then it can be determined that the current block performs inter-frame prediction in the transform domain; if the current block cannot find a reference block that meets the preset inter-frame condition in the reference point cloud, then it can be determined that the current block performs intra-frame prediction in the transform domain. Here, the reference point cloud is the reference frame of the current point cloud where the current block is located.

S1902 : When the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, determine a transform coefficient prediction value of the current block according to a reference block of the current block.

In the embodiment of the present application, if the current block performs inter-frame prediction in the transform domain, a reference block of the current block is first determined, and then a transform coefficient prediction value of the current block is determined based on the reference block of the current block.

In some embodiments, the method may include: determining a reference block of the current block based on the slice identification information in the reference point cloud.

It should be noted that, in the embodiment of the present application, the reference point cloud is divided into slices to obtain at least one slice of the reference point cloud, and the at least one slice includes the reference slice where the reference block is located.

It should also be noted that, in the embodiment of the present application, the slice ID (sliceID) here can be used to indicate a reference slice. Thus, the reference block of the current block can be determined from the reference slice indicated by the slice ID information.

That is to say, in the embodiment of the present application, for the reference block of the current block, the transformation operation is performed based on the slice divided by the reference point cloud, rather than the transformation operation based on the entire frame where the reference point cloud is located. As shown in Figure 15, the reference point cloud can be divided into at least two slices, such as slice1-ref1 and slice2-ref2. For slice1-ref1, a RAHT transformation layer ref-1 can be obtained, and the RAHT transformation layer ref-1 can include RAHT transformation block ref1-1, RAHT transformation block ref1-2, etc.; for slice2-ref2, a RAHT transformation layer ref-2 can be obtained, and the RAHT transformation layer ref-2 can include RAHT transformation block ref2-1, RAHT transformation block ref2-2, etc. In this way, by avoiding RAHT transformation of the entire frame where the reference point cloud is located, the time complexity can be reduced; and the slice-level transformation coefficients can be retained. Since the RAHT transform of the current point cloud is based on the inter-frame prediction at the slice level, the accuracy of the inter-frame prediction can be improved by using the slice-level transformation coefficients as a reference; at the same time, certain slices of the reference point cloud can be adaptively selected for inter-frame prediction, and certain slices are not used for inter-frame prediction, thereby improving the flexibility of the prediction and saving memory.

In some embodiments, for determining the reference block of the current block, the method may further include: if the candidate reference block existing in the reference point cloud and the current block meet a preset inter-frame condition, determining the candidate reference block as the reference block of the current block.

In the embodiment of the present application, if an inter-frame reference block can be found in the reference point cloud for the current block, that is, a candidate reference block that satisfies a preset inter-frame condition with the current block, then the current block is subjected to transform-domain inter-frame prediction, and the found candidate reference block is used as the reference block for the current block. Whether the found candidate reference block satisfies the preset inter-frame condition with the current block can be determined through the following possible implementations.

In a possible implementation, the candidate reference block in the reference point cloud and the current block meet the preset inter-frame condition, which may include: the coordinate information of the candidate reference block is the same as the coordinate information of the current block and the slice identification information of the candidate reference block is the same as the slice identification information of the current block. The identification information is the same and the transform layer information of the candidate reference block is the same as the current layer information of the current block.

In another possible implementation, the candidate reference block existing in the reference point cloud and the current block meet the preset inter-frame conditions, which may include: the coordinate information of the parent transform block of the candidate reference block is the same as the coordinate information of the parent transform block of the current block, and the slice identification information where the candidate reference block is located is the same as the slice identification information where the current block is located, and the transform layer information where the candidate reference block is located is the same as the current layer information where the current block is located.

In the embodiment of the present application, the coordinate information may include geometric position (x, y, z) information and Morton code information, etc. In addition, in the embodiment of the present application, the absolute coordinate information of the candidate reference block can be determined based on the coordinate information of the candidate reference block and the slice identification information where the candidate reference block is located, and the absolute coordinate information of the parent transform block of the candidate reference block can be determined based on the coordinate information of the parent transform block of the candidate reference block and the slice identification information where the candidate reference block is located.

In another possible implementation, the candidate reference block in the reference point cloud and the current block meet a preset inter-frame condition, which may include: the absolute coordinate information of the candidate reference block is the same as the absolute coordinate information of the current block and the transformation layer information of the candidate reference block is the same as the current layer information of the current block.

In another possible implementation, the candidate reference block in the reference point cloud and the current block meet a preset inter-frame condition, which may include: the absolute coordinate information of the parent transform block of the candidate reference block is the same as the absolute coordinate information of the parent transform block of the current block and the transform layer information where the candidate reference block is located is the same as the current layer information where the current block is located.

In an embodiment of the present application, the absolute coordinate information of the candidate reference block may be determined based on the coordinate information of the candidate reference block and the slice identification information (sliceID) where the candidate reference block is located.

In some embodiments, for the absolute coordinate information of the candidate reference block, the method may include: determining the coordinate information of the candidate reference block; and determining the absolute coordinate information of the candidate reference block based on the coordinate information of the candidate reference block and coordinate offset information of the slice identification information where the candidate reference block is located relative to the origin. Specifically, the absolute coordinate information of the candidate reference block may be obtained by adding the coordinate information of the candidate reference block to the coordinate offset information of the slice identification information where the candidate reference block is located relative to the origin.

It should also be noted that for the candidate reference block and the current block to meet the preset inter-frame conditions, the preset inter-frame conditions here can be the several possible implementation methods mentioned above, or other conditions that can be used to find inter-frame reference blocks. No limitation is made here.

In this way, for the reference block found in the reference point cloud, it may specifically include: the coordinate information of the reference block is the same as the coordinate information of the current block, and the slice identification information of the reference block is the same as the slice identification information of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block; or, the coordinate information of the parent transformation block of the reference block is the same as the coordinate information of the parent transformation block of the current block, and the slice identification information of the reference block is the same as the slice identification information of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block; or, the absolute coordinate information of the reference block is the same as the absolute coordinate information of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block; or, the absolute coordinate information of the parent transformation block of the reference block is the same as the absolute coordinate information of the parent transformation block of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block, etc., without any limitation here.

It should also be noted that, in the embodiment of the present application, for the absolute coordinate information of the reference block, the coordinate information of the reference block can be determined, and then jointly determined based on the coordinate information of the reference block and the coordinate offset information of the slice identification information where the reference block is located relative to the origin; for the absolute coordinate information of the parent transformation block of the reference block, the coordinate information of the parent transformation block of the reference block can be determined, and then jointly determined based on the coordinate information of the parent transformation block of the reference block and the coordinate offset information of the slice identification information where the reference block is located relative to the origin.

It can be understood that after determining the reference block of the current block, determining the transformation coefficient prediction value of the current block according to the reference block of the current block may specifically include: determining the transformation coefficient prediction value of the current block according to the transformation coefficient of the reference block.

In a specific embodiment, when inter-frame prediction in the transform domain is performed on the current block, the method may include: determining attribute information of the reference slice based on the reference slice indicated by the slice identification information; performing a region-adaptive hierarchical transform on the attribute information of the reference slice to determine the transform coefficients of at least one transform layer; determining the transform coefficients of the reference block from the transform coefficients of at least one transform layer; and determining a predicted value of the transform coefficient of the current block based on the transform coefficients of the reference block.

In an embodiment of the present application, in order to reduce time complexity, when determining the transform coefficients of the reference block, the RAHT transform can be performed on the slices (i.e., reference slices) divided based on the reference point cloud, rather than on the entire frame of the reference point cloud. In this way, the transform coefficients at the slice level can be retained. Since the RAHT transform of the current point cloud is based on the inter-frame prediction performed at the slice level, the transform coefficient prediction value of the current block can be obtained more accurately by using the transform coefficients at the slice level as a reference, thereby improving the accuracy of the inter-frame prediction. At the same time, certain slices of the reference point cloud can be adaptively selected for inter-frame prediction, while certain slices are not used for inter-frame prediction, thereby improving the flexibility of the prediction and saving memory.

That is, in the embodiment of the present application, the transform coefficients of the reference block can be determined by performing a RAHT transform on the slices (i.e., reference slices) divided by the reference point cloud. Specifically, by performing a RAHT transform on the attribute information of the reference slice, the transform coefficients of at least one transform layer can be determined. Each transform layer can include at least one transform block, from which the transform coefficients of the reference block are obtained; and then the transform coefficients of the reference block are used as the transform coefficient prediction values of the current block.

