JP5045495B2 - Video decoding device - Google Patents

Description

  The present invention relates to a moving picture decoding apparatus suitable for moving picture reproduction.

Various types of moving image playback devices including a multi-channel decoder are provided. Here, the multi-channel decoder is a decoder that executes a decoding process on a plurality of types of moving image compression-encoded data in parallel. FIG. 3A is a time chart showing an operation example of this type of decoder. As in the example shown in the figure, the conventional multi-channel decoder first executes the decoding process of the compression-encoded data of the moving image assigned to the channel 1, and when the decoding result for one frame is obtained, the channel 2 In other words, the decoding process of each channel is sequentially executed in such a manner that the decoding process of the compression-encoded data of the moving image assigned to is performed. In the moving picture reproducing apparatus, the image data which is the decoding result of the multi-channel decoder is stored for each type of moving picture in the decoded picture memory. Then, drawing processing for reflecting the image data of each moving image stored in the decoded image memory on the display image of the display device is executed in synchronization with the vertical scanning period T of the display device.
JP 2006-127206 A

In order to reproduce a composite image of a plurality of types of moving images in real time, the decoding result of each channel to be drawn is accumulated in the decoded image memory before the start timing of the drawing process using the decoding result. There is a need. However, as shown in FIG. 3B, when the time required for the decoding process of all the channels becomes longer than the vertical scanning period T, the decoding result of the channel whose execution order is later is stored in the decoded image memory. In some cases, the drawing process using the result may not be in time. In this case, in the moving image reproduction apparatus, only the decoding results of some of the channels after decoding, for example, the decoding results of channel 1 and channel 2 shown in FIG. The decoding result is not reflected in the display image. This causes a problem when the decoding result of channel 3 is important.
The present invention has been devised under such a background, and in the case where decoding processing of compression encoded data of a plurality of types of moving images is performed in parallel, decoding processing for important moving images is performed. An object of the present invention is to provide a moving picture decoding apparatus capable of preventing a delay.

A moving picture decoding apparatus according to a preferred aspect of the present invention includes a decoding unit that executes a decoding process of compression-encoded data of a moving image, and a time divided into a plurality of time slots, and each time slot is switched. A time slot for switching the execution target and causing the decoding means to sequentially and cyclically execute each of the decoding processing of the compression encoded data of the moving images of the plurality of channels, and to execute the decoding processing of each channel Parallel processing control means for controlling the length of each of them according to the priority specified for each channel.
According to this aspect, the parallel processing control unit controls the length of the time slot of the decoding process of each channel to be executed by the decoding unit according to the priority designated for each channel. Therefore, by adding a difference according to each importance level to the priority of each channel for executing the decoding process, the decoding process for the channel with the higher priority is not delayed from the drawing process using the decoding result. Can be executed.

Another preferred embodiment of the present invention is a moving picture decoding apparatus, a decoding means for executing a decoding process of compression-encoded data of a moving image, and a time is divided into a plurality of time slots, and the time slots are switched. Means for switching the execution target each time, and causing the decoding means to sequentially and cyclically execute each of the decoding processing of the compression encoded data of the moving images of the plurality of channels, the order of executing the decoding processing of each channel And parallel processing control means for controlling according to the priority specified for each channel.
According to this aspect, the parallel processing control means controls the execution order of the decoding processing of each channel according to the priority designated for each channel. Therefore, by adding a difference according to each importance level to the priority of each channel for executing the decoding process, the decoding process for the channel with the higher priority is not delayed from the drawing process using the decoding result. Can be executed.

  In addition, although it is related with the decoding process of audio | voice data, there exists patent document 1 as literature regarding the apparatus which performs the decoding process of multiple types of compression coding data. However, the apparatus disclosed in Patent Document 1 performs the decoding process of compression-encoded data of a plurality of channels by time division control, and the length of the time slot for executing the decoding process of each channel and each channel The decoding processing execution order is not executed according to the priority of each channel, and is different from the present invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a moving image playback device 50 including a moving image decoding device 10 according to an embodiment of the present invention. The moving image reproduction device 50 includes a host CPU 11, a pattern ROM 12, a decoded image memory 13, a moving image decoding device 10, a frame memory 16, a display control unit 17, a drawing processing unit 18, and a display device 19.

