JP2002290978A - Moving image error recovering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce distortion as much as possible by omitting wasteful processing in a recovering method in the case of error detection although expanding processing of a moving image is probably disabled when an error is contained in moving image data compressed by an MPEG system. SOLUTION: Even when the error is detected, expanding processing is continued on the basis of the position of a macro block inside a frame, where the error occurs, the rate of error occurrence on lines, the quantity of change from a frame timewisely adjacent with the error occurring frame, the motion vector of each of frames in the past and a position relation between the error fame and a frame which is encoded without referring to the other frames, so that the distortion can be reduced when displaying a moving image. Further, the propagation of the error to the next frame is suppressed and partial noises inside the frame are eliminated as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
In an PEG compression / expansion system, when an error occurs between a compression device and a decompression device, it is possible to minimize the disturbance of image display that occurs in the decompression device and prevent quality deterioration of a displayed moving image. And a moving image error recovery method most suitable to

[0002]

2. Description of the Related Art A variable length code is used for compressing moving picture data used in MPEG. The data length of variable-length data is not known until it is decoded, and if an error occurs in the data, the subsequent data breaks cannot be recognized. And the individual codewords are not correctly reproduced because only one bit is wrong, the number of codewords to be decoded changes,
Also, the decoder may fall into a state where decoding is impossible. That is, once a transmission error occurs, there is a possibility that all information received after the erroneous bit cannot be correctly decoded.

[0003] To cope with this, "ISO / IEC 14496-2: 1999 / Amd.1:
"2000 (E)" specifies a method for localizing an error that has occurred.

[0004] Localization of errors makes it possible to decompress data after localization.

[0005] Also, "IEEE SIGNAL PROCESSING MAGAZIN"
E JULY 2000, Error Resilient Video Coding Technique
s ”, the time at which the error was detected,
A method of estimating the content of error data from spatially neighboring data has been considered.

[0006]

The prior art for localizing the above error location is defined only in MPEG-4.
Decoders that do not use this method or MPEG-1,2
In such a case, there is a possibility that a moving image cannot be decompressed at all due to occurrence of an error. In addition, the standard does not standardize how to recover from a localized error.

Further, it is not impossible to decompress all data after an error occurs due to the localization of the error. However, there is no way to recover the data of the error generating portion, that is, there is no way to recover the data in the frame of the moving image. In some cases, it becomes impossible to display appropriate image data. As described in the second related art, the content of the error data is estimated from the neighboring data, but no specific recovery method is described.

Accordingly, an object of the present invention is to provide a compression apparatus and a decompression apparatus for copying an appropriate macroblock in a temporally adjacent frame to an error generating unit according to the position of a macroblock in which an error is detected in the frame. Determine the macroblock position to copy according to the error rate between
When the difference between the frame in which the error occurred and the frame to be copied of the macroblock is large, a frame that can be expanded without using other images is expanded and displayed. If there is a frame that does not require reference data, this is displayed, or the motion vector used at the time of decompression of the frame is held. From the macroblock located at the same position as the macroblock of the frame of the frame, a moving image data compression / expansion device which copies the area indicated by the held motion vector and suppresses the display disturbance of the image generated in the expansion device as much as possible. To provide.

[0009]

In order to achieve the above object, in a moving image data compression / decompression system in which a processing device for compressing moving image data by the MPEG system and a processing device for expanding the compressed data are connected by a network. In the data decompression device, a number is assigned to a processing unit called a macroblock in a frame which is a display unit of a moving image, and when analyzing the compressed moving image data, an error of the data is detected and the error is detected. Moving image data 1
A method of identifying a position in a frame in units of macroblocks, and after detecting an error, a method of copying all macroblocks up to the end of the frame from a temporally adjacent previous frame, and detecting an error. The method of copying all the macroblocks of the immediately preceding frame temporally adjacent to the frame is displayed by switching the error recovery position according to the position in the frame where the error is detected.

Thus, the decompression process can be continued even when an error is detected, and the disturbance in displaying a moving image can be reduced. And useless copying of data can be prevented.

