JPH06339111A - Compressed moving picture reproduction device - Google Patents

Abstract

PURPOSE:To attain reverse order reproduction for a long time even when the capacity of a buffer memory is reduced. CONSTITUTION:The device is provided with a reverse order coding means 23 setting motion picture data in the reverse reproduction order for compression coding, a buffer memory 24 storing compression-coded picture data by the reverse order coding means 23, and an input data selection means 25 selecting compression coded data of a recording medium 20 or compression coded data in the buffer memory 24, and the motion picture data decoded by the forward reproduction are compression-coded in the reverse reproduction by the reverse coding means 23 and the picture data subjected to compression coding are stored in the buffer memory 24 and in the case of reverse reproduction, the compression coded motion picture data stored in the buffer memory 24 are read and decoded in the reverse direction and displayed for the reverse reproduction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressed moving picture reproducing apparatus for decoding and reproducing compression-encoded moving picture data, and more particularly to a compressed moving picture reproducing apparatus capable of reverse reproduction. .

[0002]

2. Description of the Related Art In recent years, with the development of digital signal processing, LSI technology, and image coding technology, a technology for compressing a huge amount of moving image data has become familiar and has begun to be applied to videophones and videoconference systems. There is. Also, CD,
With the widespread use of storage media such as DAT, there is an increasing demand for services provided by media that store moving images.
Against this background, ISO-IEC / JTC1 / S
C2 / WG11 / MPEG (Moving Picture Expert Gro
up), the standardization of the moving picture coding method for storage media is in progress.

The current moving image compression coding system is roughly divided into two processes, one of which is a frame (1
Intra-frame compression (MPEG method) that regards a screen as a still image and compresses it independently of other frames. It is an inter-frame compression expressed by a small amount of information.

The basis of the above-mentioned MPEG system is that motion-compensated inter-frame prediction is performed, the prediction error thereof is subjected to DCT (discrete cosine transform), quantized and sequentially variable-length coded from low frequency components. Motion-compensated interframe predictive coding does not simply code interframe differences,
Predictive coding with motion compensation is performed from neighboring frames. Furthermore, in the MPEG method, in addition to the forward prediction that is predicted from the past frame in the inter-frame prediction, the backward prediction that is predicted from the future frame and the average value prediction of both of them are taken into consideration, and the best prediction among the three is made. By selecting, the interframe prediction efficiency is improved.

Next, the operation of decoding and reproducing moving image data encoded and recorded according to the compression encoding method of the conventional compressed moving image reproducing apparatus will be described with reference to the drawings.

FIG. 5 is a block diagram of a conventional compressed moving image reproducing apparatus.

In FIG. 5, reference numeral 1 is a recording medium on which compression-coded moving image data is recorded, 2 is a variable length decoder for variable length decoding compressed moving image data, and 3 is variable length decoding. An inverse quantizer 4 that inversely quantizes the dequantized data is an inverse DCT calculator that inversely DCTs the dequantized data. Reference numeral 5 is a frame memory B for storing already decoded past frame data required for forward inter-frame prediction, and 6 is a frame memory A for storing future frame data required for backward inter-frame prediction. . 7
Is a motion-compensated forward predictive value calculator that calculates a forward predictive value in consideration of motion compensation by referring to the frame memory B5, and 8 is a backward predictive value in consideration of motion compensation, by referring to the frame memory A6. A motion-compensated backward prediction value calculator 9 for calculating a motion compensation backward prediction value calculator 9, and a motion compensation bidirectional prediction value calculator 9 for calculating a bidirectional prediction value considering motion compensation with reference to both the frame memory B5 and the frame memory A6.
Is a switch for selecting a predictor for calculating a prediction value according to the type of inter-frame prediction when the frame to be decoded is decoded. Reference numeral 11 denotes the difference data of the image that has been inversely DCTed by the inverse DCT calculator 4 and the prediction values calculated by the motion compensation forward prediction value calculator 7, the motion compensation backward prediction value calculator 8, and the motion compensation bidirectional prediction value calculator 9. An adder for adding, 13 is a display for controlling and displaying the decoded image data, and 12 is an inverse DCT calculator depending on whether the decoded frame is intra-frame compressed or inter-frame compressed. The image data subjected to the inverse DCT by 4 is sent to the display 13 via the adder 11 or directly,
This is a switch for selecting whether to send to the display unit 13.

