JPH0863884A - Digital information coding and decoding apparatus - Google Patents

Abstract

PURPOSE: To reduce the amount of a memory in a decoding apparatus, to eliminate a need of a time stamp and to synchronously control a video signal and an audio signal by a simple constitution by a method wherein, in coded multiple data, an audio coded data train is arranged prior to a video coded data train. CONSTITUTION: A coded multiple signal is read out to a buffer 9 from a digital recording medium 8, and it is input to a simplified demultiplexer 11 via a changeover device 10. Video coded data is output to a video buffer 12, and audio coded data is output to an audio buffer 16. When the data storage amount of the buffer 12 becomes a prescribed threshold value or higher, a microcomputer 20 supplies video coded data to a video decoder 14 via a video changeover device 13. In addition, the microcomputer supplies the audio coded data to an audio decoder 18 via an audio changeover device 17. Thereby, an output signal in which a video signal agrees with an audio signal is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coding / decoding device for digital image signals and audio signals.

[0002]

2. Description of the Related Art In recent years, digital coding techniques for video signals and audio signals have been used in many media such as broadcasting, communication and information equipment. Especially in the field of AV equipment, M
A single C is used by utilizing the digital encoding method by PEG.
Up to 74 minutes of moving images and audio can be recorded on D
"D" has been standardized and is becoming widespread.

FIG. 14 shows the sector format of a video CD. The digital data of the video CD has a structure including one packet in one pack. One pack consists of 2324 bytes in one sector.

On the disc, MPEG video and audio data are recorded in time series, and they are arranged at an average ratio of 6: 1.

When digital data is recorded in a storage medium, video data and audio data are arranged in time series, unlike an analog recording VTR represented by VHS.
Therefore, it is necessary to perform synchronization processing of the output video signal and audio signal.

In the video CD, three pieces of time information are used to perform these synchronization processes. First, an SCR (system clock reference) in the pack header that sets the reference clock of the decoding device, and then a DTS (decoding time, which indicates the decoding start time of the video / audio signal in the packet header). And a PTS (Presentation Time Stamp) in the packet header and indicating the output time of the decoding result.

FIG. 15 shows the configuration of a video CD encoding circuit. 1 is a video A / D converter for converting an analog video signal input into a digital video signal, 2 is a video encoder for converting a digital video signal into an encoded video signal, 3 is a video buffer for temporarily storing the encoded video signal, 4 is an audio A / D converter for converting an analog audio signal input into a digital audio signal, 5 is an audio encoder for converting a digital audio signal into an encoded video signal, 6 is an audio buffer for temporarily storing the encoded audio signal, 24, the encoded video data and the encoded audio data are arranged in time series, and S
A multiplexer 8 that adds CR / DTS / PTS to create encoded multiplex data, and 8 is a digital storage medium that stores the encoded multiplex data.

The coded video data created by the video encoder 2 is temporarily stored in the video buffer 3, and the coded audio data created by the audio encoder 5 is temporarily stored in the audio buffer 6. The multiplexer 24 divides the coded video data and the coded audio data so as to match the format of the coded multiplex data shown in FIG. 14, rearranges them, and adds time information to the respective data, so that the data shown in FIG. The coded multiplexed data shown is output.

FIG. 16 shows the structure of a video CD decoding circuit. Reference numeral 8 is the same as the digital storage medium for storing the encoded multiplexed data shown in FIG. 9 is a buffer for storing the data from the digital storage medium 8;
Is a buffer switcher for controlling the output signal of the buffer 9, and 25 is encoded video data from encoded multiplexed data recorded in the digital storage medium, encoded audio data, and time information such as SCR / DTS / PTS. Demultiplexer that separates and outputs, a video buffer that stores encoded video data, a video buffer switcher that controls the output signal of the video buffer 12, a video decoder that decodes encoded video data, and a video decoder A video D / A converter for converting the decoded video data into an analog signal, 16 an audio buffer for storing encoded audio data, 17 an audio buffer switching device for controlling the output signal of the audio buffer 16, and 18 an encoded audio Audio decoding to decode data , 19 audio D / A converter for converting the audio data decoded into an analog signal, 20 is outputted from the demultiplexer 11 SCR
A microcomputer that controls the video buffer controller 13 and the audio buffer controller 17 based on time information such as DTS / PTS.