In the data decompression device, the error rate of the line for taking in the compressed moving image data is stored, and the n macroblocks are similarly temporally traced from the macroblock in which the error is detected according to the error rate. Adjacent one
Copy from previous frame.

Thus, in variable-length coding, the number of places where an error occurs is larger than the place where an error is detected,
Because it exists before, this can be dealt with.

Further, when encoding a frame of a moving image, the data compression apparatus encodes and compresses a change amount from a temporally adjacent frame as control data, and compresses the moving image. Based on the control data, the data decompression device that receives the data specifies the macroblock to be copied based on the position of the macroblock in which the error is detected, if the change amount is equal to or smaller than the threshold n, and determines from the temporally adjacent frame If the macro block is copied and is larger than the threshold value n, the compressed frame is displayed next without using information of other frames.

[0014] This makes it possible to minimize disturbance in displaying a moving image in which an error has occurred, and to suppress propagation of the error to the next frame.

The data compression apparatus encodes and compresses a frame cycle indicating the number of frames to be encoded without referring to other frames when encoding a moving image. The data decompression device is provided with a frame counter and counts up each time a frame is decoded. When the frame period sent from the compression device is reached, the data decompression device sets the counter to 0. The counter value is subtracted. If the result of the subtraction is equal to or smaller than the threshold value n, data is copied from a temporally adjacent frame according to the position of the macroblock. If the result of the subtraction is smaller than the threshold value n, another frame is referenced. Decompress and display the encoded image without performing it.

This makes it possible to eliminate partial noise in a frame when there is an image coded without referring to another frame at a position close in time to the frame where the error has occurred.

In the data decompression device, the motion vector used at the time of decompression of the frame is held.
The region indicated by the held motion vector is copied and displayed from the macroblock located at the same position as the macroblock in the previous frame.

This makes it possible to minimize disturbance in displaying a moving image in which an error has occurred and to suppress the transmission of the error to the next frame. Thus, the object of the present invention is achieved.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a flowchart showing a recovery method when an error is detected in a moving image data decompression process according to an embodiment showing the features of the present invention.

First, an outline will be described with reference to FIG. 2 of a system configuration example to which this processing flow diagram is applied, and then a recovery method at the time of error detection will be described in detail with reference to FIG. FIG. 2 shows an example of the system configuration. The system configuration includes an image input device (201) for inputting moving image data, a compression device (203) for compressing moving image data, an interface 1 (202) connecting the two, and a decompression device for expanding compressed data ( 205), an image output device (207) for outputting expanded moving image data, and an interface 2 for connecting the two.
(206). The compression device (203) and the decompression device (205) are connected via a network (204). Examples of the image input device (201) include a camera and a DV.
Examples of the image output device (207) include a display and the like.

Referring to FIG. 3, the structures of the compression device (203) and the expansion device (205) will be described. Compression device (203)
The decompression device (205) includes a CPU (301), a memory (302), an input control device (304), an output control device (305), and a bus (303). CP
U (301) performs arithmetic processing for compression / decompression.
The memory (302) stores data. The input control device (304) performs control of taking in moving image data from the image input device (201) to the compression device (203) in the compression device (203), and controls the decompression device (205) through the network (204). Control to take compressed data into the decompression device (205). Output control device (30
5) The compression device (203) performs control to output compressed data to the network (204), and the expansion device (205) performs control to output expanded video data to the image output device (207). . Bus (303)
Is an interface of the CPU (301), the memory (302), the input control device (304), and the output control device (305).

