JP2011217416A - Image processing apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of reducing processing on a reception side and shortening a period of time until retransmission is requested when an error occurs.SOLUTION: An image processing apparatus receives encoded data which are encoded for the unit of a block and reference information indicating whether the block is referenced when encoding another block. When the block is an error, it is determined whether to request retransmission on the basis of the reference information, and retransmission is requested based on a result of the determination.

Description

  The present invention relates to encoding and decoding of digital image data.

  In the conventional digital video communication system, when an error packet is received on the receiving side, a retransmission request is sent to the transmitting side regarding a part (block, slice, etc.) that cannot be normally decoded due to an error. Then, the transmission side that has received the retransmission request performs a process of retransmitting the encoded data corresponding to the portion requested to be retransmitted, which is a portion that cannot be normally decoded.

  On the receiving side, the number of retransmissions, the loss rate of information, the insertion interval of intra-coded frames, and the like are used as parameters, and the retransmission request priority for setting a threshold is determined based on one of the parameters. Then, the receiving side determines whether or not to send a retransmission request for a part that cannot be normally decoded by judging the set threshold value based on an arbitrary criterion.

  On the other hand, on the transmission side, a retransmission priority determination unit that sets a threshold value based on one of the parameters using the number of retransmissions, the loss rate of information, the insertion interval of intra-coded frames, and the like as parameters is provided. When a retransmission request is received from the receiving side, processing for the retransmission request from the receiving side (whether or not to perform retransmission) is performed by determining the threshold set by the retransmission priority determination unit based on an arbitrary criterion. It was decided.

  In other words, conventionally, the receiving side and the transmitting side independently performed retransmission control (see Patent Document 1).

JP-A-11-3516585

As described above, in the conventional digital video communication system, the priority order regarding the retransmission request of a video frame or a block constituting the frame is set independently on the transmission side and the reception side, and functions independently. Therefore, there is a drawback that the processing load becomes heavy in both transmission and reception.
In particular, when an error is detected on the receiving side, the priority, importance, etc. of the error occurrence location are calculated and evaluated, and then it is determined whether to execute the retransmission request. There was a problem that it took a long time to make a non-implementation decision.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of reducing the processing on the receiving side and shortening the time required to request retransmission when an error occurs. To do.

  In order to achieve the above object, an image processing apparatus according to the present invention includes encoded data encoded in units of blocks, and reference information indicating whether the block is referenced when encoding another block. Receiving means for receiving, if the block is in error, determining means for determining whether to make a retransmission request based on the reference information; and retransmission request means for making a retransmission request based on the determination result Features.

  According to the present invention, it is possible to reduce the processing on the receiving side and to shorten the time until a retransmission request is made when an error occurs.

It is a functional block diagram of the encoding apparatus by this embodiment. It is a functional block diagram of the decoding apparatus by this embodiment. It is an example of the reference map by this embodiment, and its transmission format. In this embodiment, it is a figure explaining the determination assumption of implementation of a resending request, and non-implementation. It is a figure explaining the production | generation process of the reference map by this embodiment. In this embodiment, it is a time chart used for determination whether the resending corresponding to a resending request | requirement is implemented. (A) is a flowchart of reference map generation in the encoding apparatus according to the present embodiment, and (b) is a flow chart for a retransmission request. It is a flow chart when an error occurs in the decoding apparatus according to the present embodiment.

(Embodiment 1)
The encoding apparatus according to the present embodiment and the processing on the encoding side (transmission side) will be described with reference to FIGS. 1, 3, 5, and 6. FIG.

  FIG. 1 shows an encoding apparatus according to the present embodiment. In FIG. 1, reference numeral 118 denotes an encoding unit. In the encoding unit 118, 102 is a changeover switch, 103 is an orthogonal transform unit (DCT), 104 is a quantization unit, 105 is a variable length encoding unit, 106 is a local decoding unit, 107 is an adder, 108 is a frame A memory 109 is a motion compensation unit. 101 is an input terminal, 110 is a transmission buffer (frame memory), 111 is a multiplexer (multiplexing unit), 112 is a transmission unit, 113 is a transmission data output terminal, 114 is a reference map generation unit, 115 is a conversion unit (reference map) ), 116 is a control unit, and 117 is a receiving unit.

