JPH09261647A - Moving image reproduction control method and moving image reproduction controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moving image reproduction control method and a moving image reproduction device in which decoding processing is executed with high efficiency at high speed and a succeeding reproduction is not delayed even on the occurrence of delayed decoding. SOLUTION: An image decoding section 101 and an image transfer section 104 are operated independently and the image transfer section 104 increases a time-out counter 107 by 1 every time the section 104 detects delayed decoding in order to reduce the stop time of the decoding processing in the image decoding section 101. Every time the image decoding section 101 recovers one frame of decoding delay, the section 101 decrements the time-out counter 107 by 1. According to the control as above, synchronization is taken and processing efficiency is improved and real time display is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving picture reproduction control method and apparatus for expanding and reproducing compressed moving picture data.

[0002]

2. Description of the Related Art In recent years, moving image data can be handled in personal computers and game machines due to the progress of moving image data compression technology. The compression encoding / decoding of moving image data used to require dedicated hardware before, but is being realized by software due to the progress of semiconductor technology.

MPEG is a typical moving picture compression coding technique.
There is one video (international standard ISO / IEC 11172-2). MPEG1
In video, three picture type image data (I picture, P picture, B picture) are defined. The I picture is an abbreviation for Intra coded image, and is an image compressed with only one frame without using inter-frame prediction. Decoding of this I picture is performed only on its own compressed image data. P picture is
ive) Abbreviation of coded image, preceding I picture or P
It is an image compressed by performing inter-frame prediction on a picture. The decoding of this P picture requires one frame which is the decoded I picture or P picture decoded before that. B picture is bidirectional prediction (Bidirec
abbreviation for coded image, preceded by I
Alternatively, it is an image compressed by performing bidirectional prediction using a P picture and a subsequent I or P picture. This B
Decoding of a picture requires two image data after decoding of a previously decoded I picture or P picture.

Since these picture types are selected and coded in the compressed moving image data according to the nature of the image, the actual display order and the order of the images in the compressed image data are different. FIG. 6 is an explanatory diagram showing the display order and the decoding order. In the figure, the display order is I1, B1, B2, P1, B3, B
The case of 4, ... Is illustrated. In this case, the decoding order is I1, P1, B1, B2, P2, B3, B4 ... As illustrated.

FIG. 7 shows a moving picture reproduction control apparatus for MPEG1 video by means of the first conventional software. Display unit 50
1 outputs the image data transferred from the image transfer unit 502, which will be described later, as visible information. The image transfer unit 502 transfers the image data to the display unit 501 at the time of receiving the notification from the timer 504, or at the time of completing the decoding if the notification has already been received. Image decoding unit 50
3 decodes the compressed moving image data to generate the image data. The timer 504 notifies the image transfer unit 502 of the designated time. The frame buffer 505 is an area for storing the image data generated by the image decoding unit 503.

The operation of the first conventional example will be briefly described below with reference to the flowchart shown in FIG. The image decoding unit 503 stores the image data generated by decoding the compressed moving image data for one screen in the frame buffer 505 (step 601). The image decoding unit 503 includes an image transfer unit 502.
Selects the image data to be transferred to the display unit 501. If there is no image data to be transferred next, the process returns to step 601 (step 602). If there is image data to be transferred next, the image decoding unit 503 calls the image transfer unit 502 (step 603). The called image transfer unit 50
2 determines whether the time to transfer the image data has passed. If the time has passed, the process proceeds to step 606 (step 604). If the time has not passed, the image transfer unit 502 waits until the timer 504 receives a notification that the image data transfer time has come (step 6).
05). Next, the image transfer unit 502 calls the display unit 501 and transfers the image data (step 606). The display unit 501 outputs the transferred image data as visible information (step 607). Furthermore, it is determined whether or not the decoding of all moving image compressed data has been completed. If it has not been completed, the process returns to step 601 (step 608).

Next, a moving picture reproduction control apparatus for MPEG1 video as a second conventional example is almost the same as that shown in FIG. 7 shown in the first conventional example, except that it is a hardware process.
Further, the image transfer unit 502 in the second conventional example transfers the image data to the display unit when the notification from the timer 504 is received. The frame buffer 505 in the second conventional example has three areas 0 to 2 for storing the image data decoded by the image decoding unit 503 for each picture type. Area 0 stores an I picture or P picture, area 1 stores an I picture or P picture, and area 2 stores a B picture. Areas 0 and 1 are used as reference images during B picture decoding.