The operation of the conventional compressed moving image reproducing apparatus configured as above will be described.

First, when the image data sent from the recording medium 1 is intra-frame compressed data, the compressed data is variable in the order of the variable length decoder 2, the inverse quantizer 3 and the inverse DCT calculator 4. Long decoding, inverse quantization, inverse DCT,
The decoded image data is sent to the display unit 13 and is also stored in the frame memory A6 through the path 14. When the image data stored in the frame memory A6 is next sent from the recording medium 1 as the data of the image compressed in the frame or the image compressed in the forward frame,
It is moved to the frame memory B5.

Next, when the data transmitted from the recording medium 1 is the data predicted in the forward frame, the data transmitted is the compression-coded inter-frame difference data, and this data has a variable length. The decoder 2, the inverse quantizer 3, and the inverse DCT calculator 4 are subjected to variable length decoding, inverse quantization, and inverse DCT for decoding in this order. On the other hand, the prediction value calculated by the motion compensation forward prediction value calculator 7 selected by the switch 10 is added by the decoded difference data and the adder 11. As a result, the decoded image data is sent to the display device 13 and stored in the frame memory A6 through the path 14.

When the image data sent from the recording medium 1 is the data which is compressed between the backward frames and the data which is compressed between the bidirectional frames, it is the same as the case where the image data is compressed between the forward frames. , The difference data is processed by the variable length decoder 2, the inverse quantizer 3, and the inverse DCT calculator 4, and the motion-compensated backward prediction value calculator 8 or the motion-compensated bidirectional prediction value calculator 9 selected by the switch 10 respectively. Predicted value calculated by and adder 1
The image data that has been added with 1 and decoded is sent to the display unit 13. This image data is not sent to the frame memory A6.

[0012] In the MPEG system, in consideration of special access such as random access, high speed reproduction, reverse reproduction, etc., at least one frame including a frame that has been compression-coded by intraframe compression of at least one frame, has an arbitrary length. A frame unit called GOP (Group Of Picture) configured by the number of frames is introduced. In this case, as a special reproduction method, for example, edited by Hiroshi Yasuda: "International Standard for Multimedia Coding" (published by Maruzen Co., Ltd.), p.154-155
As the method described in (1), the high-speed reproduction realizes high-speed reproduction by speeding up the cueing of only the intra-frame compression-coded image in each GOP and decoding and displaying only that. Further, as the reverse reproduction, a method of performing the reverse reproduction by storing the decoded image data for GOP in a specific memory is described.

Next, a method for performing the reverse reproduction will be described with reference to FIG.

FIG. 6 is a block diagram of a structure capable of reverse order reproduction of a conventional compressed moving picture reproducing apparatus.

In FIG. 6, reference numeral 15 is a recording medium on which compressed moving picture data is recorded, 16 is a decoder for decoding the compressed moving picture data, and 17 is a display for displaying the decoded moving picture data. Reference numeral 18 denotes a frame buffer memory for storing decoded image data to be reproduced and displayed at the time of reverse reproduction. Reference numeral 19 denotes a switch for switching the moving image data to be reproduced and displayed at the time of forward reproduction and at the time of backward reproduction between the data from the decoder 16 and the data from the frame buffer memory 18.

In this operation, first, the compressed moving image data recorded on the recording medium 15 is decoded by the decoder 16, and the decoded moving image data is sent to the display unit 17 and the frame buffer. It is stored in the memory 18. During forward playback, the moving image data decoded by the decoder 16 is sent to the display unit 17 for playback display, and during reverse playback, the moving image data stored in the frame buffer memory 18 is read out in reverse order. The reverse display is displayed on the display unit 17.

