WO2025138048A1 - Coding method, decoding method, code stream, coder, decoder and storage medium - Google Patents

Abstract

Disclosed in the present application are a coding method, a decoding method, a code stream, coders, a decoder and a storage medium. The decoding method comprises: determining the value of a first decoding parameter; when the first decoding parameter indicates skip decoding for k transform layers of the current point cloud, determining as preset values one or multiple alternating-current coefficient residual values of the k transform layers, k being an integer greater than zero; decoding a code stream, so as to determine alternating-current coefficient residual values of the other transform layers in the current point cloud except the k transform layers; and, on the basis of the alternating-current coefficient residual values of the k transform layers and the alternating-current coefficient residual values of the other transform layers, determining a reconstructed point cloud for the current point cloud. Thus, RAHT coding and decoding efficiency can be 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 geometry information and attribute information of the point cloud are encoded separately. Among them, the attribute encoding of G-PCC can include: Predicting Transform (PT), Lifting Transform (LT) and Region Adaptive Hierarchical Transform (RAHT).

For the RAHT transform, in the process of layer-by-layer calculation from the root node to the child node, as the number of layers increases, the coded AC coefficient value obtained by the transform gradually decreases, so that in the last few layers of the radar point cloud, a large number of 0s appear in the coded AC coefficient value at this time. The encoding of the AC coefficient values of the last few layers will result in a waste of code stream, reducing the coding efficiency.

Summary of the invention

The embodiments of the present application provide a coding and decoding method, a bit stream, an encoder, a decoder and a storage medium, which can improve the coding and decoding efficiency of RAHT transformation.

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, which is applied to a decoder, and the method includes:

Determining a value of a first decoding parameter;

When the first decoding parameter indicates that k transform layers of the current point cloud are to be skipped and decoded, one or more AC coefficient residual values of the k transform layers are determined to be preset values; wherein k is an integer greater than zero;

Decode the bitstream and determine the residual values of the AC coefficients of other transform layers other than the k transform layers in the current point cloud;

The reconstructed point cloud of the current point cloud is determined according to the residual values of the AC coefficients of the k transformation layers and the residual values of the AC coefficients of other transformation layers.

In a second aspect, an embodiment of the present application provides an encoding method, which is applied to an encoder, and the method includes:

Determining a value of a first encoding parameter;

When the first encoding parameter indicates that the k transformation layers of the current point cloud are to be skip-encoded, determining one or more AC coefficient residual values of the k transformation layers to be preset values; wherein k is an integer greater than zero;

One or more AC coefficient residual values of k transformation layers are coded according to preset values, and the obtained coded bits are written into the bit stream.

In a third aspect, an embodiment of the present application provides a code stream, which is generated by bit encoding according to information to be encoded; wherein the information to be encoded includes at least one of the following:

The AC coefficient residual values of multiple transformation layers corresponding to the current point cloud, the DC coefficient value of the root node of the current point cloud, the AC coefficient residual values of k transformation layers of the current point cloud are preset values, the AC coefficient residual values of other transformation layers other than the k transformation layers in the current point cloud, the value of the first coding parameter, the value of the second coding parameter and the value of the third coding parameter;

Among them, the first coding parameter is used to indicate whether to perform jump coding on the k transformation layers of the current point cloud, the second coding parameter is used to indicate whether to turn on jump coding of the current point cloud, and the third coding parameter is used to indicate whether to perform jump coding on the k transformation layers of the current point cloud to be processed.

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

A first determining unit is configured to determine a value of a first encoding parameter; when the first encoding parameter indicates that k transformation layers of the current point cloud are to be skip-encoded, one or more AC coefficient residual values of the k transformation layers are determined to be preset values; wherein k is an integer greater than zero;

The encoding unit is configured to encode one or more AC coefficient residual values of k transformation layers according to preset values, and write the obtained encoding bits into the bit stream.

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

A first memory, for storing a computer program that can be run on the first processor;

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

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

The second determination unit is configured to determine a value of the first decoding parameter; when the first decoding parameter indicates to perform skip decoding on k transformation layers of the current point cloud, determine one or more AC coefficient residual values of the k transformation layers to be a preset value; wherein k is an integer greater than zero;

A decoding unit configured to decode the bit stream and determine residual values of AC coefficients of other transform layers other than k transform layers in the current point cloud;

The reconstruction unit is configured to determine the reconstructed point cloud of the current point cloud according to the residual values of the AC coefficients of the k transformation layers and the residual values of the AC coefficients of other transformation layers.

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

A second memory for storing a computer program that can be run on a second processor;

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

In an eighth aspect, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by at least one processor, it implements the method described in the first aspect or the method described in the second aspect.

The embodiment of the present application provides a coding and decoding method, a code stream, an encoder, a decoder, and a storage medium. At the encoding end, the value of the first coding parameter is determined; when the first coding parameter indicates that the k transformation layers of the current point cloud are to be skip-encoded, one or more residual values of the AC coefficients of the k transformation layers are determined to be preset values; one or more residual values of the AC coefficients of the k transformation layers are encoded according to the preset values, and the obtained coded bits are written into the code stream. At the decoding end, the value of the first decoding parameter is determined; when the first decoding parameter indicates that the k transformation layers of the current point cloud are to be skip-decoded, one or more residual values of the AC coefficients of the k transformation layers are determined to be preset values; the code stream is decoded to determine the residual values of the AC coefficients of other transformation layers other than the k transformation layers in the current point cloud; based on the residual values of the AC coefficients of the k transformation layers and the residual values of the AC coefficients of the other transformation layers, the reconstructed point cloud of the current point cloud is determined. That is to say, whether it is the encoding end or the decoding end, when it is determined to skip encoding the k transformation layers of the current point cloud, one or more AC coefficient residual values of these k transformation layers are directly encoded according to the preset values. This can effectively improve the phenomenon of too many 0s in the AC coefficient values of the last few layers of encoding in the RAHT transform, thereby improving the encoding and decoding efficiency, and achieving quality enhancement of the reconstructed point cloud at the average bit rate at the decoding end, thereby 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 partial 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 encoding process;

FIG7A is a schematic diagram of the structure of a current node;

FIG7B is a schematic diagram of the structure of a subnode;

FIG8 is a schematic diagram of a RAHT transformation based on a transformation direction;

FIG9 is a schematic diagram of a RAHT forward transformation process;

FIG10 is a schematic diagram of an inverse transformation process of RAHT;

FIG11 is a schematic diagram of an inter-frame prediction process of RAHT;

FIG12 is a flowchart diagram 1 of a decoding method provided in an embodiment of the present application;

FIG13 is a second flow chart of a decoding method provided in an embodiment of the present application;

FIG14 is a third flow chart of a decoding method provided in an embodiment of the present application;

FIG15 is a fourth flowchart of a decoding method provided in an embodiment of the present application;

FIG16 is a flowchart diagram 5 of a decoding method provided in an embodiment of the present application;

FIG17 is a detailed flowchart of a decoding method provided in an embodiment of the present application;

FIG18 is a flowchart diagram 1 of an encoding method provided in an embodiment of the present application;

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

FIG20 is a third flow chart of an encoding method provided in an embodiment of the present application;

FIG21 is a schematic diagram of a code stream structure of a related technology;

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

FIG23 is a detailed flowchart of an encoding method provided in an embodiment of the present application;

FIG24 is a schematic diagram of the overall flow of a coding and decoding method provided in an embodiment of the present application;

FIG25 is a schematic diagram of the composition structure of an encoder provided in an embodiment of the present application;

FIG26 is a schematic diagram of a specific hardware structure of an encoder provided in an embodiment of the present application;

FIG27 is a schematic diagram of the composition structure of a decoder provided in an embodiment of the present application;

FIG28 is a schematic diagram of a specific hardware structure of a decoder provided in an embodiment of the present application;

FIG. 29 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 in conjunction with 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 those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

In the following description, reference is made to “some embodiments”, which describe 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 in 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.

Before further describing the embodiments of the present application in detail, the nouns and terms involved in the embodiments of the present application are described first. The nouns and terms involved in the embodiments of the present application are subject to the following interpretations:

Geometry-based Point Cloud Compression (G-PCC/GPCC);

Video-based Point Cloud Compression (V-PCC or VPCC);

Level of Detail (LOD);

Region Adaptive Hierarchal Transform (RAHT);

Alternating Current (AC);

Direct Current, DC;

Attribute Parameter Set (APS);

Peak Signal to Noise Ratio (PSNR);

Rate–distortion optimization (RDO);

Rate–distortion optimization Quantization (RDOQ);

Luminance component (Luminance, Luma or Y);

Chroma blue (Cb);

Red chromaticity component (Chroma red, Cr).

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 space that express the spatial structure and surface properties of a three-dimensional object or scene. FIG1A shows a three-dimensional point cloud image and FIG1B shows a partial magnified view of the three-dimensional point cloud image. It can be seen that the point cloud surface is composed of densely distributed points.

Two-dimensional images have information expressed at each pixel point, and the distribution is regular, so there is no need to record its position information additionally; however, the distribution of points in point clouds in three-dimensional space is random and irregular, so it is necessary to record the position of each point in space in order to fully express a point cloud. Similar to two-dimensional images, each position in the acquisition process has corresponding attribute information, usually RGB color values, and the color value reflects the color of the object; for point clouds, in addition to color information, the attribute information corresponding to each point is also commonly the reflectance value, which reflects the surface material of the object. Therefore, point cloud data usually includes the position information of the point and the attribute information of the point. Among them, the position information of the point can also be called the geometric information of the point. For example, the geometric information of the point can be the three-dimensional coordinate information of the point (x, y, z). The attribute information of the point can include color information and/or reflectivity, etc. For example, reflectivity can be one-dimensional reflectivity information (r); color information can be information on any color space, or color information can also be three-dimensional color information, such as RGB information. Here, R represents red (Red, R), G represents green (Green, G), and B represents blue (Blue, B). 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 a point cloud obtained according to the principle of laser measurement, the points in the point cloud may include the three-dimensional coordinate information of the points and the reflectivity value of the points. For another example, for a point cloud obtained according to the principle of photogrammetry, the points in the point cloud may include the three-dimensional coordinate information of the points and the three-dimensional color information of the points. For another example, a point cloud obtained by combining the principles of laser measurement and photogrammetry may include the three-dimensional coordinate information of the points, the reflectivity value of the points and the three-dimensional color information of the points.

As shown in Figure 2A and Figure 2B, a point cloud image and its corresponding data storage format are shown. Figure 2A provides six viewing angles of the point cloud image, and Figure 2B consists of a file header information part and a data part. The header information includes the data format, data representation type, the total number of point cloud points, and the content represented by the point cloud. For example, the point cloud is in the ".ply" format, represented by ASCII code, with a total number of 207242 points, and each point has three-dimensional coordinate information (x, y, z) and three-dimensional color information (r, g, b).

Point clouds can be divided into the following categories according to the way they are obtained:

Static point cloud: the object is stationary, and the device that obtains 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 autonomous navigation systems, real-time inspection systems, geographic information systems, visual sorting robots, disaster relief robots, etc.

Category 2: Point cloud perceived by the human eye, 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. Point clouds are obtained by directly sampling real objects, so 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.

Point clouds can be collected mainly through the following methods: computer generation, 3D laser scanning, 3D photogrammetry, etc. Computers can generate point clouds of virtual three-dimensional objects and scenes; 3D laser scanning can obtain point clouds of static real-world three-dimensional objects or scenes, and can obtain millions of point clouds per second; 3D photogrammetry can obtain point clouds of dynamic real-world three-dimensional objects or scenes, and can obtain tens of millions of point clouds per second. These technologies reduce the cost and time cycle of point cloud data acquisition and improve the accuracy of data. The change in the way point cloud data is acquired makes it possible to acquire a large amount of point cloud data. With the growth of application demand, the processing of massive 3D point cloud data encounters bottlenecks in storage space and transmission bandwidth.

For example, taking a point cloud video with a frame rate of 30 frames per second (fps) as an example, the number of points in each point cloud frame is 700,000, and each point has coordinate information xyz (float) and color information RGB (uchar). The data volume of a 10s point cloud video is about 0.7 million × (4Byte × 3 + 1Byte × 3) × 30fps × 10s = 3.15GB, where 1Byte is 10bit; and a 1280 × 720 two-dimensional video with a YUV sampling format of 4:2:0 and a frame rate of 24fps, the data volume of 10s is about 1280 × 720 × 12bit × 24fps × 10s ≈ 0.33GB, and the data volume of a 10s two-view three-dimensional video is about 0.33 × 2 = 0.66GB. It can be seen that the data volume of a point cloud video far exceeds that of a two-dimensional video and 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 will not only consume a lot of memory, but also be inconvenient for 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.

At present, the point cloud coding framework that can compress point clouds can be 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 cloud and the third type of dynamically acquired point cloud, which can be based on the point cloud compression test platform (Test Model Compression 13, TMC13), and the V-PCC codec framework can be used to compress the second type of dynamic point cloud, which 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.

The 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 point cloud encoding and decoding. 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 takes the G-PCC codec framework as an example to introduce the relevant technologies in detail.

It can be understood that in the point cloud G-PCC encoding and decoding framework, for the point cloud data to be encoded, the point cloud data is first divided into multiple slices by slice division. In each slice, the geometric information of the point cloud and the attribute information corresponding to each point are encoded separately.

FIG4 is a schematic diagram of a composition framework of a G-PCC encoder. As shown in FIG4, in the G-PCC encoding framework, for the code to be encoded The point cloud data is first divided into multiple slices through slice division. In each slice, the geometric information of the point cloud and the attribute information corresponding to each point cloud are encoded separately. In the process of geometric encoding, the coordinate transformation of the geometric information is performed so that all the point clouds are contained in a Bounding Box, and then quantization is performed. This step of quantization mainly plays a role in scaling. Due to the quantization rounding, the geometric information of a part of the point cloud is the same, so it is decided whether to remove duplicate points based on parameters. The process of quantization and removal of duplicate points is also called voxelization. Then the Bounding Box is divided into octrees. In the octree-based geometric information encoding process, the bounding box is divided into 8 sub-cubes in eight equal parts, and the non-empty (containing points in the point cloud) sub-cubes are further divided into eight equal parts until the leaf node obtained by division is a 1×1×1 unit cube. The division is stopped, and the points in the leaf nodes are arithmetically encoded to generate a binary geometric bit stream, that is, a geometric code stream. In the process of geometric information encoding based on triangle soup (Trisoup), octree division must also be performed first. However, unlike the geometric information encoding based on octree, the Trisoup does not need to divide the point cloud into unit cubes with a side length of 1×1×1 step by step. Instead, the division stops when the sub-block (Block) has a side length of 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 used to obtain at most twelve intersections (Vertex). The Vertex is arithmetically encoded (surface fitting is performed based on the intersections) to generate a binary geometric bit stream, i.e., a geometric code stream. Vertex is also used to implement the process of geometric reconstruction, and the reconstructed set information is used when encoding the attributes of the point cloud.

In the attribute encoding process, after the geometric encoding is completed and the geometric information is reconstructed, color conversion is performed to convert the color information (i.e., attribute information) from the RGB color space to the YUV color space. Then, the point cloud is recolored using the reconstructed geometric information so that the unencoded attribute information corresponds to the reconstructed geometric information. Attribute encoding is mainly performed on color information. In the color information encoding process, there are two main transformation methods: one is the distance-based lifting transformation that relies on LOD division, and the other is direct RAHT transformation. Both methods will convert color information from the spatial domain to the frequency domain, and obtain high-frequency coefficients and low-frequency coefficients through transformation. Finally, the coefficients are quantized (i.e., quantized coefficients). Finally, the geometric encoding data after octree division and surface fitting and the attribute encoding data processed by quantization coefficients are sliced and synthesized, and the Vertex coordinates of each Block are encoded in turn (i.e., arithmetic coding) to generate a binary attribute bit stream, i.e., attribute code stream.

