JP2001128161A - Device and method for encoding and decoding moving picture and recording method used for them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration of the picture quality of the transmitted moving picture and to suppress deterioration of encoding efficiency. SOLUTION: In the moving picture encoding and decoding device, an erroneously-decoded macro block number informing means 12 is installed in a decoding device section 9 and an encoded information storing means 14 which stores encoded image information and an encoding control section 13 which controls intra-refreshment and motion compensation so that no macro block section may be used as a reference image from a received erroneously-decoded macro block number 16E and the encoded image information are provided to an encoding device section 9. Since no other number than the erroneously- decoded macro block number and a normally restored macro block number is required to be informed to a communicating partner, the influence of a decrease in allocated code rate, etc., on encoded animation data, etc., is small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving picture encoding / decoding apparatus and method, and a recording medium therefor, and more particularly to a moving picture used for a videophone or video conference system, which is highly efficient and has a plurality of decoding errors. Moving image encoding / decoding apparatus / method for preventing the influence on consecutive decoded images,
It relates to the recording medium.

[0002]

2. Description of the Related Art A moving image is compressed and coded and transmitted / received to improve communication efficiency. In the compression encoding of moving images, higher efficiency is required. As a method for efficiently compressing and encoding moving images, ITU (International Telecommun
ication Union) IS such as H261 and H263 recommended
O (International Organization for Standardization)
A system that combines motion compensation such as the recommended MPEG-1, MPEG-2, and MPEG-4, two-dimensional discrete cosine transform, and Huffman coding is known. The encoded video data according to such a method has a three-layer structure of a picture, a slice, and a macroblock. A picture is a single image to be encoded. A macroblock is a picture obtained by dividing a picture into blocks, and generally has a size in which 16 pixels are arranged vertically and horizontally. A slice is a grouping of macroblocks in consecutive coding order.
It is also called a "roup of block" or a video packet. The moving image encoding process is performed on a macroblock basis.

[0003] Coding of macroblocks is roughly divided into intra mode and inter mode.
ode). In the intra mode, encoding is performed using only data in a macroblock, and when decoding, an image can be reproduced using only the data in the macroblock. In the inter mode, encoding is performed using difference information from image data motion-compensated using a reference image, and decoding requires data of a reference image and encoded data of a macroblock. The images before and after the image to be encoded are selected as the reference images. In general, the order of macroblock coding is to scan from left to right and from top to bottom starting from the upper left of the image.
The slice is appropriately configured according to the video coding algorithm. The macroblock at the head of the slice is encoded in the intra mode, and the subsequent macroblocks are encoded in either the intra mode or the inter mode.

If a macroblock at a specific position is always encoded in the inter mode, the decoded image is degraded due to accumulation of encoding errors. Is controlled. This control is called intra refresh. In the second and subsequent macroblocks in a slice, a difference value from previously encoded macroblock information is generally used as the macroblock information. At the head of the picture and slice data, there is a start code indicating the start of the data and header information, which are used as a synchronization point when the moving picture decoding apparatus decodes the coded moving picture data.

In an apparatus for encoding and decoding moving image data using such a moving image encoding method, if a code error occurs in received data, normal decoding cannot be performed at the time of decoding. The erroneous decoding process is continued until the next synchronization point, or the decoding process is temporarily stopped and skipped to the next synchronization point. As a result, in the decoded image, the reproduced image of the macroblock from the position where the error occurred to the synchronization point is deteriorated. Furthermore, since a deteriorated macroblock is in a deteriorated state until the next intra refresh, if this portion is used as a reference image during decoding processing of another macroblock, the image of the macroblock also becomes deteriorated. Would. Therefore, even if a decoding error occurs, there is a demand for a moving picture coding / decoding apparatus capable of quickly restoring an image and reproducing a good image.

In order to meet such a demand, for example,
As disclosed in Japanese Patent Application Laid-Open No. Hei 7-327755, an interpolation image is created for a macroblock in which a decoding error has occurred to replace the data of the macroblock, and a coding error is notified to an encoding device of a communication partner. Then, it has been proposed to control the encoding mode of a macroblock located in the same space of a picture immediately after that to be switched to the intra mode. The technique disclosed in this prior art document, as shown in FIG.
01 and a decoding main unit 102, a code error detecting unit 103 for received data, and an interpolated image generating unit 1 for generating an interpolated image for a macroblock in which a decoding error has occurred.
04, a code error notifying unit 105 for notifying a communication partner that a decoding error has occurred, and an encoding control unit 106 for controlling an encoding unit using the received decoding error information.