In this embodiment, MPEG (Moving Picture Experts Groove) is a method for compressing and expanding moving image data.
up) The method will be described. However, it is effective when each frame described later is compressed by information only in the frame or difference information from other frames, the frame is divided into blocks, and a variable length code is applied to image data. Here, the MPEG compression method will be described. MPEG uses a data compression method based on intra-screen correlation for one screen of a moving image (hereinafter, referred to as a frame) and a previous screen (hereinafter, referred to as a reference frame).
And a data compression method based on an inter-screen correlation with the data. The frame data compressed by the intra-screen correlation can be expanded without using information of other frames. Such a frame is referred to as an I frame. A frame compressed by the inter-screen correlation is referred to as a P frame.
In addition, a macro block (404) uses a Y component (luminance signal) of 16 × 16 pixels, a U component (color difference signal) of 8 × 8 pixels, and a V component (color difference signal) of 8 × 8 pixels in one frame as one processing unit. ). Each pixel in the macroblock is
Encoding is performed by variable length encoding. Here, the relationship between a frame and a macroblock will be described.

Referring to FIG. 4, the structure of the frame memories (401 and 402) for storing one frame of moving image data provided in the memory (302) will be described. The frame memories (401 and 402) are on the memory (302) and store one frame of moving image data for outputting a moving image by the image output device (207). In the case of a P frame in the decompression processing of the compressed data, the data of the reference frame is required for the decompression processing of the next frame.
07), the data must be retained even after the image is output. Therefore, a plurality of frame memories (401 and 402) are provided on the memory (302). A frame memory that holds data for outputting a moving image in the image output device (207) is referred to as a current frame memory (401), and a reference frame memory (402) that holds reference frame data. The current frame memory (401) and the reference frame memory (402) are configured in units of macroblocks (404), and macroblock numbers are assigned in ascending order from upper left to lower right as shown in FIG. As will be described later, this number is copied from the position of the macro block in the current frame memory (401) to the reference frame memory (40) to be copied.
It is used to determine the copy position in 2).

In this system configuration, the decompression device (20
5) is a network (20) when decompressing compressed data.
4) The input control device (304) takes in the compressed data via the bus, and writes the compressed data to the memory (302) via the bus (303). The CPU (301) has a memory (30).
The compressed data written in 2) is read in units of macroblocks via the bus (303) and decompressed. The following describes a case where the decompression device (205) performs the writing process on the memory (302) of the input control device (304) and the reading / decompression process on the memory (302) by the CPU (301) in parallel. The expansion process will be described.

A first embodiment of the error recovery method in the moving image data decompression process realized by the above system will be specifically described with reference to FIG.

First, each time a macroblock in one frame is read in step 101, a macroblock number is assigned in ascending order. In step 102, the memory (30
The compressed data read from 2) is analyzed to detect an error. If no error is detected, step 103
The moving image data expanded by the current frame memory (4
01) via the bus (303) at the same position as the currently allocated macroblock number. In step 104, it is checked whether writing of moving image data has been performed for one frame. If the processing of the moving image data for one frame has not been completed, the process returns to the macro block number assignment processing of step 101. If moving image data for one frame has been written, step 109
To copy all the moving image data in the current frame memory (401) to the same position in the reference frame memory (402). In step 110, the output control device (305) outputs the moving image data of the current frame memory (401) to the image output device (207), displays the moving image, and returns to step 101.

If an error is detected in step 102,
In step 105, an error detection position is specified according to the macroblock number. In step 106, the macroblock number at which the error is detected is compared with the threshold value (503) of the macroblock number in the threshold value table (501). The threshold table (501) is stored in the memory (302), and includes an item (502) composed of a macroblock number, a frame change amount described later, and the number of remaining frames up to the first I-frame appearing after error detection. For the threshold (50
3) is set. If the value of the macroblock number where the error is detected is less than or equal to the macroblock number threshold value (503), the reference frame memory (4
02) from the current frame memory (4
01) All copies are made at the same position. If the value of the macroblock number where the error is detected is larger than the macroblock number threshold value (503), in step 108, the last macroblock number position from the error-detected macroblock number position is read from the reference frame memory (402). The moving image data up to the current frame memory (40
Copy to the same location in 1). And step 109
Then, all the moving image data in the current frame memory (401) is copied to the same position in the reference frame memory (402). In step 110, the output control device (305) outputs the moving image data of the current frame memory (401) to the image output device (207), displays the moving image, and returns to step 101.