[0017]

When the reverse reproduction is performed by the above-mentioned conventional method, the time during which the reverse reproduction can be performed is determined by the size of the frame buffer memory 18. That is, the reverse reproduction time is determined depending on how many frames of decoded image data can be stored in the frame buffer memory 18. Therefore,
In order to perform reverse playback for a long time, the frame buffer memory 18 needs to have a large capacity so as to store a large amount of decoded image data.

For example, considering that one pixel is represented by 8 bits in an RGB image of 360 × 240 pixels as a frame format of a color moving image, the image data amount of one frame becomes about 2 Mbits. .
Assuming that one GOP is composed of 15 frames, the frame buffer memory 1 for reverse order reproduction
8 requires a memory having a size of about 30 Mbits for one GOP of image data. Further, if the reverse reproduction is performed for a long time, a frame buffer memory having an enormous size larger than that is required.

Therefore, an object of the present invention is to provide a compressed moving image reproducing apparatus capable of performing reverse reproduction for a long time even if the capacity of the buffer memory is small.

[0020]

A compressed moving picture reproducing apparatus according to the present invention comprises a decoding means for reading and decoding the compressed coded data from a recording medium on which the moving picture data is compressed and coded and recorded. In a compressed moving image reproducing apparatus including a frame memory for storing image data necessary for the decoding, and a display unit for displaying the decoded moving image data, A reverse-direction encoding means for performing compression-encoding so as to achieve a reverse-order reproduction order, a buffer memory for storing image data compression-encoded by the reverse-order encoding means, compression-encoded data of the recording medium, and And input data selecting means for selecting the compression coded data of the buffer memory.

[0021]

In the present invention, the moving picture data decoded by the forward reproduction is compression-encoded by the reverse encoding means so that the reverse reproduction order is obtained, and the compression-encoded data is stored in the buffer memory. It is stored, and when playing in reverse order,
The compression-encoded moving image data stored in the buffer memory is read in the reverse direction, is decoded, and is displayed to perform the reverse reproduction.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the compressed moving image reproducing apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing the operating principle of the compressed moving image reproducing apparatus in one embodiment of the present invention. It is also a complaint correspondence diagram.

In FIG. 1, 20 is a recording medium on which compressed moving image data is recorded, 21a is a decoding means for decoding the compressed moving image data, and 21b is a memory for storing the image data necessary for decoding. A frame memory, a display means 22 for reproducing and displaying the decoded moving image, an inverse coding means 23 for compressing and coding the decoded moving image data in reverse order, and a reference numeral 24 for the reverse order coding means 23. A buffer memory for storing encoded data, and 25 is an input data selecting means for selecting whether to decode the data from the recording medium 20 or to decode the data stored in the buffer memory 24 at the time of reverse reproduction. Is. The image data decoded by the decoding means 21a is displayed on the display means 2
2 is sent to the reverse order coding means 23, compression coded in the reverse order, and stored in the buffer memory 24. At the time of reverse reproduction, the encoded data stored in the buffer memory 24 by the input data selection means 25 is sent to the decoding means 21a, and after being decoded, it is sent to the display means 22 for reproduction display. .

That is, in the configuration of this embodiment, in the conventional compressed moving image reproducing apparatus as described above, the reverse order coding means 23 for compressing and coding the decoded image data again, and the reverse order coding means 23. A buffer memory 24 for storing the data encoded by the above is added, and the moving image data decoded by the forward reproduction is arranged in the reverse reproduction order by the reverse encoding means 23. The compression encoding is performed, the compression encoded data is stored in the buffer memory 24, and in the reverse reproduction, the compression encoding moving image data stored in the buffer memory 24 is read in the reverse direction. Then, by decoding and displaying it, reverse reproduction is performed.

FIG. 2 is a block diagram showing a concrete structure of the compressed moving image reproducing apparatus in one embodiment of the present invention.