In the second conventional example, the compressed image data is I,
The operation when decoding the compressed moving image data encoded and stored in the order of P, P, ... will be described. First, the area 0 for decoding the I picture is selected, and the first I picture is decoded. Next, area 1 is selected to decode the second P picture, and the second compressed image data is decoded. Further, an area is selected for decoding the third P picture. At this time, the frame buffer 50
If the image data of the area 0 in 5 has been transferred, the area 0 in the frame buffer 505 is secured and the third compressed image data is decoded. If it has not been transferred, it waits for the image data of the area 0 in the frame buffer 505 to be transferred, and then decodes after the transfer.

By the way, the compressed image data of MPEG is
The amount of decoding processing differs for each frame depending on the content of the moving image. For example, when predictive coding (encoding of P picture or I picture) is performed between frames with high correlation (similarity), the amount of code is small, so the amount of decoding processing is small, but on the contrary, the correlation is low. When predictive coding is performed between frames, the code amount increases and the decoding process also takes a long time. Decoding by software processing has become possible as the performance of microprocessors has improved, but there is an inherent possibility that decoding delay will occur in the case of a picture with a large code amount as described above.

[0010]

In the first conventional example, after the decoding of the image data to be displayed next is completed, the transfer of the image data is awaited (steps 604, 605). ), So there was a problem that idle time occurs. As a result, there is a problem that a decoding delay tends to occur, and a sufficiently high processing speed cannot be obtained. When such a decoding delay occurs, the display of the image is delayed, and the display of the subsequent image is also deviated from the original display time, which causes a problem that the moving image cannot be displayed in real time.

Further, in the second conventional example, when a P picture or an I picture is to be decoded, it is decoded until the area 0 or 1 becomes usable even though the area 2 in the buffer is unused. Since the processing is stopped, there is a problem that the processing speed is not sufficiently increased. In view of the above problems, it is an object of the present invention to provide a moving image reproduction control method and a moving image reproduction device that efficiently perform the decoding process to increase the speed and do not delay the subsequent reproduction even if a decoding delay occurs. To do.

[0012]

In order to solve the above-mentioned problems, a moving picture reproducing method of the present invention comprises a decoding process for decoding moving picture compressed data by predictive coding in frame units and storing in a buffer, and a decoding process in the buffer. A moving image reproduction control method comprising a transfer process of transferring a frame to a display unit at a predetermined cycle, wherein the transfer process includes a step of interrupting the decoding process at every predetermined cycle, and a frame to be transferred in a buffer. If it is determined that there is a frame to be transferred, a step of determining whether there is a frame to be transferred, a step of transferring the frame to the display unit, and a case where it is determined that there is no frame to be transferred, There is a setting step of setting information indicating that a decoding delay has occurred in a predetermined storage unit, and a step of restarting the decoding process, and the decoding process comprises:
Determining a frame to be decoded in the compressed video data, decoding the determined frame, determining whether or not a decoding delay has occurred by referring to the storage unit, and determining that there is a decoding delay. A step of invalidating one frame in the buffer when it is determined, and erasing the information from the storage section, and a step of activating the deciding step when it is determined that there is no decoding delay and when the erasure is performed. Further, the setting step in the transfer processing increments a counter as a predetermined storage unit by 1 when it is determined that there is no frame to be transferred, and the determination step in the decoding processing is whether the counter is 1 or more. It is determined whether or not there is a decoding delay of one frame by subtracting 1 from the counter in the erasing step. You may comprise so that the information which shows and may be erased.