  FIG. 3A is a reference map in units of blocks in an arbitrary frame generated by the map generation unit 114. FIG. 3B is a diagram of FIG. The reference map is converted by the conversion unit 115 from the upper left. In FIG. 3A, “1” indicates a reference block in motion compensation prediction, and “0” indicates a block that is not referenced anywhere in motion compensation prediction.

  FIG. 5 illustrates the relationship between the reference frame 501 that the encoding target frame 502 at a certain time point refers to in the motion compensation prediction and the reference map 503 corresponding to the reference frame.

  FIG. 6 is a time chart showing the time required to determine whether or not to perform retransmission corresponding to the retransmission request received from the receiving side.

  Next, processing on the encoding side (transmission side) will be described.

  In FIG. 1, the digital moving image signal is input to the changeover switch 102 via the input terminal 101. The changeover switch 102 determines the encoding mode of the input digital video signal (frame) under the control of the control unit 116 described later, and the determined encoding mode is reflected in the switching direction of the changeover switch 102. .

  When the encoding mode for the frame is inter-frame encoding (P frame or B frame), the changeover switch 102 is switched to the motion compensation unit 109 side under the control of the control unit 116. The digital moving image signal input from the input terminal 101 is input to the motion compensation unit 109 via the changeover switch 102.

  A digital moving image signal (encoding target frame) input to the motion compensation unit 109 performs a motion vector search with a reference frame stored in a frame memory 108 to be described later, according to the searched motion vector. The difference value between the encoding target frame and the reference frame is calculated. The calculated difference value is input to the orthogonal transform unit 103 as a difference moving image signal.

  The reference frame is a frame that is encoded prior to the current encoding target frame in the encoding order, decoded (local decoding), and stored in the frame memory 108.

  On the other hand, when the encoding mode for the frame is intra-frame encoding (I frame), the changeover switch 102 is switched to bypass the motion compensation unit 109 under the control of the control unit 116. The digital video signal input from the input terminal 101 is input to the orthogonal transform unit 103 via the changeover switch 102 as in the case of interframe coding.

  Here, when performing intra-frame prediction (prediction between blocks in the same frame), even in intra-frame coding, processing is performed by the motion compensation unit 109 as in inter-frame coding. To do. Here, intra-frame predictive coding refers to a case where a pixel used for prediction belongs to the same frame as a pixel to be coded. In addition, inter-frame predictive coding refers to a case where a pixel used for prediction belongs to a different frame from a pixel to be coded.

  The motion compensation unit 109 performs motion compensation prediction processing for encoding (compression). At the same time, the reference information of each block of the frame referred to in the process of motion compensation prediction is output to the reference map generation unit 114 for reference. The map generation unit 114 generates a reference map for each block constituting each reference frame from the reference information from the motion compensation unit 109.

  The reference map generation process will be described with reference to FIG. It is assumed that the motion vector search is performed in the raster scan order (basically in any order) from the upper left block in the encoding target frame in FIG.

  The reference frame for the encoding target frame is a frame that has been encoded and locally decoded in the encoding order and stored in the frame memory 108. In MPEG-1, 2, etc., the frame immediately before the frame to be encoded (in the encoding order), H.264, etc. In H.264, all frames preceding the encoding target frame become reference target frames.

  A case will be described in which the motion vector search for the block A located at the upper left of the encoding target frame is first performed and the motion vector for the block A indicates the area indicated by a on the reference frame in FIG. First, motion vector information for the block A is output from the motion compensation unit 109 to the reference map generation unit 114.

  In the reference map generation unit 114, a reference map 503 obtained by dividing each frame into blocks is prepared, and a 1-bit index is assigned to each block on the reference map (the default value is set to “0”). ).

  When the motion vector information is input, the reference map generation unit 114 calculates the area indicated by the motion vector, and sets the index of the block corresponding to the area indicated by the calculated motion vector on the reference map to “1”. Set to '.

  In the same manner, by performing all blocks in the encoding target frame in the order of blocks B, C, and D of the encoding target frame and raster scan, in parallel with the motion prediction encoding process similar to the conventional one. Reference map generation is performed and completed.

  The (difference) moving image signal output from the motion compensation unit 109 and input to the orthogonal transform unit 103 is subjected to orthogonal transform and input to the quantization unit 104 as an orthogonal transform coefficient.

