JPH08331511A - Dynamic image reproducing device and dynamic image reproducing processing circuit - Google Patents

Abstract

PURPOSE: To eliminate the need for a speed control mechanism for special reproduction in a dynamic image reproducing circuit. CONSTITUTION: This device is provided with a DSM 11 conducting special reproduction and storing digital data while operating audio and video decoder similarly to the case with usual reproduction by using a variable counter 12 to revise a clock signal being an operation reference signal, a separate circuit 131 receiving the digital data from the DSM 11 and separating the data into video and audio data, video and audio buffers 131, 132 storing data from the separate circuit 131, video and audio decoders 15, 14 decoding data of each buffer, and a variable STC counter 12 controlled by external information such as a host microcomputer 18 and controlling a timing by which the decoders 15, 14 receive data from the buffers 133, 132 and a timing when the data of the DSM 11 are sent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to compression / expansion of digital moving image / audio data, and more particularly to a moving image reproducing apparatus and a moving image reproducing processing circuit having a new mechanism for synchronous control of video and audio and management of a buffer. .

[0002]

2. Description of the Related Art MPEG is an international standard for compression and expansion of moving images, compression and expansion of audio, and synchronization of audio and moving images. In MPEG, STD (System) is used to synchronize audio and images and to manage the buffer (to prevent overflow and underflow of each audio and image data to be stored in the buffer).
It defines a virtual decoder called Target Decoder).

The STD is a system decoder (separation circuit) for separating composite data of multiplexed video data and audio data into audio and video data, and a buffer for storing each separated data (compressed data). (Audio buffer and video buffer) and decoder (audio decoder and video decoder) for decoding data from this buffer
Consists of

Further, in STD, audio data and video data are instantly decoded. That is, the following three events occur simultaneously. (i) Extraction of compressed data from each audio / video buffer. (ii) Decoding the extracted data. (iii) Display of each decoded audio / video.

Compressed data should be created so that buffer overflow or underflow does not occur in STD. In response to the data created in this way, the actual decoder should be able to perform decoding so that buffer overflow or underflow does not occur.

The compressed data includes the following information. (1) The capacity of each buffer in the STD assumed when creating data is written at the beginning of the compressed data. (2) SCR (System Clock Reference) is inserted in the middle of compressed data at the time when multiplexed data enters STD. (3) PTS, time when each separated data, that is, audio data and video data, is taken out from STD
(Presentation Time Stamp) is given to each of audio and video, and is inserted in the middle of compressed data.

Then, the compressed data enters the STD at the time indicated by the SCR, the compressed audio data is taken out from the STD at the time indicated by the audio PTS, and the video P
If the compressed data of the video is extracted from the STD at the time indicated by TS, the compressed data is created so that any buffer of the STD does not overflow or underflow, and the audio and the image are synchronized.

SCR and audio and video PTSs
90kHz called STC (System Time Clock)
Made based on the clock. That is, in compressed data (bit stream) sent from a memory medium (DSM: digital storage media), SCR and each PTS of audio and video defined by STD appear. Each decoder transfers data as shown in (2) and (3) above with reference to a counter called an STC counter that counts up at 90 kHz.

FIG. 3 is a block diagram showing the structure of a conventional moving image reproducing apparatus. Thick arrow lines show the flow of data,
The thin arrow lines indicate the supply of control signals. CD ROM
DSM (digital storage media) such as video and CD 21
In, for example, composite data (compressed data) of video data and audio data is stored.

The compressed data (bit stream) sent by the DSM 21 is taken into the STD buffer 23 at the timing of counting in the STC counter 22 according to the above-mentioned SCR, and taken out from the STD buffer 23 according to the above-mentioned PTS. That is, this STD buffer
23 is a mechanism created based on the above-mentioned STD. The SCR and PTSs have already been adjusted by an encoder (not shown) that creates compressed data.