As described above, the decompression process can be continued even when an error is detected, and disturbance in displaying a moving image can be reduced. And useless copying of data can be prevented.

Next, when an error is detected in step 102 in the moving image data decompression processing shown in FIG. 1, the network (204)
A moving image data decompression process is described in which an error recovery method is to copy the moving image data of the reference frame memory (402) to the current frame memory (401) by going back through the macroblock by the numerical value calculated according to the error rate of the current frame memory. 6 will be described.

Steps 101 to 105, 109, 110
Are the steps 101 to 105, 109, 1 shown in FIG.
This is the same as the processing content of No. 10. Therefore, step 1
From the identification of the error detection position in step 05 to step 109
The error recovery process (steps 601 to 603) performed during the process of writing the moving image data to the reference frame memory (401) in step (1) will be described.

After specifying the position of the macroblock in which the error has been detected, in step 601 the error rate table (70
From 1), the error rate of the network (204) (703)
To get. The error rate table (701) is stored in the memory (30
2) Item (70) above and representing the medium of the network
The error rate (703) is set for 2). next,
In step 602, a compression ratio (803) is obtained from the compression ratio table (801). The compression ratio table (801) is stored in the memory (302) and includes an item (8
02) is set to the compression ratio (803). In step 603, moving image data is copied from the reference frame memory (402) to the same position of the current frame memory (401) in the same manner for the n macroblocks that go back from the macroblock where the error is detected. The number n going back to the macroblock is calculated based on the data acquired in steps 601 and 602. For example,
The error rate (803) acquired in step 601 is calculated by dividing the error rate (803) by
02 is defined as the ratio of the number of bits after compression to the number of bits before compression,

[0033]

(Equation 1) Represents the error occurrence frequency in units of the number of macroblocks.

Then, in step 109, the moving image data of the current frame memory (401) is written into the reference frame memory (402), and in step 110, the output control device (305) converts the moving image data of the current frame memory (401) into an image. Output to the output device (207), and return to step 101.

As described above, in the variable-length coding, the place where the error occurred is often located before the place where the error was detected, and this can be dealt with.

Next, in the moving picture data decompression processing shown in FIG. 1, when an error is detected in step 102, the reference frame memory is stored in accordance with the amount of change in moving picture data between the frame in which the error is detected and the reference frame. The moving image data decompression processing for judging whether to copy the moving image data of (402) to the current frame memory (401) or not to output the image of the P frame until the decompression processing of the I frame is performed and performing error recovery is illustrated. 9 will be described.

When encoding a moving image frame, the compression device (203) encodes and compresses the amount of change from the immediately preceding frame that is temporally adjacent to the immediately preceding frame as control data, and decompresses it via the network (204). Transfer to device (205). The change amount of a frame represents the degree of visual change between the current frame and the immediately preceding frame temporally adjacent thereto, and quantitatively uses a difference in moving image data between frames. Scene changes and fast-moving moving images can be said to have a large amount of frame change.

In FIG. 9, steps 101 to 110 are:
The processing contents are the same as steps 101 to 110 shown in FIG. Therefore, steps 901 to 903 will be described here.

In step 901, when decompression processing is performed for each frame, data representing the amount of change from the previous frame is obtained as control data from the compressed data, and the frame change in the control data table (1001) is obtained. Acquisition data position (1003) corresponding to quantity item (1002)
Write to. The control data table (1001) is stored in the memory (302), and includes an item (1002) composed of a frame change amount and a frame period to be described later. 1003). In step 902, the frame change amount (1003) acquired in step 901 is
The threshold value (50) of the frame change amount in the threshold value table (501)
Compare 3). If the frame change amount (1003) is equal to or smaller than the frame change amount threshold (503), an error detection position is specified in step 105 according to the macroblock number, and the same processing as described above is performed. Frame change (100
If 3) is larger than the threshold value of the frame change amount (503), in step 903, the compressed data of the next frame is
Frame information indicating whether the frame is an I frame or a P frame is obtained. If the acquired frame information is a P frame, the process of step 903 is performed again. If the acquired frame information is an I frame, the process returns to step 901 to continue the processing. FIG. 11 shows a flow of the moving image display processing by adding the processing of step 903. I frame (1101 ・ 1105)
In the P frames (1102 to 1103) displayed during the period, an error is detected in the P frame (1102), and the frame change amount (1003) is changed to the frame change amount threshold (5).
If it is larger than 03), step 903 is repeated in step 903 while the next frame is a P frame, so that the moving image of the P frame is not displayed, and the I frame (1105) which appears first after error detection is displayed. I do.