FIG5 is a schematic diagram of the composition framework of a G-PCC decoder. As shown in FIG5, in the G-PCC decoding framework, for the acquired binary code stream, the geometric bit stream and the attribute bit stream in the binary code stream are first decoded independently. When decoding the geometric bit stream, the geometric information of the point cloud is obtained through arithmetic decoding-octree synthesis-surface fitting-reconstruction of geometry-inverse coordinate conversion; when decoding the attribute bit stream, the attribute information of the point cloud is obtained through arithmetic decoding-inverse quantization-LOD-based lifting inverse transform or RAHT-based inverse transform-inverse color conversion, and the three-dimensional image model of the point cloud data to be encoded is restored based on the geometric information and attribute information.

It can also be understood that for the RAHT encoding of point cloud attribute information, Figure 6 is a schematic diagram of the RAHT encoding process. As shown in Figure 6, for the original point cloud (or referred to as the "initial point cloud"), intra-frame prediction or inter-frame prediction can be performed. Among them, in the intra-frame prediction process, the original point cloud is upsampled and predicted to obtain a predicted point cloud, and then a RAHT transform is performed to determine the predicted AC coefficient; in the inter-frame prediction process, a reference point cloud can be obtained based on the adjacent frames of the original point cloud, and then a RAHT transform can also determine the predicted AC coefficient. Performing a RAHT transform on the original point cloud can determine the DC coefficient and the original AC coefficient of the root node; subtracting the original AC coefficient from the predicted AC coefficient can obtain a predicted residual, and after quantizing and entropy encoding the predicted residual, an attribute code stream can be generated.

Here, RAHT transform is based on Haar wavelet transform, and its core is to recursively transform the hierarchical tree structure from the root node to the child node from bottom to top, and pass the transformed DC coefficient to the next layer, and the AC coefficient is quantized and encoded. The main encoding process is: first, according to the octree structure divided by the point cloud, determine whether it uses upsampling prediction or inter-frame prediction; secondly, recursively change from the root node to the child node from bottom to top to obtain the AC coefficient of each layer. If there is a prediction, the predicted AC coefficient is subtracted from the original AC coefficient to obtain the current prediction residual; finally, the prediction residual of the AC coefficient is quantized and encoded to generate an attribute code stream.

It can also be understood that in the embodiment of the present application, a video frame can be understood as an image. Exemplarily, the current frame can be understood as the current image, and the reference frame can be understood as the reference image.

In a specific implementation, the detailed steps of RAHT encoding are as follows:

Step 1: RAHT transformation.

The RAHT transformation method adopted by G-PCC first performs a recursive transformation from parent nodes to child nodes along each dimension from bottom to top based on the divided octree structure. The transformation process is obtained by the following formula:

Among them, w _i,j is the weight of the jth node to be transformed in the i-th layer, g _i,j is the attribute value of the leaf node, h _i,j is the AC coefficient, and h _i,j is the DC coefficient. After each transformation, the DC coefficient is directly passed to the next layer, and the AC coefficient is quantized and entropy coded; if there is only one point in the layer, The attribute value of the point is then passed to the next layer as the DC coefficient. For the RAHT transform, Figure 7A is a schematic diagram of the structure of a current node, wherein the cube filled with a grid is the current node, and the cube filled with a diagonal line is the neighbor node of the current node. Figure 7B is a schematic diagram of the structure of a child node, specifically, the small cube filled with dots is the child node of the current node. In addition, Figure 8 is a schematic diagram of a RAHT transform based on the transformation direction. As shown in Figure 8, the black arrow indicates the transformation direction. According to the octree structure, the nodes in each layer are transformed along the dimensions of the transformation direction (for example, the x-axis direction, the y-axis direction, the z-axis direction, etc.) in a bottom-up manner. During the transformation process, the DC coefficient of the nodes in the same layer after transformation will be passed to the next layer, and the AC coefficient of each layer after transformation will be quantized and entropy encoded.

Step 2, upsample prediction.

In order to further remove redundancy and improve the compression efficiency of points, the upsampling prediction method is introduced. The core of upsampling prediction is intra-frame prediction, which uses the attribute information of the encoded points to predict the attribute information of the current point, thereby obtaining the predicted AC coefficient. Then, the prediction residual between the predicted AC coefficient and the original AC coefficient is encoded to achieve the purpose of removing redundancy.

The tree structure of RAHT transformation changes from bottom-up to top-down, and the transformation is still performed in a 2×2×2 block. The attributes of these child nodes are predicted using the reconstructed attribute values of their parent nodes and the coplanar and colinear neighbor nodes of the parent nodes to obtain the predicted attribute values of the child nodes. The original attribute values and predicted attribute values of the child nodes in these blocks are RAHT transformed to obtain the corresponding DC coefficients and AC coefficients, and the AC coefficients obtained by the real attributes are differentiated from the AC coefficients obtained by the predicted attributes to obtain the prediction residuals for quantization and entropy coding. The specific process is shown in Figure 9.

When performing the RAHT inverse transform, the DC coefficient inherits the reconstructed attribute value of the parent node in the previous layer. The AC coefficient residual obtained at the decoding end is accumulated with the predicted AC coefficient obtained by the upsampling predicted attribute value transformation, and then the RAHT inverse transform is performed together with the inherited DC coefficient to obtain the reconstructed attribute value. The specific process is shown in Figure 10.

Step 3: inter-frame prediction.

Inter-frame prediction is to use the information of the already encoded reference image to predict the current image to reduce redundancy. The reference image is divided into an octree structure. After the reference image is transformed by RAHT, the AC coefficients of each reference node are memorized to perform inter-frame prediction for the next frame. In the encoding of the target node, the coefficients of the reference image and the current image are used to calculate the coefficient residual, and the coefficient residual is entropy encoded. The decoder has the same process. Here, the inter-frame prediction process is shown in Figure 11.

Inter prediction is applied only when the current point cloud and the reference point cloud have the same octree partitioning structure and are at the same position node. If there is no prediction coefficient value in the reference buffer, inter prediction is not applied. If there is no corresponding AC coefficient in the reference buffer, inter prediction is not applied.

Step 4, encode coefficient residual and residual RDOQ.

The predicted attribute value of each point in the current 2×2×2 block is obtained through the above intra-frame prediction or inter-frame prediction. The real attribute value and predicted attribute value of the child nodes in these blocks are respectively subjected to RAHT transformation to obtain the corresponding DC coefficient and AC coefficient. For the i-th predicted AC coefficient (k is 8). Let (AC _i ) _i∈1…k-1 be the i-th original AC coefficient (i.e., the true AC coefficient), then the coded AC coefficient residual (r _i ) _i∈0…k-1 is recorded as:

Then, a rate-distortion optimization judgment is performed on the AC coefficient residual. If the rate-distortion cost RDcost of setting the coefficient to 0 is less than the rate-distortion cost RDcost of the original coding, the coefficient is set to 0.

Furthermore, the prediction residual after RDO judgment is quantified:

Among them, _Qi represents the quantized attribute residual of the current point i, and Qs is the quantization step (Quantization step, Qs), which can be calculated by the quantization parameter (Quantization Parameter, QP) specified by CTC.

Step 5: The encoding end reconstructs the attribute value.

The purpose of reconstruction at the encoding end is to predict subsequent points. Before reconstructing the attribute value, the encoded AC residual needs to be dequantized. is the residual after inverse quantization:

and predicted AC coefficient Adding together can get the i-th reconstructed AC coefficient in the current block The details are as follows:

Finally, the AC coefficients are reconstructed The reconstructed attribute value can be obtained by performing an inverse RAHT transform together with the DC coefficient inherited from the parent node in the previous layer.

That is to say, in the relevant technology, RAHT currently calculates, quantizes and encodes layer by layer from the root node to the child node. Since the DC component and its attribute information of each layer are accumulated layer by layer from the leaf node to the root node, the encoded AC coefficient value obtained by the root node transformation is relatively large, and as the number of layers increases, the encoded AC coefficient value obtained by the transformation gradually decreases, so that in the last few layers of the radar point cloud, a large number of 0s appear in the AC coefficients after RDOQ and attribute quantization. According to statistics, the number of 0s in the AC coefficients of the last few layers of the point cloud accounts for more than 95%. However, the number of AC coefficients in the last few layers of the radar point cloud accounts for more than half of all AC coefficients; therefore, the encoding of the AC coefficients of the last few layers will inevitably result in a large waste of code streams.

Based on this, an embodiment of the present application provides an encoding method to determine the value of a first encoding parameter; when the first encoding parameter indicates that the k transformation layers of the current point cloud are to be skip encoded, one or more residual values of the AC coefficients of the k transformation layers are determined to be preset values; one or more residual values of the AC coefficients of the k transformation layers are encoded according to the preset values, and the obtained encoded bits are written into the code stream. An embodiment of the present application also provides a decoding method to determine the value of a first decoding parameter; when the first decoding parameter indicates that the k transformation layers of the current point cloud are to be skip decoded, one or more residual values of the AC coefficients of the k transformation layers are determined to be preset values; the code stream is decoded to determine the residual values of the AC coefficients of other transformation layers other than the k transformation layers in the current point cloud; based on the residual values of the AC coefficients of the k transformation layers and the residual values of the AC coefficients of the other transformation layers, the reconstructed point cloud of the current point cloud is determined.

That is to say, whether it is the encoding end or the decoding end, when it is determined to skip encoding the k transformation layers of the current point cloud, one or more AC coefficient residual values of these k transformation layers are directly encoded according to the preset values. This can effectively improve the phenomenon of too many 0s in the AC coefficient values of the last few layers of encoding in the RAHT transform, thereby improving the encoding and decoding efficiency, and achieving quality enhancement of the reconstructed point cloud at the average bit rate at the decoding end, thereby 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, FIG12 is a flowchart of a decoding method provided by the embodiment of the present application. As shown in FIG12, the method may include:

S1201: Determine a value of a first decoding parameter.

It should be noted that in the embodiment of the present application, the method is applied to a point cloud decoder (hereinafter referred to as "decoder"). Here, a point cloud decoding method is mainly provided, more specifically, a skip decoding method for RAHT transform coefficients, which can improve the phenomenon that too many 0s appear in the last few layers of coded AC coefficient values in RAHT transform.

It should also be noted that, in the embodiment of the present application, for the first decoding parameter, the first decoding parameter can be used to indicate whether to perform jump decoding on the k transform layers of the current point cloud. In some embodiments, if the value of the first decoding parameter is a first value, it is determined that the first decoding parameter indicates that the k transform layers of the current point cloud are to be skipped and decoded; if the value of the first decoding parameter is a second value, it is determined that the first decoding parameter indicates that the k transform layers of the current point cloud are not to be skipped and decoded. Wherein, k is an integer greater than zero.

In some embodiments, for determining the value of the first decoding parameter, the method may include: decoding a bitstream, and determining the value of the first decoding parameter.

It should be noted that, in the embodiment of the present application, the first decoding parameter can be expressed in the form of a syntax element. In this case, the first decoding parameter can be called the first syntax element, represented by flagzero. In other words, in the embodiment of the present application, it can also be: decode the code stream and determine the value of the first syntax element. Among them, the first syntax element can also be used to indicate whether to skip decode the k transform layers of the current point cloud. If the value of the first syntax element is the first value, it is determined that the k transform layers of the current point cloud are skip decoded; if the value of the first syntax element is the second value, it is determined that the k transform layers of the current point cloud are not skip decoded.

It should also be noted that in the embodiment of the present application, the first value is different from the second value. The first value can be set to an integer greater than zero, such as 1, 2, 3, etc.; the second value can be set to 0.

It can be understood that there is an association between the value of k and the first value. In a specific embodiment, the method further includes: when the first decoding parameter indicates to perform skip decoding on k transform layers of the current point cloud, the value of k can be set to be equal to the first value.

It can also be understood that, for a code stream, it may include a geometric code stream unit, an attribute code stream unit, an attribute parameter set (APS) unit, etc. In some embodiments, decoding the code stream and determining the value of the first decoding parameter may include: decoding the attribute code stream unit in the code stream and determining the value of the first decoding parameter. That is, when decoding the code stream, the first decoding parameter is specifically the attribute code stream unit located in the code stream.

S1202, when the first decoding parameter indicates to skip decoding the k transformation layers of the current point cloud, determine that one or more AC coefficient residual values of the k transformation layers are preset values.

It should be noted that, in the embodiment of the present application, the preset value can be set to 0. In this way, if it is determined to perform skip decoding on the k transformation layers of the current point cloud, then one or more AC coefficient residual values of the k transformation layers can be restored to 0 at this time.

It should also be noted that, in the embodiment of the present application, k is an integer greater than 0. When determining to perform skip decoding on k transform layers of the current point cloud, the value of k can be set to be equal to the first value of the determined first decoding parameter, or the first value of the first syntax element.

That is to say, for decoding the first decoding parameter, if the first value of the first decoding parameter is k, then it can be determined that the k transform layers of the current point cloud will be skip decoded; if the second value of the first decoding parameter is 0, then it can be determined that the k transform layers of the current point cloud will not be skip decoded, that is, at this time it is necessary to decode the AC coefficient residual values of all transform layers of the current point cloud.

In some embodiments, the method may further include: decoding the bitstream, and determining that one or more residual values of the AC coefficients of the k transform layers are preset values. That is, in the embodiment of the present application, for one or more residual values of the AC coefficients of the k transform layers, the bitstream is written according to the preset values. In this way, the decoding end also needs to decode the bitstream to determine that one or more residual values of the AC coefficients of the k transform layers are preset values.

In some embodiments, the method may further include: determining that all AC coefficient residual values of k transformation layers are preset values. That is, in an embodiment of the present application, for determining one or more AC coefficient residual values of k transformation layers, when determining to jump decode the k transformation layers of the current point cloud, it is also possible to determine that all AC coefficient residual values of the k transformation layers are preset values.

In some embodiments, the method may further include: dividing the points in the current point cloud into layers, determining multiple transformation layers corresponding to the current point cloud and the root node of the current point cloud; wherein the multiple transformation layers include k transformation layers and other transformation layers.

It should be noted that in the embodiment of the present application, the points in the current point cloud can be divided into layers based on the octree structure to obtain multiple transformation layers. Specifically, for the divided octree structure, each layer can be transformed from the root node to the child node from top to bottom.

It should also be noted that, in practical applications, in the last few layers of the current point cloud, the number of residual values of the AC coefficients in these layers that are 0 accounts for more than 95%. In order to improve the encoding and decoding efficiency, in some embodiments, the method may also include: setting the k transformation layers to be the last k transformation layers from the root node from top to bottom in the multiple transformation layers.

That is to say, here it is mainly about whether to perform skip decoding on the last k transform layers of the current point cloud. For example, when the first decoding parameter indicates to perform skip decoding on the last k transform layers of the current point cloud, then one or more AC coefficient residual values of the last k transform layers can be restored to 0, thereby improving the encoding and decoding efficiency.

S1203, decoding the code stream, and determining the residual values of the AC coefficients of other transformation layers other than the k transformation layers in the current point cloud.

S1204, determining a reconstructed point cloud of the current point cloud according to the AC coefficient residual values of k transformation layers and the AC coefficient residual values of other transformation layers.

It should be noted that, in the embodiment of the present application, the AC coefficient residual value is located in the attribute code stream unit of the code stream. In some embodiments, the method may include: decoding the attribute code stream unit in the code stream to determine the AC coefficient residual value of other transform layers.