The data in the DSM 21 is first fetched by the separation circuit 231 in the STD buffer 23 according to the SCR. This separation circuit 231 includes a demultiplexer structure, and combines the composite data from the DSM21 with the audio data ADAT.
Separated into A and video data VDATA. The bit streams of the audio data and the video data are transmitted to the audio buffer 232 and the video buffer 233, respectively, and the data are accumulated.

As described above, the PTS is a timing control signal that exists individually for audio and video, and that appropriately responds to the information amount of each bit stream based on the STD buffer 23. This allows the audio buffer
232, video buffer 233 Audio decoder 24, video decoder 25 at a timing such that data overflow or underflow does not occur in each buffer
The corresponding data is transmitted to each. Audio decoder 2
4. The video decoder 25 decodes the respective input data, and reproduces the sound on the loudspeaker 26 and the image on the display device 27 synchronously based on the timing of the STC counter 22.

As described above, the MPEG standard defines the meanings of the following three pieces of time information. First, STC
The counter 22 is a counter that functions as a clock for the entire system, and counts up at a constant frequency of 90 kHz. Second is the SCR, the time when the bitstream is taken into the STD buffer 23. Third, PTS, the bitstream is removed from the STD buffer 23,
In other words, it is the time at which each decoding is performed, which is for video and audio respectively. The timing of the SCR and PTS is determined by the STD buffer 23 as described above, and is associated with the bit stream.

The STC counter 22 counts up at a constant frequency, but when the timing discrepancy with the STC in any of the SCR, video PTS, and audio PTS signals becomes large, adjustment of the moving image reproducing system is necessary. is necessary. There are four possible adjustment methods.

First, the moving picture reproducing system is constructed so that the STC counter is not adjusted. That is, the DSM 21 sends the bitstream to the STD buffer 23 according to the STC.
Send to Images and sounds should be decoded according to STC. The video and audio decoders compare the values of the PTS and the STC counter 22, and if the PTS is larger, the decoding is suspended until the STC counter catches up with the PTS. If the STC counter value is larger,
Hurry up to skip the data and let the PTS catch up with the STC counter.

Secondly, the moving picture reproducing system has a structure adapted to SCR. When DSM21 sends the bitstream to buffer 23, STC is aligned with SCR (SC
Substitute the R signal into the STC counter). Images and sounds should be decoded according to STC.

Thirdly, the moving picture reproducing system has a structure adapted to the PTS of the video. When the video decoder 25 performs decoding, the STCs are aligned with the video PTSs (the video PTS signal is substituted into the STC counter). The DSM 21 sends the bit stream to the buffer 23 according to the STC. Audio is decoded according to STC.

Fourthly, the moving image reproducing system has a structure adapted to the PTS of the audio. Audio decoder
When 24 decodes, STC audio PT
Align with S (substitute the signal of audio PTS in the STC counter). The DSM 21 sends the bit stream to the buffer 23 according to the STC. The image is decoded according to STC.

According to the above construction, since the STC counter 22 is always counted up at 90 kHz, the STC counter 22 is in progress during special reproduction such as slow, fast forward, pause and the like.
The STD buffer 23 using 22 cannot be managed.

Therefore, for the audio decoder and the video decoder, the speed control mechanism 28 for special reproduction,
29 are provided. Thus, during special reproduction, the switching circuits 31 and 32 separate the speed control mechanisms 28 and 29 from the time management of the STC counter 22 during special reproduction.
The operation is controlled after switching to.

That is, during the special reproduction, the reproduction speed is changed by switching to the speed control mechanism 31, 32 during the special reproduction, so that the video and audio are not reproduced with STC as a reference. Therefore, when returning from the special reproduction to the normal reproduction, the management of the STD buffer 23 has to be redone, and the following measures have been taken.

First, after the SCR timing appears in the bit stream sent from the DSM 21, the DSM 21 substitutes the SCR into the STC counter 22.
At this time, the STC value is not guaranteed from the return to the appearance of the SCR in the bitstream, and the video and audio decoders operate according to the STC, so that the moving image and audio are disturbed.