Reference numeral 20 is a recording medium on which compression encoded data is recorded, 27 is a variable length decoder for performing variable length decoding on the compression encoded data, and 28 is an inverse quantization for dequantizing the variable length decoded data. Quantizer 29 is an inverse DCT calculator that performs an inverse DCT operation on the inversely quantized data, 31 is a motion-compensated forward prediction value calculator that calculates a forward inter-frame prediction value in consideration of motion compensation, and 32 is a motion A motion-compensated backward-predicted-value calculator that calculates a backward inter-frame predicted value in consideration of compensation, 33 is a motion-compensated bi-directional predicted-value calculator that calculates a bidirectional inter-frame predicted value in consideration of motion compensation,
Reference numeral 34 is a frame memory A for storing the frame data necessary for the motion compensation backward prediction value calculator 32 to calculate the prediction value. Reference numeral 35 is necessary for the motion compensation forward prediction calculation device 31 to calculate the prediction value. A frame memory B for storing frame data, 36 is a switch for switching between three types of inter-frame prediction value calculators depending on the type of inter-frame prediction of a moving image to be decoded, 37 is an inverse DCT by an inverse DCT calculator 29. Decoded difference data, motion compensation forward prediction value calculator 31, motion compensation backward prediction value calculator 3
2. This is an adder that adds the prediction values calculated by the inter-frame prediction value calculator of the motion compensation bidirectional prediction value calculator 33.

Further, 39 is a DCT calculator for performing DCT calculation on the decoded moving image data during forward reproduction,
40 is a quantizer that quantizes the DCT-computed data, 41 is a variable-length coder that performs variable-length coding on the quantized data, and 42 is a forward-looking one that takes motion compensation into consideration. A motion-compensated forward predictor for calculating an inter-frame predicted value, 43 is a motion-compensated backward predictor for calculating a backward predicted value in consideration of motion compensation, and 44 is a motion for calculating a bidirectional predicted value in consideration of motion compensation. A compensating bidirectional predictor, 45 is a switch for switching predictors consisting of three types of a motion compensating forward predictor 42, a motion compensating backward predictor 43, and a motion compensating bidirectional predictor 44, depending on the type of interframe prediction of a moving image to be encoded, Reference numeral 46 is a frame calculated from the predictors of the motion-compensated forward predictor 42, the motion-compensated backward predictor 43, and the motion-compensated bidirectional predictor 44 from the moving image data to be encoded. A subtracter for subtracting the prediction value, 24 is a buffer memory for storing the data that is variable-length coded by the variable-length encoder 41, and 48 is a buffer memory for decoding the image data from the recording medium 20 or the buffer memory 24. A switch for switching 49 is a display for reproducing and displaying the decoded moving image.

The variable length decoder 27 shown in FIG.
Inverse quantizer 28, inverse DCT calculator 29, motion compensation forward prediction value calculator 31, motion compensation backward prediction value calculator 32, motion compensation bidirectional prediction value calculator 33, adder 37.
Constitutes the decoding means 21a shown in FIG. Similarly, the DCT calculator 39, the quantizer 40, the variable length encoder 41, the motion-compensated forward predictor 42, the motion-compensated backward predictor 43, the motion-compensated bidirectional predictor 44, and the display 49 are:
It constitutes the reverse order encoding means 23 shown in FIG. And
The frame memory A34 and the frame memory B35 form the frame memory 21b shown in FIG.

Next, the overall operation of the compressed moving image reproducing apparatus of this embodiment will be described.

First, when the data sent from the recording medium 20 is the intra-frame compressed data, the data is variable length decoded by the variable length decoder 27, the dequantizer 28, and the inverse DCT calculator 29, respectively. , Inverse quantization, inverse DCT
The calculated and decoded image data is sent to the display device 49 and is also transmitted through the path 30 to the frame memory A34.
Memorized in. The decoded image data stored in the frame memory A34 is sent from the storage medium 26 as image data compressed in the frame or image data compressed in the forward frame, and is decoded when the frame memory B is used.
Moved to 35.