It should also be noted that, in the embodiment of the present application, the multiple transformation layers corresponding to the current point cloud may include k transformation layers and other transformation layers except the k transformation layers. In this way, the reconstructed point cloud of the current point cloud is determined according to the residual values of the AC coefficients of the k transformation layers and the residual values of the AC coefficients of the other transformation layers, that is, according to the residual values of the AC coefficients of the multiple transformation layers.

In some embodiments, referring to FIG. 13 , after step S1201, the method may further include:

S1301, when the first decoding parameter indicates that the k transform layers of the current point cloud are not to be skip-decoded, decode the bitstream to determine the residual values of the AC coefficients of the multiple transform layers corresponding to the current point cloud.

S1302, determining a reconstructed point cloud of the current point cloud according to the AC coefficient residual values of multiple transformation layers.

It should be noted that, in the embodiment of the present application, if the k transform layers of the current point cloud are not skip-decoded, it can be said that the multiple transform layers corresponding to the current point cloud all need to decode their respective AC coefficient residual values. In some embodiments, the method may also include: decoding the attribute code stream unit in the code stream to determine the AC coefficient residual values of the multiple transform layers.

That is, in the embodiment of the present application, the first decoding parameter and the AC coefficient residual value are both located in the attribute code stream unit of the code stream. Specifically, in some embodiments, the method may also include: in the attribute code stream unit, determining that the field corresponding to the first decoding parameter is located after the field corresponding to the AC coefficient residual value.

In this way, the decoding end first decodes the value of the first decoding parameter to determine the number of transformation layers of the AC coefficient residual value that needs to be decoded, and then decodes the AC coefficient residual value that needs to be decoded according to the indication of the first decoding parameter, and restores the AC coefficient residual values of the k transformation layers for performing jump decoding to 0.

In some embodiments, the method may further include: decoding the code stream and determining the DC coefficient value of the root node of the current point cloud.

It should be noted that, in the embodiment of the present application, only the DC coefficient value of the root node needs to be written into the bitstream. In some embodiments, the method may also include: decoding the attribute bitstream unit in the bitstream to determine the DC coefficient value of the root node of the current point cloud.

It should also be noted that in the embodiment of the present application, for multiple transformation layers, the DC coefficient value can be directly passed to the next layer at each transformation, but the AC coefficient value needs to be residually calculated, and the AC coefficient residual value of each layer needs to be quantized and entropy encoded. In addition, if a certain transformation layer has only one point, the attribute value of the point can be directly passed to the next layer as the DC coefficient value.

In some embodiments, the method further includes: saving the DC coefficient value of the root node to the first parameter matrix of the current point cloud. In addition, the method may further include: saving the residual values of the AC coefficients of k transformation layers and the residual values of the AC coefficients of other transformation layers to the first parameter matrix of the current point cloud. In other words, the residual values of the AC coefficients of multiple transformation layers may be saved to the first parameter matrix of the current point cloud.

In the embodiment of the present application, the decoding end parses the bitstream and first decodes the first decoding parameter at the end of the bitstream. If the decoded value of the first decoding parameter is k, the residual values of the AC coefficients of the k transform layers are all decoded as 0, and the residual values of the AC coefficients of other transform layers are decoded normally and stored in the first parameter matrix; if the decoded value of the first decoding parameter is 0, all the residual values of the AC coefficients of multiple transform layers are decoded and stored in the first parameter matrix. It should be noted that in the process of decoding the residual values of the AC coefficients, the DC coefficient value of the decoded root node will also be stored in the first parameter matrix.

In some embodiments, the method may further include: performing inverse quantization processing on parameter values in the first parameter matrix of the current point cloud.

That is to say, in the embodiment of the present application, before performing the RAHT inverse transform, both the DC coefficient values and the AC coefficient residual values in the first parameter matrix need to be dequantized.

In some embodiments, for determining a reconstructed point cloud of a current point cloud, referring to FIG. 14 , the method may include:

S1401, determine attribute prediction values of points in multiple transformation layers.

S1402, performing region-adaptive hierarchical transformation on the attribute prediction values of the points in the multiple transformation layers to determine the AC coefficient prediction values of the points in the multiple transformation layers.

S1403, determining a second parameter matrix of the current point cloud according to the first parameter matrix of the current point cloud and the predicted values of the AC coefficients of the points in the multiple transformation layers.

S1404, performing a region-adaptive hierarchical inverse transform on the second parameter matrix of the current point cloud to determine a reconstructed point cloud of the current point cloud.

It should be noted that, in the embodiment of the present application, the reconstructed point cloud of the current point cloud can be determined by: determining the predicted values of the AC coefficients of the points in multiple transformation layers; then determining the second parameter matrix of the current point cloud based on the first parameter matrix of the current point cloud and the predicted values of the AC coefficients of the points in multiple transformation layers; and then performing a regional adaptive hierarchical inverse transformation on the second parameter matrix of the current point cloud to determine the reconstructed point cloud of the current point cloud. Among them, the DC coefficient can also be called the low-frequency coefficient, represented by the DC coefficient; the AC coefficient can also be called the high-frequency coefficient, represented by the AC coefficient.

It should also be noted that in the embodiments of the present application, in order to determine the AC coefficient prediction values of points in multiple transformation layers, it is first necessary to determine the attribute prediction values of points in the current point cloud. In some embodiments, the method may include: when the current point cloud allows the use of intra-frame prediction, intra-frame prediction is performed on the points in multiple transformation layers to determine the attribute prediction values of the points in the multiple transformation layers; when the current point cloud allows the use of inter-frame prediction, a reference point cloud of the current point cloud is determined, and inter-frame prediction is performed on the points in multiple transformation layers based on the reference point cloud to determine the attribute prediction values of the points in the multiple transformation layers.

In this way, after determining the attribute prediction values of points in multiple transformation layers, the corresponding AC coefficient prediction values can be determined based on the regional adaptive hierarchical transformation. The regional adaptive hierarchical transformation can be represented by T _node . The corresponding attribute transformation formula is as follows:

In some embodiments, the second parameter matrix of the current point cloud is determined based on the first parameter matrix of the current point cloud and the AC coefficient prediction values of the points in the multiple transformation layers. Taking the current transformation layer among the multiple transformation layers as an example, the method may include: determining the AC coefficient residual values of the points of the current transformation layer in the first parameter matrix based on the points of the current transformation layer in the current point cloud, and determining the AC coefficient prediction values of the points of the current transformation layer; adding the AC coefficient residual values and the AC coefficient prediction values to obtain the AC coefficient reconstruction values of the points of the current transformation layer; after obtaining the AC coefficient reconstruction values of the points of the multiple transformation layers, determining the second parameter matrix of the current point cloud based on the DC coefficient value of the root node and the AC coefficient reconstruction values of the points of the multiple transformation layers.

For example, taking the dth transformation layer as an example, the dth transformation layer includes m nodes. The first parameter matrix can be expressed as The predicted value of the AC coefficient can be expressed as The second parameter matrix can be expressed as In this way, according to the first parameter matrix of the current point cloud and the predicted values of the AC coefficients of the points in the multiple transformation layers, the second parameter matrix of the current point cloud is determined. Specifically, the first parameter matrix of the current point cloud and the predicted values of the AC coefficients of the points in the multiple transformation layers are added to determine the second parameter matrix of the current point cloud, as shown below:

In some embodiments, a regional adaptive hierarchical inverse transform is performed on the second parameter matrix of the current point cloud to determine a reconstructed point cloud of the current point cloud. The method may include: when the current transformation layer is the first transformation layer, a regional adaptive hierarchical inverse transform is performed based on the DC coefficient value of the root node and the AC coefficient reconstruction value of the points of the current transformation layer to obtain the reconstructed attribute values of the points of the first transformation layer; when the current transformation layer is not the first transformation layer, the DC coefficient value of the points of the current transformation layer is determined based on the reconstructed attribute values of the points of the previous transformation layer of the current transformation layer, and a regional adaptive hierarchical inverse transform is performed based on the DC coefficient value of the points of the current transformation layer and the AC coefficient reconstruction value of the points of the current transformation layer to obtain the reconstructed attribute values of the points of the non-first transformation layer.

It should be noted that in the embodiment of the present application, the decoding process is still carried out from top to bottom. First, the DC coefficient value of the root node and the residual value of the AC coefficient of the first layer are obtained, and the RAHT inverse transform is performed to obtain the reconstructed attribute value of the first layer; if the configuration allows intra-frame prediction or inter-frame prediction, the AC coefficient residual value of the first layer is first added to the predicted AC coefficient value to obtain the reconstructed AC coefficient value, and the obtained reconstructed AC coefficient value and the DC coefficient value of the root node are subjected to the RAHT inverse transform to obtain the reconstructed attribute value of the first layer. Then the obtained 8 reconstructed attribute values can be used to calculate the DC coefficients of the 8 nodes of the second layer, and then the decoded AC coefficient residual value of the second layer is added to the predicted AC coefficient value to obtain the reconstructed AC coefficient value of the second layer; the reconstructed AC coefficient value of the second layer is subjected to the RAHT inverse transform together with the DC coefficient value to obtain the reconstructed attribute value of the third layer, and so on, until all transformation layers are fully decoded.

Exemplarily, still taking the dth transformation layer as an example, the reconstruction property value of the dth transformation layer can be expressed as The regional adaptive hierarchical inverse transformation can be represented by T _node ^-1 . The corresponding attribute inverse transformation formula is as follows:

In some embodiments, based on the decoding method shown in FIG. 12 , referring to FIG. 15 , step S1201 may include:

S1501: Determine a value of a second decoding parameter.

S1502, when the second decoding parameter indicates to start skip decoding of the current point cloud, determine the value of the first decoding parameter.

It should be noted that in the embodiment of the present application, for the second decoding parameter, the second decoding parameter can be used to indicate whether to enable the jump decoding of the current point cloud, that is, to indicate whether the technical solution of the embodiment of the present application is enabled. In some embodiments, if the value of the second decoding parameter is the third value, it is determined that the second decoding parameter indicates to enable the jump decoding of the current point cloud; if the value of the second decoding parameter is the fourth value, it is determined that the second decoding parameter indicates not to enable the jump decoding of the current point cloud.

In some embodiments, for determining the value of the second decoding parameter, the method may include: decoding a bitstream, and determining the value of the second decoding parameter.

It should be noted that, in the embodiment of the present application, the method may further include: decoding the attribute parameter set unit in the code stream to determine the value of the second decoding parameter. That is, when decoding the code stream, the second decoding parameter is specifically the attribute parameter set unit in the code stream.

It should also be noted that, in the embodiment of the present application, the second decoding parameter can be expressed in the form of a syntax element. In this case, the second decoding parameter can be called a second syntax element, represented by skip_raht_enabled_flag. In other words, in the embodiment of the present application, it can also be: decode the code stream and determine the value of the second syntax element. Among them, the second syntax element can also be used to indicate whether to enable skip decoding of the current point cloud, that is, to indicate whether the technical solution of the embodiment of the present application is enabled. In some embodiments, if the value of the second syntax element is the third value, it is determined that the second syntax element indicates that skip decoding of the current point cloud is enabled; if the value of the second syntax element is the fourth value, it is determined that the second syntax element indicates that skip decoding of the current point cloud is not enabled.

It should also be noted that in the embodiment of the present application, the third value is different from the fourth value. The third value can be set to 1 and the fourth value can be set to 0; or, the third value can be set to 0 and the fourth value can be set to 1; or, the third value can be set to true (true) and the fourth value can be set to false (false); or, the third value can be set to false (false) and the fourth value can be set to true (true). In a specific embodiment, the third value is set to 1 and the fourth value is set to 0, but this is not limited to any limitation.

In some embodiments, referring to FIG. 16 , the method may further include:

S1601, decoding a bitstream and determining a value of a third decoding parameter.

S1602: When the third decoding parameter indicates to skip decoding the components to be processed of the k transform layers of the current point cloud, determine that one or more AC coefficient residual values of the components to be processed of the k transform layers are preset values.

S1603, decoding the code stream, and determining the AC coefficient residual values of the components to be processed in other transformation layers other than the k transformation layers in the current point cloud.

S1604, determining the reconstructed point cloud of the to-be-processed component of the current point cloud according to the AC coefficient residual values of the to-be-processed components of k transformation layers and the AC coefficient residual values of the to-be-processed components of other transformation layers.

It should be noted that, in the embodiment of the present application, the component to be processed may include at least one of the first color component, the second color component and the third color component.

It should also be noted that, in an embodiment of the present application, the third decoding parameter can be expressed in the form of a syntax element, and the third decoding parameter can be referred to as a third syntax element. Among them, when the component to be processed is the first color component (for example, the Y component), it can be represented by flag_Y at this time to indicate whether the Y component of the k transform layers of the current point cloud is skip-decoded; when the component to be processed is the second color component (for example, the U component), it can be represented by flag_U at this time to indicate whether the U component of the k transform layers of the current point cloud is skip-decoded; when the component to be processed is the third color component (for example, the V component), it can be represented by flag_V at this time to indicate whether the V component of the k transform layers of the current point cloud is skip-decoded. That is to say, in the color attributes of the dense point cloud, it can be extended to three channels and use the skip decoding mode for RAHT transform coefficients at the same time. At this time, for the third coding parameter, three flags flag_Y, flag_U, and flag_V can be set to record the number of coefficient layers for skip decoding respectively.

In a specific embodiment, FIG17 is a detailed flowchart of a decoding method provided by an embodiment of the present application. As shown in FIG17, in the attribute code stream, the first decoding parameter (flag bit flag) is first decoded. If flag = 0, then it is necessary to decode the DC and all AC coefficients (specifically, the DC coefficient value and all AC coefficient residual values); if flag = k, then it is necessary to decode the coefficients (specifically, the DC coefficient value and the AC coefficient residual value of other layers, and the last k layer is decoded as 0); and then dequantize these coefficients. When prediction is allowed, the AC coefficient prediction value can be determined based on intra-frame prediction or inter-frame prediction, and then the AC coefficient reconstruction value can be determined based on the AC coefficient prediction value and the dequantized AC coefficient residual value. After the AC coefficient reconstruction value is subjected to RAHT inverse transform, To obtain the corresponding reconstructed attribute value.

In the embodiment of the present application, the specific implementation of the program on the decoding end is as follows. First, the flag .skip_raht_enabled_flag is decoded in the attribute parameter set APS. This flag determines whether the technical solution of the embodiment of the present application is turned on; if it is true, the flag flag in the attribute code stream is first decoded in the code stream and transmitted to the RAHT sub-function. If the decoded flag value is k, the residual value of the AC coefficient of the last k layers of RAHT is restored according to the value of 0 for the next attribute reconstruction; if the decoded flag value is 0, the residual value of the AC coefficient of all layers of RAHT is restored according to the original coding value. Here, the residual value of the AC coefficient is stored in the parameter matrix transformPredBuf.

The embodiment of the present application provides a decoding method, which determines the value of a first decoding parameter; when the first decoding parameter indicates that the k transform layers of the current point cloud are to be skip decoded, determines that one or more residual values of the AC coefficients of the k transform layers are preset values; decodes the code stream to determine the residual values of the AC coefficients of other transform layers other than the k transform layers in the current point cloud; and determines the reconstructed point cloud of the current point cloud based on the residual values of the AC coefficients of the k transform layers and the residual values of the AC coefficients of other transform layers. In this way, when it is determined that the k transform layers of the current point cloud are to be skip encoded, one or more residual values of the AC coefficients of the k transform layers are directly decoded according to the preset values, which can effectively improve the phenomenon that too many 0s appear in the residual values of the AC coefficients of the last few layers in the RAHT transform, thereby improving the encoding and decoding efficiency, and using a flag to record whether the skip decoding operation is performed and on which layers it is performed, thereby improving the reconstruction quality at the average bit rate, and thus improving the encoding and decoding performance of the point cloud.