As described above, it is possible to minimize disturbance in displaying a moving image in which an error has occurred and to suppress the transmission of the error to the next frame.

Next, in the moving image data decompression process shown in FIG. 1, when an error is detected in step 102, the reference frame memory (402) is stored in the reference frame memory (402) according to the number of frames up to the first I frame after the error is detected. FIG. 12 shows a moving image data decompression process for performing error recovery by adding a process of determining whether to copy moving image data to the current frame memory (401) or not to output a P frame image until an I frame decompression process is performed. This will be described with reference to FIG.

The compression device (203) encodes and compresses a frame cycle indicating how many I frames are present at the time of encoding a moving image frame.
4) to the expansion device (205).

In FIG. 12, steps 101-110
Are the same as the processing contents of steps 101 to 110 shown in FIG. Therefore, here, steps 1201 to
Step 1204 will be described.

In step 1201, prior to step 101, the number of I-frame periods is obtained from the compressed data as control data, and the obtained data position (1003) corresponding to the frame period item (1002) in the control data table (1001) Write to. In step 1202, 1
When processing moving image data for a frame, the value of the frame counter (403) is counted up. The frame counter (403) is in the memory (302). When the value of the frame counter (403) becomes equal to the data value (1003) of the control data table (1001) frame period, the counter value is set to 0. Step 1
At 203, the frame period value (1003) of the control data table (1001) and the frame counter (403)
, The number of remaining P-frames is calculated, and the threshold value (503) of the frame period in the threshold value table (501) is compared. The value of the remaining number of P frames is a threshold value table (501)
If it is less than or equal to the threshold value (503) of the frame period, the error detection position is specified in step 105 according to the macroblock number, and the same processing as described above is performed. If the value of the number of remaining P frames is larger than the threshold value (503) of the frame period in the threshold value table (501), at step 1204, it is determined from the compressed data of the next frame whether the frame is an I frame or a P frame. Obtain frame information to represent. If the acquired frame information is a P frame,
The processing of step 1204 is performed again. If the acquired frame information is an I frame, the frame counter (40
The value of 3) is reset to 0, and the process returns to step 1202 to continue. As described above with reference to FIG. 11, the processing content of step 1204 is that the moving image of the P frame is not displayed until the processing of the I frame is performed after the error detection.

As described above, when there is an image encoded without referring to another frame at a position near the time of the frame in which the error has occurred, partial noise in the frame can be eliminated.

Next, in the moving image data decompression process shown in the first embodiment as a second embodiment, a motion vector for use in error recovery from a motion vector of a temporally adjacent previous frame is extracted. When the information is calculated and stored, and an error is detected, the image data indicated by the calculated motion vector is converted from the macroblock at the same position as the macroblock of the current frame memory (401) in the reference frame memory (402). A moving image data decompression process in which copying to (401) and displaying the image data is an error recovery method will be described. The details of the error recovery process will be described with reference to FIG.

Steps 101 to 105, 109, 110
Are steps 101 to 10 shown as the first embodiment.
5, 109 and 110 are the same as the processing contents. Therefore, steps 1301 and 10302 will be described here. In step 1301, moving image data from the macroblock number position where the error is detected to the last macroblock number position is stored in the reference frame memory (40).
From 2), the current frame memory (4) is determined using the motion vector corresponding to the macroblock of the motion vector table (405) obtained in step 1303 described later.
01) and proceed to step 109 to the reference frame memory (402) to the current frame memory (401).
And the processing is continued.