On the other hand, the decoded image data for one frame is first sent to the subtractor 46 via the path 50 for the purpose of encoding, but nothing is subtracted and the DCT calculator 39, The quantizer 40 and the variable length encoder 41 are respectively subjected to DCT operation, quantization and variable length coding, and the compression coded data is stored in the buffer memory 24.

When the data sent from the recording medium 20 is the data predicted in the forward frame, the difference data sent is the variable length decoder 2 as in the case described above.
7, the inverse quantizer 28, and the inverse DCT calculator 29 respectively perform a decoding process, and the prediction value calculated by the motion compensation forward prediction value calculator 31 is added by the adder 37.
The image data thus decoded is sent to the display 49 and stored in the frame memory 34 through the path 30. In addition, the decoded image data is stored in the path 50.
Sent to the subtractor 46 through the motion compensation forward predictor 4
The predicted value predicted by 2 is subtracted in the subtractor 46. The inter-frame difference data generated by subtraction is D
The CT calculator 39, the quantizer 40, and the variable-length encoder 41 perform DCT, quantization, and variable-length encoding, respectively, and compression-encode them. Then, this encoded difference data is stored in the buffer memory 24.

When the data sent from the recording medium 20 is backward interframe prediction or bidirectional interframe prediction data, variable length decoding is performed as in the case of decoding the forward interframe prediction data. Chemicalizer 2
7, the inverse quantizer 28, and the inverse DCT calculator 29 perform the decoding processing, and the predicted values calculated by the motion-compensated backward prediction value calculator 32 and the motion-compensated bidirectional predicted value calculator 33 are added by the adder 37. It The resulting decoded image data is sent to the display 49 and the subtractor 46 through the path 50, and the backward frames between the backward frames predicted by the motion-compensated backward predictor 43 and the motion-compensated bidirectional predictor 44, respectively. The predicted value and the bidirectional interframe predicted value are subtracted to form interframe difference data.
This difference data is stored in the DCT calculator 39, the quantizer 40,
The variable-length encoder 41 performs DCT calculation, quantization, variable-length encoding, and compression encoding, respectively, and then the buffer memory 2
Stored in 4.

At the time of reverse reproduction, the data to be decoded is switched from the recording medium 20 to the buffer memory 24 by the switch 48, the compression coded data stored in the buffer memory 24 is read in the reverse order, and the variable length decoder is used. 27, an inverse quantizer 28, and an inverse DCT calculator 29 to perform variable length decoding, inverse quantization, and inverse DCT operation, respectively. Next, if the compression-coded data is not the one that has been intraframe-compressed by the reverse-order coding path, the inverse DCT calculator 29 performs the inverse DCT.
The calculated data is sent to the display device 49 and reproduced and displayed.

If the data is compressed between frames,
The data subjected to the inverse DCT calculation by the inverse DCT calculator 29 has a motion compensation forward prediction value calculator 3 depending on whether the interframe compression is forward, backward, or bidirectional.
1, a motion compensation backward prediction value calculator 32, a motion compensation bidirectional prediction value calculator 33, and a prediction value calculated by any prediction value calculator are added in the adder 37, and the decoded image data obtained by the addition is It is sent to the display device 49 and reproduced and displayed.

Next, the procedure of image data processing in this embodiment will be described.

FIG. 3 is an explanatory diagram of a data processing procedure of the compressed moving image reproducing apparatus in one embodiment of the present invention, and FIG. 4 is an explanatory diagram of a reverse-order reproduction data processing procedure of the compressed moving image reproducing apparatus.

In FIG. 3, I indicates image data compressed in a frame, P indicates image data compressed by forward inter-frame prediction, B indicates image data compressed by bidirectional prediction, and numbers are displayed. Shows the order. Each of the frame memory A34 and the frame memory B35 is divided into three memory parts, that is, a memory a62, a memory b63, and a memory c64, and stores decoded image data. It is assumed that it takes a display period of one frame to decode each compressed image data.