In another embodiment of the present application, FIG18 is a flow chart of a coding method provided in an embodiment of the present application. As shown in FIG18 , the method may include:

S1801, determine the value of the first encoding parameter.

It should be noted that in the embodiment of the present application, the method is applied to a point cloud encoder (hereinafter referred to as "encoder"). Here, a point cloud encoding method is mainly provided, more specifically, a skip encoding method for RAHT transform coefficients, which can improve the phenomenon that too many 0s appear in the last few layers of encoded AC coefficient values in RAHT transform.

It should also be noted that, in the embodiment of the present application, for the first encoding parameter, the first encoding parameter can be used to indicate whether to perform skip encoding on the k transformation layers of the current point cloud. In some embodiments, referring to FIG. 19 , the method may include:

S1901, determining a first generation value for encoding all AC coefficient residual values of k transformation layers, and determining a second generation value for encoding one or more AC coefficient residual values of k transformation layers according to a preset value.

S1902: If the first generation value is greater than the second generation value, determine that the value of the first encoding parameter is the first value.

S1903: If the first generation value is less than the second generation value, determine that the value of the first encoding parameter is the second value.

It should be noted that in the embodiment of the present application, after the first generation value and the second generation value are determined, the value of the first encoding parameter can be determined according to the first generation value and the second generation value. Or it can be said that it is determined whether to perform jump encoding on the k transformation layers of the current point cloud according to the first generation value and the second generation value. Where k is an integer greater than zero.

It should also be noted that, in the embodiments of the present application, the cost value here can be determined according to the cost result of Rate-Distortion Optimization (RDO), or according to the cost result of Sum of Absolute Difference (SAD), or even according to the cost result of Sum of Absolute Transformed Difference (SATD), but no limitation is made here.

Understandably, in the field of video coding, the bit rate and distortion after coding are in a contradictory relationship. If you want to obtain a higher quality reconstructed video with less distortion, you need to increase the transmission bit rate; however, the bit rate cannot be increased indefinitely. In some cases, you need to reduce the bit rate to ensure the smoothness of video transmission. In order to better improve the efficiency of coding, it is necessary to comprehensively consider the bit rate and distortion and find a compromise between the two so that the distortion is as small as possible under the condition of a fixed bit rate. The formula can be expressed as:

Where D represents distortion, R represents bit rate, Represents the conditional parameter configuration of the encoding, such as the quantization step size, etc. Formula (11) is a constrained optimization problem, which can be transformed into the following form using Lagrange multipliers:

Among them, RDcost is the rate-distortion cost, and λ is the Lagrange multiplier. This is the rate-distortion optimization problem in the field of video coding.

In the embodiment of the present application, it is proposed to calculate the RDOcost of the m-layer, m-1-layer...AC coefficient residual values of the current point cloud multi-parameters without encoding, and the RDOcost of the coefficient residual values with all encoded values, and compare them to decide whether to encode these coefficient residual values to improve the encoding efficiency. Since the RDcost calculation is inconvenient, the method of calculating ΔRDcost can be adopted. Taking the k-layer as an example, the calculation formula is as follows:

ΔR＝R _org -1 (14)
ΔRDcost＝ΔD-λ·ΔR (15)

Among them, ΔD can be represented by the square value of all AC coefficient residual values of k transform layers, which is used to refer to the distortion cost after all these coefficient residual values are not encoded, _Rorg is the bitstream consumption in the coding scheme of the related technology, and the bitrate consumption after all the AC coefficient residual values of k transform layers are not encoded is only 1 bit occupied by the first syntax element (flag bit flag), so ΔR represents the difference in bitrate consumption between not encoding and encoding the residual values of k transform layers AC coefficients, that is, the bitstream saved by not encoding the residual values of k transform layers AC coefficients. At this time, if the calculated ΔRDcost is greater than 0, it means that the distortion cost of not encoding is large, and the flag bit flag is set to 0; if the calculated ΔRDcost is less than 0, it means that the bitrate saving of not encoding is large, and it is necessary to continue to compare the ΔRDcost of other transform layers to decide whether to set the flag bit flag to k.

The Lagrange multiplier λ is selected in the form of H.266/VCC video coding, as shown in the following formula:

Where c is a constant and QP is a quantization step size. The values of c are selected as 0.01, 0.1, 0.2, 0.3, and 0.4, and the attribute compression performance of the test point cloud under the C1 condition is selected to analyze and find the optimal interval of c. The search step size is further reduced, and the optimal value of the constant c is finally determined to be 0.12.

Here, taking the rate-distortion optimization method as an example, for determining the first generation value for encoding all the residual values of the AC coefficients of the k transform layers, the cost of encoding all the residual values of the AC coefficients of the k transform layers using the rate-distortion optimization method can be calculated to obtain the first generation value. For determining the second generation value for encoding one or more residual values of the AC coefficients of the k transform layers according to the preset value, the cost of encoding one or more residual values of the AC coefficients of the k transform layers according to the preset value can be calculated to obtain the second generation value.

In one possible implementation, for determining whether to perform skip encoding on the k transformation layers of the current point cloud, the method may include: if the first generation value is greater than the second generation value, determining to perform skip encoding on the k transformation layers of the current point cloud; if the first generation value is less than the second generation value, determining not to perform skip encoding on the k transformation layers of the current point cloud.

In another possible implementation, for determining whether to skip encode the k transform layers of the current point cloud, the method may include: if the value of the first encoding parameter is a first value, determining that the first encoding parameter indicates that skip encoding is to be performed on the k transform layers of the current point cloud; if the value of the first encoding parameter is a second value, determining that the first encoding parameter indicates that no skip encoding is to be performed on the k transform layers of the current point cloud.

It should be noted that, in an embodiment of the present application, the first coding parameter can be expressed in the form of a syntax element. In this case, the first coding parameter can be called a first syntax element, represented by flagzero. Among them, the first syntax element can also be used to indicate whether to skip-code the k transform layers of the current point cloud. In some embodiments, the method may also include: determining a first generation value for encoding all AC coefficient residual values of the k transform layers, and determining a second generation value for encoding one or more AC coefficient residual values of the k transform layers according to a preset value; determining the value of the first syntax element based on the first generation value and the second generation value.

In a possible implementation, the method may further include: if the first generation value is greater than the second generation value, determining that the first syntax element indicates that the k transform layers of the current point cloud are skip encoded; if the first generation value is less than the second generation value, determining that the first syntax element indicates that the k transform layers of the current point cloud are not skip encoded.

In this implementation, for determining the value of the first syntax element, the method may include: if the k transform layers of the current point cloud are skip-coded, then determining the value of the first syntax element to be the first value; if the k transform layers of the current point cloud are not skip-coded, then Determine that a value of the first syntax element is a second value.

It should also be noted that, for the case where the first-generation value is equal to the second-generation value, it can be processed with reference to the case where the first-generation value is greater than the second-generation value, such as determining to skip encoding the k transformation layers of the current point cloud; or, it can be processed with reference to the case where the first-generation value is less than the second-generation value, such as determining not to skip encoding the k transformation layers of the current point cloud. No limitation is made here.

In some embodiments, the method may further include: performing encoding processing on the value of the first encoding parameter, and writing the obtained encoding bits into a bit stream.

It can be understood that, for a code stream, it may include a geometric code stream unit, an attribute code stream unit, an attribute parameter set (APS) unit, etc. In some embodiments, encoding the value of the first encoding parameter and writing the obtained encoding bits into the code stream may include: encoding the value of the first encoding parameter and writing the obtained encoding bits into the attribute code stream unit in the code stream. That is, the first encoding parameter is specifically an attribute code stream unit in the code stream.

It should be noted that in the embodiment of the present application, the first value is different from the second value. The first value can be set to an integer greater than zero, such as 1, 2, 3, etc.; the second value can be set to 0.

It should also be noted that there is an association between the value of k and the first value. In a specific embodiment, the method further includes: when the first encoding parameter indicates skip encoding of k transformation layers of the current point cloud, the first value can be set to be equal to the value of k.

In some embodiments, for the value of k, referring to FIG. 20 , the method may include:

S2001, determining a third generation value for encoding all AC coefficient residual values of m transformation layers, and determining a fourth generation value for encoding one or more AC coefficient residual values of m transformation layers according to a preset value.

S2002, when the third generation value is greater than the fourth generation value, determine the fifth generation value of the i transformation layers of the current point cloud encoded according to the preset value, where i = 1, 2, ..., m, m is an integer greater than zero.

S2003, after obtaining m fifth-generation values, determine the minimum value from the m fifth-generation values.

S2004, determining the value of k according to the value of i corresponding to the minimum cost value.

It should be noted that, in the embodiment of the present application, still taking the rate-distortion optimization method as an example, for determining the third generation value for encoding all the residual values of the AC coefficients of the m transform layers, the cost of encoding all the residual values of the AC coefficients of the m transform layers using the rate-distortion optimization method can be calculated to obtain the third generation value. For determining the fourth generation value for encoding one or more residual values of the AC coefficients of the m transform layers according to the preset value, the cost of encoding one or more residual values of the AC coefficients of the m transform layers according to the preset value can be calculated to obtain the fourth generation value.

It should also be noted that when it is determined based on the third-generation value and the fourth-generation value that one or more AC coefficient residual values of m transform layers are skip-coded, the value of k can be further determined, that is, one or more AC coefficient residual values of several transform layers are skip-coded. Here, the RDOcost of the AC coefficient residual values of m layers, m-1 layers, ..., 2 layers, and 1 layer that are not coded can be determined, and then the minimum RDOcost value is selected therefrom, and the number of layers corresponding to the minimum RDOcost value is determined as the value of k.

It should be noted that, for the case where the third-generation value is equal to the fourth-generation value, reference can be made to the case where the third-generation value is greater than the fourth-generation value, that is, the fifth-generation value of the i (i=1,2,...,m) transformation layers of the current point cloud encoded according to the preset value is determined, so as to further determine the jump encoding of the k transformation layers of the current point cloud; or, reference can be made to the case where the third-generation value is less than the fourth-generation value, that is, the step of encoding all the AC coefficient residual values of the current point cloud is executed, and no limitation is made here.

S1802, when the first encoding parameter indicates to skip encode the k transformation layers of the current point cloud, determine that one or more AC coefficient residual values of the k transformation layers are preset values.

It should be noted that, in the embodiment of the present application, the preset value can be set to 0. In this way, if it is determined to perform skip encoding on the k transformation layers of the current point cloud, then one or more AC coefficient residual values of the k transformation layers can be encoded as 0 at this time.

It should also be noted that, in the embodiment of the present application, k is an integer greater than 0. When determining to perform skip encoding on k transformation layers of the current point cloud, the value of the first encoding parameter may be set equal to the value of k.

That is to say, for the first coding parameter, if the first value of the first coding parameter is k, then it can be determined that the k transformation layers of the current point cloud are skipped and encoded; if the second value of the first coding parameter is 0, then it can be determined that the k transformation layers of the current point cloud are not skipped and encoded, that is, at this time, the residual values of the AC coefficients of all the transformation layers of the current point cloud need to be encoded.

In some embodiments, the method may further include: encoding one or more AC coefficient residual values of k transform layers according to preset values, and writing the obtained coded bits into the bitstream. That is, in the embodiment of the present application, for one or more AC coefficient residual values of k transform layers, the bitstream is written according to the preset values. In this way, the decoding end also needs to decode the bitstream to determine that one or more AC coefficient residual values of k transform layers are the preset values.

In some embodiments, the method may further include: determining that all AC coefficient residual values of k transform layers are preset values. That is, in the embodiment of the present application, for determining one or more AC coefficient residual values of k transform layers, when determining to skip-code the k transform layers of the current point cloud, all AC coefficient residual values of the k transform layers may also be determined as preset values.

In some embodiments, the method may further include: dividing the points in the current point cloud into layers, determining multiple transformation layers corresponding to the current point cloud and the root node of the current point cloud; wherein the multiple transformation layers include k transformation layers and other transformation layers.

It should be noted that in the embodiment of the present application, the points in the current point cloud can be divided into layers based on the octree structure to obtain multiple transformation layers. Specifically, for the divided octree structure, each layer can be transformed from the root node to the child node from top to bottom.

It should also be noted that, in practical applications, in the last few layers of the current point cloud, the number of AC coefficient residual values in these layers that are 0 accounts for more than 95%. In order to improve coding efficiency, in some embodiments, the method may also include: setting the k transformation layers to be the last k transformation layers from the root node from top to bottom in the multiple transformation layers.

That is to say, here it is mainly about whether to skip code the last k transformation layers of the current point cloud. For example, when the first coding parameter indicates to skip code the last k transformation layers of the current point cloud, then one or more AC coefficient residual values of the last k transformation layers can be directly coded as 0, thereby improving coding efficiency.

S1803, performing encoding processing on one or more AC coefficient residual values of k transformation layers according to preset values, and writing the obtained encoding bits into the bit stream.

It should be noted that, in the embodiment of the present application, the AC coefficient residual value is located in the attribute code stream unit of the code stream. In some embodiments, the method may include: encoding one or more AC coefficient residual values of k transform layers according to preset values, and writing the obtained encoding bits into the attribute code stream unit in the code stream.

It should also be noted that, in an embodiment of the present application, the multiple transformation layers corresponding to the current point cloud may include k transformation layers and other transformation layers except the k transformation layers. In this way, except for the k transformation layers, the residual values of the AC coefficients of other transformation layers need to be encoded normally. In some embodiments, the method may also include: when the first encoding parameter indicates that the k transformation layers of the current point cloud are to be skipped, determining the residual values of the AC coefficients of other transformation layers except the k transformation layers in the multiple transformation layers; encoding the residual values of the AC coefficients of other transformation layers, and writing the obtained encoding bits into the bitstream.

In a specific embodiment, encoding the AC coefficient residual values of other transformation layers and writing the obtained coded bits into the bitstream may include: encoding the AC coefficient residual values of other transformation layers and writing the obtained coded bits into the attribute bitstream unit in the bitstream.

In some embodiments, the method may further include: determining AC coefficient prediction values of points in multiple transformation layers; determining AC coefficient residual values of multiple transformation layers based on the AC coefficient initial values of points in multiple transformation layers and the AC coefficient prediction values of points in multiple transformation layers.

It should be noted that, in an embodiment of the present application, the method also includes: determining the initial values of the attributes of points in multiple transformation layers; performing regional adaptive hierarchical transformation on the initial values of the attributes of points in multiple transformation layers, and determining the initial values of the AC coefficients of the points in multiple transformation layers and the DC coefficient value of the root node.

Here, the DC coefficient can also be called a low-frequency coefficient and is represented by a DC coefficient; the AC coefficient can also be called a high-frequency coefficient and is represented by an AC coefficient. For example, taking the dth transformation layer as an example, the dth transformation layer includes m nodes. The regional adaptive hierarchical transformation can be represented by T _node . For the initial value of the attribute, the corresponding attribute transformation formula is as follows:

It should also be noted that, in an embodiment of the present application, the method also includes: determining the attribute prediction values of points in multiple transformation layers; performing regional adaptive hierarchical transformation on the attribute prediction values of points in multiple transformation layers to determine the AC coefficient prediction values of points in multiple transformation layers.