In another specific embodiment, for the transform coefficients of the reference block, the method may include: determining the transform coefficient residual value of the reference block; quantizing the transform coefficient residual value of the reference block to determine the quantized coefficient residual value of the reference block; inverse quantizing the quantized coefficient residual value of the reference block to determine the reconstructed transform coefficient residual value of the reference block; and performing a transform coefficient prediction on the reference block and the reconstructed transform coefficient residual value of the reference block according to the transform coefficient prediction value of the reference block and the reconstructed transform coefficient residual value of the reference block. The coefficient residual value is used to determine the transformation coefficient of the reference block.

In an embodiment of the present application, when the transform coefficients of a reference block need to be predicted, the transform coefficient residual values of the reference block can be determined, and then the transform coefficient residual values of the reference block are quantized and dequantized to determine the reconstructed transform coefficient residual values of the reference block; based on the transform coefficient prediction values of the reference block and the reconstructed transform coefficient residual values of the reference block, the transform coefficients of the reference block can be determined.

In an embodiment of the present application, after quantizing the transform coefficient residual value of the reference block and determining the quantized coefficient residual value of the reference block, the method may further include: encoding the quantized coefficient residual value of the reference block and writing the obtained coded bits into the bitstream.

In another specific embodiment, when the transform coefficients of the reference block do not need to be predicted, the transform coefficients of the reference block can be directly written into the bitstream. Specifically, the transform coefficients of the reference block can be quantized to determine the quantized coefficients of the reference block; then, the quantized coefficients of the reference block can be encoded, and the resulting coded bits can be written into the bitstream.

It should be noted that after obtaining the transform coefficients of the reference block, they can be stored in a memory module. In a specific embodiment, the method may further include: determining storage information of the reference block; and storing the storage information of the reference block in the memory module. The storage information of the reference block may include at least one of the following: the transform coefficients of the reference block, the coordinate information of the reference block, the slice identification information where the reference block is located, and the transform layer information where the reference block is located.

It should also be noted that after the storage information of the reference block is saved to the memory module, in some embodiments, when the current block is subjected to inter-frame prediction in the transform domain, the method may include: determining the transform coefficient of the reference block based on the corresponding storage information of the reference block in the memory module; and determining the predicted value of the transform coefficient of the current block based on the transform coefficient of the reference block.

It should be noted that, in an embodiment of the present application, the storage information corresponding to the reference block can be pre-stored in the memory module. As shown in Figure 15, based on the multiple slices divided by the reference point cloud, the memory module can retain information on multiple RAHT transformation layers of the reference point cloud. In this way, after determining the reference block of the current block, the transformation coefficients of the reference block can be quickly obtained from the memory module according to the sliceID where the reference block is located, and then the transformation coefficients of the reference block are used as the transformation coefficient prediction values of the current block, thereby further reducing the time complexity and making the inter-frame prediction more accurate.

In some embodiments, the storage information corresponding to the reference block in the memory module may include at least one of the following: the transformation coefficient of the reference block, the coordinate information of the reference block, the slice identification information where the reference block is located, the transformation layer information where the reference block is located, and the absolute coordinate information of the reference block.

It should also be noted that, in embodiments of the present application, the absolute coordinate information of the reference block can be determined based on the coordinate information of the reference block and the slice ID information where the reference block is located. In some embodiments, for the absolute coordinate information of the reference block, the method may include: determining the coordinate information of the reference block; and determining the absolute coordinate information of the reference block based on the coordinate information of the reference block and the coordinate offset information of the slice ID where the reference block is located relative to the origin. Specifically, the absolute coordinate information of the reference block can be obtained by adding the coordinate information of the reference block to the coordinate offset information of the slice ID where the reference block is located relative to the origin.

It should also be noted that, in the embodiment of the present application, the coordinate information may include geometric position (x, y, z) information and Morton code information. Taking the reference block as an example, the coordinate information of the reference block refers to the position information of the reference block when the RAHT transform is performed, and the absolute coordinate information of the reference block refers to the absolute position information of the reference block in the reference frame.

In this way, if the current block performs inter-frame prediction in the transform domain, after finding a reference block that meets the preset inter-frame condition in the reference frame, the transform coefficient prediction value of the current block can be determined based on the transform coefficient of the reference block.

In some embodiments, when the prediction mode identification information indicates that the current block performs intra-frame prediction in the transform domain, the method may further include: determining the transform coefficient prediction values of the neighboring blocks of the current block, the transform coefficient prediction values of the parent transform block of the current block, and the transform coefficient prediction values of the neighboring blocks of the parent transform block; performing a weighted operation on the transform coefficient prediction values of the neighboring blocks of the current block, the transform coefficient prediction values of the parent transform block of the current block, and the transform coefficient prediction values of the neighboring blocks of the parent transform block to determine the transform coefficient prediction value of the current block.

That is, if no candidate reference block that meets the preset inter-frame condition can be found in the reference point cloud, the current block is determined to be intra-predicted in the transform domain, and the resulting intra-prediction value can be used as the transform coefficient prediction value of the current block. The intra-prediction value can be obtained by weighted calculation of the transform coefficient prediction values of the neighboring blocks of the current block, the parent transform block of the current block, and the neighboring blocks of the parent transform block.

It should also be noted that in the embodiments of the present application, transform coefficients may include low-frequency coefficients and high-frequency coefficients. The low-frequency coefficients may also be referred to as direct current coefficients or DC coefficients, and the high-frequency coefficients may also be referred to as alternating current coefficients or AC coefficients. It should be noted that the transform coefficient prediction values herein primarily refer to the high-frequency coefficient prediction values of the current block.

S1903 , determining a transform coefficient residual value of the current block according to the transform coefficient prediction value of the current block.

S1904: Encode the transform coefficient residual value of the current block, and write the obtained coded bits into the bitstream.

In an embodiment of the present application, encoding the transform coefficient residual values of the current block and writing the obtained coded bits into the bitstream may include: quantizing the transform coefficient residual values to determine the quantized coefficient residual values of the current block; encoding the quantized coefficient residual values of the current block and writing the obtained coded bits into the bitstream.

In some embodiments, the method may further include: performing inverse quantization on the quantized coefficient residual values of the current block to determine the reconstructed transform coefficient residual values of the current block; and determining the transform coefficients of the current block based on the transform coefficient prediction values of the current block and the reconstructed transform coefficient residual values of the current block. Specifically, the transform coefficients of the current block may be obtained by adding the transform coefficient prediction values of the current block and the reconstructed transform coefficient residual values of the current block.

It can be understood that in the embodiment of the present application, the method further includes: determining the storage information of the current block; and saving the storage information of the current block into the memory module.

Furthermore, in some embodiments, the method further includes: when the current point cloud containing the current block meets the conditions for being used as a reference point cloud, saving the storage information of the current block to a memory module. In other words, in embodiments of the present application, if the frame containing the current point cloud is likely to be used as a reference frame for subsequent frames, the storage information of the current block can be saved to the memory module; thereby, when performing subsequent transform domain inter-frame prediction, the required reference block related information can be obtained from the memory module.

It can also be understood that in an embodiment of the present application, the storage information of the current block may include at least one of the following: the transformation coefficient of the current block, the coordinate information of the current block, the slice identification information where the current block is located, the current layer information where the current block is located, and the absolute coordinate information of the current block.

In some embodiments, for the absolute coordinate information of the current block, the method may include: determining the coordinate information of the current block; determining the absolute coordinate information of the current block based on the coordinate information of the current block and the coordinate offset information of the slice identification information where the current block is located relative to the origin.

That is to say, in an embodiment of the present application, the absolute coordinate information of the current block can be obtained by performing an addition operation based on the coordinate information of the current block and the coordinate offset information of the slice identification information where the current block is located relative to the origin. In this way, when searching for a reference block, the reference block of the current block can be determined based on the fact that the absolute coordinate information of the candidate reference block is the same as the absolute coordinate information of the current block and the transformation layer information where the candidate reference block is located is the same as the current layer information where the current block is located, or the reference block of the current block can be determined based on the fact that the absolute coordinate information of the parent transformation block of the candidate reference block is the same as the absolute coordinate information of the parent transformation block of the current block and the transformation layer information where the candidate reference block is located is the same as the current layer information where the current block is located, and so on. No limitation is made here.

In some embodiments, the method may further include: determining geometric information of the current slice; performing octree decomposition on the geometric information of the current slice to determine at least one transformation layer; wherein the at least one transformation layer includes the current layer where the current block is located.

