JPH11136687A - Moving image reproducing device and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent unavailability of reproduction of a compression coded moving image signal due to restriction of processing capacity capability of the reproducing device and a frame memory. SOLUTION: This device is made up of a control means 20 that discriminates whether or not reproduction is available as a moving image and controls reproduction processing based on the processing capability and the frame memory capacity of the moving image reproducing device while considering an image size and a frame rate of an image decoded by a 1st decoding means 14 from the coded data in the case of reproducing moving image coded data combined with intra-frame coding and inter-frame coding, a means 11 that selects intra- frame coding data from the moving image coding data in the case the moving image is unable to be reproduced, 2nd decoding means 16-19 decode respectively the moving image coding data and the intra-frame coding data respectively when the moving image is reproduced, a means 22 that applies sub-sampling to image data produced by decoding the intra-frame coding data selected by the selection means; and a means 24 that stores the sub-sampled image data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing apparatus for a moving picture signal which has been compression-encoded, and which uses a standard TV receiver to realize a high-definition TV.
The present invention relates to a device that can obtain a V-received reproduction image.

[0002]

2. Description of the Related Art Conventional techniques for compressing and encoding moving images include intra-frame encoding (I-frame encoding) and inter-frame encoding (P-frame encoding, B-frame encoding) such as MPEG1 and MPEG2. Combined encoding methods are known.

FIG. 2 is a block diagram showing a conventional example of a moving picture reproducing apparatus compatible with MPEG2 encoding. The encoded data is input to the buffer circuit 33 and the encoding rate is smoothed. The decoding circuit 34 includes header information indicating the characteristics of the entire encoded data such as the image size and the frame rate, header information indicating the encoding method and characteristics for each frame, and prediction control information that has been variable-length encoded. The quantized coefficients are decoded. In the encoded data of the MPEG2 system, the image size, the frame rate, and the like are encoded as a sequence header, and the encoding method and characteristics for each frame are encoded as a picture header.

[0004] The control circuit 40 determines whether or not the encoded data characteristics such as the image size and frame rate of the decoded image from the decoding circuit 34 depend on the processing capability of the reproducing apparatus 30 and the restrictions on the amount of frame memory. Determine whether it is possible.
When the control circuit 40 determines that the moving image can be reproduced, the control circuit 40 controls each processing block to perform a predetermined moving image reproducing process.

[0003] When the control circuit 40 determines that a moving image cannot be reproduced, the control circuit 40 controls each processing block so as not to perform processing. Processing for video playback is
For example, it is performed as follows. Upon receiving the DCT quantization coefficient for each 8 × 8 pixel block from the decoding circuit 34, the inverse quantization circuit 35 performs an inverse quantization process.

The IDCT circuit 36 performs IDCT processing on the inversely quantized DCT coefficients. Here, when the reproduced frame is I-frame encoded, all the predicted values from the prediction circuit 38 are supplied to the adder 37 as zero. In the case of P frame encoding and B frame encoding, the IDCT circuit 36
The motion compensation prediction value corresponding to the 8 × 8 pixel block from is generated by the prediction circuit 38 using the reproduced frame stored in the frame memory 1 (39) and supplied to the adder 37.

The adder 37 sequentially adds the output from the IDCT circuit 36 and the prediction value from the prediction circuit 38 and stores the result in the frame memory 2 (44) for display. Also,
When the reproduced frame is I-frame encoded or P-frame encoded, the reproduced frame is stored in the frame memory 1 (39) in order to generate a predicted value for a frame to be reproduced later. The reproduction of the moving image is performed as described above.