Here, the attribute prediction values of points in multiple transform layers can be determined based on intra-frame prediction or inter-frame prediction. In some embodiments, the method may include: when the current point cloud allows the use of intra-frame prediction, intra-frame prediction is performed on the points in multiple transform layers to determine the attribute prediction values of the points in the multiple transform layers; when the current point cloud allows the use of inter-frame prediction, a reference point cloud of the current point cloud is determined, and inter-frame prediction is performed on the points in multiple transform layers based on the reference point cloud to determine the attribute prediction values of the points in the multiple transform layers.

In this way, after determining the attribute prediction values of points in multiple transformation layers, the corresponding AC coefficient prediction values can be determined based on the regional adaptive hierarchical transformation. The regional adaptive hierarchical transformation can be represented by T _node . The corresponding attribute transformation formula is as follows:

In some embodiments, determining AC coefficient residual values of multiple transformation layers based on AC coefficient initial values of points in multiple transformation layers and AC coefficient predicted values of points in multiple transformation layers can include: performing subtraction operations on the AC coefficient initial values of points in multiple transformation layers and the AC coefficient predicted values of points in multiple transformation layers to obtain AC coefficient prediction residuals of points in multiple transformation layers; and quantizing the AC coefficient prediction residuals of points in multiple transformation layers to obtain AC coefficient residual values of multiple transformation layers.

For example, taking the dth transformation layer as an example, the dth transformation layer includes m nodes. For the AC coefficient prediction residuals of points in multiple transformation layers, it can be obtained by subtracting the initial value of the AC coefficient from the predicted value of the AC coefficient, as shown below:

In some embodiments, the method may further include: when the first coding parameter indicates that the k transformation layers of the current point cloud are not to be skip-coded, encoding the residual values of the AC coefficients of the multiple transformation layers, and writing the obtained coding bits into the bitstream.

It should be noted that, in the embodiment of the present application, if the k transformation layers of the current point cloud are not skip-coded, it can be said that the multiple transformation layers corresponding to the current point cloud all need to encode their respective AC coefficient residual values. In some embodiments, the method may also include: encoding the AC coefficient residual values of the multiple transformation layers, and writing the obtained encoding bits into the attribute code stream unit in the code stream.

That is, in the embodiment of the present application, the first coding parameter and the AC coefficient residual value are both located in the attribute code stream unit of the code stream. Specifically, in some embodiments, the method may also include: in the attribute code stream unit, determining that the field corresponding to the first coding parameter is located after the field corresponding to the AC coefficient residual value.

It should be noted that, in the embodiment of the present application, only the DC coefficient value of the root node needs to be written into the bitstream. In some embodiments, the method may further include: encoding the DC coefficient value of the root node, and writing the obtained encoding bits into the bitstream.

It should be noted that, in an embodiment of the present application, the method may further include: encoding the DC coefficient value of the root node, and writing the obtained encoding bits into the attribute code stream unit in the code stream.

It should also be noted that in the embodiment of the present application, for multiple transformation layers, the DC coefficient value can be directly passed to the next layer at each transformation, but the residual calculation of the AC coefficient value is required, and the residual value of the AC coefficient of each layer is quantized and entropy encoded. In addition, if there is only one point in a transformation layer, the attribute value of the point can be directly passed to the next layer as the DC coefficient value. In this process, only the DC coefficient value of the root node needs to be written into the bitstream.

For the attribute code stream, Figure 21 is a schematic diagram of a code stream structure of a related technology, and Figure 22 is a schematic diagram of a code stream structure provided by an embodiment of the present application. Among them, as shown in Figure 22, bits and flag represent the coded quantization coefficient residual and the RDO layer zero flag respectively, and n represents the total number of points in the point cloud. During encoding, the DC coefficient value of the root node and all AC coefficient residual values are entropy encoded and written into the code stream, and then the flag flag is written into the code stream using arithmetic coding. In this way, at the decoding end, the flag can be first decoded to determine the number of transformation layers of the AC coefficient residual value that needs to be decoded, and then the AC coefficient residual value that needs to be decoded is decoded according to the indication of the first decoding parameter, and the AC coefficient residual value of the k transformation layers for performing jump decoding is restored to 0.

In some embodiments, the method may further include: determining a value of a second encoding parameter; and when the second encoding parameter indicates starting jump encoding of the current point cloud, executing the step of determining a value of the first encoding parameter.

It should be noted that in the embodiment of the present application, for the second encoding parameter, the second encoding parameter can be used to indicate whether to enable the jump encoding of the current point cloud, that is, to indicate whether the technical solution of the embodiment of the present application is enabled. In some embodiments, if the value of the second encoding parameter is the third value, it is determined that the second encoding parameter indicates that the jump encoding of the current point cloud is enabled; if the value of the second encoding parameter is the fourth value, it is determined that the second encoding parameter indicates that the jump encoding of the current point cloud is not enabled.

In some embodiments, the method further comprises: encoding the value of the second encoding parameter, and writing the obtained encoding bits into the bitstream. In a specific embodiment, encoding the value of the second encoding parameter, and writing the obtained encoding bits into the attribute parameter set unit in the bitstream. That is, the second encoding parameter is specifically an attribute parameter set unit in the bitstream.

It should also be noted that, in the embodiment of the present application, the second coding parameter can be expressed in the form of a syntax element. In this case, the second coding parameter can be called a second syntax element, represented by skip_raht_enabled_flag. Among them, the second syntax element can also be used to indicate whether the skip coding of the current point cloud is enabled, that is, to indicate whether the technical solution of the embodiment of the present application is enabled. In some embodiments, if the skip coding of the current point cloud is enabled, the value of the second syntax element is determined to be a third value; if the skip coding of the current point cloud is not enabled, the value of the second syntax element is determined to be a fourth value.

That is, in the embodiment of the present application, determining the value of the second coding parameter according to the value of the second syntax element may include: setting the value of the second coding parameter to be equal to the value of the second syntax element.

It should also be noted that in the embodiment of the present application, the third value is different from the fourth value. The third value can be set to 1 and the fourth value can be set to 0; or, the third value can be set to 0 and the fourth value can be set to 1; or, the third value can be set to true (true) and the fourth value can be set to false (false); or, the third value can be set to false (false) and the fourth value can be set to true (true). In a specific embodiment, the third value is set to 1 and the fourth value is set to 0, but this is not limited to any limitation.

In some embodiments, the method may also include: when skip encoding the to-be-processed components of the k transformation layers of the current point cloud, determining that one or more AC coefficient residual values of the to-be-processed components of the k transformation layers are preset values; encoding the one or more AC coefficient residual values of the to-be-processed components of the k transformation layers according to the preset values, and writing the obtained coded bits into the bit stream.

It should be noted that in an embodiment of the present application, the method may also include: determining the AC coefficient residual values of the components to be processed in other transformation layers other than the k transformation layers in the current point cloud; encoding the AC coefficient residual values of the components to be processed in other transformation layers, and writing the obtained coded bits into the bit stream.

It should also be noted that, in an embodiment of the present application, the method may further include: determining a value of a third coding parameter; wherein the second coding parameter is used to indicate whether to perform jump coding on the to-be-processed components of the k transformation layers of the current point cloud; encoding the value of the third coding parameter, and writing the obtained coding bits into the bit stream.

It should be noted that, in the embodiment of the present application, the component to be processed may include at least one of the first color component, the second color component and the third color component.

It should also be noted that in an embodiment of the present application, the third coding parameter can be expressed in the form of a syntax element, and the third coding parameter can be called a third syntax element. Among them, when the component to be processed is the first color component (for example, the Y component), it can be represented by flag_Y at this time to indicate whether the Y component of the k transform layers of the current point cloud is skip-coded; when the component to be processed is the second color component (for example, the U component), it can be represented by flag_U at this time to indicate whether the U component of the k transform layers of the current point cloud is skip-coded; when the component to be processed is the third color component (for example, the V component), it can be represented by flag_V at this time to indicate whether the V component of the k transform layers of the current point cloud is skip-coded. That is to say, in the color attributes of the dense point cloud, it can be extended to three channels and use the skip coding mode for RAHT transform coefficients at the same time. At this time, for the third coding parameter, three flags flag_Y, flag_U, and flag_V can be set to record the number of coefficient layers for skip coding respectively.

In a specific embodiment, FIG23 is a detailed flow chart of a coding method provided by an embodiment of the present application. As shown in FIG23, intra-frame prediction or inter-frame prediction can be performed for the original point cloud (or referred to as "initial point cloud"). In the intra-frame prediction process, the original point cloud is upsampled and predicted to obtain a predicted point cloud, and then a RAHT transform is performed to determine the predicted AC coefficient; in the inter-frame prediction process, a reference point cloud can be obtained according to the adjacent frames of the original point cloud, and then a RAHT transform can also be performed to determine the predicted AC coefficient. Performing a RAHT transform on the original point cloud can determine the DC coefficient and the original AC coefficient of the root node; subtracting the original AC coefficient from the predicted AC coefficient can obtain a predicted residual, and after quantizing the predicted residual, the jump coding mode for the RAHT transform coefficient can be determined according to the value of the flag. In the RAHT algorithm, the original point cloud starts from the root node, and RAHT transforms each 2×2×2 block layer by layer from top to bottom. For the latter m layers of multiple parameters, the AC coefficient residual values of the latter k (k = 1, 2, ..., m) layers are respectively subjected to RDO judgment. If the rate-distortion cost of coding is high, the flag is set to the minimum RDcost corresponding layer k, and only the AC coefficient residual values of the previous transformed layers are coded; if the rate-distortion cost of not coding is high, the flag is set to 0, and all AC coefficient residual values are coded to obtain the attribute code stream. The specific operation flow is shown in Figure 23.

In another embodiment of the present application, the embodiment of the present application provides 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:

The AC coefficient residual values of multiple transformation layers corresponding to the current point cloud, the DC coefficient value of the root node of the current point cloud, one or more AC coefficient residual values of k transformation layers of the current point cloud are preset values, the AC coefficient residual values of other transformation layers outside the k transformation layers in the current point cloud, the value of the first coding parameter, the value of the second coding parameter and the value of the third coding parameter.

In an embodiment of the present application, the first encoding parameter is used to indicate whether to perform jump encoding on the k transformation layers of the current point cloud, the second encoding parameter is used to indicate whether to turn on jump encoding of the current point cloud, and the third encoding parameter is used to indicate whether to perform jump encoding on the k transformation layers of the current point cloud to be processed.

It should also be noted that in the embodiment of the present application, for the encoding parameters, the parameters obtained by the decoding end through decoding the code stream can be called "decoding parameters", and the meanings of the two are the same, but the names at the encoding end and the decoding end are different.

The embodiment of the present application provides a coding method, which determines the value of a first coding parameter; when the first coding parameter indicates that the k transformation layers of the current point cloud are to be skip-coded, determines that one or more residual values of the AC coefficients of the k transformation layers are preset values; encodes the one or more residual values of the AC coefficients of the k transformation layers according to the preset values, and writes the obtained coded bits into the bitstream. In this way, when it is determined that the k transformation layers of the current point cloud are to be skip-coded, the one or more residual values of the AC coefficients of the k transformation layers are directly encoded according to the preset values, which can effectively improve the phenomenon that too many 0s appear in the AC coefficient values of the last few layers of coding in the RAHT transform, thereby improving the coding efficiency, achieving quality enhancement of the point cloud reconstructed at the decoding end at the average bit rate, and further improving the encoding and decoding performance of the point cloud.

In another embodiment of the present application, based on the encoding and decoding method described in the above embodiment, a jump coding mode for RAHT transform coefficients is proposed here. Among them, in the process of layer-by-layer calculation of the RAHT algorithm from the root node to the child node, as the number of layers increases, the number of coded AC coefficients obtained by the transformation gradually increases, and the coefficient value gradually decreases. In the last few layers of the radar point cloud, the number of AC coefficients occupies more than half of all AC coefficients, but the number of 0s in these layers occupies more than 95%, so the encoding of the last few layers of AC coefficients must have a large waste of code stream. This technical solution proposes to judge the jump coding mode of RAHT transform coefficients based on the rate-distortion optimization method, and use rate-distortion optimization to determine the RDO cost of not encoding the AC coefficients of the last m layers, m-1 layers... of multiple parameters, and the RDO cost of encoding all coefficients. If the cost of not encoding the AC coefficient is less than the total encoding cost, the RDO cost of not encoding is the smallest when used for several layers, and the value of the flag is set to the number of layers k corresponding to the minimum cost, and entropy coding is performed at the same time. When the decoder decodes, if the decoded flag flag is k, the AC coefficient residual value of the last k layers is reconstructed as 0; if the decoded flag is 0, all are reconstructed according to the original value. The overall process of this technical solution is shown in Figure 24, which may specifically include:

S2401, calculate the RDcost of each layer of the multi-parameter layer level _nm ~ level _n AC coefficient residual value encoding and the RDcost of each layer not encoded and After comparison, if the uncoded RDcost is smaller, the flag is set to the total number of layers k corresponding to the minimum cost RDcost, otherwise it is set to 0.

S2402, perform arithmetic coding on the flag bit flag.

S2403, the decoding end first decodes the flag flag, and if the value of flag is k, the AC coefficient residual values of level _n-k+1 to level _n are reconstructed as 0, otherwise they are reconstructed as original values.

In a specific implementation, the implementation process of the encoding and decoding method may include:

(1) Principle of rate-distortion optimization technology.

In the field of video coding, the bit rate and distortion after coding are in a contradictory relationship. If you want to obtain a higher quality reconstructed video with smaller distortion, you need to increase the transmission bit rate; however, the bit rate cannot be increased indefinitely. In some cases, you need to reduce the bit rate to ensure the smoothness of video transmission. In order to better improve the efficiency of coding, it is necessary to comprehensively consider the bit rate and distortion and find a compromise between the two so that the distortion is as small as possible under the condition of a fixed bit rate, as shown in formula (11). Where D represents distortion, R represents bit rate, represents the conditional parameter configuration of encoding, such as quantization step size. The above formula is a constrained optimization problem, which can be transformed into the form shown in formula (12) using Lagrange multipliers. Among them, RDcost is the rate-distortion cost, and λ is the Lagrange multiplier. This is the rate-distortion optimization problem in the field of video coding.

In the embodiment of the present application, it is proposed to calculate the RDOcost of the last m layers, m-1 layers...AC coefficient residual values of the radar point cloud multi-parameters without coding, and compare them with the RDOcost of all the coefficient residual values encoded, so as to decide whether to encode these coefficient residual values. The method of improving the coding efficiency. Since the calculation of RDcost is inconvenient, the method of calculating ΔRDcost can be adopted. Taking the k layer as an example, the calculation formula is shown in equations (13) to (15). Among them, ΔD is represented by the square value of all AC coefficient residual values of the last k layers, which is used to refer to the distortion cost after all these coefficient residual values are not encoded, R _org is the code stream consumption in the coding scheme of the related technology, and the code rate consumption after all the last k layers of AC coefficient residual values are not encoded is only 1 bit occupied by the flag bit flag, so ΔR represents the difference in code rate consumption between the last k layers of AC coefficient residual values not encoded and encoded, that is, the code stream saved by not encoding the last k layers of AC coefficient residual values. At this time, if the calculated ΔRDcost is greater than 0, it means that the distortion cost of not encoding is large, and the flag is set to 0; if the calculated ΔRDcost is less than 0, it means that the bit rate saving of not encoding is large, and it is necessary to continue to compare the ΔRDcost of other layers to decide whether to set the flag to k.

The Lagrange multiplier λ is selected in the form of H.266/VCC video coding, as shown in equation (16). Where c is a constant and QP is the quantization step size. The values of c are selected as 0.01, 0.1, 0.2, 0.3, and 0.4, and the attribute compression performance of the test point cloud under the C1 condition is selected to analyze and find the optimal interval of c. The search step size is further reduced, and the optimal value of the constant c is finally determined to be 0.12.