In the embodiment of the present application, the slice identification information (sliceID) of the current block can be used to indicate the current slice. The current slice is determined by the slice division of the current point cloud. For the current slice, the geometric information of the current slice is decomposed into an octree and transformed based on the hierarchical structure of the octree. Specifically, the RAHT inverse transformation is performed from top to bottom on the root node of the octree, and the RAHT inverse transformation is performed on the nodes in each layer from the three dimensions of x, y, and z until the inverse transformation reaches the leaf node of the octree.

In some embodiments, the method may further include: when the current layer is the L-1th layer in at least one transformation layer, determining the low-frequency coefficient values of the nodes in the Lth layer, and performing regional adaptive hierarchical transformation based on the low-frequency coefficient values of the nodes in the Lth layer, determining the low-frequency coefficient values and the original values of the high-frequency coefficients of the nodes in the L-1th layer, until the low-frequency coefficient values and the original values of the high-frequency coefficients of the root node of the current point cloud are determined; wherein L is a positive integer.

In an embodiment of the present application, determining the transform coefficient residual value of the current block based on the transform coefficient prediction value of the current block may include: determining the original high-frequency coefficient values of the current block in the current layer; and determining the high-frequency coefficient residual value of the current block based on the original high-frequency coefficient values of the current block and the high-frequency coefficient prediction value of the current block. Thus, in some embodiments, the method further includes: encoding the high-frequency coefficient residual value of the current block and writing the resulting coded bits into the bitstream.

In an embodiment of the present application, after obtaining the low-frequency coefficient value of the root node of the current point cloud, the method may further include: encoding the low-frequency coefficient value of the root node and writing the obtained encoding bits into the bitstream.

That is to say, in an embodiment of the present application, the low-frequency coefficient value of the root node and the high-frequency coefficient residual value of each layer can be written into the code stream, so that the RAHT inverse transform can be implemented at the decoding end to restore the reconstructed attribute information of the current point cloud.

It should also be noted that in the embodiment of the present application, for the obtained transformation layer, the DC coefficient obtained after the transformation of the nodes in the same layer (layer L) is transferred to the nodes in the next layer (layer L-1) for further transformation using the attribute information of the point cloud. The transformation matrix will be updated as the weights corresponding to each point change adaptively. The above process will be continuously iterated and updated according to the division structure of the octree until the root node of the octree. Among them, the DC coefficient of the root node and all AC coefficients are collectively referred to as transformation coefficients.

Specifically, assume that g′ _L,2x,y,z and g′ _L,2x+1,y,z are the attribute DC coefficients of two neighboring nodes in layer L. After linear transformation, the information in layer L-1 is the AC coefficient f′ _L-1,x,y,z and the DC coefficient g′ _L-1,x,y,z . Then, f′ _L-1,x,y,z is directly quantized and encoded without further transformation. g′ _L-1,x,y,z will continue to search for neighboring nodes for transformation. If no neighboring nodes are found, they will be directly passed to layer L-2. In other words, the RAHT transform is only effective for nodes with neighboring nodes; nodes without neighboring nodes are directly passed to the previous layer. In the above transformation process, the weights (the number of non-empty child nodes in the node) corresponding to g′ _L,2x,y,z and g′ _{L,2x+1,y ,z are w′ L,2x,y,z} and w′ _L,2x+1,y,z (abbreviated as w′ ₀ and w′ ₁ ) respectively, and the weight of g′ _L-1,x,y,z is w′ _L-1,x,y,z . Then the RAHT transformation formula is:

Based on the RAHT transform, the transform coefficients of the current block, specifically the original values of the transform coefficients, can be determined. Then, based on the original values of the transform coefficients of the current block and the predicted values of the transform coefficients of the current block, the transform coefficient residual values of the current block can be calculated.

The embodiment of the present application provides a coding method, specifically a coding scheme for fast inter-frame attribute transformation of point clouds. Prediction mode identification information; when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, the transform coefficient prediction value of the current block is determined based on the reference block of the current block; the transform coefficient residual value of the current block is determined based on the transform coefficient prediction value of the current block; the transform coefficient residual value of the current block is encoded, and the obtained coded bits are written into the bitstream. In other words, when the current block performs inter-frame prediction in the transform domain, the transform coefficient prediction value of the current block can be determined based on the reference block of the current block. The reference block can be transformed based on slices divided by the reference point cloud, rather than based on the entire frame of the reference point cloud, thereby reducing time complexity; and the transform coefficients of the reference block can be stored in a memory module, so that when the transform coefficients of the reference block are needed, they can be directly obtained from the memory module, further reducing time complexity, thereby improving the attribute encoding efficiency of the point cloud, and thus improving the encoding performance of the point cloud.

In another embodiment of the present application, based on the encoding and decoding methods described in the previous embodiments, this technical solution proposes caching the decoded geometric information and transform coefficients of possible reference point clouds in a memory module (buffer) for later use as reference frames. This reduces time complexity by avoiding the need to repeatedly perform octree decomposition and RAHT transformation on the reference frame, while also retaining information from multiple RAHT transform layers of the reference frame for inter-frame prediction.

In an embodiment of the present application, Figure 15 is a schematic diagram of the logical structure of an inter-frame prediction transformation provided by an embodiment of the present application. As shown in Figure 15, the reference point cloud can be divided into at least two slices, so that during RAHT transformation, the transformation can be performed based on the divided slices rather than the entire frame, reducing time complexity and retaining information from multiple RAHT transformation layers of the reference frame for inter-frame prediction.

In a specific embodiment, as shown in FIG20 , the process at the decoding end is as follows:

S201, parsing the code stream.

Input the attribute code stream and decode it to obtain the quantized transform coefficient residual value.

S202, point cloud geometry octree decomposition.

The geometric information of the decoded point cloud is decomposed into an octree and transformed based on the hierarchical structure of the octree. The nodes in each layer are inversely transformed from the x, y, and z dimensions until they are inversely transformed to the leaf nodes of the octree.

S203, dequantization.

The decoded quantized transform coefficient residual value is inversely quantized to obtain a transform coefficient residual value.

Depending on whether an inter-frame reference block can be found in the reference point cloud, it is determined whether to enter RAHT inter-frame prediction or RAHT intra-frame prediction; the transform coefficient can be obtained by adding the transform coefficient residual value to the transform coefficient prediction value.

S204, RAHT inter-frame prediction.

Calculate the absolute geometric position of the current block (i.e., the aforementioned "absolute coordinate information"): The position of the current block during transformation is a relative geometric position (i.e., the aforementioned "coordinate information"). The absolute geometric position of the current block in the current frame can be calculated. Specifically, the absolute geometric position of the current block is equal to the relative geometric position of the current transformed block plus the geometric position offset of the slice to which the current block belongs relative to the origin;

Find inter-frame reference blocks: For each transform block in the RAHT transform of the current frame, find the inter-frame prediction transform block of the current layer in the memory module. Taking the current block as an example, find a transform block in the reference frame whose absolute geometric position is the same as the absolute geometric position of the current block and the same layer number as the current block as the reference block, or find a transform block in the reference frame whose absolute geometric position is the same as the absolute geometric position of the parent transform block of the current block and the same layer number as the current block as the reference block, or find a transform block in the reference frame whose geometric position is the same as the geometric position of the current block, the same layer number as the current block and the same sliceID as the current block as the reference block, or find a transform block in the reference frame whose geometric position is the same as the geometric position of the parent transform block of the current block, the same layer number as the current block and the same sliceID as the current block as the reference block.

If an inter-frame reference block is found in the memory module, the transform coefficient corresponding to the inter-frame reference block in the memory module can be used as the transform coefficient prediction value of the current block.

S205, RAHT intra-frame prediction.

If no inter-frame reference block is found, the intra-frame prediction value is used as the transformation coefficient prediction value of the current block, wherein the intra-frame prediction value is obtained by weighted prediction of the neighboring blocks of the current block, the parent transformation block and the neighboring blocks of the parent transformation block.

S206, saving to the memory module.

If the currently decoded frame may be used as a reference frame for subsequent frames, at least one of the transform coefficient, absolute geometric position, geometric position, sliceID, and number of RAHT transform layers of the current block may be stored in the memory module as inter-frame prediction reference information for subsequent frames; otherwise, the RAHT inverse transform may be performed directly.

S207, inverse RAHT transform.