The data on the recording medium 20 is recorded in the arrangement shown in the figure in consideration of the time of expanding the image data.

First, the intraframe-compressed image data I0 on the recording medium 20 is subjected to variable length decoding, inverse quantization, and inverse D.
After the CT calculation is performed, it is decoded during one frame display period and stored in the frame memory a. The image data P3 compressed by the forward inter-frame prediction on the next incoming recording medium 20 is decoded and stored in the frame memory b. Further, the image data B1 compressed by the bidirectional prediction on the next recording medium 20 is decoded and stored in the frame memory c, and the image of the image data I0 compressed in the frame is displayed and the image data I0 is displayed. Store in buffer memory.

Similarly, the image data B2 compressed by the bidirectional prediction on the subsequent recording medium 20 is decoded and stored in the frame memory c, the image data B1 is displayed, and the image data B2 is compressed by the forward inter-frame prediction of the frame memory b. The image data P1 and the image data I0 in the frame memory a are referred to and the image data B1 is compressed by the motion compensation bidirectional prediction and stored in the buffer memory 24. Next, the image data P6 compressed by the forward inter-frame prediction on the recording medium 20 is decoded and stored in the frame memory a, the image of the image data B2 is displayed, and the image data P2 is compressed by the forward inter-frame prediction in the frame memory b. The image data P3 and the image data I0 in the frame memory a are referred to
Data is compressed by the motion compensation bidirectional prediction and stored in the buffer memory 24. Next, the image data B4 compressed by the bidirectional prediction on the recording medium 20 is decoded and stored in the frame memory c, the image of the image data P3 compressed by the forward inter-frame prediction is displayed, and the image data of the frame memory a is displayed. With reference to P6, the image data P3 in the frame memory b is compressed by motion-compensated one-way prediction and stored in the buffer memory 24. Thereafter, similarly, such processing is performed until the image of the image data P9 compressed by the forward inter-frame prediction is displayed.

Here, the data processing procedure for performing the reverse reproduction at the time when the display of the image of the image data P9 compressed by the forward inter-frame prediction is finished will be described with reference to FIG.

At the time when the display of the image data P9 compressed by the forward inter-frame prediction is finished, the frame memory A3
The image data stored in 4 is three images of image data I12, image data P9, and image data B8.

First, the image data P6 is read from the buffer memory 24, decoded and stored in the frame memory a, and the image of the image data P9 in the frame memory b is displayed. Next, the image data B7 is read from the buffer memory 24, decoded and stored in the frame memory c, and the image of the image data B8 is displayed. Next, the buffer memory 2
The image data P3 is read from 4 to be decoded and stored in the frame memory b, and the image of the image data B7 is displayed. Next, the image data B5 is read from the buffer memory 24, decoded and stored in the frame memory c, and the image of the image data P6 is displayed. Next, the image data B4 is read from the buffer memory 24, decoded and stored in the frame memory c, and the image of the image data B5 is displayed. Next, the image data I0 is read from the buffer memory 24, decoded and stored in the frame memory a, and the image of the image data B4 is displayed.

After that, the reverse reproduction is performed by performing such processing until the image of the image data I0 compressed in the frame on the recording medium 20 is displayed.

As described above, the compressed moving image reproducing apparatus of the present embodiment includes the decoding means 21a for reading and decoding the compressed encoded data from the recording medium 20 in which the moving image data is compressed and encoded and recorded. In a compressed moving image reproducing apparatus comprising a frame memory 21b for storing image data necessary for the decoding, and a display means 22 comprising a display 49 for displaying the decoded moving image data. ,
A reverse encoding unit 23 that performs compression encoding on the moving image data so that the moving image data is in an order of reverse reproduction, a buffer memory 24 that stores the image data compressed and encoded by the reverse encoding unit 23, It is provided with an input data selecting means 25 for selecting the compression coded data of the recording medium 20 and the compression coded data of the buffer memory 24.