In this known technique, the presence or absence of a code error in all decoded macroblocks, and if there is an error, the information of the GOB number and the macroblock address is transmitted to the coding apparatus, so that a low bit rate communication of about 64 kbps is performed. In the case of, the error information data becomes relatively large,
There is a problem that the amount of data to which the moving image encoded data is allocated is reduced and the image quality of the moving image to be transmitted is deteriorated. Further, when the erroneous macroblock is in the moving area, the coding apparatus is controlled so as to encode all the macroblocks included in the moving area in the intra mode, and is not affected by the error. Macroblocks are coded in the intra mode, which causes a problem that coding efficiency is reduced and image quality of a moving image to be transmitted is reduced.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a moving picture coding / decoding apparatus and method capable of suppressing a drop in coding efficiency and a picture quality of a moving picture to be transmitted.
It is to provide the recording medium. Another object of the present invention is to provide a moving picture coding / decoding apparatus / method, which suppresses a drop in coding efficiency and suppresses a drop in picture quality of a moving picture to be transmitted even when a macroblock is in a moving area. It is to provide a recording medium.

[0009]

Means for solving the problem are described as follows. The technical items appearing in the expression are appended with numbers, symbols, and the like in parentheses (). The numbers, symbols, etc. are technical items that constitute at least one embodiment or a plurality of examples of the embodiments or examples of the present invention, in particular, the embodiments or the examples. Corresponds to the reference numerals, reference symbols, and the like assigned to the technical matters expressed in the drawings corresponding to the above. Such reference numbers and reference symbols clarify the link between the technical matters described in the claims and the technical matters of the embodiments or examples. Such a bridging does not mean that the technical matters described in the claims are interpreted as being limited to the technical matters of the embodiments or the examples.

[0010] A moving picture encoding / decoding apparatus according to the present invention comprises:
A receiving unit (6) for receiving, from the partner, the error occurrence number (16E) of the macroblock on the transmission side in which a decoding error has occurred and the normal recovery number (16R) of the macroblock on the transmission side in which decoding has returned to normal; And an encoding control unit (1) for controlling the compression encoding of the transmission side moving image to be transmitted on the transmission side based on the error occurrence number (16E) and the normal recovery number (16R).
3).

Since the notification of the decoding error notifies only the occurrence of the error and the macroblock number corresponding to the error only when the error is restored, the amount of transmission data is small, and the influence on the video encoding is small. Deterioration in image quality due to a decrease in the code amount can be suppressed.

The control of the coding control unit (13) is performed by executing macroblock coding from the error occurrence number (16E) to the normal recovery number (16R) in the intra mode in the coding of the next picture. is there. Since the encoding device performs intra-refresh only on the macroblock in which an error has occurred, it is possible to minimize the increase in the amount of code due to intra-mode encoding. Furthermore, since the motion compensation is controlled so that the macroblock degraded due to the error is not used as the reference image, it is possible to suppress the propagation of the degraded part of the image to other parts.

In the above-mentioned moving picture coding apparatus, when a compression coding is performed on the other party and a moving picture transmitted from the other party is received and decoded, a decoding error occurs. The error occurrence number (16E) of the other party's macroblock
A macroblock number notifying unit (12) for notifying the other party of the normal recovery number (16R) of the macroblock of the other party whose decoding has returned to normal is further included. If the macro block number notifying section (12) is also provided on this side, bidirectional compressed image communication can be performed between the other side and this side, and the TV
The efficiency of data transmission of telephone and TV conference systems is promoted.

A moving picture encoding / decoding method according to the present invention comprises:
Transmitting the compression-encoded moving image to the other party,
Receiving the error occurrence number (16E) of the macroblock in which the decoding error has occurred and the normal recovery number (16R) of the macroblock in which the decoding has been restored normally after receiving the moving image on the receiving side, The encoding includes compression-encoding a macroblock between the error occurrence number macroblock and the normal recovery number macroblock in the intra mode.