Further, a moving picture reproduction control apparatus for solving the above-mentioned problem is a decoding processing section for decoding moving picture compressed data by predictive coding in frame units and storing it in a buffer, and a decoding section for displaying decoded frames in the buffer at a predetermined cycle. And a transfer processing unit for transferring to the transfer processing unit, wherein the transfer processing unit transfers the transfer processing unit and a determination unit that determines whether or not there is a frame to be transferred in the buffer at each predetermined cycle. If it is determined that there is a frame to be transferred, transfer means that transfers the frame to the display unit, and if it is determined that there is no frame to be transferred, information indicating that a decoding delay has occurred is specified. And a setting unit configured to set the storage unit of the decoding unit, and the decoding processing unit determines a frame to be decoded in the compressed video data, and a decoding unit to decode the determined frame. And a determination unit that determines whether or not a decoding delay has occurred by referring to the storage unit, invalidates one frame in the buffer when it is determined that the decoding delay has occurred, and stores the information in the storage unit. There is provided updating means for updating the information indicating that the delay in decoding has been regained, and control means for activating the deciding means when it is determined that there is no decoding delay and when erasure is made.

Further, the storage unit is a counter, the setting means in the transfer processing unit increments the counter by 1 when it is determined that there is no frame to be transferred, and the determination means in the decoding processing unit, The updating unit in the decoding processing unit may determine whether or not the counter is 1 or more, and subtract 1 from the counter when one frame is invalidated.

Further, the buffer has at least four areas for holding decoded frames, and the moving picture reproduction control apparatus further has a transfer flag indicating whether or not the decoded frames in the storage area have been transferred to the display means. , A transfer flag holding means for holding each of the areas in correspondence with an area, an unnecessary flag holding means for holding an unnecessary flag indicating whether or not a decoded frame in the area is unnecessary for decoding processing, and a next transfer time. And a pointer holding unit that holds a pointer that points to an area that holds a decoded frame to be transferred. If the area pointed to by the pointer has not been transferred, the transfer processing section transfers the decoded frame to the display section and sets a transfer flag. Set it to transferred
If the area pointed to by the pointer has already been transferred, the counter is set to 1
In addition, the decoding processing unit is configured to update the pointer after the decoding of the frame is completed, determine the storage destination area of a new frame based on the transfer flag and unnecessary flag, and update both flags. Good.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a moving picture reproduction control apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram of a moving picture reproduction control device for MPEG1 video according to the present embodiment. The moving image reproduction control device includes an image decoding unit 101, a frame buffer 102, and a timer 10.
3, image transfer unit 104, display unit 105, identifier holding unit 1
06, a timeout counter 107, a transfer flag holding unit 108, and an unnecessary flag holding unit 109.

The image decoding unit 101 decodes compressed moving image data for one screen, stores the decoded image data in the frame buffer 102, and sets information to be transferred to the identifier holding unit 106 and information indicating the order thereof. . In the decoding process, the image decoding unit 101 detects a decoding delay (when the timeout counter 107 is 1 or more).
In order to recover the decoding delay, the image to be transferred set in the identifier holding unit 106 is skipped.

The frame buffer 102 has a capacity of 4 frames (the identifiers of the four areas are 0 to 3), and stores the decoded image data and the image data being decoded by the image decoding unit 101. Timer 103
Causes a timeout at a cycle of about 1/30 second, and activates the image transfer unit 104 at each timeout.

The image transfer unit 104 is periodically activated by the timer 103, and the image data in the frame buffer 102 is displayed on the display unit 1 based on the contents of the identifier holding unit 106.
Transfer to 05. More specifically, if there is image data to be transferred at the periodically activated transfer time, it is transferred to the display unit 105, but if there is no image data to be transferred, the transfer at that transfer time is skipped and a timeout counter 107 is incremented by 1. The reason why the timeout counter is incremented by 1 here is to notify the image decoding unit 101 that a delay in the decoding process has occurred.

The display unit 105 is a CRT which displays the image data transferred from the image transfer unit 104 as visible information,
A display device such as an LCD. Identifier holding unit 10
Reference numeral 6 holds the identifier of the area in the frame buffer 102 in which the image data to be transferred is stored, in order of transfer. The held contents are set and updated mainly by the image decoding unit 101. FIG.
(C) is an explanatory view showing the state of the frame buffer 102 and the contents held in the identifier holding unit 106 corresponding thereto. As shown in the figure, the identifier holding unit 106 has four identifier sets (a set of identifiers and pointers), a read pointer and a write pointer. The read pointer and the write pointer always point to either set of identifiers.