The host CPU 11 is a control center of the moving image playback device 50.
The pattern ROM 12 is a read-only memory that stores compression-coded data of a plurality of types of moving images such as backgrounds and characters.
The decoded image memory 13 is a memory for temporarily storing image data as a decoding result, and is configured by, for example, a RAM.

The moving picture decoding apparatus 10 includes a decoding unit 14 and a parallel processing control unit 15. Here, the decoding unit 14 is a device that executes a decoding process for a plurality of channels under the control of the parallel processing control unit 15. In the decoding process for each channel, one type of compressed encoded data of a moving image is read from the pattern ROM 12 and decoded. The area associated with each of the channels is used as a ring buffer, and the obtained decoded image data is associated with the serial number and stored.
The parallel processing control unit 15 serves to control the decoding process performed by the decoding unit 14. More specifically, in the present embodiment, when displaying a plurality of types of moving images on the display device 19, negotiation is performed between the host CPU 11 and the parallel processing control unit 15, and the parallel processing control unit 15 performs the negotiation. The following information is acquired from the host CPU 11.
a. Storage address at the head of each compression encoded data of each moving picture in pattern ROM 12 b. Channel number of the channel for executing the decoding process of the compression encoded data of each moving picture c. Storage addresses at the beginning and end of the ring buffer to which the decoding result of each channel is written in the decoded image memory 13 d. The priority of each channel

Then, the parallel processing control unit 15 divides the time into a plurality of time slots, switches the execution target channel every time the time slot is switched, and performs each of the decoding processing of the compression encoded data of the moving images of the plurality of channels. Are sequentially and cyclically executed by the decoding unit 14. At that time, the parallel processing control unit 15 determines the length of the time slot for executing the decoding processing of each channel according to the priority designated for each channel. In addition, the parallel processing control unit 15 determines the execution order of the decoding processing of each channel according to the priority designated for each channel. More specifically, the parallel processing control unit 15 determines the execution order of the decoding processing of each channel so that the order of priority is high. In this embodiment, the priority has 16 levels from level 1 to level 16. Here, level 16 is the highest priority level, and level 1 is the lowest priority level. When there are a plurality of channels designated with the same priority level, the parallel processing control unit 15 sets the execution order of these channels in ascending order of channel numbers. The time slot for continuing the decoding process for each channel is obtained by multiplying the priority level of each channel by a sufficiently short unit allocation time t.
The parallel processing control unit 15 notifies the decoding unit 14 of the channel number of the channel to be executed in order to sequentially and cyclically execute the decoding processing of each channel, and the time slot corresponding to the channel has elapsed. Sometimes the process of notifying the decoding unit 14 of the channel number of the next channel is cyclically repeated.
On the other hand, each time a new channel number is notified from the parallel processing control unit 15, the decoding unit 14 interrupts the decoding process of the channel that has been executed so far, and determines the channel corresponding to the new channel number. The cycle of moving to the decryption process is repeated. When the decoding process of each channel is interrupted, the decoding unit 14 saves information necessary for resuming the decoding process of the interrupted channel in the next cycle in the built-in memory.

The frame memory 16 is a memory that stores image data to be displayed on the display device 19. The display control unit 17 performs display processing for reading the image data in the frame memory 16 in the order of raster scan and displaying the image data on the display device 19 every time the vertical scanning period T having a certain length of time is switched.
The drawing processing unit 18 acquires a drawing command indicating the drawing position of the decoding result of each channel in the frame memory 16 from the host CPU 11, and executes the drawing processing according to the drawing command. This drawing process is a process of reading the decoded image data of each channel from the decoded image memory 13 and reflecting it in the image data in the frame memory 16. The drawing processing unit 18 executes this drawing processing every time the vertical scanning period T is switched. That is, the drawing processing unit 18 counts the number of switching of the vertical scanning period T by a counter built in itself, and each time the counter counts up, the drawing processing unit 18 is associated with the same serial number as the counted number after counting up. The decoded image data of each channel is searched from each buffer of the decoded image memory 13, and the decoded image data is drawn at the drawing position of the frame memory 16 indicated by the drawing command. Here, depending on the progress of the decoding process by the decoding unit 14, there may be a case where all of the decoded image data to be searched cannot be stored in the decoded image memory 13 by the search by the drawing processing unit 18. . In this case, the drawing processing unit 18 reflects only the decoded image data of a part of the channels that can be searched from the decoded image memory 13 in the image data of the frame memory 16.