As described above, a time lag occurs because the above process is performed when returning from the special reproduction to the normal reproduction, which causes a problem that the smooth recovery cannot be performed.
Further, since a special mechanism such as a speed control mechanism at the time of special reproduction is required, cost and integration are greatly affected.

[0024]

Conventionally, since the STC counter is always counted up at a constant frequency, when performing special reproduction such as slow, fast forward, and pause, the special reproduction is separated from the STC counter. However, there is a problem that it takes time to resynchronize and to re-manage the STD buffer when returning from the special reproduction to the normal reproduction.

The present invention has been made in consideration of the above circumstances, and its purpose is to perform STC during special reproduction.
With a configuration that does not use a speed control mechanism that separates from the counter,
It is an object of the present invention to provide a moving picture reproducing apparatus and a moving picture reproducing processing circuit that can smoothly return to normal reproduction.

[0026]

SUMMARY OF THE INVENTION A moving image reproducing apparatus of the present invention includes a medium in which digital data is stored, a separation circuit for capturing the digital data from the medium and separating the data into audio data and video data, and the separation circuit. An audio buffer and a video buffer for accumulating the respective data from the circuit, an audio decoder and a video decoder for decoding the data of the respective buffers, and count control by external information, and the respective decoders from the respective buffers. A variable counter means is provided for controlling the timing of taking in the data and the timing of transmitting the data from the medium.

The moving image reproduction processing circuit of the present invention comprises a separation circuit for separating digital data into audio data and video data, an audio buffer and a video buffer for accumulating respective data from the separation circuit, and An audio decoder and a video decoder that decode the data in each buffer, and a variable that is count-controlled by external information and that controls the timing at which each decoder takes in data from each buffer and the timing at which the digital data is sent to the separation circuit. And a counter means.

In the present invention, the variable counter means
Change the clock itself, which is the reference of the operation timing,
Special playback is performed while operating the audio decoder and video decoder in the same manner as during normal playback. If data transfer from the medium is also controlled by the variable counter means, the buffer is managed even during special reproduction and each decoder is synchronized, so that it is not necessary to re-initialize the variable counter when returning to normal reproduction. .

[0029]

1 is a block diagram showing the structure of a moving image reproducing apparatus according to a first embodiment of the present invention.
Thick arrow lines indicate the flow of data, and thin arrow lines indicate the supply of control signals. DSM (digital storage medi
a) It is assumed that 11 stores composite data (compressed data) of video data and audio data. This D
The compressed data (bit stream) sent from the SM 11 is passed through the buffer 134 and then fetched in the buffer 13 at the timing when the value of the variable STC counter 12 matches the SCR (System Clock Reference). Above D
First, the data in SM11 is STD (System Target Deco
der) Captured by the separation circuit 131 in the buffer 13. The buffer 134 is provided to store the necessary amount of data before separation when the separation circuit 131 cannot operate in synchronization with the data transfer from the DSM 11.

The demultiplexing circuit 131 includes a demultiplexer structure and converts the composite data from the DSM 11 into audio data AD.
Separated into ATA and video data VDATA. The audio data ADATA and video data VDATA bitstreams are respectively the audio buffer 132 and the video buffer.
It is transmitted to 133 and the data is accumulated. PTS (Presenta
tion Time Stamp) is a timing control signal that appropriately corresponds to the amount of information of each bit stream based on the STD buffer.

The PTS exists for each of video and audio. The PTS adjusts the timing so that data overflow or underflow does not occur in each of the audio buffer 132 and the video buffer 133, and the audio decoder 14 and the video decoder 15
The corresponding data is transmitted to each. Audio decoder 1
4. The video decoder 15 decodes the respective input data, and reproduces the sound on the loudspeaker 16 and the image on the display device 17 synchronously based on the timing of the variable STC counter 12. Both the SCR and PTS are placed under the control of the design of the STD buffer as in the conventional case, and the timing is determined.