Here, the identifier set represents a pointer indicating the identifier of the storage area of the decoded image data to be transferred and the identifier of the next rank. The entire identifier set is linked on the loop by this pointer. The read pointer indicates an identifier set having an identifier of an area to be transferred during or after the next transfer time. When the identifier of the identifier set pointed by the read pointer is invalid (null), it means that there is no area to be transferred.

The write pointer points to an identifier set having an identifier of an area to be transferred next in order. When the identifier of the identifier set pointed to by the write pointer is invalid (null), it indicates that writing is possible. These read pointers and write pointers are updated according to the pointers in the identifier set indicated by each. In the same figure (a), in the frame buffer 102, the area 0
Is used for decoding work, and areas 1 to 3 are null. In this case, all the identifiers of the four identifier sets are invalid. The read pointer points to an identifier set that has an invalid identifier because there is no data to transfer. The write pointer also points to an identifier set with an invalid identifier.

In FIG. 2B, the frame buffer 102
Area 0 in the area has been decoded (I-picture has a transfer order of 1
Area), area 1 has been decoded (P picture has no transfer order), area 2 has been decoded (B picture has transfer order 2)
Area), area 3 is decoding work (B picture has transfer order 3
Rank) is used as an example. in this case,
The identifier set holds 0, 2, and 3 as identifiers.
The identifier set pointer connects these identifiers in a transfer order (order of 0, 2, 3). The read pointer points to the identifier set with identifier 0. The write pointer points to an identifier set with an invalid identifier.

Similarly, in the case of FIG. 6C, the identifier holding unit 106 reflects the state in the frame buffer 102. The timeout counter 107 includes the image transfer unit 104.
To synchronize the image decoding unit 101 with the image transfer unit 1,
When the decoding delay is sensed by 04, 1 is added, and when the image decoding unit 101 performs the processing of regaining the decoding delay for one frame, 1 is subtracted. That is, the timeout counter 107 is incremented by 1 by the image transfer unit 104 when the read pointer points to an identifier set having an invalid identifier even at the transfer time, and when the timeout counter 107 is 1 or more in the decoding process. The frame decoded by the image decoding unit 101 is discarded and 1 is subtracted. As described above, the timeout counter 107 is provided as a medium for notifying the image decoding unit 101 that the image transfer unit 104 has detected the decoding delay.

The transfer flag holding unit 108 holds a transfer flag indicating that transfer has been completed, corresponding to each area of the frame buffer 102. Each transfer flag is set to "1" by the image transfer unit 104 at the end of transfer, and reset to "0" by the image decoding unit 101 when the decoded image is stored. At startup (at initialization), all are "1". FIG. 3A shows a specific example of the transfer flag. FIG. 9A shows that the image data of the area 2 in the frame buffer 102 has been transferred.

The unnecessary flag holding unit 109 holds, as a reference frame, an unnecessary flag indicating that it is unnecessary for the decoding process, corresponding to each area of the frame buffer 102.
Here, the reference frame is a frame that is a P or I picture and is used for decoding another (P or B) picture. Each unnecessary flag is reset by the image decoding unit 101 to "0" when the P or I picture is decoded, and is set to "1" when the P or I picture is no longer needed as a reference frame. For the B picture, "1" is set after the decoding until the end of the post transfer. At startup (at initialization), all are "1".
FIG. 3B shows a specific example of the unnecessary flag. FIG. 2B shows that the areas 2 and 3 in the frame buffer 102 are unnecessary for decoding.

The operation of the moving picture reproduction control apparatus having the above-mentioned structure will be described below. FIG. 4 is a flowchart showing the detailed operation of the image decoding unit 101. First, the image decoding unit 101 determines the picture type of the image to be decoded next from the information in the header of the compressed image data (step 201), and determines whether the image data to be decoded is the first frame. To do.

If the image data to be decoded is the first frame (step 202: yes), the frame buffer 1
The area in 02 is obtained and decoded (steps 207, 2).
08,209,216,213: no). If the image data to be decoded is not the first frame (step 202: n
o), the image decoding unit 101 stores the image data to be transferred next in the decoded image data based on the picture type of the previously decoded image data and the picture type of the compressed image data to be decoded this time. Is determined (step 203). If there is no image data to be transferred, the process proceeds to step 206.