  According to the above configuration, the decoding unit 14 of the video decoding device 10 according to the present embodiment executes a decoding process using each of a plurality of pieces of compressed encoded data in the pattern ROM 12 as a processing target of each channel. Then, the parallel processing control unit 15 controls the length of the time slot of each channel according to the priority of each channel. Therefore, by making a difference between the priorities of the respective channels, it is possible to prevent the decoding result of the channel having a higher priority from being lost and affecting the display contents.

  This action will be described more specifically with reference to FIGS. 2 (A) and 2 (B). 2A and 2B are time charts showing a state of decoding processing by the moving image decoding apparatus 10 and drawing processing by the drawing processing unit 18 during the period corresponding to three vertical scanning periods T. FIG. It is. In the example of FIGS. 2A and 2B, there are three channels from channel 1 to channel 3 for decoding processing by the decoding unit 14. The horizontal width of the rectangles discretely arranged on the solid line indicating the passage of the time axis of each channel indicates the length of execution time of the decoding process in those channels, and the vertical scanning period T is switched in the chain line. The drawing processing execution timing executed by the drawing processing unit 18 is shown. The number above each rectangle indicates the frame number of the frame drawn based on the decoding result of each channel. Hereinafter, the compression encoded data of the nth frame is referred to as compression encoded data (n).

Here, in the case of the example of FIG. 2A in which the priorities of all three channels are set to level 1, the decoding unit 14 switches those channels in the order of channel 1, channel 2, and channel 3, The time slot length of each channel is made the same. In this case, the decoding result of the compressed encoded data (1) of the channel 1 can be obtained before the first frame is drawn, but the decoding result of the compressed encoded data (1) of the channel 2 and the channel 3 is obtained up to that time. Can't get to.
On the other hand, in the example of FIG. 2B in which the priority of channel 3 among the three channels is set to level 2 and the priority of channels 1 and 2 is set to level 1, the decoding unit 14 determines those channels as Channel 3, channel 1, and channel 2 are switched in this order so that the time slot length of channel 3 is longer than that of each time slot of channels 1 and 2. In this case, although the time to obtain the decoding result of the compressed encoded data (1) of channel 2 is delayed from the example of FIG. 2A, the decoded result of the compressed encoded data (1) of channel 1 and the compressed code of channel 3 The decoding result of the digitized data (1) can be obtained before the first frame is drawn.

  As shown in this example, according to the video decoding device 10 according to the present embodiment, the time at which the decoding result of the channel with the higher priority is obtained is earlier than the time at which the decoding result of the channel with the lower priority is obtained. Thus, it is possible to control the decoding unit 14 such that the decoding result of a channel with a high priority is made in time for drawing. Some patterns appearing in each frame have a very large change between successive frames, while others have a very small change. The former pattern attracts the attention of the viewer. According to the present embodiment, the priority of the channel for decoding the compression-encoded data of the pattern with a small change between successive frames is lowered, and the priority of the channel for decoding the compression-encoded data of the pattern with a large change By increasing the value, it is possible to prevent the decoding result of a pattern having a large change that attracts the viewer's attention from being lost.