[0007]

The moving image reproducing apparatus has an upper limit on the reproducible image size and the number of frames per unit time (frame rate) due to the limitations of the processing capacity and the amount of frame memory. Conventionally, when coded data having characteristics exceeding the upper limit of a reproducible image size or frame rate set in advance to a moving image reproducing device is input, the reproducing device up to now performs moving image reproduction. The reproduction process was not performed because it was impossible. For example, the standard T
V level (SDTV) image size and frame rate characteristics (720 pixels × 480 lines, 29.97H
z), a reproduction device having an upper limit of reproduction of encoded data having the characteristics of image size and frame rate at a high definition TV level (hereinafter, HDTV) (1920 pixels × 1080)
When encoded data having a line (29.97 Hz) is supplied, such a reproducing apparatus cannot reproduce the content of the encoded data of the high definition TV at all.

[0008] For this reason, for example, in the case of digital television broadcasting, a viewer who owns a reproducing apparatus whose reproduction is limited to a standard TV level (SDTV) obtains all information of digital television broadcasting (HDTV). There was a problem that it was not possible.

The above problems are caused by the limitations on the processing capability and the amount of frame memory of the conventional reproducing apparatus. Therefore, the above-mentioned problem is solved by reproducing only the I-frame coded data and sub-sampling it into a predetermined image size when storing it in the frame memory.

The I-frame coded data is, for example,
A54 of US Advanced Television Systems Committe
As described in the document, it is generally sent about every 0.5 seconds.
For this reason, even if only the I-frame encoded data is reproduced,
It can be reproduced as an image every about 0.5 seconds.
This allows the viewer to know the contents of the encoded data.

[0011]

In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a moving picture for reproducing moving picture coded data by a coding method combining intra-frame coding and inter-frame coding. In the image reproducing apparatus, a first decoding unit that decodes an image size and a frame rate of a moving image from the encoded data, and the moving image based on the image size and the frame rate decoded by the first decoding unit. Based on the processing capacity of the image reproduction device and the amount of frame memory,
Control means for judging whether or not reproduction as a moving image is possible and controlling reproduction processing, means for selecting intra-frame coded data from the coded video data when reproduction as a moving image is impossible, Second decoding means for decoding the encoded video data when the video can be reproduced and the intra-frame encoded data when the video cannot be reproduced, There is provided a moving image reproducing apparatus comprising: means for subsampling image data obtained by decoding encoded data; and means for storing image data subsampled by the subsampling means.

Further, the invention according to claim 2 is a moving image reproducing method for reproducing moving image coded data by a coding method which combines intra-frame coding and inter-frame coding. From a first decoding step of decoding an image size and a frame rate, and an image size and a frame rate decoded by the first decoding step, based on the processing capability and the amount of frame memory of the moving image reproducing apparatus, A control step of judging whether or not it can be reproduced as a moving image and controlling a reproduction process, and, when the reproduction cannot be performed as a moving image, a step of selecting intra-frame coded data from the coded video data, Decoding the encoded video data when the video can be reproduced and the intra-frame encoded data when the video cannot be reproduced. 2, a step of sub-sampling image data obtained by decoding the intra-frame encoded data selected by the selecting unit, and a step of storing the image data sub-sampled by the sub-sampling step. And a moving image reproducing method characterized by the following.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a moving picture reproducing apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a moving image reproducing apparatus according to the present invention. Here, the playback device 10 of the present embodiment uses the SDTV image size and frame rate characteristics (720 pixels × 480 pixels).
Line, 29.97 Hz, etc.). The encoded data is supplied to the buffer circuit 13 via the switch SW1 (12), and the encoding rate is smoothed.

The decoding circuit 14 decodes sequence header information, picture header information for each frame, variable length encoded prediction control information, and quantization coefficients. The control circuit 20 determines whether the encoded data characteristics such as the image size and the frame rate decoded from the sequence header by the decoding circuit 14 indicate that the moving image can be reproduced in accordance with the processing capability of the reproducing apparatus 10 and the restrictions on the amount of frame memory. First, it is determined whether or not it is possible.