Further, when the time-out counter 107 is 1 or more, that is, when there is a delay in the decoding process, the image decoding unit 101 regards the area determined in step 203 as being transferred in order to recover the decoding delay. All transfer flags are set (steps 204 and 215). Also, the image decoding unit 101 uses the timeout counter 107.
Is 0, the area determined in step 203 is set as the read pointer of the identifier holding unit 106 (step 205), and if there is image data unnecessary for decoding processing, the unnecessary flag corresponding to that area is set. Set. If there is no unnecessary image data, nothing is done (step 206).

Next, the image decoding unit 101 refers to the transfer flag holding unit 108 and the unnecessary flag holding unit 109 to select an area to be used for decoding work, and updates the write pointer of the identifier holding unit 106 according to this selection. . Specifically, on the condition that both the corresponding transfer flag and unnecessary flag are "1" (transferred and unnecessary as a reference frame), an area that satisfies this condition is selected, and one of the identifier sets is selected. The identifier of the selected area is set to, and the write pointer is updated to point to the identifier set (step 207). Further, the unnecessary flag and the transfer flag corresponding to the selected area are reset to "0" (step 208).

Further, when the compressed image data to be decoded this time is an I picture or a P picture, the image decoding unit 101 decodes one frame (steps 209 and 2).
16). Further, when the compressed image data to be decoded this time is a B picture, and when the timeout counter 107 is 1 or more, the image decoding unit 101 cancels the decoding of the B picture in order to recover the decoding delay, and the step 201. Return to (steps 209 and 210). in this case,
If the timeout counter 107 is 0, decoding processing for one macroblock is performed (step 211) and the process returns to step 210. As a result, in the decoding process of the B picture, the timeout process is monitored every 1 macroblock by the loop process of steps 210 to 212 to synchronize with the transfer process.

When the decoding process for one B picture frame is completed in this way, the process returns to step 210 (steps 212 and 213). Decoding of all image data is completed,
If the transfer process is also completed, the process is completed (step 2).
14). FIG. 5 is a flowchart showing the detailed operation of the image transfer unit 104.

The image transfer unit 104 is activated by a timer interrupt every 1/30 seconds. Immediately after startup, the image transfer unit 104
Determines whether it has timed out, that is, whether the area set to the read pointer of the identifier holding unit 106 has been transferred, and if it has timed out (step 30
1: Yes) Since the decoding process is delayed, the timeout counter 107 is incremented by 1 to notify the image decoding unit 101 (step 303) and the interrupt process is skipped.

If the timeout has not occurred (step 301: no), the image transfer section 104 transfers the decoded frame in the area pointed to by the read pointer of the identifier holding section 106 to the display section 105 (step 302). , Set a transfer flag corresponding to the area (step 3)
04, 305). As described above, according to the moving image reproduction control apparatus of the present invention, the image decoding unit 101 advances the decoding process while the transfer process by the image transfer unit 104 is not being performed, so that the decoding process can be performed efficiently. It can be done and the speed is increased. Furthermore, when the image transfer unit 104 detects that a decoding delay has occurred, it notifies the image decoding unit 101 via the timeout counter 107, and the image decoding unit 101 receives the notification and recovers the decoding delay. Even if there is, the real-time display can be maintained without delaying the subsequent labeling. Further, since the frame buffer 102 has at least four areas and can be used for decoded data of any picture type, the decoding processing can be made flexible.

[0035]

The moving image reproducing method of the present invention comprises a decoding process and a transfer process. The transfer process includes a step of interrupting the decoding process at every predetermined cycle, and a frame to be transferred in the buffer. Determining whether or not,
When it is determined that there is a frame to be transferred, a step of transferring the frame to the display unit, and when it is determined that there is no frame to be transferred, information indicating that a decoding delay has occurred is displayed. And a step of restarting the decoding process, the decoding process determining a frame to be decoded in the moving image compressed data, a step of decoding the determined frame, A step of determining whether or not a decoding delay has occurred by referring to the storage section; a step of invalidating one frame in the buffer when the decoding delay is determined, and deleting the information from the storage section; According to the configuration including the step of activating the determination step when it is determined that there is no decoding delay and when the deletion is performed, the transfer processing is performed. Since Except The times may perform decoding processing, faster decoding processing is achieved without causing idle time. In addition, when a decoding delay occurs, that is, when there is no frame to be transferred in the transfer processing, information indicating that is transmitted from the transfer processing to the decoding processing via the storage unit, and the decoding delay is notified in the decoding processing. Since it is regained, there is an effect that the real-time display of the moving image can be maintained.