(2) Implementation details on the encoding side.

In the RAHT algorithm, the original point cloud starts from the root node, and RAHT transforms each 2×2×2 block layer by layer from top to bottom. If intra-frame prediction or inter-frame prediction is allowed, the predicted points are RAHT transformed, and the predicted AC coefficient value is subtracted from the original AC coefficient value, and the residual value is quantized. For the last m layers of multiple parameters, the AC coefficient residual values of the last k (k=1,2,...,m) layers are respectively subjected to RDO judgment. If the encoding rate-distortion cost is high, the flag is set to the minimum RDcost corresponding to the layer number k, and only the AC coefficient residual values of the previous layers are encoded; if the rate-distortion cost of not encoding is high, the flag is set to 0, and all AC coefficient residual values are encoded to obtain the attribute code stream. The operation flow chart at the encoding end is shown in the aforementioned Figure 23.

(3) Code stream structure.

Here, the code stream structure diagram is shown in Figures 21 and 22, where bits and flag represent the coded quantization coefficient residual and the RDO layer zero flag respectively, and n represents the total number of points in the point cloud. During encoding, the DC coefficient value of the root node and all the AC coefficient residual values are entropy encoded and written into the code stream, and then the flag flag is arithmetic encoded and written into the code stream. At the decoding end, the flag is first decoded to obtain the number of RAHT parameter layers to be decoded, and then the AC coefficient residual values to be decoded are decoded into the corresponding parameter matrix by entropy decoding according to the indication of the flag flag, and the AC coefficient residual values of the remaining layers are restored to 0.

(4) Implementation details of the decoding end.

The operation flow chart at the decoding end is shown in Figure 17. The decoding end reads the bit stream and first decodes the zero flag flag at the end of the bit stream. If the decoded flag value is k, the last k layers of AC coefficient residual values are all decoded as 0, and the remaining coefficients are decoded normally and stored in the parameter matrix; if the decoded flag value is 0, the DC coefficient value and all AC coefficient residual values are solved and stored in the parameter matrix.

Then all decoded coefficients are dequantized, and the decoding process is still carried out from top to bottom. First, the DC coefficient value of the root node and the residual value of the AC coefficient of the first layer are obtained, and the RAHT inverse transform is performed to obtain the reconstructed attribute value; if the configuration allows intra-frame prediction or inter-frame prediction, the first-layer AC residual obtained is first added to the predicted AC coefficient to obtain the reconstructed AC coefficient, and the obtained reconstructed AC coefficient is subjected to the RAHT inverse transform together with the DC coefficient of the root node to obtain the reconstructed attribute value of the first layer. The 8 reconstructed attribute values obtained can be used to calculate the DC coefficient values of the 8 nodes of the second layer, and then the decoded second-layer AC residual is added to the predicted AC coefficient to obtain the reconstructed AC coefficient. The obtained DC coefficient value is subjected to the RAHT inverse transform with the reconstructed AC coefficient of the second layer respectively, and the reconstructed attribute value of the third layer can be obtained, and so on. If the flag value is k, when decoding to the last k layers, the AC coefficient residual values are all restored to 0. At this time, it is only necessary to pass the DC coefficient value calculated by the previous layer downward, and use the DC coefficient value passed by the previous layer plus the obtained reconstructed AC coefficient to calculate the reconstructed attribute value of the child node until the leaf node, at which point the decoding process ends.

In the case of this application, the specific implementation of the decoding end program is as follows: first, the flag is decoded in the attribute parameter set APS .skip_raht_enabled_flag, this flag determines whether the technical solution of the embodiment of the present application is enabled; if it is true, the flag flag in the code stream is first decoded in the attribute code stream and transmitted to the RAHT sub-function. If the decoded flag value is k, the last k layers of RAHT AC coefficient residual values are restored according to the value of 0 for the next attribute reconstruction; if the decoded flag value is 0, all AC coefficient residual values of RAHT are restored according to the original coding value. Here, the attribute AC coefficient residual is stored in the parameter matrix transformPredBuf.

It should also be noted that in the embodiment of the present application, the RDO judgment scheme for whether to encode the last few layers of coefficients of the RAHT transformation of the point cloud attributes in the technical solution can replace the original entire encoding scheme.

It should also be noted that in the embodiment of the present application, for the flag bit flag in the technical solution, it can be expanded to three channels in the dense point cloud color attributes and use the skip coding mode for RAHT transform coefficients at the same time, and set three flag bits flag_Y, flag_U, and flag_V to respectively record the number of coefficient layers that are not encoded.

Exemplarily, the technical solution proposed in the embodiment of the present application was implemented on the G-PCC reference software TMC13V23.0 and GES-TM V2.0, and then tested under the CTC-C1 and CTC-C2 test conditions. The test results are detailed in Tables 1 to 4. Among them, Table 1 is a test result under the C1 condition, Table 2 is a test result under the C2 condition, Table 3 is another test result under the C1 condition, and Table 4 is another test result under the C2 condition. Among them, the C1 condition is a lossless geometry, lossless attribute coding method (lossless geometry, lossy attribute), and the C2 condition is a lossless geometry, lossy attribute coding method (lossless geometry, lossy attribute). End-to-End BD-AttrRate in Tables 1 to 4 represents the BD-Rate of the end-to-end attribute value for the attribute bitstream. BD-Rate reflects the difference in PSNR curves between the two cases (with or without filtering). When BD-Rate decreases, it means that when PSNR is equal, the bit rate decreases and the performance improves; otherwise, the performance decreases. That is, the more BD-Rate decreases, the better the compression effect. Cat3-frame average represents the average value of the test results of multi-frame radar point cloud datasets, Cat3-fused average dataset represents the fused point cloud dataset, and Cat2 dataset is a multi-frame dense point cloud. Finally, Overall average is the average value of the test results of all sequences.

Table 1

Table 2

Table 3

Table 4

Compared with the related art, the present technical scheme obtains a gain of -1.3% on the Reflectance component of the Cat3-frame average data set under TMC13 and CTC-C1 test conditions, a gain of -2.6% on the Reflectance component of the Cat3-frame average data set under CTC-C2 test conditions, and a gain of 0.6%, -6.8%, and -7.0% on the Luma, Chroma Cb, and Chroma Cr components of the Cat3-fused average data set, respectively. Compared with the related art, the present technical scheme obtains a gain of 0.2%, -0.5%, and -0.2% on the Luma, Chroma Cb, and Chroma Cr components of the Cat2 data set under GES-TM and CTC-C1 test conditions, and a gain of 0.8%, -1.8%, and -0.5% on the Luma, Chroma Cb, and Chroma Cr components of the Cat2 data set under CTC-C2 test conditions, respectively.

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 scheme of the aforementioned embodiments, a skip coding mode for RAHT transform coefficients is proposed here. Through the rate-distortion optimization technology, the rate-distortion cost of encoding the latter layers of the point cloud with more 0 values in the RAHT transform is determined, and the AC coefficients of the latter layers of the point cloud with high rate-distortion cost are not encoded. At the same time, the flag bit is encoded to record whether the non-encoding operation is performed and for which layers it is performed. This effectively improves the phenomenon of too many 0 values in the encoding coefficients of the latter layers in the RAHT algorithm, improves the encoding efficiency, and realizes quality enhancement at the average bit rate of the reconstructed point cloud at the decoding end, which can improve the reconstruction quality at the average bit rate of the attribute encoding, thereby improving the encoding and decoding efficiency.

In another embodiment of the present application, based on the same inventive concept as the above-mentioned embodiment, FIG25 is a schematic diagram of the composition structure of an encoder provided in an embodiment of the present application. As shown in FIG25, the encoder 250 may include a first determining unit 2501 and an encoding unit 2502, wherein:

The first determining unit 2501 is configured to determine a value of a first coding parameter; when the first coding parameter indicates that k transformation layers of the current point cloud are skip-coded, determine that one or more AC coefficient residual values of the k transformation layers are preset values; wherein k is an integer greater than zero;

The encoding unit 2502 is configured to encode one or more AC coefficient residual values of k transformation layers according to preset values, and write the obtained encoding bits into the bit stream.

In some embodiments, the first determining unit 2501 is further configured to determine a first generation value for encoding all the AC coefficient residual values of the k transform layers, and to determine a second generation value for encoding one or more AC coefficient residual values of the k transform layers according to a preset value. value; determine the value of the first encoding parameter according to the first generation value and the second generation value.

In some embodiments, the first determination unit 2501 is further configured to determine the value of the first encoding parameter to be the first value if the first generation value is greater than the second generation value; and to determine the value of the first encoding parameter to be the second value if the first generation value is less than the second generation value.

In some embodiments, the first determination unit 2501 is further configured to, if the value of the first encoding parameter is a first value, determine that the first encoding parameter indicates that the k transformation layers of the current point cloud are skip encoded; if the value of the first encoding parameter is a second value, determine that the first encoding parameter indicates that the k transformation layers of the current point cloud are not skip encoded.

In some embodiments, the encoding unit 2502 is further configured to perform encoding processing on the value of the first encoding parameter and write the obtained encoding bits into the bit stream.

In some embodiments, the encoding unit 2502 is further configured to perform encoding processing on the value of the first encoding parameter, and write the obtained encoding bits into the attribute code stream unit in the code stream.

In some embodiments, the first determination unit 2501 is further configured to set the first value equal to the value of k when the first encoding parameter indicates that k transform layers of the current point cloud are to be skip encoded.

In some embodiments, the first determination unit 2501 is further configured to determine a third generation value for encoding all AC coefficient residual values of m transformation layers, and to determine a fourth generation value for encoding one or more AC coefficient residual values of m transformation layers according to a preset value; when the third generation value is greater than the fourth generation value, determine a fifth generation value for encoding i transformation layers of the current point cloud according to a preset value, where i = 1, 2, ..., m, and m is an integer greater than zero; and after obtaining m fifth generation values, determine a minimum cost value from the m fifth generation values; and determine the value of k based on the value of i corresponding to the minimum cost value.

In some embodiments, the first determination unit 2501 is further configured to determine that all AC coefficient residual values of k transformation layers are preset values.

In some embodiments, referring to FIG. 25 , the encoder 250 may further include a first division unit 2503 configured to perform layer division on points in the current point cloud, determine multiple transformation layers corresponding to the current point cloud and a root node of the current point cloud; wherein the multiple transformation layers include k transformation layers and other transformation layers.

In some embodiments, the first determining unit 2501 is further configured to set the k transformation layers as the last k transformation layers from the root node in a downward direction among the multiple transformation layers.

In some embodiments, referring to FIG. 25 , the encoder 250 may further include a first transformation unit 2504, configured to determine initial attribute values of points in a plurality of transformation layers; and perform regional adaptive hierarchical transformation on the initial attribute values of the points in the plurality of transformation layers to determine initial AC coefficient values of the points in the plurality of transformation layers and DC coefficient values of the root nodes.

In some embodiments, the first determination unit 2501 is also configured to determine the AC coefficient prediction values of points in multiple transformation layers; and determine the AC coefficient residual values of multiple transformation layers based on the AC coefficient initial values of points in multiple transformation layers and the AC coefficient prediction values of points in multiple transformation layers.

In some embodiments, the first determination unit 2501 is also configured to perform a subtraction operation on the initial values of the AC coefficients of points in multiple transformation layers and the predicted values of the AC coefficients of points in multiple transformation layers to obtain the AC coefficient prediction residuals of the points in multiple transformation layers; and to quantize the AC coefficient prediction residuals of the points in multiple transformation layers to obtain the AC coefficient residual values of multiple transformation layers.

In some embodiments, the first determination unit 2501 is further configured to determine the residual values of the AC coefficients of other transformation layers other than k transformation layers among multiple transformation layers when the first encoding parameter indicates that the k transformation layers of the current point cloud are to be skip encoded; the encoding unit 2502 is further configured to encode the residual values of the AC coefficients of other transformation layers and write the obtained encoding bits into the bitstream.

In some embodiments, the encoding unit 2502 is further configured to perform encoding processing on the AC coefficient residual values of other transform layers, and write the obtained encoding bits into the attribute code stream unit in the code stream.

In some embodiments, the encoding unit 2502 is further configured to encode the residual values of the AC coefficients of multiple transform layers when the first encoding parameter indicates that the k transform layers of the current point cloud are not to be skip-encoded, and write the obtained encoding bits into the bitstream.

In some embodiments, the encoding unit 2502 is further configured to perform encoding processing on the AC coefficient residual values of multiple transform layers, and write the obtained encoding bits into the attribute code stream unit in the code stream.

In some embodiments, the first determining unit 2501 is further configured to determine, in the attribute code stream unit, that the field corresponding to the first coding parameter is located after the field corresponding to the AC coefficient residual value.

In some embodiments, the first transformation unit 2504 is further configured to determine the attribute prediction values of points in multiple transformation layers; and perform regional adaptive hierarchical transformation on the attribute prediction values of points in multiple transformation layers to determine the AC coefficient prediction values of points in multiple transformation layers.

In some embodiments, the first determination unit 2501 is further configured to perform intra-frame prediction on points in multiple transformation layers and determine attribute prediction values of the points in multiple transformation layers when the current point cloud allows the use of intra-frame prediction; when the current point cloud allows the use of inter-frame prediction, determine the reference point cloud of the current point cloud, and perform inter-frame prediction on points in multiple transformation layers based on the reference point cloud to determine the attribute prediction values of the points in multiple transformation layers.

In some embodiments, the encoding unit 2502 is further configured to encode the DC coefficient value of the root node and write the obtained encoding bits into the bit stream.

In some embodiments, the first determination unit 2501 is further configured to determine a value of a second encoding parameter; when the second encoding parameter indicates to start skip encoding of the current point cloud, the step of determining a value of the first encoding parameter is performed.

In some embodiments, the encoding unit 2502 is further configured to perform encoding processing on the value of the second encoding parameter and write the obtained encoding bits into the bit stream.

In some embodiments, the encoding unit 2502 is further configured to perform encoding processing on the value of the second encoding parameter, and write the obtained encoding bits into the attribute parameter set unit in the bitstream.

In some embodiments, the first determination unit 2501 is further configured to determine the value of a third encoding parameter; wherein the third encoding parameter is used to indicate whether to perform jump encoding on the to-be-processed components of the k transformation layers of the current point cloud; the encoding unit 2502 is further configured to perform encoding processing on the value of the third encoding parameter and write the obtained encoding bits into the bitstream.

In some embodiments, the component to be processed includes at least one of a first color component, a second color component, and a third color component.

In some embodiments, the first determination unit 2501 is further configured to determine that one or more AC coefficient residual values of the k transform layers to be processed are preset values when jump encoding is performed on the k transform layers to be processed components of the current point cloud; the encoding unit 2502 is further configured to encode one or more AC coefficient residual values of the k transform layers to be processed components according to the preset values, and write the obtained encoding bits into the bit stream.

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

If the integrated unit is implemented in the form of a software function module and is not sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this embodiment is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) or a processor to perform all or part of the steps of the method described in this embodiment. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program codes.

Therefore, an embodiment of the present application provides a computer-readable storage medium, which is applied to the encoder 250. The computer-readable storage medium stores a computer program, and when the computer program is executed by the first processor, the method described in any one of the aforementioned embodiments is implemented.