FIG. 1 shows a method of determining moving image data to be copied.
4 will be described. The motion vector is a macro block (1401) on the current frame memory (401).
Macro block (1402) at the same position in the reference frame memory (402) and the current frame memory (401) in the reference frame memory (402)
A positional relationship of a region (1403) having a macroblock size very similar to the moving image data of the upper macroblock (1401) is shown using a vector amount (1404) in pixel units. Therefore, the macro block (14) of the reference frame memory (402) corresponding to the macro block (1401) on the current frame memory (401)
02), a macroblock-sized area (1403) located at a position shifted by the motion vector (1404) becomes moving image data to be copied. After error detection, similar processing is performed on the macroblock.

Next, step 1302 will be described. After the moving image data expanded in step 103 is written in the current frame memory (401) at the same position as the currently allocated macroblock number via the bus (303), in step 1302, the motion vector used for the expansion processing is written. The information is stored in the motion vector table (405) on the memory (302). Motion vector table (40
5) holds a motion vector corresponding to one frame of macroblock. If the frame is an I frame, the motion vector value is set to 0.

Here, the held motion vector corresponding to the macroblock position where the error has occurred is used as it is. It is also possible to easily determine the copy area by applying the average of the motion vectors.

As described above, it is possible to minimize the disturbance in displaying a moving image in which an error has occurred and to suppress the transmission of the error to the next frame.

[0052]

According to the present invention, the macroblock to be copied in a temporally adjacent frame is determined based on the position of the macroblock in the frame where the error has occurred and the error rate of the line. Can be extended even when an error is detected, and the disturbance in displaying a moving image can be reduced. In addition, according to the amount of change between the frame in which the error occurred and the frame temporally adjacent to each other, when the change is large, instead of the error frame, the encoded frame is displayed without referring to the information of the other frame. , The propagation of the error to the next frame can be suppressed. In addition, if there is an image coded without referring to another frame at a position near the time of the frame in which the error occurred, this is displayed instead of the frame in which the error occurred, thereby reducing the partial noise in the frame. Can be eliminated. Also, the motion vector used at the time of decompression of the frame is held, and a moving image data area indicated by the motion vector held from the macroblock in the immediately preceding frame temporally adjacent is determined and copied to the macroblock. As a result, disturbance in the display of a moving image can be reduced, and propagation of an error to the next frame can be suppressed.

[Brief description of the drawings]

FIG. 1 is an error recovery flowchart in an MPEG moving image compression / decompression system.

FIG. 2 is a diagram showing a network configuration example.

FIG. 3 is a diagram showing a configuration example of a compression device / expansion device.

FIG. 4 is a diagram showing a relationship between a frame memory and a macro block on a memory.

FIG. 5 is a diagram showing a threshold table used in the error recovery processing.

FIG. 6 is an error recovery flowchart using a transmission error rate.

FIG. 7 is a diagram showing a transmission error rate table used in the error recovery processing.

FIG. 8 is a view showing a compression ratio table of a moving image used in the error recovery processing.

FIG. 9 is an error recovery flowchart using a frame change amount.

FIG. 10 is a new S diagram of the control data storage table used in the error recovery processing.

FIG. 11 is a diagram showing a flow of image display by an error recovery process using a frame change amount.

FIG. 12 is an error recovery flowchart using the remaining number of P frames.

FIG. 13 is an error recovery flowchart using a motion vector of a reference frame.

FIG. 14 is a diagram illustrating a relationship between a motion vector of a reference frame and a copy position.