Further, in the setting step in the transfer processing, when it is determined that there is no frame to be transferred, 1 is added to the counter as the predetermined storage unit, and in the determination step in the decoding processing, the counter is 1 or more. The number of frames in which the decoding delay occurs is determined by determining whether or not the decoding step determines whether or not the information indicating that the decoding delay of one frame has occurred is subtracted in the erasing step. Can be represented by a count value, and there is an effect that the storage unit can be realized by a simple configuration of a counter.

Further, it comprises a decoding processing unit for decoding the compressed video data by predictive coding frame by frame and storing it in the buffer, and a transfer processing unit for transferring the decoded frames in the buffer to the display unit at a predetermined cycle. The transfer processing unit determines whether or not there is a frame to be transferred in the buffer at each of the predetermined cycles, and when it is determined that there is a frame to be transferred, displays the frame in the display unit. And a setting unit configured to set information indicating that a decoding delay has occurred in a predetermined storage unit when it is determined that there is no frame to be transferred, and the decoding processing unit, Determining means for determining a frame to be decoded in the moving image compressed data, decoding means for decoding the determined frame, and determining whether or not a decoding delay has occurred by referring to the storage section. Setting means, an updating means for invalidating one frame in the buffer when it is determined that there is a decoding delay, and updating the information in the storage unit to information indicating that the decoding delay has been recovered, and there is no decoding delay. According to the configuration provided with the control means that activates the determining means when it is determined that, and when the erasing is performed, the decoding process can be executed except the time when the transfer process is performed,
The decoding process is speeded up without causing idle time. In addition, when a decoding delay occurs, that is, when there is no frame to be transferred in the transfer processing, information indicating that is transmitted from the transfer processing to the decoding processing via the storage unit, and the decoding delay is notified in the decoding processing. Since it is regained, there is an effect that the real-time display of the moving image can be maintained.

Further, the storage unit is a counter, and the setting unit in the transfer processing unit increments the counter by 1 when it is determined that there is no frame to be transferred, and the determination unit in the decoding processing unit is According to the configuration of determining whether or not the counter is 1 or more, the updating unit in the decoding processing unit subtracts 1 from the counter when one frame is invalidated. Can be represented by, and the storage unit can be realized by a simple configuration of a counter.

Further, the buffer has at least four areas for holding decoded frames, and the moving picture reproduction control apparatus further comprises a transfer flag indicating whether or not the decoded frames in the storage area have been transferred to the display means. , A transfer flag holding means for holding each of the areas in correspondence with an area, an unnecessary flag holding means for holding an unnecessary flag indicating whether or not a decoded frame in the area is unnecessary for decoding processing, and a next transfer time. And a pointer holding unit that holds a pointer that points to an area that holds a decoded frame to be transferred. If the area pointed to by the pointer has not been transferred, the transfer processing section transfers the decoded frame to the display section and sets a transfer flag. Set it to transferred
If the area pointed to by the pointer has already been transferred, the counter is set to 1
According to the configuration, the decoding processing unit updates the pointer after the decoding of the frame is completed, determines the storage area of a new frame based on the transfer flag and the unnecessary flag, and updates both flags. The buffer area can be used efficiently, and moreover, the transfer processing unit and the decoding processing unit can be synchronized by simply exchanging information such as a transfer flag, an unnecessary flag, and a pointer.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a moving image reproduction control device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state of a frame buffer 102 and contents held in an identifier holding unit 106 corresponding to the state.

FIG. 3A is a diagram showing a specific example of a transfer flag. (B) It is not a specific example of the unnecessary flag.

FIG. 4 is a flowchart showing a detailed operation of the image decoding unit 101.

5 is a flowchart showing a detailed operation of the image transfer unit 104. FIG.