If it is determined that moving image reproduction is possible, for example, if coded data having image size and frame rate characteristics corresponding to SDTV is input,
The control circuit 20 includes switches, SW1 (12) and SW2-1.
(21), SW2-2 (23) are all switched to the b side of the switch. Then, the control circuit 20 controls each processing block so as to perform predetermined processing for reproducing a moving image.

When it is determined that moving image reproduction is impossible, for example, when coded data having characteristics of an image size and a frame rate corresponding to HDTV is input, the control circuit 20 controls each processing block. Is controlled to perform the following processing. The control circuit 20 includes switches, SW1 (12), SW2-1 (21), and SW2-2 (2).
3) All are switched to the switch a side. Buffer circuit 1
3 is input with data from the I-frame coded data selection circuit 11.

The I-frame encoded data selection circuit 11
A sequence header and I-frame encoded data are selected from the input encoded data and output to the buffer circuit 13.
In the subsequent processing blocks, only the I-frame encoded data can be reproduced. For example, when the frame frequency is 30 Hz and the I-frame interval is 0.5 second, the processing amount is
It becomes 1/15 or less as compared with the case where all the frames are reproduced.

Here, the buffer memory amount of the buffer circuit 13 is an amount sufficient to temporarily store the I frame encoded data of the HDTV moving image encoded data. For example, M
PEG2 encoding method MP @ HL (main profile
High-level) mode HDTV video encoded data I
Approximately 1.2M when corresponding to frame encoded data
The buffer amount is B or more.

As a result, the HDT whose image size is about six times
By reproducing the V-frame encoded data only at the interval of 0.5 seconds, but only the I-frame encoded data, the processing amount can be sufficiently reproduced by the SDTV encoded video data reproducing apparatus. The encoded data from the buffer circuit 13 is decoded by a decoding circuit 14 and is sequentially dequantized by an inverse quantization circuit 15
The processing is performed by the T circuit 16.

Since only the I-frame coded data is used, a prediction value of always zero from the prediction circuit 18 is supplied to the adder 17 and added to the processing result of the IDCT circuit 16. The output from the adder 17 is supplied to the sub-sampling circuit 22 via the switch SW2-1 (21).

The sub-sampling circuit 22 controls the reproduced image of the HDTV I-frame encoded data output from the adder 17 so that the reproduced image has an image size that can be stored in the frame memory 2 (24) corresponding to the SDTV. A sampling signal is supplied from the circuit 20, and a sub-sampling process is sequentially performed.

The processing of the sub-sampling circuit 22 is based on the HDTV
Has an aspect ratio of 16: 9 and an SDTV has an aspect ratio of 4: 3. Therefore, for example, one of the following two methods can be selected.

The first sub-sampling method performs sub-sampling at a ratio of 4/9 in each of the horizontal and vertical directions.
In this method, since the horizontal direction is 853 pixels, only the center 720 pixels are selected and output to the frame memory 2 (24).

In the second sub-sampling method, sub-sampling is performed at a ratio of 3/8 in each of the horizontal and vertical directions. In this method, since the vertical direction is 405 lines, for example, the upper 38 lines and the lower 37 lines are output to the frame memory 2 (24) as dummy black lines.

The output signal of the sub-sampling circuit 22 is supplied to the frame memory 2 (24). Here, a control signal from the control circuit 20 is supplied and output to the outside as an image signal switched at 0.5 second intervals.

In the present invention, a decoding circuit for decoding the encoded data when the moving image can be reproduced and a decoding circuit for decoding the intra-frame encoded data when the moving image cannot be reproduced are provided. Most can be shared. The IDCT circuit 16, the adder 17, the prediction circuit 18, and the frame memory 1 (19) (second decoding means) are also standard TV (SDT)
V) and each circuit can be shared at the time of reproduction of a high definition TV (HDTV).

Therefore, when coded data having a characteristic exceeding the upper limit of the reproducible image size or frame rate set in advance to the moving image reproducing apparatus is input,
Generally, I-frame encoded data encoded at 0.5 second intervals can be subsampled, reproduced, and output.