[Explanation of symbols]

201 image input device, 202, 206 interface, 203 compression device, 204 network 205
... decompression device, 207 ... image output device, 301 ... CPU,
302 ... memory, 303 ... bus, 304 ... input control device, 305 ... output control device, 401 ... current frame memory, 402 ... reference frame memory, 403 ... frame counter, 404 ... macroblock, 405 ... motion vector table, 501 ... Threshold table, 701: error rate table, 801: compression rate table, 1001: control data table.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mizuho Saijo 5-2-1-1, Josuihonmachi, Kodaira-shi, Tokyo Inside Hitachi Super-LSI Systems Co., Ltd. (72) Inventor Hiroshi Morita Tokyo 5-22-1, Josuihoncho, Kodaira-shi Within Hitachi Ultra-LII Systems Co., Ltd. Inventor Yoshifumi Fujikawa 1099 Ozenji Temple, Aso-ku, Kawasaki City, Kanagawa Prefecture Inside Hitachi, Ltd.System Development Laboratory (72) Inventor Masao Ishiguro 1099 Ozenji, Aso-ku, Kawasaki City, Kanagawa Prefecture F-term in Hitachi, Ltd. (Reference) 5C059 MA00 MC38 ME01 PP05 PP06 PP16 RC02 RC37 RF01 RF09 RF14 UA05 UA33 5J064 AA01 BA01 BB 03 BB08 BC01 BC27 BD02 5K014 AA01 FA07 GA02

Claims (5)

[Claims] In a moving image data compression / expansion system in which a processing device for compressing moving image data by the MPEG system and a processing device for expanding the compressed data are connected by a network, the data expansion device includes: A first step of numbering processing units called macroblocks in a frame as a display unit in ascending order;
(2) a second step of detecting an error in the data when analyzing the compressed moving image data; and (3) a third step of specifying a position in one frame of the moving image data in which the error is detected in macroblock units. A step, (4) a fourth step of copying all macroblocks up to the end of the frame after detecting an error from a temporally adjacent previous frame, and (5) detecting an error. A fifth step of copying all macroblocks of the previous frame temporally adjacent to the frame;
(6) The position where an error is detected in the frame is stored as a macroblock number, and the fourth step is applied when the macroblock number at the position where the error is detected is larger than a threshold value n. A moving image error recovery method, comprising: a sixth step of applying the fifth step; and (7) a seventh step of displaying a frame whose error has been recovered by the steps 1 to 6. 2. The moving image data compression / decompression system according to claim 1, wherein the fourth step of the data decompression device comprises: (1) storing an error rate of a line for receiving the compressed moving image data; (2) the fourth step;
The n-th macroblock, which is traced back from the macroblock in which an error is detected in accordance with the error rate of one step, also includes a 4-2th step of copying from a temporally adjacent previous frame. Moving image error recovery method. 3. The moving image data compression / decompression system according to claim 1, wherein the data compression device calculates a change amount from a temporally adjacent immediately preceding frame when encoding a moving image frame. The data decompression device that encodes and compresses the control data and receives the compressed data of the moving image, based on the control data, when the change amount is equal to or less than a threshold value n, from the first step according to the first item. The seventh step is performed, and when the value is larger than the threshold value n, a frame compressed without using information of another frame is displayed next instead of the fourth to seventh steps. Video error recovery method. 4. The moving picture data compression / decompression system according to claim 1, wherein the data compression apparatus performs a coding of a moving picture by referring to the number of frames to be encoded without referring to another frame. The data decompression apparatus encodes and compresses a frame period indicating whether the frame is present in the frame, and (1) prior to the first step, (1) providing a frame counter and counting up each time a frame is decoded; (2) a 1-2 step for setting the counter to 0 when the frame period sent from the compression device has been reached, and (3) subtracting the counter value from the frame period when an error is detected. No. 1-
Step 3 is performed. (4) When the subtraction result is equal to or larger than the threshold value n, the first to seventh steps are performed. (5) When the subtraction result is smaller than the threshold value n, A moving image error recovery method characterized by expanding and displaying an encoded image without referring to another frame instead of the fourth to seventh steps. 5. The moving image data compression / decompression system according to claim 1, wherein the data decompression device holds the motion vector used at the time of decompression of the frame in correspondence with the macroblock, and when the error is detected, the data decompression device stores the motion vector. Step 7
Instead of the step of
A moving image error recovery method, comprising determining an area to be copied from a temporally adjacent previous frame to a frame in which an error has occurred.