According to the obtained transformation coefficients, the attributes of the point cloud are inversely transformed along the octree decomposition from top to bottom, and the nodes in each layer are inversely transformed from the three dimensions of x, y, and z until they are transformed to the leaf nodes of the octree. In the process of hierarchical transformation, the DC coefficient and AC coefficient of the nodes in the same layer (L-1 layer) are inversely transformed to obtain the DC coefficient of the next layer (Lth layer). The transformation matrix will be updated as the weights corresponding to each point change adaptively. The above process will be iteratively updated according to the division structure of the octree until the leaf nodes of the octree. Assuming that g′ _L-1,2x,y,z is the DC coefficient of the attribute in the L-1 layer, and f′ _L-1,2x,y,z is the AC coefficient of the attribute in the L-1 layer, then RAHT The calculation formulas of the inverse transformation are shown in Equations (3) and (4). Finally, the point cloud attributes can be obtained.

That is to say, as shown in Figure 20, by performing point cloud geometric octree decomposition on the geometric information of the point cloud to be decoded and parsing the attribute code stream, the quantized transform coefficient residual value can be obtained, and then the quantized transform coefficient residual value is dequantized to obtain the transform coefficient residual value of the point cloud to be decoded; the transform coefficient prediction value of the point cloud to be decoded can be determined according to RAHT inter-frame prediction or RAHT intra-frame prediction; then, the transform coefficient of the point cloud to be decoded is obtained by performing an addition operation on the transform coefficient residual value and the transform coefficient prediction value; the transform coefficient is saved in the memory module, so that when performing inter-frame prediction later, the transform coefficient of the reference block can be directly obtained from the memory module; finally, the transform coefficient is subjected to RAHT inverse transformation to reconstruct the point cloud attributes.

In a specific embodiment, as shown in FIG21 , the process of the encoding end is as follows:

S211, point cloud geometry octree decomposition.

The geometric information of the point cloud to be encoded is input and the octree decomposition is performed to obtain the RAHT transformation layer. For each layer, the nodes are transformed in the x, y, and z dimensions until they reach the root node of the octree.

S212, RAHT transform.

For the obtained RAHT transformation layer, the DC coefficient obtained after the transformation of the nodes in the same layer (layer L) is passed to the nodes in the next layer (layer L-1) to continue the transformation. The transformation matrix will be updated as the weights corresponding to each point change adaptively. The above process will be continuously iterated and updated according to the partitioning structure of the octree until the root node of the octree. The DC coefficient of the root node and all AC coefficients are collectively referred to as the transformation coefficient;

The absolute geometric position of the current block relative to the origin can be calculated. This is equal to the relative geometric position of the current block plus the geometric position offset of the slice to which the current block belongs relative to the origin. Assume that g′ _L,2x,y,z and g′ _L,2x+1,y,z are the attribute DC coefficients of two neighboring nodes in layer L. After linear transformation, the information in layer L-1 is the AC coefficient f′ _L-1,x,y,z and the DC coefficient g′ _L-1,x,y,z . Then, f′ _L-1,x,y,z is no longer transformed and is directly quantized and encoded. g′ _L-1,x,y,z will continue to search for neighboring nodes for transformation. If no neighboring nodes are found, they are directly passed to layer L-2. In other words, the RAHT transform is only effective for nodes with neighboring nodes; nodes without neighboring nodes are directly passed to the previous layer. In the above transformation process, the weights (the number of non-empty child nodes within the node) corresponding to g′ _L,2x,y,z and g′ _{L,2x+1,y ,z are w′ L,2x,y,z} and w′ _L,2x+1,y,z (abbreviated as w′ ₀ and w′ ₁ ), respectively, and the weight of g′ _L-1,x,y,z is w′ _L-1,x,y,z . Therefore, the calculation formulas for the inverse RAHT transform are shown in Equations (5) and (6). Finally, the transform coefficients can be obtained.

Depending on whether an inter-frame reference block can be found in the reference point cloud, it is determined whether to enter RAHT inter-frame prediction or RAHT intra-frame prediction; the transform coefficient prediction value is subtracted from the transform coefficient to obtain the transform coefficient residual value.

S213, RAHT inter-frame prediction.

Calculate the absolute geometric position of the current block (i.e., the aforementioned "absolute coordinate information"): The position of the current block during transformation is a relative geometric position (i.e., the aforementioned "coordinate information"). The absolute geometric position of the current block in the current frame can be calculated. Specifically, the absolute geometric position of the current block is equal to the relative geometric position of the current transformed block plus the geometric position offset of the slice to which the current block belongs relative to the origin;

Find inter-frame reference blocks: For each transform block in the RAHT transform of the current frame, find the inter-frame prediction transform block of the current layer in the memory module. Taking the current block as an example, find a transform block in the reference frame whose absolute geometric position is the same as the absolute geometric position of the current block and the same layer number as the current block as the reference block, or find a transform block in the reference frame whose absolute geometric position is the same as the absolute geometric position of the parent transform block of the current block and the same layer number as the current block as the reference block, or find a transform block in the reference frame whose geometric position is the same as the geometric position of the current block, the same layer number as the current block and the same sliceID as the current block as the reference block, or find a transform block in the reference frame whose geometric position is the same as the geometric position of the parent transform block of the current block, the same layer number as the current block and the same sliceID as the current block as the reference block.

If an inter-frame reference block is found in the memory module, the transform coefficient corresponding to the inter-frame reference block in the memory module can be used as the transform coefficient prediction value of the current block.

S214, RAHT intra prediction.

If no inter-frame reference block is found, the intra-frame prediction value is used as the transformation coefficient prediction value of the current block, wherein the intra-frame prediction value is obtained by weighted prediction of the neighboring blocks of the current block, the parent transformation block and the neighboring blocks of the parent transformation block.

S215, quantification.

The transform coefficient residual value is quantized to obtain a quantized transform coefficient residual value.

S216, encoding.

The quantized transform coefficient residual value is encoded and written into the bitstream.

S217, dequantization.

The quantized transform coefficient residual value is inversely quantized to obtain a reconstructed transform coefficient residual value (ie, a reconstructed transform coefficient residual value).

S218, save to the memory module.

The reconstructed transform coefficient residual value is added to the transform coefficient prediction value to obtain the reconstructed transform coefficient. If the current frame may be used as a reference frame for subsequent frames after encoding, at least one of the reconstructed transform coefficient, absolute geometric position, geometric position, sliceID, and the number of layers of the RAHT transform layer where the current block is located can be stored in the memory module as the inter-frame prediction reference information for subsequent frames; otherwise, it is directly performed. Inverse RAHT transform.

S219, inverse RAHT transform.

By performing RAHT inverse transformation on the reconstructed transformation coefficients, the reconstructed point cloud attributes can be obtained.

That is, as shown in Figure 21, the geometric information of the point cloud to be encoded is decomposed into a point cloud geometry octree, and the attribute information of the point cloud to be encoded is subjected to a RAHT transform to determine the transform coefficients of the point cloud to be encoded. The transform coefficient prediction value of the point cloud to be encoded can be determined based on RAHT inter-frame prediction or RAHT intra-frame prediction. The transform coefficient residual value is obtained by subtracting the transform coefficient of the point cloud to be encoded from the transform coefficient prediction value. The transform coefficient residual value is then quantized to obtain the quantized transform coefficient residual value. On the one hand, the quantized transform coefficient residual value can be encoded and written into the attribute code stream. On the other hand, the quantized transform coefficient residual value can be dequantized to obtain the reconstructed transform coefficient residual value. The reconstructed transform coefficient residual value is then added to the transform coefficient prediction value to obtain the reconstructed transform coefficient. The transform coefficient is saved in a memory module, so that when performing inter-frame prediction later, the transform coefficient of the reference block can be directly obtained from the memory module. Finally, the reconstructed transform coefficient is subjected to a RAHT inverse transform to obtain the reconstructed point cloud attributes.

Exemplarily, based on the encoding and decoding method of the aforementioned embodiment, Table 1 is the performance results based on the latest tmc13v24 under the test conditions of lossy geometry and lossy attribute (Lossy geometry, Lossy attribute) provided by the embodiment of the present application.

Table 1

According to the performance results based on the latest TMC13v24 shown in Table 1, it can be seen that the time complexity of the encoding end is reduced by 7%, and the time complexity of the decoding end is reduced by 19%.

In the embodiments of the present application, the specific implementation of the aforementioned embodiments is elaborated in detail through the above embodiments. It can be seen that, according to the technical solution of the aforementioned embodiments, it is proposed to cache the geometric position of the possible reference frame after decoding, the slice ID to which it belongs, and the transformation coefficient into a buffer for use by subsequent frames, thereby avoiding the reference frame from having to undergo octree decomposition and RAHT transformation again, reducing the time for the codec end to perform RAHT transformation again for the predicted frame, significantly reducing the time complexity, and retaining the information of multiple RAHT transformation layers of the reference frame, making inter-frame prediction more accurate, thereby improving the coding and decoding performance.