  As the orthogonal transform coefficient input to the quantization unit 104, a quantization coefficient (or scale) is selected under the control of the control unit 116. Then, a quantization operation on the orthogonal transform coefficient (operation for obtaining a quotient of each coefficient of the orthogonal transform coefficient and the corresponding quantization coefficient) is performed, and the variable length encoding unit 105, as a quantized orthogonal transform coefficient, And output to local decoding section 106.

  The quantized orthogonal transform coefficient input to the variable length coding unit 105 is assigned a variable length code (entropy code) corresponding to the appearance probability, and is stored in the transmission buffer 110 as a coded frame.

  In this embodiment, in order to synchronize with a reference map to be described later, the transmission buffer 110 has (N × 2) when the interframe distance between the encoding target frame and the reference frame is N in each encoding format. ) A capacity of +1 frame or more is secured. Therefore, it is possible to immediately respond to a retransmission request from the receiving side.

  The transmission buffer 110 according to the present embodiment is a ring buffer type storage unit, and is configured so that the oldest stored data is overwritten when new data is written.

  The quantized orthogonal transform coefficient input to the local decoding unit 106 is subjected to an inverse operation (inverse quantization, inverse orthogonal transform) that pairs with the quantization of the quantization unit 104 and the orthogonal transform of the orthogonal transform unit 103. The Then, it is output to the adder 107 as a decoded moving image signal (or decoded differential moving image signal) for the encoding target frame.

  When the encoding mode of the encoding target frame is intra-frame encoding, the adder 107 passes the addition operation (or adds zero to all pixel values), and outputs a locally decoded frame. Next, a case where the encoding mode of the encoding target frame is inter-frame predictive encoding or intra-frame predictive encoding will be described. A corresponding reference frame (or block) is read from the frame memory 108 in accordance with the motion vector corresponding to each block of the encoding target frame searched by the motion compensation unit 109. And it adds with the decoding difference video signal which is the output of the local decoding part 106, and is output from the adder 107 as a local decoding frame. The locally decoded frame output from the adder 107 is stored in the frame memory 108 as a reference frame for motion compensation prediction.

  When the encoding process for all blocks of the encoding target frame 502 is completed, the generation of the reference map for the reference frame (see FIG. 3A) is also completed.

  The reference map generated by the reference map generation unit 114 is input to the conversion unit 115. In the conversion unit 115, for example, as shown in FIG. 3B, following the start code (arbitrary number of bits) at the beginning, the frame number for identifying the corresponding frame and each block of the reference map An index corresponding to is assigned. The indexes corresponding to the blocks are basically in arbitrary order in block units, but are arranged in an order such as raster scan or zigzag scan. Finally, an end code (arbitrary number of bits) is added to form a packet suitable for transmission data.

  The reference map packetized by the conversion unit 115 is input to the multiplexing unit 111. At the same time, under the control of the control unit 116, an encoded frame corresponding to the packetized reference map input to the multiplexing unit 111 is read from the transmission buffer 110 and input to the multiplexing unit 11. Then, the reference map corresponding to the encoded frame is multiplexed and input to the transmission unit 112.

  In the present embodiment, the reference map may be multiplexed with another encoded frame and transmitted for reasons such as avoiding simultaneous errors with the encoded frame, or may be transmitted separately from the encoded frame ( It may be transmitted independently using a dedicated line or the like.

  Under the control of the control unit 116, the transmission unit 112 converts the multiplexed encoded frame and reference map into a format suitable for transmission (transport stream or arbitrary file format) according to a predetermined format. And it is possible to transmit to the receiving side from the output terminal 113 via the transmission line.

  The receiving unit 117 receives and extracts information on the retransmission request accompanying the error from the receiving side and the state of the transmission path (line capacity, error rate, etc.) and inputs the information to the control unit 116. When the receiving unit 117 receives a retransmission request for a specific block (or frame) from the receiving terminal, the receiving unit 117 outputs information specifying the block (or frame) corresponding to the retransmission request to the control unit 116.

  The control unit 116 receives the information of the target block (or frame) requested for retransmission by the receiving side, selects data corresponding to the retransmission request target block (or frame) from the transmission buffer 110, and is the same as Retransmission is performed to the receiving side via the transmission unit 112 and the output terminal 113.

  At this time, if there is no data (encoded frame) corresponding to the block (or frame) subject to the retransmission request in the transmission buffer 110, the control unit 116 discards the received retransmission request and performs retransmission. Not implemented.