In the present invention, the variable STC counter 12 is provided instead of the STC counter that counts up at a constant frequency unlike the conventional STC counter. Then, the conventional speed control mechanism at the time of special reproduction becomes unnecessary. The variable STC counter 12 is configured to be frequency-divided by an external system clock signal and a command signal of the host microcomputer 18, for example. As a result, the audio decoder 14 and the video decoder 15 can perform special playback such as fast-forward and slow while synchronizing with each other according to STC.

That is, according to the configuration of the present invention, it is possible to manage the STD buffer even during special reproduction, and while using the same synchronization deviation correction mechanism as in the conventional example,
A major feature is that special playback is possible.

More specifically, SCR and video P
In either TS or audio PTS signal,
When the timing discrepancy with STC becomes large,
Special reproduction is possible by the two methods of adjusting the moving picture reproducing system shown in the first and second embodiments. For this reason, the moving image reproduction system of the present invention can smoothly return to normal reproduction. There are the following two methods of adjusting the synchronization deviation correction. It should be noted that the STC described below is a variable STC (System Time Clock) applied in the present invention.

First, the moving picture reproducing system is constructed so that the STC counter is not adjusted. That is, the DSM 11 sends the bit stream to the STD buffer 13 according to the STC.
Send to Images and sounds should be decoded according to STC.

Secondly, the moving image reproducing system has a structure adapted to SCR. When the DSM 11 sends the bit stream to the STD buffer 13, the STC is aligned with the SCR (the signal of the SCR is assigned to the STC counter). Images and sounds should be decoded according to STC.

According to the configuration of the first embodiment, the variable STC counter 12 becomes the master of time management, and the DSM 11
Transfers data at a speed adapted to the variable STC counter 12. That is, sending of data from the DSM 11 and synchronization control of the audio decoder 14 and the video decoder 15 can be easily achieved. The variable counter 12 can change the count-up speed according to the playback speed during special playback.
In normal reproduction after returning from special reproduction, synchronization using STC and buffer management of data accumulation can be easily performed.

Here, the first example of the method of realizing each special reproduction is described.
~ Shown as the fourth. First, slow slows the operation of the variable STC counter. Second, fast forward speeds the operation of the variable STC counter. Third, the pause / stop is variable S
Stop the TC counter. Fourth, frame advance / scan
The variable STC counter is intermittently counted up.
In this scan, it is sufficient to complete the reproduction by skipping the data without decoding some pictures. Fifth, freeze / blank is the same as normal playback. Here, freeze means that decoding is performed at the same speed as normal playback, but the display device is in a pause state, and blank means that decoding is performed at the same speed as normal playback but video display is blank ( (Nothing is displayed).

FIG. 2 is a block diagram showing the structure of a moving picture reproducing apparatus according to the second embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals. In FIG. 2, the DSM serves as a master for time management. Audio decoder 14
The video decoder 15 and the video decoder 15 can perform special reproduction such as fast-forwarding and slow-moving while synchronizing with each other according to STC.

Further, the host microcomputer 18 controls the command for sending data to the DSM 11 while monitoring the amount of data before separation from the DSM 11. Host microcomputer 18 is variable STC
The speed of the counter 12 is controlled, and an appropriate STC value of the variable STC counter 12 is determined according to the data transmission of the DSM 11.

According to each of the above-mentioned embodiments, since the clock itself which is the reference of the operation timing is changed by the variable STC counter, special reproduction is performed while operating the audio decoder and the video decoder in the same manner as in normal reproduction. It can be carried out.

Conventionally, the STC counter is always counted up at a constant frequency. Therefore, when performing special playback such as slow, fast forward, and pause, it is necessary to use a speed control mechanism for special playback that is separate from the STC counter, and when the special playback is restored to normal playback There is a problem in that it takes time to retake and redo the management of the STD buffer.

The present invention uses a variable STC counter to
Since the STD buffer including the audio and video buffers can be managed even during trick play, it is possible to smoothly return to normal play. Especially when the STC is the master, it is not necessary to re-manage the STD buffer when returning from the special reproduction to the normal reproduction.