In yet another embodiment of the present application, based on the same inventive concept as the aforementioned embodiment, FIG22 is a schematic diagram of the composition structure of an encoder provided in an embodiment of the present application. As shown in FIG22 , the encoder 220 may include a first determination unit 2201, a first prediction unit 2202, and an encoding unit 2203, wherein:

A first determining unit 2201 is configured to determine prediction mode identification information of a current block;

The first prediction unit 2202 is configured to determine a transform coefficient prediction value of the current block according to a reference block of the current block when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain;

The first determining unit 2201 is further configured to determine a transform coefficient residual value of the current block according to the transform coefficient prediction value of the current block;

The encoding unit 2203 is configured to perform encoding processing on the transform coefficient residual value of the current block and write the obtained encoding bits into the bitstream.

In some embodiments, the first determination unit 2201 is further configured to quantize the transform coefficient residual value to determine the quantized coefficient residual value of the current block; the encoding unit 2203 is further configured to encode the quantized coefficient residual value of the current block and write the obtained encoded bits into the bitstream.

In some embodiments, the first determining unit 2201 is further configured to determine a reference block of the current block according to the slice identification information in the reference point cloud.

In some embodiments, the first determining unit 2201 is further configured to determine a predicted value of a transform coefficient of the current block according to the transform coefficient of the reference block.

In some embodiments, the first determination unit 2201 is further configured to determine the attribute information of the reference slice based on the reference slice indicated by the slice identification information; perform region-adaptive hierarchical transformation on the attribute information of the reference slice to determine the transformation coefficients of at least one transformation layer; and determine the transformation coefficients of the reference block from the transformation coefficients of at least one transformation layer.

In some embodiments, the first determining unit 2201 is further configured to determine a transform coefficient residual value of a reference block; quantize the transform coefficient residual value of the reference block to determine a quantized coefficient residual value of the reference block; dequantize the quantized coefficient residual value of the reference block to determine a reconstructed transform coefficient residual value of the reference block; and determine, based on the transform coefficient prediction value of the reference block and the reconstructed transform coefficient residual value of the reference block, Transform coefficients of the reference block.

In some embodiments, referring to FIG22 , the encoder 220 further includes a first saving unit 2204; the first determining unit 2201 is further configured to determine storage information of the reference block, wherein the storage information of the reference block includes at least one of the following: transformation coefficients of the reference block, coordinate information of the reference block, slice identification information of the reference block, and transformation layer information of the reference block; the first saving unit 2204 is configured to save the storage information of the reference block into the memory module.

In some embodiments, the first determining unit 2201 is further configured to determine the transformation coefficient of the reference block according to the storage information corresponding to the reference block in the memory module.

In some embodiments, the first determination unit 2201 is further configured such that the coordinate information of the reference block is the same as the coordinate information of the current block, the slice identification information of the reference block is the same as the slice identification information of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block.

In some embodiments, the first determination unit 2201 is further configured such that the coordinate information of the parent transform block of the reference block is the same as the coordinate information of the parent transform block of the current block, the slice identification information of the reference block is the same as the slice identification information of the current block, and the transform layer information of the reference block is the same as the current layer information of the current block.

In some embodiments, the first determination unit 2201 is further configured to determine the coordinate information of the reference block; and determine the absolute coordinate information of the reference block based on the coordinate information of the reference block and the coordinate offset information of the slice identification information where the reference block is located relative to the origin.

In some embodiments, the first determining unit 2201 is further configured to determine that the absolute coordinate information of the reference block is the same as the absolute coordinate information of the current block and the transform layer information of the reference block is the same as the current layer information of the current block.

In some embodiments, the first determination unit 2201 is further configured such that the absolute coordinate information of the parent transform block of the reference block is the same as the absolute coordinate information of the parent transform block of the current block and the transform layer information where the reference block is located is the same as the current layer information where the current block is located.

In some embodiments, the first determination unit 2201 is further configured to determine that the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain if there is a reference block in the reference point cloud that satisfies the preset inter-frame condition with the current block; if there is no reference block in the reference point cloud that satisfies the preset inter-frame condition with the current block, determine that the prediction mode identification information indicates that the current block performs intra-frame prediction in the transform domain.

In some embodiments, the first prediction unit 2202 is further configured to determine the transform coefficient prediction values of the neighboring blocks of the current block, the transform coefficient prediction values of the parent transform block of the current block, and the transform coefficient prediction values of the neighboring blocks of the parent transform block when the prediction mode identification information indicates that the current block performs intra-frame prediction in the transform domain; and perform weighted operations on the transform coefficient prediction values of the neighboring blocks of the current block, the transform coefficient prediction values of the parent transform block of the current block, and the transform coefficient prediction values of the neighboring blocks of the parent transform block to determine the transform coefficient prediction value of the current block.

In some embodiments, the first determination unit 2201 is further configured to perform inverse quantization on the quantization coefficient residual value of the current block to determine the reconstructed transform coefficient residual value of the current block; and determine the transform coefficient of the current block based on the transform coefficient prediction value of the current block and the reconstructed transform coefficient residual value of the current block.

In some embodiments, the first determination unit 2201 is further configured to determine the storage information of the current block, wherein the storage information of the current block includes at least one of the following: the transformation coefficient of the current block, the coordinate information of the current block, the slice identification information where the current block is located, and the current layer information where the current block is located; the first saving unit 2204 is further configured to save the storage information of the current block into the memory module.

In some embodiments, the first saving unit 2204 is further configured to save the storage information of the current block into the memory module when the current point cloud where the current block is located meets the conditions for being used as a reference point cloud.

In some embodiments, the first determination unit 2201 is further configured to determine the geometric information of the current slice; wherein the current slice is determined by slice division of the current point cloud; and perform octree decomposition on the geometric information of the current slice to determine at least one transformation layer; wherein the at least one transformation layer includes the current layer where the current block is located.

In some embodiments, the first determination unit 2201 is further configured to determine the low-frequency coefficient values of the nodes in the Lth layer when the current layer is the L-1th layer in at least one transformation layer, and perform regional adaptive hierarchical transformation based on the low-frequency coefficient values of the nodes in the Lth layer to determine the low-frequency coefficient values and the original values of the high-frequency coefficients of the nodes in the L-1th layer until the low-frequency coefficient values and the original values of the high-frequency coefficients of the root node of the current point cloud are determined; wherein L is a positive integer.

In some embodiments, the encoding unit 2203 is further configured to encode the low-frequency coefficient value of the root node of the current point cloud and write the obtained encoding bits into the bitstream.

In some embodiments, the first determination unit 2201 is further configured to determine the original value of the high-frequency coefficient of the current block; and determine the residual value of the high-frequency coefficient of the current block based on the original value of the high-frequency coefficient of the current block and the predicted value of the high-frequency coefficient of the current block; the encoding unit 2203 is further configured to encode the residual value of the high-frequency coefficient of the current block and write the obtained encoding bits into the bitstream.

It is understandable that in the embodiments of the present application, a "unit" can be a portion of a circuit, a portion of a processor, a portion of a program or software, etc., and of course it can also be a module, or it can be non-modular. Moreover, the various components in this embodiment can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into a single unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional modules.

In another embodiment of the present application, FIG23 is a schematic diagram of a specific hardware structure of an encoder provided in an embodiment of the present application. As shown in FIG23, the encoder 220 may include: a first communication interface 2301, a first memory 2302 and a first processor 2303; each component The first bus system 2304 is coupled together. It is understood that the first bus system 2304 is used to realize the connection and communication between these components. In addition to the data bus, the first bus system 2304 also includes a power bus, a control bus, and a status signal bus. However, for the sake of clarity, in FIG23, various buses are labeled as the first bus system 2304.

The first communication interface 2301 is used to receive and send signals when sending and receiving information with other external network elements;

A first memory 2302 is used to store computer programs that can be run on the first processor 2303;

The first processor 2303 is configured to, when running the computer program, execute:

Determining prediction mode identification information of the current block; when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, determining a transform coefficient prediction value of the current block based on a reference block of the current block; determining a transform coefficient residual value of the current block based on the transform coefficient prediction value of the current block;

The transform coefficient residual value of the current block is coded, and the obtained coded bits are written into the bitstream.