In the first embodiment according to the present invention, assuming an average receiver specification,
1) Estimated required time (Tx) from when a frame is first transmitted for encoding until it is received at the receiving side
2) Estimated required time (Ty) from when an encoded frame is received until the error is detected and the retransmission request is transmitted.
By calculating 1) and 2) above, the capacity of the transmission buffer 110 is set to a capacity capable of holding the encoded frame for a time corresponding to (2 × Tx) + Ty from the time when the encoded frame was first transmitted. It is set.

  The transmission buffer 110 may be shared with the frame memory 108 and may have a specification that can dynamically change the capacity as necessary. At this time, it is desirable that the control unit 116 can dynamically calculate the values 1) and 2) at arbitrary time intervals.

  In addition to the functions described above, the control unit 116 obtains information on the transmission path traffic (effective speed, capacity) received by the reception unit 117, and controls the quantization unit 104 to perform block or frame unit information. The generated code amount is controlled.

  Control of the number of encoded frames and frame numbers stored in the transmission buffer 110, and control of writing and reading, and monitoring of the number of reference frames and frame numbers stored in the frame memory 108, and control of writing and reading I do.

  FIG. 7A is a flowchart of reference map generation in the encoding apparatus.

  First, in step S1001, it is determined whether the encoding target frame is intraframe encoding. That is, it is determined whether the encoding target frame refers to another frame or block. If step S1001 is NO, as described in the reference map generation unit 114, a reference map is generated from the motion vector information for the block to be encoded. If step S1001 is YES, the process ends.

  FIG. 7B is a flowchart for a retransmission request in the encoding apparatus.

  First, in step S1011, a retransmission request is received.

Further, the actual time (Tr) from when the encoded frame is transmitted from the output terminal 113 until the retransmission request corresponding to the encoded frame is received is measured for each encoded frame, and the measured time (Tr) is measured. Based on this, it took time (Tp) for the retransmission data to be retransmitted from the time when it was transmitted until it was received at the receiving side, and the time required from when the retransmission request was transmitted from the receiving side until it was received at the transmitting side. The time (Ta) and the maximum time (Tz) from the time when the receiving side sends the retransmission request to the time when the retransmission data is received, that is, the maximum time in time for the normal display time by decoding the retransmission data are predicted. ,
Ta + Tp + α <Tz ---- (1)
It is determined whether or not the condition of the above formula (1) is satisfied (step S1012). (See Figure 6)
If the condition of Equation (1) is satisfied, it is determined that the retransmission data is decoded in the correct order on the receiving side, and retransmission is executed according to the retransmission request (step S1014).

  On the other hand, if the condition is not satisfied, it is determined that the retransmission data is not correctly decoded or displayed, such as being discarded on the receiving side, the retransmission request is discarded, and the retransmission is not executed (step S1013). ).

  Processing on the decoding device and the decoding side (receiving side) according to the present embodiment will be described with reference to FIGS.

  In FIG. 2, reference numeral 212 denotes a decoding unit. 212 is a decoding unit, 205 is a variable length decoding unit, 206 is an inverse quantization unit, 207 is an inverse orthogonal transform unit (IDCT), 208 is a changeover switch, 209 is a motion compensation unit, and 210 is a frame memory. . Further, 201 is a reception data input terminal, 202 is a reception unit, 203 is a reception buffer (frame memory), 204 is a demultiplexer (demultiplexing unit), 211 is a decoded image data output terminal, 213 is a conversion unit, 214 Is a map buffer, 215 is an error detection unit, 216 is a control unit, and 217 is a retransmission request transmission unit.

  FIG. 4A shows an example of a motion compensation prediction and a reference map regarding a frame to be encoded 403 on the transmission side (encoding side) and frames positioned in front and behind (in display order). It is. FIG. 4B shows an example of error propagation on the assumption that an error is detected on the receiving side (decoding side) corresponding to the frame 4002 of the encoded image shown in the frame (a) indicated by 4002. It is shown.

  Next, processing on the decoding side (receiving side) will be described.

  In FIG. 2, the data transmitted via the transmission path is input from the reception data input terminal 201 to the reception unit 202. Received data input to the receiving unit 202 is released from a transport package such as a transport stream, encoded on the transmission side, and multiplexed with optional additional data, and stored in the reception buffer 203. To do.

  The reception buffer 203 is a ring buffer type memory similar to the transmission buffer (110 in FIG. 1) in the first embodiment.

  The multiplexed data stored in the reception buffer 203 is appropriately read in the order of writing under the control of the control unit 216 and input to the demultiplexing unit 204.