Further, the other party is notified of the error occurrence number (16E) of the macroblock in which the decoding error has occurred and the normal recovery number (16R) of the macroblock in which decoding has been restored normally after receiving the moving picture of the other party. And the other party:
In the coding of the next picture, a macroblock between the macroblock of the error occurrence number and the macroblock of the normal recovery number is compression-coded in the intra mode.
Thereby, two-way communication is possible. Such a method is realized by a program, and the program is recorded on a recording medium in a computer-readable manner.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Corresponding to the drawings, in the embodiment of the moving picture coding / decoding apparatus according to the present invention, a moving picture coding section is provided together with a moving picture decoding section. As shown in FIG. 1, input moving image data 2 which is a moving image is input to the moving image encoding unit 1. The moving image encoding unit 1 performs an encoding process on the input moving image data 2 and outputs encoded moving image data 3.

The moving picture coding unit 1 is connected to a multiplexing unit 4. The multiplexing unit 4 sends out the coded video data output 3 and the coded data output 5 obtained by multiplexing the coded audio data and other data to the transmission path. The demultiplexing unit 6
The received encoded data input 7 is separated into audio encoded data, video encoded data 8 and other data. The demultiplexer 6 is connected to the video decoder 9. The moving picture decoding unit 9 decodes the coded moving picture data 8 and outputs a reproduced moving picture 11.

The main moving picture coding / decoding apparatus further includes a macroblock number notifying means 12 and a coding control means 13.
And an encoded information storage unit 14. The video decoding unit 9 outputs the presence / absence 15 of the decoded error macroblock and the macroblock number 16 thereof. The macroblock number notifying means 12, which receives the presence / absence 15 of the decoding error macroblock and the macroblock number 16, multiplexes the macroblock number 16E at the start of the decoding error and the macroblock number 16R at the time of normal recovery. Send to Part 4. The macroblock number 16 is multiplexed with other encoded data and transmitted to another video encoding / decoding device (not shown) of the communication partner.

The demultiplexing section 6 is connected to the encoding control means 13. The encoding control means 13 receives the macroblock number 16E at the start of the decoding error and the macroblock number 16R restored to the normal state via the demultiplexing unit 6. The macroblock number 16E at the start of the decoding error and the macroblock number 16R that has returned to the normal state are stored in the encoded information storage unit 14. The encoding control unit 13 controls the moving image encoding unit 1 while referring to encoding information such as an intra macroblock and a slice configuration, and stores the encoding information in the encoding information storage unit 14. Video encoding unit 1
The moving picture decoding unit 9 is a conventional means.

The video decoding unit 9 determines whether a decoding error has occurred when decoding a macroblock, and notifies the decoding error macroblock number notifying unit 12 of the determination result and the macroblock number 16. The determination of the presence / absence 15 of a macroblock having a decoding error can be made based on the appearance of a symbol that is not in the code table, the appearance of information that is not possible due to the context. Macro block number 16E, 1
6R is assigned so that the position of the macroblock can be uniquely identified by the number. For example, starting from the upper left of the image, numbers may be assigned from left to right, from top to bottom, 1, 2, 3,. It is assumed that the encoding device and the decoding device share the same information.

FIG. 2 shows the operation of the decoding error macroblock number notifying means 12. When the video decoding process is started, the macroblock number notifying unit 12 receives a macroblock error determination result output from the video decoding unit 9 (Step S1), and determines whether or not there is an error. When there is an error, the number 16E of the macroblock in which the error first occurs is sent to the multiplexing unit 4 (step S2). Continue receiving the determination result (step S
3), the number 16E of the macroblock in which the error further occurred
Is transmitted to the multiplexing unit 4, and when a macroblock determined to have been decoded without error appears, the number 16R of the macroblock that has returned to normal is transmitted (step S4).

Such a plurality of steps are normally and continuously executed. Normally, a macroblock that has returned to normal appears from a synchronization point in a picture or slice. However, an error may be mixed in the data at the synchronization point, and in that case, an error macroblock may be generated over a plurality of slices.

FIG. 3 shows the structure of a slice. The encoding control unit 13 causes the encoding information storage unit 14 to store the image encoding conditions. The coding conditions include information such as the configuration of the slice 21 and intra refresh.
If there is no notification of a decoding error, slice 2
1 and the intra refresh is performed.

When receiving the number 16E of the macroblock in which the decoding error has occurred and the number 16R of the macroblock that has returned to the normal state, the macroblock in that section is recorded as an erroneous macroblock, and the moving picture is displayed so that the macroblock is intra-refreshed. The image encoding unit 1 is controlled.
Further, when compensating for the motion of a macroblock to be coded in the inter mode, the motion compensation is controlled so as not to use the image data included in the error macroblock.