With this configuration, the moving picture data decoded by the forward reproduction is compression-encoded by the reverse encoding means 23 so that the reverse reproduction is performed, and the compression-encoded data is obtained. Are stored in the buffer memory 24, and in the reverse order reproduction, the compression-coded moving image data stored in the buffer memory 24 is read out in the reverse direction, is decoded, and is displayed to reverse order. Playback can be performed.

That is, the moving image data decoded at the time of forward reproduction is compressed and coded again, and the compressed coded data is stored in the buffer memory 24. At the time of reverse reproduction, this compressed coded data is decoded. , Since it is configured to display the playback, compared to the case where the decoded moving image data itself at the time of forward playback is stored in the buffer memory, less data can be stored in the buffer memory,
It is possible to perform reverse playback for a longer time with a smaller capacity buffer memory.

Therefore, the amount of data stored in the buffer memory becomes smaller than that in the case of storing the image data itself at the time of decoding in the conventional buffer memory, and the capacity of the buffer memory can be reduced as compared with the conventional method. Therefore, it is possible to perform reverse playback for a longer time with respect to the buffer memory having the same capacity.

By the way, in the above embodiment, the handling in the range between the intra-frame compressed image data has been described. However, in the case of implementing the present invention, the handling should be performed in the unit between the intra-frame compressed image data. Therefore, the moving picture data is compressed in the reverse order so that the moving picture data is reproduced in the reverse order. The buffer memory 24 stores the image data compressed and coded by the reverse order coding means 23.
If the number of circuits of is increased or the number of circuits of the whole is increased, the addressing of the image data is reversed, and the reproduction in the forward direction and the reverse direction is alternately performed in the unit between the image data compressed in the frame, Reverse recording of the recording medium 20 can be continuously performed.

[0052]

As described above, according to the compressed moving image reproducing apparatus of the present invention, the moving image data decoded by the forward reproduction in units of the intra-frame compressed image data is compressed and encoded again. , The coded data is stored in the buffer memory, and the coded data is decoded and displayed at the time of reverse playback, so the moving image data itself decoded at the time of forward playback is stored in the buffer memory. The amount of data stored in the buffer memory is smaller than that in the case where the buffer memory is stored in advance, and the reverse order reproduction can be performed for a longer time with a smaller capacity buffer memory. Therefore, even if the capacity of the buffer memory is reduced, it is possible to perform reverse playback for a long time.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an operation principle of a compressed moving image reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a compressed moving image reproducing apparatus according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a data processing procedure of the compressed moving image reproducing apparatus according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a data processing procedure of reverse order reproduction of the compressed moving image reproducing apparatus according to an embodiment of the present invention.

FIG. 5 is a block diagram of a conventional compressed moving image reproducing apparatus.

FIG. 6 is a block diagram of a configuration capable of reverse order reproduction of a conventional compressed moving image reproduction device.

[Explanation of symbols]

 20 recording medium 21a decoding means 21b frame memory 22 display means 23 reverse order encoding means 24 buffer memory 25 input data selecting means 27 variable length decoder 28 inverse quantizer 29 inverse DCT calculator 31 motion compensation forward prediction value calculator 32 motion compensation backward prediction value calculator 33 motion compensation bidirectional prediction value calculator 34 frame memory A 35 frame memory B 39 DCT calculator 40 quantizer 41 variable length encoder 42 motion compensation forward predictor 43 motion compensation backward predictor 44 motion compensation bidirectional predictor 49 indicator

Claims (1)

[Claims] 1. A decoding means for reading and decoding the compression-encoded data from a recording medium in which the moving image data is compression-encoded and recorded, and image data necessary for the decoding are stored. In a compressed moving image reproducing apparatus comprising a frame memory for storing and a display unit for displaying the decoded moving image data, a reverse order of performing compression encoding on the moving image data so as to make the order of reverse order reproduction. Encoding means, buffer memory for storing image data compressed and encoded by the reverse encoding means, input data selecting means for selecting compression encoded data of the recording medium and compression encoded data of the buffer memory And a compressed moving image reproducing apparatus.