Although one embodiment of the present invention has been described above, the present invention may have other embodiments. For example, it is as follows.
(1) In the above embodiment, the length of the time slot for executing the decoding process for each channel in the decoding unit 14 and the execution order of the decoding process for each channel are changed in accordance with each priority. However, only the length of the time slot of each channel may be changed according to each priority, or the decoding processing execution order of each channel may be changed according to each priority.
(2) In the above embodiment, the priority level that can be specified through the operation of the operation unit may be increased or decreased from 16 levels. For example, three stages of “high”, “medium”, and “low” may be used.
(3) In the above embodiment, the priority of each channel is fixed from the start to the end of the moving image. However, depending on the type of video, the general priority need not be so high, but there is an important image in a specific section, and the image in that section is to be displayed on the display device 19 reliably. There is also. Therefore, it may be configured to be able to handle the priority that changes with time for each channel. Various means can be considered as a means for giving the parallel processing control unit 15 the priority that changes with the passage of time. However, the priority that changes with the passage of time is given to the compressed encoded data of the moving image itself. A mode in which the time series information shown is included is conceivable. In this aspect, the compression encoded data of the pattern ROM 12 is supplied to the decoding unit 14 via a FIFO (First-In First-Out) type buffer inserted between the pattern ROM 12 and the decoding unit 14. Like that. After that, the parallel processing control unit 15 monitors the priority of the compression encoded data waiting for decoding processing of each channel stored in the buffer. When the parallel processing control unit 15 detects that the priority of a certain channel is high as a result of monitoring, the parallel processing control unit 15 starts decoding the compressed encoded data in the section having the high priority of the channel. The time slot used for the decoding process of the channel is lengthened before a certain time. In addition, when it is detected that the priority of the channel has returned to the original low value after the time slot has been lengthened in this way, the length of the time slot of the channel is restored. According to this aspect, it is possible to preferentially handle only important sections without causing a loss of decoding results. Instead of increasing the time slot of a channel with higher priority, the execution order of the channel may be moved forward. Alternatively, the time slot may be lengthened and the execution order may be moved forward.
(4) In the above-described embodiment, the priority is given to the decoding process of the compression encoded data of the pattern that is reproduced irregularly or has a time allowance until the reproduction time and has a long decoding time. It may be executed in the background processing by the lowered channel.

It is a block diagram which shows the structure of the moving image reproduction apparatus containing the moving image decoding apparatus concerning one Embodiment of this invention. It is a time chart which shows the mode of the decoding process by the decoding part of the moving image decoding apparatus concerning the embodiment, and the drawing process by a drawing process part. It is a time chart which shows the mode of the decoding process by the conventional decoder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Moving picture decoding apparatus, 11 ... Host CPU, 12 ... Pattern ROM, 13 ... Decoded image memory, 14 ... Decoding part, 15 ... Parallel processing control part, 16 ... Frame memory, 17 ... Display control part, 18 ... Drawing processing unit, 19... Display device, 50.

Claims (4)

Decoding means for executing decoding processing of compression-encoded data of a moving image and storing decoded image data as a decoding result in a decoded image memory ;
The time is divided into a plurality of time slots, the execution target is switched each time the time slot is switched, and each of the decoding processing of the compressed encoded data of the moving images of the plurality of channels is sequentially and cyclically executed by the decoding means. Parallel processing control means for controlling the length of the time slot for executing the decoding process of each channel and the execution order of the decoding process of each channel according to the priority designated for each channel; Prepared ,
The decoding means executes a drawing process using one or a plurality of channels of decoded image data corresponding to a new frame stored in the decoded image memory every time the vertical scanning cycle is switched. Therefore, one or a plurality of channels of decoded image data is generated and stored in the decoded image memory. For this purpose, a decoding process of one or a plurality of moving image compression-encoded data is executed, Each time decoded image data that is a decoding result for one frame is obtained, the decoded image data is stored in the decoded image memory.
The parallel processing control means uses the time slot for the channel to perform the vertical scanning when the decoding means executes decoding processing for one frame of compressed encoded data of moving image of one channel. A moving picture decoding apparatus characterized by causing the decoding means to continuously execute a decoding process of a subsequent frame of the channel without waiting for a cycle change . The parallel processing control means includes:
Information indicating the priority of each channel as information indicating the priority of each channel, and the length of the time slot for performing the decoding process of each channel according to the information indicating the priority of each channel according to the information indicating the priority of each channel And the execution order of the decoding process of each channel is changed with time
The moving picture decoding apparatus according to claim 1. The moving image compression-coded data includes time-series information indicating a priority level that changes with time, and the parallel processing control unit includes a time-series indicating a priority level included in the compression-coded data of the moving image of each channel. According to the information, the length of the time slot for executing the decoding process of each channel and the execution order of the decoding process of each channel are changed over time.
  The moving picture decoding apparatus according to claim 2, wherein: The compressed encoded data of the moving image is supplied to the decoding unit via a buffer, and the parallel processing control unit stores the compressed encoded data waiting for decoding processing of each channel stored in the buffer. When the priority is monitored and it is detected that the priority of a certain channel is high as a result of the monitoring, before the decoding process of the compressed encoded data of the section with the high priority of the channel is started, The time slot used for the decoding process of the channel is lengthened, and after that, when it is detected that the priority of the channel returns to the original low value, the length of the time slot of the channel is restored. The moving picture decoding apparatus according to claim 2 or 3.

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