Based on the composition of the above-mentioned encoder 250 and the computer-readable storage medium, Figure 26 is a schematic diagram of the specific hardware structure of an encoder provided in an embodiment of the present application. As shown in Figure 26, the encoder 250 may include: a first communication interface 2601, a first memory 2602 and a first processor 2603; each component is coupled together through a first bus system 2604. It can be understood that the first bus system 2604 is used to realize the connection and communication between these components. In addition to the data bus, the first bus system 2604 also includes a power bus, a control bus and a status signal bus. However, for the sake of clarity, various buses are marked as the first bus system 2604 in Figure 26. Among them,

The first communication interface 2601 is used for receiving and sending signals during the process of sending and receiving information with other external network elements;

A first memory 2602, used to store a computer program that can be run on the first processor 2603;

The first processor 2603 is configured to, when running the computer program, execute:

Determine the value of the first coding parameter; when the first coding parameter indicates that k transformation layers of the current point cloud are to be skip-coded, determine that one or more AC coefficient residual values of the k transformation layers are preset values; wherein k is an integer greater than zero; encode the one or more AC coefficient residual values of the k transformation layers according to the preset values, and write the obtained coded bits into the bitstream.

It can be understood that the first memory 2602 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 (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM bus RAM (DRRAM). The first memory 2602 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 2603 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by a hardware integrated logic circuit or software instructions in the first processor 2603. The first processor 2603 may be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), or a processor. Specific Integrated Circuit, ASIC), field programmable gate array (Field Programmable Gate Array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiments of the present application can be directly embodied as a hardware decoding processor to be executed, or a combination of hardware and software modules in the decoding processor to be executed. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the first memory 2602, and the first processor 2603 reads the information in the first memory 2602, 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 (Application Specific Integrated Circuits, ASIC), digital signal processors (Digital Signal Processing, DSP), digital signal processing devices (DSP Device, DSPD), programmable logic devices (Programmable Logic Device, PLD), field programmable gate arrays (Field-Programmable Gate Array, FPGA), general 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 a module (such as a process, function, etc.) that performs 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 2603 is further configured to execute the method described in any one of the aforementioned embodiments when running the computer program.

The present embodiment provides an encoder, which, when determining to skip encode the k transformation layers of the current point cloud, directly encodes one or more AC coefficient residual values of the k transformation layers according to preset values, can effectively improve the phenomenon of too many zeros in the AC coefficient values of the last few layers of encoding in the RAHT transform, thereby improving the encoding and decoding efficiency, and achieving quality enhancement of the reconstructed point cloud at the decoding end at an average bit rate, thereby improving the encoding and decoding performance of the point cloud.

In yet another embodiment of the present application, based on the same inventive concept as the above-mentioned embodiment, FIG27 is a schematic diagram of the composition structure of a decoder provided in an embodiment of the present application. As shown in FIG27 , the decoder 270 may include a second determination unit 2701, a decoding unit 2702, and a reconstruction unit 2703, wherein:

The second determining unit 2701 is configured to determine a value of the first decoding parameter; when the first decoding parameter indicates to perform skip decoding on k transform layers of the current point cloud, determine one or more AC coefficient residual values of the k transform layers to be a preset value; wherein k is an integer greater than zero;

A decoding unit 2702 is configured to decode the bit stream and determine the residual values of the AC coefficients of other transform layers other than the k transform layers in the current point cloud;

The reconstruction unit 2703 is configured to determine the reconstructed point cloud of the current point cloud according to the AC coefficient residual values of the k transformation layers and the AC coefficient residual values of other transformation layers.

In some embodiments, the decoding unit 2702 is further configured to decode the code stream and determine the value of the first decoding parameter.

In some embodiments, the decoding unit 2702 is further configured to decode an attribute code stream unit in the code stream to determine a value of the first decoding parameter.

In some embodiments, the decoding unit 2702 is further configured to decode the attribute code stream unit in the code stream to determine the residual values of the AC coefficients of other transform layers.

In some embodiments, the second determining unit 2701 is further configured to determine, in the attribute code stream unit, that the field corresponding to the first decoding parameter is located after the field corresponding to the AC coefficient residual value.

In some embodiments, the second determination unit 2701 is further configured to determine a value of a second decoding parameter; and when the second decoding parameter indicates to start jump decoding of the current point cloud, execute the step of determining a value of the first decoding parameter.

In some embodiments, the decoding unit 2702 is further configured to decode the code stream and determine a value of the second decoding parameter.

In some embodiments, the decoding unit 2702 is further configured to decode the attribute parameter set unit in the code stream to determine the value of the second decoding parameter.

In some embodiments, the second determination unit 2701 is further configured to determine that all AC coefficient residual values of k transformation layers are preset values.

In some embodiments, referring to FIG. 27 , the decoder 270 may further include a second division unit 2704 configured to perform layer division on points in the current point cloud, determine multiple transformation layers corresponding to the current point cloud and a root node of the current point cloud; wherein the multiple transformation layers include k transformation layers and other transformation layers.

In some embodiments, the second determining unit 2701 is further configured to set the k transformation layers as the last k transformation layers from the root node in a downward direction among the multiple transformation layers.

In some embodiments, the decoding unit 2702 is further configured to decode the code stream and determine the residual values of the AC coefficients of multiple transform layers corresponding to the current point cloud when the first decoding parameter indicates that the k transform layers of the current point cloud do not need to be skipped and decoded; the second determination unit 2701 is further configured to determine the reconstructed point cloud of the current point cloud based on the residual values of the AC coefficients of multiple transform layers.

In some embodiments, the decoding unit 2702 is further configured to decode the attribute code stream unit in the code stream to determine the communication of multiple transformation layers. The coefficient residual values.

In some embodiments, the second determination unit 2701 is further configured to, if the value of the first decoding parameter is a first value, determine that the first decoding parameter indicates skip decoding of the k transform layers of the current point cloud; if the value of the first decoding parameter is a second value, determine that the first decoding parameter indicates not skip decoding of the k transform layers of the current point cloud.

In some embodiments, the second determination unit 2701 is further configured to set the value of k to be equal to the first value when the first decoding parameter indicates to skip decoding k transform layers of the current point cloud.

In some embodiments, the decoding unit 2702 is further configured to decode the code stream, determine the DC coefficient value of the root node of the current point cloud; and save the DC coefficient value of the root node to the first parameter matrix of the current point cloud.

In some embodiments, the decoding unit 2702 is further configured to save the AC coefficient residual values of k transformation layers and the AC coefficient residual values of other transformation layers into the first parameter matrix of the current point cloud.

In some embodiments, the second determining unit 2701 is further configured to perform inverse quantization processing on the parameter values in the first parameter matrix of the current point cloud.

In some embodiments, the second determination unit 2701 is further configured to determine the predicted values of the AC coefficients of points in multiple transformation layers; determine the second parameter matrix of the current point cloud based on the first parameter matrix of the current point cloud and the predicted values of the AC coefficients of points in multiple transformation layers; the reconstruction unit 2703 is further configured to perform a regional adaptive hierarchical inverse transform on the second parameter matrix of the current point cloud to determine the reconstructed point cloud of the current point cloud.

In some embodiments, referring to FIG. 27 , the decoder 270 may further include a second transformation unit 2705 configured to determine attribute prediction values of points in multiple transformation layers; and perform regional adaptive hierarchical transformation on the attribute prediction values of points in multiple transformation layers to determine AC coefficient prediction values of points in multiple transformation layers.

In some embodiments, the second determination unit 2701 is further configured to perform intra-frame prediction on points in multiple transformation layers and determine attribute prediction values of the points in multiple transformation layers when the current point cloud allows the use of intra-frame prediction; when the current point cloud allows the use of inter-frame prediction, determine the reference point cloud of the current point cloud, and perform inter-frame prediction on points in multiple transformation layers based on the reference point cloud to determine the attribute prediction values of the points in multiple transformation layers.

In some embodiments, the second determination unit 2701 is further configured to determine the AC coefficient residual value of the points of the current transformation layer in the first parameter matrix and the AC coefficient prediction value of the points of the current transformation layer based on the points of the current transformation layer in the current point cloud; add the AC coefficient residual value and the AC coefficient prediction value to obtain the AC coefficient reconstruction value of the points of the current transformation layer; and after obtaining the AC coefficient reconstruction values of the points of multiple transformation layers, determine the second parameter matrix of the current point cloud according to the DC coefficient value of the root node and the AC coefficient reconstruction values of the points of multiple transformation layers.

In some embodiments, the second reconstruction unit 2703 is further configured to perform a regional adaptive hierarchical inverse transform based on the DC coefficient value of the root node and the AC coefficient reconstruction value of the point of the current transformation layer when the current transformation layer is the first transformation layer, so as to obtain the reconstructed attribute value of the point of the first transformation layer; when the current transformation layer is not the first transformation layer, determine the DC coefficient value of the point of the current transformation layer based on the reconstructed attribute value of the point of the previous transformation layer of the current transformation layer, and perform a regional adaptive hierarchical inverse transform based on the DC coefficient value of the point of the current transformation layer and the AC coefficient reconstruction value of the point of the current transformation layer to obtain the reconstructed attribute value of the point of the non-first transformation layer.

In some embodiments, the decoding unit 2702 is further configured to decode the code stream and determine that one or more AC coefficient residual values of k transform layers are preset values.

In some embodiments, the decoding unit 2702 is further configured to decode the bitstream and determine a value of a third decoding parameter;

The second determining unit 2701 is further configured to determine one or more AC coefficient residual values of the components to be processed of the k transform layers to be processed as preset values when the third decoding parameter indicates to skip decoding the components to be processed of the k transform layers of the current point cloud;

The decoding unit 2702 is further configured to decode the code stream to determine the residual values of the AC coefficients of the components to be processed in other transform layers other than the k transform layers in the current point cloud;

The reconstruction unit 2703 is further configured to determine the reconstructed point cloud of the to-be-processed component of the current point cloud according to the AC coefficient residual values of the to-be-processed components of the k transformation layers and the AC coefficient residual values of the to-be-processed components of other transformation layers.

In some embodiments, the component to be processed includes at least one of a first color component, a second color component, and a third color component.

It can be understood that in this embodiment, a "unit" can be a part of a circuit, a part of a processor, a part of a program or software, etc., and of course it can also be a module, or it can be non-modular. Moreover, the 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 one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional module.

If the integrated unit is implemented in the form of a software function module and is not sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, this embodiment provides a computer-readable storage medium, which is applied to the decoder 270, and the computer-readable storage medium stores a computer program. When the computer program is executed by the second processor, the method described in any one of the above embodiments is implemented.

Based on the composition of the above decoder 270 and the computer-readable storage medium, FIG. 28 is a decoder provided in an embodiment of the present application. Specific hardware structure diagram. As shown in Figure 28, the decoder 270 may include: a second communication interface 2801, a second memory 2802 and a second processor 2803; each component is coupled together through a second bus system 2804. It can be understood that the second bus system 2804 is used to achieve connection and communication between these components. In addition to the data bus, the second bus system 2804 also includes a power bus, a control bus and a status signal bus. However, for the sake of clarity, various buses are marked as the second bus system 2804 in Figure 28. Among them,

The second communication interface 2801 is used for receiving and sending signals during the process of sending and receiving information with other external network elements;

The second memory 2802 is used to store a computer program that can be run on the second processor 2803;

The second processor 2803 is configured to, when running the computer program, execute:

Determine the value of the first decoding parameter; when the first decoding parameter indicates to skip decoding the k transformation layers of the current point cloud, determine one or more AC coefficient residual values of the k transformation layers as preset values; wherein k is an integer greater than zero; decode the code stream to determine the AC coefficient residual values of other transformation layers other than the k transformation layers in the current point cloud; determine the reconstructed point cloud of the current point cloud based on the AC coefficient residual values of the k transformation layers and the AC coefficient residual values of other transformation layers.

Optionally, as another embodiment, the second processor 2803 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 2802 and the first memory 2602 are similar, and the hardware functions of the second processor 2803 and the first processor 2603 are similar; they will not be described in detail here.

The present embodiment provides a decoder, which, when determining to skip encode the k transformation layers of the current point cloud, directly encodes one or more AC coefficient residual values of the k transformation layers according to preset values, can effectively improve the phenomenon of too many zeros in the AC coefficient values of the last few layers of encoding in the RAHT transform, thereby improving the encoding and decoding efficiency, and achieving quality enhancement of the reconstructed point cloud at the decoding end at an average bit rate, thereby improving the encoding and decoding performance of the point cloud.

In yet another embodiment of the present application, FIG29 is a schematic diagram of the composition structure of a coding and decoding system provided in an embodiment of the present application. As shown in FIG29 , the coding and decoding system 290 may include an encoder 2901 and a decoder 2902 .

In the embodiment of the present application, the encoder 2901 may be the encoder described in any one of the aforementioned embodiments, and the decoder 2902 may be the decoder described in any one of the aforementioned embodiments.

It should be noted that, in this application, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

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

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

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

The features disclosed in 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 is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Industrial Applicability

In an embodiment of the present application, at the encoding end, the value of the first encoding parameter is determined; when the first encoding parameter indicates that the k transform layers of the current point cloud are to be skip-encoded, one or more residual values of the AC coefficients of the k transform layers are determined to be preset values; one or more residual values of the AC coefficients of the k transform layers are encoded according to the preset values, and the obtained encoded bits are written into the bitstream. At the decoding end, the value of the first decoding parameter is determined; when the first decoding parameter indicates that the k transform layers of the current point cloud are to be skip-decoded, one or more residual values of the AC coefficients of the k transform layers are determined to be preset values; the bitstream is decoded to determine the residual values of the AC coefficients of other transform layers other than the k transform layers in the current point cloud; based on the residual values of the AC coefficients of the k transform layers and the residual values of the AC coefficients of the other transform layers, the reconstructed point cloud of the current point cloud is determined. That is to say, whether it is the encoding end or the decoding end, when it is determined to skip encoding the k transformation layers of the current point cloud, one or more AC coefficient residual values of these k transformation layers are directly encoded according to the preset values. This can effectively improve the phenomenon of too many 0s in the AC coefficient values of the last few layers of encoding in the RAHT transform, thereby improving the encoding and decoding efficiency, and achieving quality enhancement of the reconstructed point cloud at the average bit rate at the decoding end, thereby improving the encoding and decoding performance of the point cloud.