It is understood that the first memory 2302 in the embodiment of the present application can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous DRAM (DDR SDRAM), enhanced synchronous DRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM (DRRAM). The first memory 2302 of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

The first processor 2303 may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method can be completed by the hardware integrated logic circuit in the first processor 2303 or by instructions in the form of software. The above-mentioned first processor 2303 may be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. The various methods, steps, and logic block diagrams disclosed in the embodiments of this application can be implemented or executed. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in conjunction with the embodiments of this application can be directly embodied as being executed by a hardware decoding processor, or can be executed by a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium mature in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers, etc. The storage medium is located in the first memory 2302 , and the first processor 2303 reads the information in the first memory 2302 and completes the steps of the above method in combination with its hardware.

It is understood that the embodiments described in this application can be implemented in hardware, software, firmware, middleware, microcode, or a combination thereof. For hardware implementation, the processing unit can be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), general-purpose processors, controllers, microcontrollers, microprocessors, other electronic units for performing the functions described in this application, or a combination thereof. For software implementation, the technology described in this application can be implemented by modules (such as processes, functions, etc.) that perform the functions described in this application. The software code can be stored in a memory and executed by a processor. The memory can be implemented in the processor or outside the processor.

Optionally, as another embodiment, the first processor 2303 is further configured to execute the method described in any one of the aforementioned embodiments when running the computer program.

This embodiment provides an encoder that, when performing inter-frame prediction in the transform domain on a current block, can determine a predicted value of the transform coefficient of the current block based on a reference block of the current block. The reference block can be transformed based on slices of a reference point cloud, rather than on the entire frame of the reference point cloud, thereby reducing time complexity. Furthermore, the transform coefficients of the reference block can be stored in a memory module, so that when the transform coefficients of the reference block are needed, they can be directly retrieved from the memory module, further reducing time complexity, thereby improving the efficiency of point cloud attribute coding and, consequently, enhancing point cloud coding performance.

In yet another embodiment of the present application, based on the same inventive concept as the aforementioned embodiment, FIG24 is a schematic diagram of the structure of a decoder provided in an embodiment of the present application. As shown in FIG24 , the decoder 240 may include a second determination unit 2401, a second prediction unit 2402, and a decoding unit 2403, wherein:

The second determining unit 2401 is configured to determine prediction mode identification information of the current block;

The second prediction unit 2402 is configured to determine a transform coefficient prediction value of the current block according to a reference block of the current block when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain;

The decoding unit 2403 is configured to decode the code stream and determine the transform coefficient residual value of the current block;

The second determining unit 2401 is further configured to determine the transform coefficient of the current block according to the transform coefficient prediction value of the current block and the transform coefficient residual value of the current block.

In some embodiments, the second determining unit 2401 is further configured to determine a reference block of the current block according to the slice identification information in the reference point cloud.

In some embodiments, the second determining unit 2401 is further configured to determine a predicted value of a transform coefficient of the current block according to the transform coefficient of the reference block.

In some embodiments, the second determination unit 2401 is further configured to determine the attribute information of the reference slice based on the reference slice indicated by the slice identification information; perform region-adaptive hierarchical transformation on the attribute information of the reference slice to determine the transformation coefficients of at least one transformation layer; and determine the transformation coefficients of the reference block from the transformation coefficients of at least one transformation layer.

In some embodiments, the decoding unit 2403 is further configured to decode the code stream and determine the transform coefficient residual value of the reference block; the second determination unit 2401 is further configured to determine the transform coefficient of the reference block based on the transform coefficient prediction value of the reference block and the transform coefficient residual value of the reference block.

In some embodiments, the decoding unit 2403 is further configured to decode the code stream to determine the transform coefficients of the reference block.

In some embodiments, referring to FIG. 24 , the decoder 240 further includes a second saving unit 2404; the second determination unit 2401 is further configured to determine storage information of the reference block, wherein the storage information of the reference block includes at least one of the following: transformation coefficients of the reference block, coordinate information of the reference block, slice identification information of the reference block, and transformation layer information of the reference block; the second saving unit 2404 is configured to save the storage information of the reference block into the memory module.

In some embodiments, the second determining unit 2401 is further configured to determine the transformation coefficient of the reference block according to the storage information corresponding to the reference block in the memory module.

In some embodiments, the second determination unit 2401 is further configured such that the coordinate information of the reference block is the same as the coordinate information of the current block, the slice identification information where the reference block is located is the same as the slice identification information where the current block is located, and the transformation layer information where the reference block is located is the same as the current layer information where the current block is located.

In some embodiments, the second determination unit 2401 is further configured such that the coordinate information of the parent transform block of the reference block is the same as the coordinate information of the parent transform block of the current block, the slice identification information of the reference block is the same as the slice identification information of the current block, and the transform layer information of the reference block is the same as the current layer information of the current block.

In some embodiments, the second determination unit 2401 is further configured to determine the coordinate information of the reference block; and determine the absolute coordinate information of the reference block based on the coordinate information of the reference block and the coordinate offset information of the slice identification information where the reference block is located relative to the origin.

In some embodiments, the second determining unit 2401 is further configured to determine that the absolute coordinate information of the reference block is the same as the absolute coordinate information of the current block and the transform layer information of the reference block is the same as the current layer information of the current block.

In some embodiments, the second determination unit 2401 is further configured to ensure that the absolute coordinate information of the parent transform block of the reference block is the same as the absolute coordinate information of the parent transform block of the current block and the transform layer information of the reference block is the same as the current layer information of the current block.

In some embodiments, the second determination unit 2401 is further configured to determine that the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain if there is a reference block in the reference point cloud that satisfies the preset inter-frame condition with the current block; if there is no reference block in the reference point cloud that satisfies the preset inter-frame condition with the current block, determine that the prediction mode identification information indicates that the current block performs intra-frame prediction in the transform domain.

In some embodiments, the second prediction unit 2402 is further configured to determine the transform coefficient prediction values of the neighboring blocks of the current block, the transform coefficient prediction values of the parent transform block of the current block, and the transform coefficient prediction values of the neighboring blocks of the parent transform block when the prediction mode identification information indicates that the current block performs intra-frame prediction in the transform domain; and perform weighted operations on the transform coefficient prediction values of the neighboring blocks of the current block, the transform coefficient prediction values of the parent transform block of the current block, and the transform coefficient prediction values of the neighboring blocks of the parent transform block to determine the transform coefficient prediction value of the current block.

In some embodiments, the second determination unit 2401 is further configured to determine the storage information of the current block, wherein the storage information of the current block includes at least one of the following: the transformation coefficient of the current block, the coordinate information of the current block, the slice identification information where the current block is located, and the current layer information where the current block is located; the second saving unit 2404 is further configured to save the storage information of the current block into the memory module.

In some embodiments, the second saving unit 2404 is configured to save the storage information of the current block into the memory module when the current point cloud where the current block is located meets the conditions for being used as a reference point cloud.

In some embodiments, the decoding unit 2403 is further configured to decode the code stream to determine the quantization coefficient residual value of the current block; the second determination unit 2401 is further configured to dequantize the quantization coefficient residual value to determine the transform coefficient residual value of the current block.

In some embodiments, the second determination unit 2401 is further configured to determine the geometric information of the current slice; wherein the current slice is determined by slice division of the current point cloud; and perform octree decomposition on the geometric information of the current slice to determine at least one transformation layer; wherein the at least one transformation layer includes the current layer where the current block is located.

In some embodiments, the second determination unit 2401 is further configured to perform a regional adaptive hierarchical inverse transform on the reconstructed transform coefficients of the current block in the L-1 layer when the current layer is the L-1 layer in at least one transform layer, to determine the reconstruction attribute information of the nodes in the L layer; wherein L is a positive integer.

It is understandable that in this embodiment, a "unit" may be a part of a circuit, a part of a processor, a part of a program or software, etc. It can be modular or non-modular. Moreover, the various components in this embodiment can be integrated into a single processing unit, or each unit can exist physically separately, or two or more units can be integrated into a single unit. The aforementioned integrated units can be implemented in the form of hardware or software functional modules.

In another embodiment of the present application, FIG25 is a schematic diagram of the specific hardware structure of a decoder provided in an embodiment of the present application. As shown in FIG25 , the decoder 240 may include: a second communication interface 2501, a second memory 2502, and a second processor 2503; each component is coupled together through a second bus system 2504. It can be understood that the second bus system 2504 is used to achieve connection and communication between these components. In addition to the data bus, the second bus system 2504 also includes a power bus, a control bus, and a status signal bus. However, for the sake of clarity, various buses are labeled as the second bus system 2504 in FIG25. Among them,

The second communication interface 2501 is used to receive and send signals during the process of sending and receiving information between other external network elements;

The second memory 2502 is used to store computer programs that can be run on the second processor 2503;

The second processor 2503 is configured to, when running the computer program, execute:

Determine prediction mode identification information of the current block; when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, determine a transform coefficient prediction value of the current block based on a reference block of the current block; decode the code stream to determine a transform coefficient residual value of the current block; and determine a transform coefficient of the current block based on the transform coefficient prediction value of the current block and the transform coefficient residual value of the current block.