By doing so, the outline of the contents of the high-definition TV (HDTV) level received / reproduced image can be known by the standard TV (SDTV) level receiving / reproducing apparatus.

[0029]

According to the present invention, there is provided a moving picture reproducing apparatus for reproducing moving picture coded data by a coding method combining intra-frame coding and inter-frame coding. The first decoding means 14 for decoding the rate and whether the image can be reproduced as a moving image based on the processing capacity and the amount of frame memory of the moving image reproducing apparatus based on the image size and the frame rate decoded by the decoding means Control means for judging whether or not the reproduction processing is performed, means for selecting intra-frame encoded data from the encoded video data when reproduction as a moving image is impossible, and Second decoding means for decoding the video encoded data and the intra-frame encoded data when the video cannot be reproduced,
Since it is constituted by means for sub-sampling the image data obtained by decoding the intra-frame encoded data selected by the selecting means and means for storing the sub-sampled image data, it is set in advance for the moving image reproducing apparatus. When coded data having a characteristic exceeding the upper limit of the reproducible image size or frame rate is input, generally, the coded data is set to 0.1.
I-frame encoded data encoded at 5-second intervals can be subsampled, reproduced, and output.

According to the present invention, a standard TV (SDTV) can be received and reproduced, and a high-definition TV (HDTV) can be partially received and reproduced to know the outline of the image content.

[Brief description of the drawings]

FIG. 1 is a diagram showing a block configuration of a moving image reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a block configuration of an example of a conventional moving image reproducing apparatus.

[Explanation of symbols]

 10, 30 Moving picture reproducing apparatus 11 I-frame coded data selection circuit 12, 21, 23 SW (switch) 13, 33 Buffer circuit 14 Decoding circuit (first decoding means) 15, 35 Inverse quantization circuit 16 IDCT Circuit (second decoding means) 17 Adder (second decoding means) 18 Prediction circuit (second decoding means) 19 Frame memory 1 (second decoding means) 20, 40 Control circuit 22 Sub Sample circuit 24 Frame memory 2 (means for storing image data) 34 Decoding circuit 36 IDCT circuit 37 Adder 38 Prediction circuit 39 Frame memory 1 44 Frame memory 2

Claims (2)

[Claims] 1. A moving picture reproducing apparatus for reproducing moving picture coded data by a coding method in which intra-frame coding and inter-frame coding are combined, wherein a picture size and a frame rate of a moving picture are decoded from the coded data. A first decoding unit that converts the image into a video based on the processing capacity and the amount of frame memory of the moving image reproducing apparatus based on the image size and the frame rate decoded by the first decoding unit. Control means for judging whether or not the reproduction processing is performed, means for selecting intra-frame encoded data from the encoded video data when reproduction as a moving image is impossible, and A second decoding unit that decodes the encoded video data and the intra-frame encoded data when the video cannot be reproduced, and the selecting unit. Means for subsampling the image data decoded more selected frames in the encoded data, a moving image reproducing apparatus characterized by a more configurations and means for storing the image data subsampled by the subsampling to means. 2. A moving picture reproducing method for reproducing moving picture coded data by a coding method in which intra-frame coding and inter-frame coding are combined, wherein a picture size and a frame rate of a moving picture are decoded from the coded data. A first decoding step for converting the image and a picture size and a frame rate decoded in the first decoding step, based on the processing capability and the amount of frame memory of the moving picture reproducing apparatus, whether or not the moving picture can be reproduced. A control step of judging whether or not the reproduction processing is performed, a step of selecting intra-frame coded data from the coded video data when reproduction as a moving image is impossible, and A second decoding step of respectively decoding the encoded video data and the intra-frame encoded data when the video cannot be reproduced as a video. Moving image data obtained by decoding the intra-frame encoded data selected by the selecting means; and storing the image data subsampled by the subsampling step. Playback method.