Claims (60)

A decoding method, applied to a decoder, comprising: Determining a value of a first decoding parameter; When the first decoding parameter indicates skip decoding of k transform layers of the current point cloud, determining one or more AC coefficient residual values of the k transform layers to be preset values; wherein k is an integer greater than zero; Decoding the bit stream to determine residual values of AC coefficients of other transform layers other than the k transform layers in the current point cloud; The reconstructed point cloud of the current point cloud is determined according to the AC coefficient residual values of the k transformation layers and the AC coefficient residual values of the other transformation layers. The method according to claim 1, wherein determining the value of the first decoding parameter comprises: Decode the code stream to determine the value of the first decoding parameter. The method according to claim 2, wherein the decoding bitstream and determining the value of the first decoding parameter comprises: Decode the attribute code stream unit in the code stream to determine the value of the first decoding parameter. The method according to claim 3, wherein the decoding bit stream determines the AC coefficient residual values of other transform layers other than the k transform layers in the current point cloud, comprising: Decode the attribute code stream unit in the code stream to determine the AC coefficient residual value of the other transformation layer. The method according to claim 4, wherein the method further comprises: In the attribute code stream unit, it is determined that the field corresponding to the first decoding parameter is located after the field corresponding to the AC coefficient residual value. The method according to claim 1, wherein the method further comprises: Determining a value of a second decoding parameter; When the second decoding parameter indicates to start the jump decoding of the current point cloud, the step of determining the value of the first decoding parameter is performed. The method according to claim 6, wherein determining the value of the second decoding parameter comprises: Decode the code stream to determine the value of the second decoding parameter. The method according to claim 7, wherein the decoding bitstream and determining the value of the second decoding parameter comprises: Decode the attribute parameter set unit in the code stream to determine the value of the second decoding parameter. The method according to claim 1, wherein determining one or more AC coefficient residual values of the k transform layers as preset values comprises: Determine that all AC coefficient residual values of the k transformation layers are the preset values. The method according to claim 1, wherein the method further comprises: Divide the points in the current point cloud into layers to determine a plurality of transformation layers corresponding to the current point cloud and a root node of the current point cloud; wherein the plurality of transformation layers include the k transformation layers and the other transformation layers. The method according to claim 10, wherein the method further comprises: The k transformation layers are set to be the last k transformation layers from the root node in a downward direction among the multiple transformation layers. The method according to claim 1, wherein the method further comprises: When the first decoding parameter indicates that the k transform layers of the current point cloud are not to be skip-decoded, decoding the bitstream to determine the residual values of the AC coefficients of the multiple transform layers corresponding to the current point cloud; A reconstructed point cloud of the current point cloud is determined according to the AC coefficient residual values of the multiple transformation layers. The method according to claim 12, wherein the decoding bit stream determines the AC coefficient residual values of multiple transform layers corresponding to the current point cloud, comprising: The attribute code stream unit in the code stream is decoded to determine the AC coefficient residual values of the multiple transformation layers. The method according to claim 1, wherein the method further comprises: If the value of the first decoding parameter is a first value, determining that the first decoding parameter indicates skip decoding of k transform layers of the current point cloud; If the value of the first decoding parameter is the second value, it is determined that the first decoding parameter indicates not to perform jump decoding on the k transform layers of the current point cloud. The method according to claim 14, wherein the method further comprises: When the first decoding parameter indicates skip decoding of k transform layers of the current point cloud, the value of k is set to be equal to the first value. The method according to claim 1 or 12, wherein the method further comprises: Decoding the code stream to determine the DC coefficient value of the root node of the current point cloud; The DC coefficient value of the root node is saved in the first parameter matrix of the current point cloud. The method according to claim 16, wherein the method further comprises: The AC coefficient residual values of the k transformation layers and the AC coefficient residual values of the other transformation layers are saved in the first parameter matrix of the current point cloud. The method according to claim 17, wherein the method further comprises: Dequantization is performed on parameter values in a first parameter matrix of the current point cloud. The method according to claim 18, wherein the determining a reconstructed point cloud of the current point cloud comprises: Determining predicted values of AC coefficients for points in the plurality of transform layers; Determining a second parameter matrix of the current point cloud according to the first parameter matrix of the current point cloud and the predicted values of the AC coefficients of the points in the plurality of transformation layers; Performing a region-adaptive hierarchical inverse transform on the second parameter matrix of the current point cloud to determine a reconstructed point cloud of the current point cloud. The method according to claim 19, wherein determining the AC coefficient prediction values of the points in the plurality of transform layers comprises: Determining predicted attribute values of points in the plurality of transformation layers; Performing regional adaptive hierarchical transformation on the attribute prediction values of the points in the multiple transformation layers to determine the AC coefficient prediction values of the points in the multiple transformation layers. The method according to claim 20, wherein determining the attribute prediction values of the points in the plurality of transformation layers comprises: When the current point cloud allows intra-frame prediction, performing intra-frame prediction on the points in the multiple transformation layers to determine attribute prediction values of the points in the multiple transformation layers; When the current point cloud allows inter-frame prediction, a reference point cloud of the current point cloud is determined, and inter-frame prediction is performed on the points in the multiple transformation layers according to the reference point cloud to determine attribute prediction values of the points in the multiple transformation layers. The method according to claim 19, wherein determining the second parameter matrix of the current point cloud according to the first parameter matrix of the current point cloud and the AC coefficient prediction values of the points in the plurality of transformation layers comprises: Based on the points of the current transformation layer in the current point cloud, determining the AC coefficient residual values of the points of the current transformation layer in the first parameter matrix, and determining the AC coefficient prediction values of the points of the current transformation layer; Performing an addition operation on the AC coefficient residual value and the AC coefficient prediction value to obtain an AC coefficient reconstruction value of the point on the current transformation layer; After obtaining the AC coefficient reconstruction values of the points of the multiple transformation layers, the second parameter matrix of the current point cloud is determined according to the DC coefficient value of the root node and the AC coefficient reconstruction values of the points of the multiple transformation layers. The method according to claim 22, wherein the performing a region-adaptive hierarchical inverse transform on the second parameter matrix of the current point cloud to determine a reconstructed point cloud of the current point cloud comprises: When the current transformation layer is the first transformation layer, performing a regional adaptive hierarchical inverse transformation according to the DC coefficient value of the root node and the AC coefficient reconstruction value of the point of the current transformation layer to obtain the reconstructed attribute value of the point of the first transformation layer; When the current transformation layer is not the first transformation layer, the DC coefficient value of the point of the current transformation layer is determined according to the reconstructed attribute value of the point of the previous transformation layer of the current transformation layer, and a regional adaptive hierarchical inverse transformation is performed according to the DC coefficient value of the point of the current transformation layer and the reconstructed AC coefficient value of the point of the current transformation layer to obtain the reconstructed attribute value of the point of the non-first transformation layer. The method according to any one of claims 1 to 23, wherein determining one or more AC coefficient residual values of the k transform layers as preset values comprises: The code stream is decoded to determine that one or more AC coefficient residual values of the k transformation layers are preset values. The method according to any one of claims 1 to 23, wherein the method further comprises: Decoding the code stream to determine a value of a third decoding parameter; When the third decoding parameter indicates to perform skip decoding on the components to be processed of the k transform layers of the current point cloud, determining one or more AC coefficient residual values of the components to be processed of the k transform layers to be preset values; Decoding the bit stream, and determining the AC coefficient residual values of the components to be processed of other transformation layers other than the k transformation layers in the current point cloud; The reconstructed point cloud of the to-be-processed component of the current point cloud is determined according to the AC coefficient residual values of the to-be-processed components of the k transformation layers and the AC coefficient residual values of the to-be-processed components of the other transformation layers. The method according to claim 25, wherein the component to be processed includes at least one of a first color component, a second color component, and a third color component. A coding method, applied to an encoder, comprising: Determining a value of a first encoding parameter; When the first encoding parameter indicates that k transform layers of the current point cloud are skipped, determining one or more of the k transform layers A plurality of AC coefficient residual values are preset values; wherein k is an integer greater than zero; One or more AC coefficient residual values of the k transformation layers are coded according to the preset values, and the obtained coded bits are written into the bit stream. The method according to claim 27, wherein determining the value of the first encoding parameter comprises: Determine a first generation value for encoding all the AC coefficient residual values of the k transform layers, and determine a second generation value for encoding one or more AC coefficient residual values of the k transform layers according to the preset value; A value of the first encoding parameter is determined according to the first generation value and the second generation value. The method according to claim 28, wherein determining the value of the first encoding parameter according to the first generation value and the second generation value comprises: If the first generation value is greater than the second generation value, determining that the value of the first encoding parameter is a first value; If the first generation value is less than the second generation value, the value of the first encoding parameter is determined to be the second value. The method according to claim 28, wherein the method further comprises: If the value of the first encoding parameter is a first value, determining that the first encoding parameter indicates skip encoding of k transform layers of the current point cloud; If the value of the first encoding parameter is the second value, it is determined that the first encoding parameter indicates that no skip encoding is performed on the k transformation layers of the current point cloud. The method according to claim 27, wherein the method further comprises: The value of the first encoding parameter is encoded, and the obtained encoding bits are written into a bit stream. The method according to claim 31, wherein the step of encoding the value of the first encoding parameter and writing the obtained encoding bits into a bitstream comprises: The value of the first coding parameter is coded, and the obtained coded bits are written into the attribute code stream unit in the code stream. The method according to claim 30, wherein the method further comprises: When the first encoding parameter indicates skip encoding of k transform layers of the current point cloud, the first value is set equal to the value of k. The method according to claim 33, wherein the method further comprises: Determine a third generation value for encoding all the AC coefficient residual values of the m transform layers, and determine a fourth generation value for encoding one or more AC coefficient residual values of the m transform layers according to the preset value; When the third generation value is greater than the fourth generation value, determining a fifth generation value of i transformation layers of the current point cloud encoded according to the preset value, wherein i=1, 2, ..., m, and m is an integer greater than zero; After obtaining m fifth-generation values, determining a minimum cost value from the m fifth-generation values; The value of k is determined according to the value of i corresponding to the minimum cost value. The method according to claim 27, wherein determining one or more AC coefficient residual values of the k transform layers as preset values comprises: Determine that all AC coefficient residual values of the k transformation layers are the preset values. The method according to claim 27, wherein the method further comprises: Divide the points in the current point cloud into layers to determine a plurality of transformation layers corresponding to the current point cloud and a root node of the current point cloud; wherein the plurality of transformation layers include the k transformation layers and the other transformation layers. The method according to claim 36, wherein the method further comprises: The k transformation layers are set to be the last k transformation layers from the root node in a downward direction among the multiple transformation layers. The method according to claim 36, wherein the method further comprises: Determining initial values of attributes of points in the plurality of transformation layers; Performing regional adaptive hierarchical transformation on the initial attribute values of the points in the multiple transformation layers, and determining the initial AC coefficient values of the points in the multiple transformation layers and the DC coefficient value of the root node. The method according to claim 38, wherein the method further comprises: Determining predicted values of AC coefficients for points in the plurality of transform layers; According to the initial values of the AC coefficients of the points in the multiple transformation layers and the predicted values of the AC coefficients of the points in the multiple transformation layers, the residual values of the AC coefficients of the multiple transformation layers are determined. The method according to claim 39, wherein the determining the AC coefficient residual values of the multiple transform layers according to the AC coefficient initial values of the points in the multiple transform layers and the AC coefficient predicted values of the points in the multiple transform layers comprises: Performing a subtraction operation on the initial values of the AC coefficients of the points in the multiple transformation layers and the predicted values of the AC coefficients of the points in the multiple transformation layers to obtain the predicted residuals of the AC coefficients of the points in the multiple transformation layers; The AC coefficient prediction residuals of the points in the multiple transformation layers are quantized to obtain the AC coefficient residuals of the multiple transformation layers. value. The method according to claim 39, wherein the method further comprises: When the first encoding parameter indicates that skip encoding is performed on k transform layers of the current point cloud, determining AC coefficient residual values of other transform layers other than the k transform layers in the multiple transform layers; The AC coefficient residual values of the other transformation layers are coded, and the obtained coded bits are written into the bit stream. The method according to claim 41, wherein the encoding of the AC coefficient residual values of the other transform layers and writing the obtained coded bits into the bitstream comprises: The AC coefficient residual values of the other transformation layers are coded, and the obtained coded bits are written into the attribute code stream unit in the code stream. The method according to claim 39, wherein the method further comprises: When the first encoding parameter indicates that the k transformation layers of the current point cloud are not to be skip-encoded, the AC coefficient residual values of the multiple transformation layers are encoded, and the obtained encoding bits are written into the bitstream. The method according to claim 43, wherein the encoding of the AC coefficient residual values of the multiple transform layers and writing the obtained coded bits into the bitstream comprises: The AC coefficient residual values of the plurality of transform layers are coded, and the obtained coded bits are written into the attribute code stream unit in the code stream. The method according to claim 42 or 44, wherein the method further comprises: In the attribute code stream unit, it is determined that the field corresponding to the first coding parameter is located after the field corresponding to the AC coefficient residual value. The method of claim 39, wherein determining the AC coefficient prediction values of the points in the plurality of transform layers comprises: Determining predicted attribute values of points in the plurality of transformation layers; Performing regional adaptive hierarchical transformation on the attribute prediction values of the points in the multiple transformation layers to determine the AC coefficient prediction values of the points in the multiple transformation layers. The method of claim 46, wherein determining the attribute prediction values of the points in the plurality of transformation layers comprises: When the current point cloud allows intra-frame prediction, performing intra-frame prediction on the points in the multiple transformation layers to determine attribute prediction values of the points in the multiple transformation layers; When the current point cloud allows inter-frame prediction, a reference point cloud of the current point cloud is determined, and inter-frame prediction is performed on the points in the multiple transformation layers according to the reference point cloud to determine attribute prediction values of the points in the multiple transformation layers. The method according to claim 38, wherein the method further comprises: The DC coefficient value of the root node is encoded, and the obtained encoding bits are written into the bit stream. The method according to claim 27, wherein the method further comprises: Determining a value of a second encoding parameter; When the second encoding parameter indicates starting the skip encoding of the current point cloud, the step of determining the value of the first encoding parameter is performed. The method according to claim 49, wherein the method further comprises: The value of the second encoding parameter is encoded, and the obtained encoding bits are written into a bit stream. The method according to claim 50, wherein the step of encoding the value of the second encoding parameter and writing the obtained encoding bits into a bitstream comprises: The value of the second coding parameter is coded, and the obtained coded bits are written into the attribute parameter set unit in the code stream. The method according to any one of claims 27 to 51, wherein the method further comprises: Determining a value of a third encoding parameter; wherein the third encoding parameter is used to indicate whether to perform skip encoding on the to-be-processed components of the k transformation layers of the current point cloud; The value of the third encoding parameter is encoded, and the obtained encoding bits are written into the bit stream. The method according to claim 52, wherein the component to be processed includes at least one of a first color component, a second color component, and a third color component. The method according to claim 52, wherein the method further comprises: When skip encoding is performed on the components to be processed of the k transformation layers of the current point cloud, determining one or more AC coefficient residual values of the components to be processed of the k transformation layers to be preset values; One or more AC coefficient residual values of the components to be processed of the k transformation layers are coded according to the preset values, and the obtained coded bits are written into the 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: The AC coefficient residual values of multiple transformation layers corresponding to the current point cloud, the DC coefficient value of the root node of the current point cloud, one or more AC coefficient residual values of k transformation layers of the current point cloud are preset values, the AC coefficient residual values of other transformation layers other than the k transformation layers in the current point cloud, the value of the first encoding parameter, the value of the second encoding parameter and the value of the third encoding parameter; Among them, the first encoding parameter is used to indicate whether to perform jump encoding on the k transformation layers of the current point cloud, the second encoding parameter is used to indicate whether to turn on jump encoding of the current point cloud, and the third encoding parameter is used to indicate whether to perform jump encoding on the k transformation layers to be processed of the current point cloud. An encoder comprises a first determining unit and an encoding unit, wherein: The first determination unit is configured to determine a value of a first encoding parameter; when the first encoding parameter indicates that k transformation layers of the current point cloud are to be skip-encoded, determine that one or more AC coefficient residual values of the k transformation layers are preset values; wherein k is an integer greater than zero; The encoding unit is configured to encode one or more AC coefficient residual values of the k transformation layers according to the preset values, 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 27 to 54 when running the computer program. A decoder comprises a second determining unit, a decoding unit and a reconstruction unit, wherein: The second determination unit is configured to determine a value of the first decoding parameter; when the first decoding parameter indicates to perform skip decoding on k transform layers of the current point cloud, determine that one or more AC coefficient residual values of the k transform layers are preset values; wherein k is an integer greater than zero; The decoding unit is configured to decode the code stream to determine the residual values of the AC coefficients of other transform layers other than the k transform layers in the current point cloud; The reconstruction unit is configured to determine a reconstructed point cloud of the current point cloud based on the AC coefficient residual values of the k transformation layers and the AC coefficient residual values of the other transformation layers. A decoder comprises 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 26 when running the computer program. A computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by at least one processor, the method according to any one of claims 1 to 26 or the method according to any one of claims 27 to 54 is implemented.