Optionally, as another embodiment, the second processor 2503 is further configured to execute any one of the methods described in the foregoing embodiments when running the computer program.

It can be understood that the hardware functions of the second memory 2502 are similar to those of the first memory 2302, and the hardware functions of the second processor 2503 are similar to those of the first processor 2303; they will not be described in detail here.

This embodiment provides a decoder that, when performing inter-frame prediction in the transform domain on a current block, can determine a predicted value of the transform coefficients of the current block based on a reference block of the current block. The reference block can be transformed based on slices of a reference point cloud, rather than on the entire frame of the reference point cloud, thereby reducing time complexity. Furthermore, the transform coefficients of the reference block can be stored in a memory module so that when the transform coefficients of the reference block are needed, they can be directly retrieved from the memory module, further reducing time complexity. This improves the efficiency of encoding and decoding point cloud attributes, and thus enhances point cloud encoding and decoding performance.

In yet another embodiment of the present application, FIG26 is a schematic diagram of the structure of a coding and decoding system provided by an embodiment of the present application. As shown in FIG26 , the coding and decoding system 260 may include an encoder 2601 and a decoder 2602 .

In the embodiment of the present application, the encoder 2601 may be the encoder described in any one of the aforementioned embodiments, and the decoder 2602 may be the decoder described in any one of the aforementioned embodiments.

In some embodiments, the present application further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor (eg, the first processor or the second processor), implements the method as described in any of the aforementioned embodiments.

In some embodiments, embodiments of the present application further provide a computer program product, including a computer program or instructions. When the computer program or instructions are executed by a processor (e.g., a first processor or a second processor), the method described in any one of the aforementioned embodiments is implemented.

In some embodiments, the embodiments of the present application further provide a computer program, which, when executed by a processor (eg, a first processor or a second processor), implements the method as described in any one of the aforementioned embodiments.

Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application is essentially or partially contributed to the existing technology. Part of this technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of this application. The aforementioned storage medium includes: a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, etc., various media that can store program code.

It should be noted that, in this application, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

The serial numbers of the above embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

The methods disclosed in the several method embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments.

The features disclosed in the several product embodiments provided in this application can be arbitrarily combined without conflict to obtain new product embodiments.

The features disclosed in the several method or device embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments.

The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Industrial Applicability

In an embodiment of the present application, at the encoding end, the prediction mode identification information of the current block is determined; when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, the transform coefficient prediction value of the current block is determined based on the reference block of the current block; based on the transform coefficient prediction value of the current block, the transform coefficient residual value of the current block is determined; the transform coefficient residual value of the current block is encoded, and the obtained coded bits are written into the bitstream. At the decoding end, the prediction mode identification information of the current block is determined; when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, the transform coefficient prediction value of the current block is determined based on the reference block of the current block; the bitstream is decoded to determine the transform coefficient residual value of the current block; and the transform coefficient of the current block is determined based on the transform coefficient prediction value of the current block and the transform coefficient residual value of the current block. In this way, whether at the encoding end or the decoding end, when the current block performs inter-frame prediction in the transform domain, the transform coefficient prediction value of the current block can be determined based on the reference block of the current block. Among them, the reference block can be transformed based on the slices divided by the reference point cloud, rather than based on the entire frame of the reference point cloud, which reduces the time complexity; and the transformation coefficients of the reference block can be stored in the memory module, so that when the transformation coefficients of the reference block are needed, they can be directly obtained from the memory module, further reducing the time complexity, thereby improving the attribute encoding and decoding efficiency of the point cloud, and thus improving the encoding and decoding performance of the point cloud.

Claims (48)