FIG. 3 shows the configuration of a slice 21 of a coded image by enclosing it with a thick line. The mark x in the figure indicates the position of the macroblock 22 where the decoding error has occurred, and the mark ○ indicates the position of the macroblock 23 that has returned to normal. The encoding control means 13 marks the macroblock in the section from the occurrence of the error to the return to normal as an error macroblock. This is indicated by a triangle in the figure.

When coding the next picture, the moving picture coding unit 1 is controlled so that the error macroblock is coded in the intra mode. In the other macroblocks, macroblocks to be coded in the inter mode are controlled so that image data in a region including an error macroblock is not used for motion compensation.

FIG. 4 shows an embodiment in which the moving picture encoding / decoding apparatus is realized as a program of a microprocessor. The recording medium 31 stores a program for realizing a moving image encoding / decoding process. Recording medium 31
Can be formed of a magnetic disk, a semiconductor memory, or another recording medium. The moving image encoding / decoding program is read from the recording medium 31 by the microprocessor 32 and controls the operation of the microprocessor 32. The microprocessor 32 performs the above-described steps shown in FIG. Information necessary for decoding, such as sequence information and the number of macroblocks, is stored in the memory 33.

In the circuit block shown in FIG. 1, only the transmitting side or the receiving side is shown. By using this circuit block on the transmitting side and the receiving side, two-way communication becomes possible and a TV conference system can be configured. A program for executing the operation of such a moving picture coding / decoding apparatus is input to a recording medium.

[0029]

The moving picture encoding / decoding apparatus according to the present invention
Since the method and the recording medium need only notify the communication partner of the macroblock number at which the decoding error has occurred and the macroblock number at which the decoding has returned to normal, the influence of a decrease in the amount of code allocated to the moving picture coded data and the like is not affected. Few.

Further, since the erroneous macro block is refreshed, the deteriorated image quickly returns to a normal state. Further, macroblocks in which no error has occurred are coded in the inter mode although there is a limitation in motion compensation, so that an increase in the code amount can be suppressed as compared with the case where all are coded in the intra mode.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing an embodiment of a moving picture encoding / decoding apparatus according to the present invention.

FIG. 2 is a flowchart showing an embodiment of a moving picture encoding / decoding method according to the present invention.

FIG. 3 is a diagram showing blocks of a moving image.

FIG. 4 is a circuit block diagram showing an embodiment of a recording medium according to the present invention.

FIG. 5 is a circuit block diagram showing a known device.

[Explanation of symbols]

 12 macroblock number notification unit 13 encoding control unit 16E error occurrence number 16R normal return number

Claims (6)

[Claims] A receiving unit for receiving, from a partner, an error occurrence number of a macroblock on the transmission side in which a decoding error has occurred and a normal recovery number of a macroblock on the transmission side in which decoding has returned to normal; A moving image encoding / decoding apparatus including: an encoding control unit configured to control compression encoding of a current moving image to be transmitted on the current side based on an occurrence number and the normal recovery number. 2. The encoding control unit according to claim 1, wherein the control of the coding control unit is performed for a macroblock to be transmitted to the other party between the error occurrence number and the normal recovery number in the coding of the next picture. A moving picture coding / decoding apparatus which performs the coding in an intra mode. 3. The moving picture coding apparatus according to claim 1, wherein the moving picture coding apparatus is selected from the claims 1 and 2, and compression coding is performed on the other party and transmitted from the other party. Macro that notifies the other party of the error occurrence number of the other-side macroblock in which a decoding error has occurred and the normal recovery number of the other-side macroblock whose decoding has returned to normal when receiving and decoding A moving image encoding / decoding device including a block number notifying unit. 4. A compression-encoded transmitting side video is transmitted to the other party, and an error occurrence number of a macroblock in which a decoding error has occurred upon reception of the receiving side video and a macro whose decoding has been restored to normal. Notifying us of the normal return number of the block, and compressing and encoding the macroblock between the macroblock of the error occurrence number and the macroblock of the normal return number in intra mode in the encoding of the next picture And a moving image encoding / decoding method. 5. The communication system according to claim 4, further comprising: an error occurrence number of a macroblock in which a decoding error has occurred in receiving the moving image of the other party and a normal recovery number of the macroblock in which decoding has been restored to the other party. A moving picture that compresses and encodes the macroblock between the macroblock of the error occurrence number and the macroblock of the normal return number in intra mode in the encoding of the next picture. Image encoding / decoding method. 6. A recording medium on which a program for executing the moving picture encoding / decoding method according to claim 4 is recorded.