  The demultiplexing unit 204 performs a process of separating the multiplexed data into an encoded frame (encoded video signal) and a reference map.

  The encoded frame subjected to the separation processing by the demultiplexing unit 204 is input to the decoding unit 212 and the error detection unit 215.

  On the other hand, similarly, the reference map separated by the demultiplexing unit 204 is sent to the conversion unit 213 from the format shown in FIG. 3A in the first embodiment, only the reference map portion. It is converted into a reference map shown in FIG. 3B in the first embodiment taken out.

  The reference map converted by the conversion unit 213 is stored in the reference map buffer 214 and is referred to by the control unit 216 as necessary.

  The variable length decoding unit 205 decodes the variable length code of the encoded frame input to the decoding unit 212 and outputs a quantized orthogonal transform coefficient.

  The quantized orthogonal transform coefficient is input to the inverse quantization unit 206. The inverse quantization unit 206 performs inverse quantization processing on the input quantized orthogonal transform coefficient and outputs an orthogonal transform coefficient.

  The orthogonal transform coefficient is input to the inverse orthogonal transform unit 207. The inverse orthogonal transform unit 207 converts the input orthogonal transform coefficient into a moving image signal (when the coding mode is intra-frame coding) or a differential moving image signal (the coding mode is inter-frame predictive coding or intra-frame coding). In the case of predictive coding).

  The control of the control unit 216 determines the encoding mode converted into the moving image signal converted by the inverse orthogonal transform unit 207 or the differential moving image signal.

  When the determined encoding mode is intra-frame encoding, the changeover switch 208 is switched to the “Intra” side under the control of the control unit 216. The moving image signal subjected to the inverse orthogonal transformation bypasses the motion compensation unit 209 and is stored in the frame memory 210, and at the same time, is output as a displayable moving image signal to the output terminal 211.

  On the other hand, when the determined coding mode is inter-frame predictive coding or intra-frame predictive coding, the changeover switch 208 is switched to the “Inter” side under the control of the control unit 216. The differential video signal subjected to inverse orthogonal transform is input to the motion compensation unit 209. The motion compensation unit 209 controls the reference frame (decoded preceding frame) of the differential video signal subjected to inverse orthogonal transform according to the motion vector corresponding to the differential video signal subjected to inverse orthogonal transform under the control of the control unit 216. read out. The read reference frame is added to the difference video signal under the control of the control unit 216 to generate and output a decoded video signal. The decoded video signal output from the motion compensator 209 is stored in the frame memory 210 and can be displayed from the output terminal 211 at the same time as in the case where the encoding mode is intra-frame encoding. Is output as

  Next, the operation on the decoding side according to the present embodiment when an error occurs in the encoded data input via the input terminal 201 will be described with reference to FIG.

  Assuming that an error has occurred in block (1) on frame 4002 in FIG. 4B, in the example shown in FIG. 4B, block (1) in frame 4002 is block (2) in frame 4003. Referenced from. Block (2) of frame 4003 is referenced from block (3) of frame 4004. Therefore, unless the error generated in the block (1) on the frame 4002 in FIG. 4B is corrected, the error generated in the block (1) on the frame 4002 in FIG. 2) Propagate sequentially to block (3) of frame 4004. That is, the image is disturbed over two frames or more.

  On the other hand, assuming that an error has occurred in the block (4) on the frame 4002 in FIG. 4B, in the example shown in FIG. 4B, the block (4) in the frame 4002 has another frame (or No reference from block). Therefore, even if the error generated in the block (4) on the frame 4002 in FIG. 4B is not corrected, the error is limited to only the block (4) on the frame 4002 in FIG. 4B. That is, image disturbance is limited to only one frame.

  The encoded frame separated and output by the demultiplexing unit 204 is input to the decoding unit 212 and the error detection unit 215 as described above.

  Assume that the error detection unit 215 detects an error in the block (1) and the block (4) of the frame indicated by 4002 (or 402) in FIG.

  The error detection unit 215 notifies the control unit 216 of the position information (frame number and coordinates of the error occurrence block) for the error block ((1), (4)). The control unit 216 that has received the position information of the error block refers to the reference map buffer 214 and stores the reference map corresponding to the position information of the notified error block ((1) and (4) in FIG. 4). Detect numerical values.