A decoding method, applied to a decoder, comprising: Determining prediction mode identification information of the current block; When the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, determining a transform coefficient prediction value of the current block according to a reference block of the current block; Decoding a bitstream to determine a transform coefficient residual value of the current block; The transform coefficient of the current block is determined according to the transform coefficient prediction value of the current block and the transform coefficient residual value of the current block. The method according to claim 1, further comprising: A reference block of the current block is determined according to the slice identification information in the reference point cloud. The method according to claim 2, wherein determining the transform coefficient prediction value of the current block based on the reference block of the current block comprises: A transform coefficient prediction value of the current block is determined according to the transform coefficient of the reference block. The method according to claim 3, wherein the method further comprises: determining attribute information of the reference slice based on the reference slice indicated by the slice identification information; Performing a region-adaptive hierarchical transformation on the attribute information of the reference slice to determine a transformation coefficient of at least one transformation layer; The transform coefficients of the reference block are determined from the transform coefficients of the at least one transform layer. The method according to claim 3, wherein the method further comprises: Decoding a code stream to determine a transform coefficient residual value of the reference block; The transform coefficient of the reference block is determined according to the transform coefficient prediction value of the reference block and the transform coefficient residual value of the reference block. The method according to claim 3, wherein the method further comprises: The code stream is decoded to determine the transform coefficient of the reference block. The method according to claim 5 or 6, wherein the method further comprises: Determining storage information of the reference block, wherein the storage information of the reference block includes at least one of the following: a transform coefficient of the reference block, coordinate information of the reference block, slice identification information of the reference block, and transform layer information of the reference block; The storage information of the reference block is saved in a memory module. The method according to claim 7, wherein the method further comprises: Determine the transformation coefficient of the reference block according to the storage information corresponding to the reference block in the memory module. The method according to claim 1, further comprising: The coordinate information of the reference block is the same as the coordinate information of the current block, the slice identification information of the reference block is the same as the slice identification information of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block. The method according to claim 1, further comprising: The coordinate information of the parent transform block of the reference block is the same as the coordinate information of the parent transform block of the current block, and the slice identification information of the reference block is the same as the slice identification information of the current block, and the transform layer information of the reference block is the same as the current layer information of the current block. The method according to claim 1, further comprising: Determining coordinate information of the reference block; The absolute coordinate information of the reference block is determined according to the coordinate information of the reference block and the coordinate offset information of the slice identification information where the reference block is located relative to the origin. The method according to claim 11, wherein the method further comprises: The absolute coordinate information of the reference block is the same as the absolute coordinate information of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block. The method according to claim 11, wherein the method further comprises: The absolute coordinate information of the parent transform block of the reference block is the same as the absolute coordinate information of the parent transform block of the current block, and the transform layer information of the reference block is the same as the current layer information of the current block. The method according to any one of claims 1 to 13, wherein the method further comprises: If there is a reference block in the reference point cloud that satisfies a preset inter-frame condition with the current block, determining that the prediction mode identification information indicates that the current block is to be subjected to transform domain inter-frame prediction; If there is no reference block in the reference point cloud that satisfies a preset inter-frame condition with the current block, it is determined that the prediction mode identification information indicates that the current block is to be subjected to transform domain intra-frame prediction. The method according to claim 14, wherein the method further comprises: When the prediction mode identification information indicates that the current block performs transform-domain intra prediction, determining transform coefficient prediction values of neighboring blocks of the current block, transform coefficient prediction values of a parent transform block of the current block, and transform coefficient prediction values of neighboring blocks of the parent transform block; A weighted operation is performed on the transform coefficient prediction values of the neighboring blocks of the current block, the transform coefficient prediction value of the parent transform block of the current block, and the transform coefficient prediction values of the neighboring blocks of the parent transform block to determine the transform coefficient prediction value of the current block. The method according to any one of claims 1 to 13, wherein the method further comprises: Determining storage information of the current block, wherein the storage information of the current block includes at least one of the following: a transform coefficient of the current block, coordinate information of the current block, slice identification information of the current block, and current layer information of the current block; The storage information of the current block is saved in the memory module. The method according to claim 16, wherein saving the storage information of the current block to the memory module comprises: When the current point cloud where the current block is located meets the condition of being used as a reference point cloud, the storage information of the current block is saved in the memory module. The method according to any one of claims 1 to 17, wherein, the decoding of the code stream and determining the transform coefficient residual value of the current block comprises: Decoding a code stream to determine a quantization coefficient residual value of the current block; Dequantize the quantized coefficient residual value to determine the transform coefficient residual value of the current block. The method according to any one of claims 1 to 17, wherein the method further comprises: Determine geometric information of a current slice; wherein the current slice is determined by slice division of the current point cloud; Performing octree decomposition on the geometric information of the current slice to determine at least one transform layer; wherein the at least one transform layer includes the current layer where the current block is located. The method according to claim 19, wherein the method further comprises: When the current layer is the L-1th layer in the at least one transformation layer, a regional adaptive hierarchical inverse transformation is performed on the reconstructed transformation coefficients of the current block in the L-1th layer to determine the reconstruction attribute information of the nodes in the Lth layer; wherein L is a positive integer. A coding method, applied to an encoder, comprising: Determining prediction mode identification information of the current block; When the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, determining a transform coefficient prediction value of the current block according to a reference block of the current block; Determining a transform coefficient residual value of the current block according to the transform coefficient prediction value of the current block; The transform coefficient residual value of the current block is coded, and the obtained coded bits are written into a bitstream. The method according to claim 21, wherein encoding the transform coefficient residual value of the current block and writing the obtained coded bits into the bitstream comprises: quantizing the transform coefficient residual value to determine the quantized coefficient residual value of the current block; The quantization coefficient residual value of the current block is coded, and the obtained coded bits are written into a bit stream. The method according to claim 21, wherein the method further comprises: A reference block of the current block is determined according to the slice identification information in the reference point cloud. The method according to claim 23, wherein determining the transform coefficient prediction value of the current block based on the reference block of the current block comprises: A transform coefficient prediction value of the current block is determined according to the transform coefficient of the reference block. The method according to claim 24, wherein the method further comprises: determining attribute information of the reference slice based on the reference slice indicated by the slice identification information; Performing a region-adaptive hierarchical transformation on the attribute information of the reference slice to determine a transformation coefficient of at least one transformation layer; The transform coefficients of the reference block are determined from the transform coefficients of the at least one transform layer. The method according to claim 24, wherein the method further comprises: determining a transform coefficient residual value of the reference block; quantizing the transform coefficient residual value of the reference block to determine the quantized coefficient residual value of the reference block; Dequantizing the quantized coefficient residual value of the reference block to determine the reconstructed transform coefficient residual value of the reference block; The transform coefficient of the reference block is determined according to the transform coefficient prediction value of the reference block and the reconstructed transform coefficient residual value of the reference block. The method according to claim 26, wherein the method further comprises: Determining storage information of the reference block, wherein the storage information of the reference block includes at least one of the following: a transform coefficient of the reference block, coordinate information of the reference block, slice identification information of the reference block, and transform layer information of the reference block; The storage information of the reference block is saved in a memory module. The method according to claim 27, wherein the method further comprises: Determine the transformation coefficient of the reference block according to the storage information corresponding to the reference block in the memory module. The method according to claim 21, wherein the method further comprises: The coordinate information of the reference block is the same as the coordinate information of the current block, the slice identification information of the reference block is the same as the slice identification information of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block. The method according to claim 21, wherein the method further comprises: The coordinate information of the parent transform block of the reference block is the same as the coordinate information of the parent transform block of the current block, and the slice identification information of the reference block is the same as the slice identification information of the current block, and the transform layer information of the reference block is the same as the current layer information of the current block. The method according to claim 21, wherein the method further comprises: Determining coordinate information of the reference block; The absolute coordinate information of the reference block is determined according to the coordinate information of the reference block and the coordinate offset information of the slice identification information where the reference block is located relative to the origin. The method according to claim 32, wherein the method further comprises: The absolute coordinate information of the reference block is the same as the absolute coordinate information of the current block, and the transformation layer information of the reference block is the same as the current layer information of the current block. The method according to claim 32, wherein the method further comprises: The absolute coordinate information of the parent transform block of the reference block is the same as the absolute coordinate information of the parent transform block of the current block, and the transform layer information of the reference block is the same as the current layer information of the current block. The method according to any one of claims 21 to 33, wherein the method further comprises: If there is a reference block in the reference point cloud that satisfies a preset inter-frame condition with the current block, determining that the prediction mode identification information indicates that the current block is to be subjected to transform domain inter-frame prediction; If there is no reference block in the reference point cloud that satisfies a preset inter-frame condition with the current block, it is determined that the prediction mode identification information indicates that the current block is to be subjected to transform domain intra-frame prediction. The method according to claim 34, wherein the method further comprises: When the prediction mode identification information indicates that the current block performs transform-domain intra prediction, determining transform coefficient prediction values of neighboring blocks of the current block, transform coefficient prediction values of a parent transform block of the current block, and transform coefficient prediction values of neighboring blocks of the parent transform block; A weighted operation is performed on the transform coefficient prediction values of the neighboring blocks of the current block, the transform coefficient prediction value of the parent transform block of the current block, and the transform coefficient prediction values of the neighboring blocks of the parent transform block to determine the transform coefficient prediction value of the current block. The method according to claim 22, wherein the method further comprises: Dequantizing the quantized coefficient residual value of the current block to determine the reconstructed transform coefficient residual value of the current block; The transform coefficient of the current block is determined according to the transform coefficient prediction value of the current block and the reconstructed transform coefficient residual value of the current block. The method according to claim 36, wherein the method further comprises: Determining storage information of the current block, wherein the storage information of the current block includes at least one of the following: a transform coefficient of the current block, coordinate information of the current block, slice identification information of the current block, and current layer information of the current block; The storage information of the current block is saved in the memory module. The method according to claim 37, wherein saving the storage information of the current block to the memory module comprises: When the current point cloud where the current block is located meets the condition of being used as a reference point cloud, the storage information of the current block is saved in the memory module. The method according to any one of claims 21 to 38, wherein the method further comprises: Determine geometric information of a current slice; wherein the current slice is determined by slice division of the current point cloud; Performing octree decomposition on the geometric information of the current slice to determine at least one transform layer; wherein the at least one transform layer includes the current layer where the current block is located. The method according to claim 39, wherein the method further comprises: When the current layer is the L-1th layer in the at least one transformation layer, the low-frequency coefficient values of the nodes in the L-1th layer are determined, and a regional adaptive hierarchical transformation is performed based on the low-frequency coefficient values of the nodes in the L-1th layer to determine the low-frequency coefficient values and the original values of the high-frequency coefficients of the nodes in the L-1th layer until the low-frequency coefficient values and the original values of the high-frequency coefficients of the root node of the current point cloud are determined; wherein L is a positive integer. The method according to claim 40, wherein the method further comprises: The low-frequency coefficient value of the root node of the current point cloud is encoded, and the obtained encoded bits are written into a bitstream. The method according to claim 40, wherein the method further comprises: Determining original values of high-frequency coefficients of the current block; Determining a high-frequency coefficient residual value of the current block according to an original high-frequency coefficient value of the current block and a predicted high-frequency coefficient value of the current block; The high frequency coefficient residual value of the current block is coded, and the obtained coded bits are written into a bit stream. A code stream, wherein the code stream is generated by bit encoding according to information to be encoded; wherein the information to be encoded includes at least one of the following: a low-frequency coefficient value of a root node and a high-frequency coefficient residual value of a current block. An encoder includes a first determining unit, a first predicting unit, and an encoding unit, wherein: The first determining unit is configured to determine prediction mode identification information of the current block; The first prediction unit is configured to determine, when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain, a transform coefficient prediction value of the current block based on a reference block of the current block; The first determining unit is further configured to determine a transform coefficient residual value of the current block according to the transform coefficient prediction value of the current block; The encoding unit is configured to perform encoding processing on the transform coefficient residual value of the current block and write the obtained encoding bits into the bit stream. An encoder comprises a first memory and a first processor, wherein: The first memory is used to store a computer program that can be run on the first processor; The first processor is configured to execute the method according to any one of claims 21 to 42 when running the computer program. A decoder comprising a second determining unit, a second predicting unit, and a decoding unit, wherein: The second determining unit is configured to determine prediction mode identification information of the current block; The second prediction unit is configured to determine a transform coefficient prediction value of the current block according to a reference block of the current block when the prediction mode identification information indicates that the current block performs inter-frame prediction in the transform domain; The decoding unit is configured to decode the code stream and determine the transform coefficient residual value of the current block; The second determining unit is further configured to determine the transform coefficient of the current block according to the transform coefficient prediction value of the current block and the transform coefficient residual value of the current block. A decoder comprising a second memory and a second processor, wherein: The second memory is used to store a computer program that can be run on the second processor; The second processor is configured to execute the method according to any one of claims 1 to 20 when running the computer program. A computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the method according to any one of claims 1 to 20 is implemented, or the method according to any one of claims 21 to 42 is implemented.