The data read from the digital storage medium 8 is input to the buffer 9. The buffer 9 absorbs the difference between the data reading speed from the digital storage medium 8 and the data reading speed of the demultiplexer. The demultiplexer 25 separates video data, audio data, SCR / DTS / PTS time information, etc. from the data read from the digital storage medium 8. As a result, the video data is stored in the video buffer 12,
The audio data is sent to the audio buffer 16 and SCR
・ Time information of DTS / PTS is microcomputer 2
To 0 respectively.

The video buffer 12 continuously outputs the encoded video data output from the demultiplexer 25 to the video decoder through the video buffer switching unit 13. The video decoder 14 decodes the input video coded data and outputs a digital video signal to the video D / A converter 15. Video D / A
The converter 15 converts the digital video signal output from the video decoder 14 into an analog video signal and outputs it as a video signal output.

On the other hand, the audio buffer 16 outputs the audio data intermittently output from the demultiplexer 25 to the audio decoder through the audio buffer switching unit 17. The audio decoder 18 decodes the input audio encoded data and outputs a digital audio signal to the audio D / A converter 19. The audio D / A converter 19 converts the digital audio signal output from the audio decoder 18 into an analog audio signal and outputs it as an audio signal output.

SC output from the demultiplexer 25
The time information of R / DTS / PTS is input to the microcomputer 20. In the microcomputer 20,
The time of the clock of the entire system is adjusted based on the SCR. Then, the connection between the video buffer switching unit 13 and the audio buffer switching unit 17 is adjusted using the information of DTS or PTS, and the output timing of the output signal is adjusted to synchronize the output of the video signal and the audio signal.

[0014]

In the synchronization processing in the video CD encoding / decoding circuit as shown in FIGS. 15 and 16, the accuracy of synchronization between video and audio is determined by the frequency of the clock used for synchronization. It becomes possible to perform synchronization with extremely high accuracy. However, there is a problem in that a time stamp is inserted by a multiplexer, time information is separated by a demultiplexer, and synchronization processing is performed by a time stamp control unit, which makes the decoding device complicated and expensive. It was

The present invention has been made in order to solve such a problem, does not require a time stamp, and
It is an object of the present invention to obtain a device that controls the synchronization of video and audio with a simple structure.

[0016]

According to a first aspect of the present invention, there is provided a digital information encoding / decoding device in which audio encoded data is encoded in a video encoded data sequence and an audio encoded data sequence in which the heads of data are at the same time. A multiplexer for arranging the sequence before the video encoded data sequence to create encoded multiplex data, and a video decoder and an audio decoder for simultaneously starting the decoding of the respective head data of the video encoded data sequence and the audio encoded data sequence. Be prepared.

Further, in the digital information coding / decoding apparatus according to the invention of claim 2, in the video coded data string and the audio coded data string whose data heads are at the same time, the audio coded data string is video coded. A multiplexer that creates encoded multiplex data by dividing each data row in a vertical column by dividing the data row at the same time as the division of the encoded data row or by a time difference such that a synchronization shift between video and audio cannot be detected, and arranging each divided data row in a column. It is provided with a video decoder and an audio decoder for simultaneously starting the decoding of each head data of the video coded data string and the audio coded data string.

Further, in the digital information coding / decoding apparatus according to the invention of claim 3, in the video coded data string and the audio coded data string whose data heads are the same time, the audio coded data string is video coded. A multiplexer that creates encoded multiplex data by dividing each data row in a vertical column by dividing the data row at the same time as the division of the encoded data row or by a time difference such that a synchronization shift between video and audio cannot be detected, and arranging each divided data row in a column. It is provided with a video decoder which starts decoding by receiving the start code in the video coded data string, and an audio decoder which starts decoding at the same time when decoding of the video decoder is started.

Further, in the digital information coding / decoding apparatus according to the invention of claim 4, in the video coded data string and the audio coded data string whose data heads are at the same time, the audio coded data string is video coded. The divided data string is divided into columns at the same time as the division of the encoded data string or at an earlier time with a time difference such that synchronization deviation between video and audio cannot be detected, the divided data strings are arranged in columns, and the start code in the video encoded data is at the same time. Multiplexer that creates encoded multiplexed data by arranging immediately before the audio data of, the video decoder that starts decoding by receiving the start code in the above video encoded data string, and the decoding that starts at the same time when the video decoder starts decoding. It is equipped with an audio decoder to start.