FIG. 6 is a diagram illustrating a display order and a decoding order of pictures in MPEG.

FIG. 7 shows a moving image playback control device for MPEG1 video by software of the first prior art.

FIG. 8 is a flowchart showing the operation of the first conventional technique.

[Explanation of symbols]

 Reference Signs List 101 image decoding unit 102 frame buffer 103 timer 104 image transfer unit 105 display unit 106 identifier holding unit 107 timeout counter 108 transfer flag holding unit 109 unnecessary flag holding unit

Claims (5)

[Claims] 1. A moving image reproduction control method comprising a decoding process of decoding compressed moving image data by predictive coding in frame units and storing it in a buffer, and a transfer process of transferring a decoded frame in the buffer to a display unit at a predetermined cycle. In the transfer processing, the step of interrupting the decoding processing at each of the predetermined cycles, the step of determining whether there is a frame to be transferred in the buffer, and the step of determining that there is a frame to be transferred are determined. If the frame is transferred, the frame is transferred to the display unit, and if it is determined that there is no frame to be transferred, a setting step of setting information indicating that a decoding delay has occurred in a predetermined storage unit. And a step of restarting the decoding process, wherein the decoding process determines a frame to be decoded in the compressed video data, and the determined frame. Decoding a frame, determining whether a decoding delay has occurred by referring to the storage unit, invalidating one frame in the buffer when it is determined that a decoding delay has occurred, and And a step of activating the determination step when it is determined that there is no decoding delay, and when the deletion has been performed. 2. The setting step in the transfer processing comprises:
When it is determined that there is no frame to be transferred, 1 is added to the counter as the predetermined storage unit, the determination step in the decoding process determines whether or not the counter is 1 or more, and the erasing step is the 2. The moving image reproduction control method according to claim 1, wherein the information indicating that the decoding delay for one frame has occurred is subtracted by subtracting 1 from the counter. 3. A decoding processing unit for decoding moving image compressed data by predictive coding in frame units and storing the decoded data in a buffer.
A moving image reproduction control device comprising a transfer processing unit for transferring a decoded frame in a buffer to a display unit at a predetermined cycle, wherein the transfer processing unit has a frame to be transferred in the buffer at every predetermined cycle. Determination means for determining whether or not there is a frame to be transferred, transfer means for transferring the frame to the display unit, and if it is determined that there is no frame to be transferred, The decoding processing unit includes a setting unit that sets information indicating that a decoding delay has occurred in a predetermined storage unit, and the decoding processing unit determines a frame to be decoded in the compressed video data, and a decoding unit that decodes the determined frame. Decoding means, a judging means for judging whether or not a decoding delay has occurred by referring to the storage section, and invalidating one frame in the buffer when it is judged that the decoding delay has occurred. Then, updating means for updating the information in the storage unit to information indicating that the decoding delay has been recovered, and control means for activating the determining means when it is determined that there is no decoding delay and when the erasing is performed. A video playback device comprising: 4. The storage unit is a counter, the setting unit in the transfer processing unit increments the counter by 1 when it is determined that there is no frame to be transferred, and the determination unit in the decoding processing unit is 4. The moving image reproduction control apparatus according to claim 3, wherein it is determined whether the counter is 1 or more, and the updating unit in the decoding processing unit subtracts 1 from the counter when one frame is invalidated. 5. The buffer has at least four areas for holding decoded frames, and the moving picture reproduction control device further sets a transfer flag indicating whether or not the decoded frames in the storage area have been transferred to the display means. A transfer flag holding unit that holds the area, a unnecessary flag holding unit that holds an unnecessary flag indicating whether the decoded frame in the area is unnecessary for the decoding process, and a transfer flag at the next transfer time. A pointer holding unit that holds a pointer that points to an area that holds a decoded frame to be transferred, and the transfer processing unit transfers the decoded frame to the display unit and transfers a transfer flag if the area pointed to by the pointer has not been transferred. If the area pointed to by the pointer has been transferred, the counter is incremented by 1, and the decoding unit updates the pointer after the decoding of the frame is completed and transfers the transfer flag. Video playback control apparatus according to claim 4, wherein the making a decision and updating of both flag storage destination area of a new frame based on grayed and unnecessary flag.