  The control unit 216 detects the numerical values of the reference map corresponding to the detected error blocks (1) and (4), so that the blocks specified by the position information (blocks (1) and (4) in FIG. 4) are detected. It is determined whether the frame is referenced from another frame or another block.

  Whether or not the block corresponding to the position information of the error blocks (1) and (4) is referenced from another frame or another block is determined by referring to the numerical value (see FIG. 3) is performed by the control unit 216 determining.

  In the case of the example of FIG. 4, the numerical value of the reference map of the error block (block (4) of the frame 4002) is “0”, so the retransmission request for the error of the block (4) of FIG. That is, no retransmission is performed. On the other hand, for the block (1) in FIG. 4, since the numerical value of the reference map is “1”, the retransmission request transmission unit 217 generates a retransmission request for the error in the block (1) in FIG. Side).

  FIG. 8 is a flowchart when an error occurs in the decoding apparatus. First, in step S2001, an error is detected. Next, in step S2002, the error block reference map is referred to, and as described with reference to FIG. 4, it is determined whether it is referenced in another frame or another block (step S2003). If YES in step S2003, a retransmission request is made (step S2005), but if NO, no retransmission request is made (step S2004).

  In the present embodiment, the retransmission request is implemented using a separate line from the transmission of the moving image signal (encoded frame), but for the transmission unit and the used line, a format that allows the transmission side to receive the retransmission request. If so, it is basically arbitrary.

  According to the present embodiment, a reference map indicating whether a certain block is referenced by another block or frame is generated on the transmission side, and is transmitted to the reception side together with the encoded image data. Side processing is reduced.

  According to the present embodiment, when an error occurs on the receiving side, by referring to the corresponding reference map, whether or not the block in which the error has occurred is referred to by another block, that is, the error that has occurred is determined. Whether or not to propagate can be determined without performing arithmetic processing. Further, since it is possible to make a retransmission request by selecting only an error that affects other blocks or frames, it is also possible to reduce the traffic amount of the transmission path. Furthermore, it is possible to shorten the time from error detection to retransmission request.

  According to the present embodiment, when a retransmission request is received from the reception side on the transmission side, it is clear that the block requested to be retransmitted is a block in which an error spreads to other blocks. According to the retransmission request, an immediate retransmission is performed. Therefore, it is possible to reduce the time from when the transmission side receives a retransmission request until it is retransmitted.

  According to the present embodiment, at the time of receiving the retransmission request, the transmitting side determines whether or not the encoded frame to be retransmitted from now on is correctly decoded and displayed in the correct order on the receiving side. Judgment. For this reason, retransmission is not performed for retransmission requests that are discarded on the receiving side even if they are retransmitted, are not correctly decoded, or are not displayed in the correct order. It is possible to avoid an increase in.

  In the present embodiment, the reference map indicating whether a certain block is referred to by another block or frame has been described. However, even if it is not a reference map, it may be information indicating whether it is referenced by another block or frame. Needless to say, it doesn't have to be a map.

<Other embodiments>
An object of the present invention is to supply a recording medium (or storage medium) that records software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and the computer of the system or apparatus (or CPU or MPU). Needless to say, this can also be achieved by reading and executing the program code stored in the recording medium. In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiment, and the recording medium on which the program code is recorded constitutes the present invention.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.

  Furthermore, after the program code read from the recording medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion card or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

  When the present invention is applied to the recording medium, program code corresponding to the flowchart described above is stored in the recording medium.

Claims (6)

Receiving means for receiving encoded data encoded in units of blocks and reference information indicating whether the block is referenced when encoding another block;
When the block is in error, a determination unit that determines whether to perform a retransmission request based on the reference information;
An image processing apparatus comprising: a retransmission requesting unit that makes a retransmission request based on the determination result.   The image processing apparatus according to claim 1, wherein the determination unit determines to make a retransmission request when the reference information indicates that the reference information is being referred to. A receiving step of receiving encoded data encoded in units of blocks and reference information indicating whether the block is referred to when encoding another block;
If the block is in error, a determination step of determining whether to perform a retransmission request based on the reference information;
An image processing method in an image processing apparatus, comprising: a retransmission request step for making a retransmission request based on the determination result.   The image processing method according to claim 3, wherein the determination step determines that a retransmission request is made when the reference information indicates that the reference information is being referred to.   A computer program for executing the image processing method according to claim 3.   A computer-readable storage medium storing the program according to claim 5 and readable by a computer.

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