Further, in the digital information coding / decoding apparatus according to the invention of claim 5, in the video coded data string and the audio coded data string whose data heads are at the same time, the audio coded data string is video coded. The divided data string is divided into columns at the same time as the division of the encoded data string or at an earlier time with a time difference such that synchronization deviation between video and audio cannot be detected, the divided data strings are arranged in columns, and the start code in the video encoded data is at the same time. A multiplexer that creates encoded multiplexed data by arranging immediately before the audio data of, and when the audio encoded data string is first input and the start code does not exist at the beginning of the video encoded data string immediately after that. A demultiplexer that discards the first input audio encoded data string and the video encoding demultiplexer described above. A video decoder to start decoding by receiving the start code in the data column, those having an audio decoder to start at the same time decoding and decoding the start of the video decoder.

[0021]

According to the first aspect of the present invention, by arranging the audio encoded data sequence in the encoded multiplexed data before the video encoded data sequence, the amount of memory in the digital information decoding apparatus can be reduced.

According to the second aspect of the present invention, the encoded audio data sequence is divided at the same time as the encoded video data sequence or at a time with a time difference that is too early to detect a synchronization shift between video and audio, and each divided encoding is performed. By arranging the data to create the encoded multiplexed data, when the decoding starts from the middle of the encoded multiplexed data and the synchronization shift between the video and the audio occurs, the audio is always delayed below the detection limit.

According to the third aspect of the present invention, the decoding by the video decoder is started by receiving the start code in the video encoded data, and the decoding by the audio decoder is started at the same time when the decoding by the video decoder is started. Even if the decoding is started in the middle of the encoded multiplexed data, it is possible to obtain a decoded signal with almost no synchronization deviation between video and audio.

According to the fourth aspect of the present invention, the start code of the video coded data is arranged immediately before the audio data, so that the video and the audio are synchronized even when the coded data is decoded from any position in the middle. It is possible to obtain a decoded signal with almost no deviation.

According to the invention of claim 5, the start code of the video coded data is arranged immediately before the audio data to create coded multiplexed data, and the start code of the video coded data is not input to the video decoder. By discarding the encoded audio data, it is possible to obtain a decoded signal with almost no synchronization deviation even when the encoded multiplexed data is decoded from any position in the middle.

[0026]

【Example】

Example 1. 1 is a block diagram showing the configuration of a digital information coding apparatus according to a first embodiment of the present invention. When FIG. 1 is compared with FIG. 15 of the conventional example, it is the same as FIG. 15 except that the multiplexer 7 is a simplified type multiplexer 7.

The operation of the simplified multiplexer 7 will be described with reference to FIG.

First, as shown in FIG. 2, the video signal and the audio signal to be encoded are separated at an appropriate time. In the first embodiment, the cutting is performed every 0.5 seconds. At this time,
The start times of the video signal and audio signal should match.

Next, the simplified multiplexer 7 creates and outputs encoded video data and audio encoded data, which are divided at the same time, and encoded multiplexed data in which video data is arranged next to audio data. .

The output state of the simplified multiplexer 7 is
This will be described with reference to FIG. First, a pack header and a packet header containing the length of the data and information indicating the distinction between audio coded data and video coded data are added to the beginning of each audio coded data and video coded data. .

Then, the audio encoded data is first output from the simple multiplexer.

Next, the video coded data is output.
In FIG. 3, the audio coded data divided into 0.5 seconds is further divided into N pieces, and a pack header and a packet header are added to each and outputted.

In FIG. 3, the coded video data are coded data 1.1 to video coded data 1. Although it is divided into N pieces up to N, it may be outputted as one data without division.

After a set of audio coded data and video coded data is output, the data is repeatedly output in the order of audio coded data and video coded data.

Next, an example of the pack header and the packet header is shown in FIG. The ID in the packet header indicates whether the data contained in the packet is video data or audio data. In addition, SCR
Although the time information field such as PTS is set, the simple multiplexer may output meaningless data such as "0". However, SCR / PTS
When it is desired to perform decoding even in a decoding device that requires such time information, that is, to provide compatibility, the simple multiplexer outputs the time information.

Next, the operation of the decoding circuit will be described with reference to FIG. The coded multiplexed signal read from the digital recording medium 8 is input to the buffer 9. Buffer 9
Is the reading speed of data from the digital recording medium 8 and the video decoder 14 and audio decoder 18
It absorbs the difference from the speed of the data required for the decoding process in.