If the sound can be reproduced fast / slow, the image and the sound are synchronized even during the special reproduction. Furthermore, it should be noted that the mechanism for controlling the reproduction speed for special reproduction (28 and 29 shown in FIG. 1) is not required as long as there is a mechanism for reproducing according to the variable STC counter.

[0045]

As described above, according to the present invention,
The variable STC counter changes the clock itself, which is the reference of the operation timing, so that special reproduction can be performed while operating the audio decoder and the video decoder in the same manner as during normal reproduction. Since the audio and video buffers are managed even during trick play,
You can smoothly return to normal playback. Further, it is possible to provide an image reproduction device and a moving image reproduction processing circuit which do not require a mechanism for controlling the reproduction speed for special reproduction and contribute to circuit integration and cost reduction.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional moving image reproducing apparatus.

[Explanation of symbols]

11 ... DSM (digital storage media) 12 ... Variable STC counter 13 ... STD buffer (STD: system target decoder)
) 14 ... Audio decoder 15 ... Video decoder 16 ... Loudspeaker 17 ... Display device 131 ... Separation circuit 132 ... Audio buffer 133 ... Video buffer 134 ... Buffer

Claims (8)

[Claims] 1. A medium in which digital data is stored, a separation circuit for taking the digital data from the medium and separating the data into audio data and video data, and an audio buffer for accumulating the respective data from the separation circuit, A video buffer, an audio decoder and a video decoder for decoding the data in the buffers, a count control by external information, a timing at which the decoders fetch data from the buffers, and a timing at which the medium transmits data. And a variable counter means for controlling the moving picture reproducing apparatus. 2. A medium in which digital data is stored, a separation circuit for taking the digital data from the medium and separating the data into audio data and video data, and an audio buffer for accumulating each data from the separation circuit, A video buffer, an audio decoder and a video decoder that decode the data in each buffer, a transmission control unit that controls the timing of transmitting the data of the medium according to external information, and each decoder by the transmission control unit. And a variable counter means for controlling the timing of fetching data from each of the buffers. 3. A buffer unit for accumulating unseparated data before being taken in by the separating circuit when the digital data is taken in from the medium. 2. The moving image reproducing device described in 2. 4. A medium in which digital data is stored, a buffer means for capturing the digital data from the medium and storing the data separately as audio data and video data, and an audio decoder for decoding the data from the buffer means, A moving image comprising a video decoder and variable counter means which is count-controlled by external information and controls the timing at which each decoder fetches data from the buffer means and the timing at which the medium transmits data. Image reproduction device. 5. A medium in which digital data is stored, a buffer means for capturing the digital data from the medium and separately storing the audio data and video data, an audio decoder for decoding the data from the buffer means, and A video decoder, transmission control means for controlling the timing of transmitting data on the medium according to external information, and variable counter means for controlling the timing of fetching data from the buffers of the decoders by the transmission control means. A moving image reproducing apparatus characterized by being provided. 6. A buffer unit for accumulating the digital data before being separated in the buffer means, when the digital data is taken in from the medium, is provided. The moving image reproducing apparatus described. 7. A separation circuit for separating digital data into audio data and video data, an audio buffer and a video buffer for storing the respective data from the separation circuit, and an audio for decoding the data in each buffer. And a video decoder, and variable counter means for controlling the timing at which each decoder takes in data from each buffer and the timing at which the digital data is sent to the separation circuit according to an external control signal. And a moving image reproduction processing circuit. 8. A separation circuit for separating digital data into audio data and video data, an audio buffer and a video buffer for accumulating each data from the separation circuit, and an audio for decoding the data in each buffer. Decoder and video decoder, transmission control means for controlling the timing of sending the digital data to the separation circuit according to external information, and the transmission control means for controlling the timing of fetching data from the buffers of the decoders. A moving image reproduction processing circuit comprising a variable counter means.