The coded multiplexed data read from the buffer 9 is input to the simplified demultiplexer 11 through the switch 10. The simplified demultiplexer 11 is
The packet header of the coded multiplexed data is read to determine whether it is a packet of audio coded data or a packet of video coded data, the video coded data is output to the video buffer 12, and the audio coded data is output to the audio buffer 16. To do.

The video buffer 12 and the audio buffer 16 read out the discontinuous video data and audio data output from the simplified demultiplexer 11 as continuous data at a data reading speed required by the video decoder and the audio decoder, respectively. For output to each decoder.

The microcomputer 20 constantly monitors the amount of data stored in the video buffer 12. When the amount of data stored in the video buffer 12 becomes equal to or larger than a predetermined threshold value, the video switch 13 is closed, the video coded data is output from the video buffer 12 to the video decoder 14, and the video decoder 14 starts decoding.

At the same time, the audio switch 17 is closed and the encoded audio data is transferred to the audio buffer 1.
Output from 6 to the audio decoder, and the audio decoder 18 starts decoding. That is, the decoding by the video decoder and the audio decoder is started at the same time. This makes it possible to obtain an output signal in which video and audio are synchronized.

Time from input of encoded video data to the video decoder to output of video data, that is, from video decoder delay and from input of encoded audio data to audio decoder to output of audio data If there is a difference between this time, that is, the audio decoder delay, the timing at which the video switch 13 and the audio switch 17 are closed is shifted. For example, when the video decoder delay is longer than the audio decoder delay by t [sec], the video switcher 1
After t [sec] when 3 is closed, the audio switch 17
Shall be closed. As a result, even if there is a difference in the delay between the video decoder and the audio decoder, it is possible to obtain an output signal in which video and audio are synchronized.

The encoded video data is recorded by the video decoder 1.
4 is decoded, converted by a video D / A converter 15 into an analog video signal, and output. The encoded audio data is decoded by the audio decoder 18, converted into an analog audio signal by the audio D / A converter 19, and output.

Here, the encoded multiplexed data is such that audio data at the same time is output before video data. In the encoded multiplexed data, audio data and video data at the same time are multiplexed in time series. Here, the time-series multiplexing is roughly divided into
There are two possible cases: sending audio data first and sending video data first. For example, when video data is sent first, the decoding device must hold the previously received video data without decoding until the audio data at the same time is sent after receiving the video data. There is. Here, comparing the data amounts of the audio data and the video data, the audio data is usually much smaller than the video data. Therefore, when storing information for a fixed time, the amount of memory required for storing audio data is much smaller than that for storing video data.

By transmitting the audio data at the same time earlier than the video data as in the first embodiment, the amount of memory required for the entire decoding device becomes very small. As a result, the decoding device can be configured with a very simple configuration.

Further, in the digital information decoding apparatus shown in FIG. 5, when reading coded multiplexed data from the digital storage medium 8, consider a case of reading from the middle of the data. This is a case where the recorded video and audio signals are decoded halfway. Considering decoding from the middle of the data, if decoding is started with a pair of audio coded data and video coded data, that is, when reading from point A shown in FIG. 3, the video data and audio data are As shown in FIG. 2, since data at the same time are recorded as a set, a decoded signal in which video and audio are synchronized can be obtained.

In the first embodiment, the apparatus for decoding the video coded data and the audio coded data recorded on the digital recording medium without causing the synchronization deviation has been described. It is not limited. For example, audio signals from various musical instruments and vocal audio signals may be encoded individually and synchronized reproduction may be performed.

In the first embodiment, the configuration for reading the coded multiplexed data from the digital storage medium has been described, but the present invention is not limited to this. For example, the encoded multiplexed data may be read from a communication medium such as a cable television.

Further, in the above-described first embodiment, the configuration in which the video coded data and the audio coded data from the coded multiplexed data are separated by using the multiplexer external to the microcomputer has been described, but in the same microcomputer. You may divide by.

Example 2. Next, in the digital information coding / decoding apparatus according to the first embodiment, even when the video coded data and the audio coded data cannot be divided at exactly the same time, a decoded signal in which video and audio are synchronized is obtained. The case where a function capable of performing the above is incorporated will be described.

The digital information coding apparatus is shown in FIG.
The configuration is the same as that of the digital information encoding apparatus according to the first embodiment shown in FIG. However, the structure of video data and audio data is limited. This will be described below.

First, FIG. 6 shows the structure of video data and audio data, and also shows how data is divided by the simplified multiplexer 7 according to the second embodiment. As shown in FIG. 6, one frame of a video signal to be encoded is a unit of one picture, and 15 pictures are one GO, for example.
The entire video signal is divided as a unit of P (group of pictures). One GOP is about 0.
It is 5 seconds.

Here, the structure of image coded data in the second embodiment will be described with reference to FIG. Example 2
Then, it is assumed that a sequence header representing the beginning of the encoded image data is added to the beginning of each GOP. The sequence header is followed by a GOP header, which is followed by picture data for 15 pictures. A series of image coded data starting with these sequence headers is 1 GOP of image coded data.

In the second embodiment, 1 GOP of the video signal is used.
Is composed of 15 pictures, but is not limited to this.

Further, as shown in FIG. 6, the audio signal is divided for each frame from the point where it temporally coincides with the leading picture of the video signal. One frame here is, for example, 48k
This represents 1152 samples of digital audio data sampled in Hz.

In the second embodiment, one frame of the audio signal is set to 1152 samples of 48 kHz sampling, but the sampling frequency and the number of samples of one frame are not limited to this.

The simplified multiplexer 7 converts the video coded data created by the video encoder 2 into 1G.
Divide by OP.

Further, it is impossible to divide the audio coded data created by the audio encoder 5 so as to always match the temporal GOP boundary line of the video coded data. Therefore, in the second embodiment,
The audio coded data is a boundary line of an audio frame that coincides with a temporal GOP boundary line of video coded data, or an audio frame boundary that temporally precedes the GOP boundary line when the boundary lines do not match. The line is divided at the boundary of the audio frame closest to the boundary of the GOP.

In FIG. 6, the video data is divided by the GOP boundary lines at 0.5 seconds and 1.0 seconds.
The audio data is split between audio frames 20 and 21 and between audio frames 41 and 42. That is, the first divided data of the video encoded data is a GOP composed of the first picture to the fifteenth picture, and the first divided data of the audio encoded data is the first frame to the twentieth frame. Is a series of encoded audio data.
In this division method, the number of frames in one division unit of audio encoded data is 20 or 21.

Next, the simplified multiplexer 7 outputs the divided video coded data and audio coded data at approximately the same time in such an order that the video data is output next to the audio data.

The output state of the simple multiplexer 7 is
This will be described with reference to FIG. First, at the beginning of each of the audio coded data and the video coded data, a pack header including a data length, information indicating the distinction between audio data and video data, and a packet header are added.

Then, first, data obtained by encoding the first to twentieth frames of the audio is output.

Next, 1 GOP worth of video data, that is, data obtained by coding the first to fifteenth pictures, is divided into appropriate sizes and output. In addition, in the second embodiment, the encoded video data is divided into an appropriate size for output, but may be output without being divided.

After a set of audio data and video data is output, the data is repeatedly output in the order of audio data and video data.

As shown in FIG. 6, the start time difference between each set of audio data and video data is one frame or less of the audio data. In the second embodiment, since one frame of audio data corresponds to 1152 samples of 48 kHz sampling, the time is 24 m.
sec. That is, the beginning of the audio data is
It precedes the beginning of the video data with a shift of 24 msec or less.

As the pack header and the packet header, the same ones as shown in FIG. 4 shown in the first embodiment are used.

Further, as the digital information decoding device, the same device as that of FIG. 5 shown in the first embodiment is used.

Here, in the digital information decoding apparatus shown in FIG. 5, when reading the coded multiplexed data from the digital storage medium 8, the case of reading from the middle of the data will be considered. This is a case where the recorded video and audio signals are decoded halfway. When considering decoding from the middle of the data, if decoding is started with a pair of audio coded data and video coded data, that is, when reading from point A shown in FIG. As shown in FIG. 6, since data at almost the same time are recorded as a set, it is possible to obtain a decoded signal that is substantially in synchronization.

Further, since the time difference between the boundary line of 1 GOP of video coded data and the boundary line of division of audio coded data is at most one frame of audio coded data, that is, 24 msec, it is decoded. The maximum deviation of synchronization between the video signal and the audio signal is 24 msec.

Since the dividing line of the audio coded data is always set to a time earlier than the boundary line of the video coded data, when synchronization error occurs in the decoded signal, the audio is always delayed. Therefore, the audio is not output earlier than the video.

From the above two points, if decoding is started with a set of audio coded data and video coded data, even if a synchronization error occurs, the audio is always delayed, and the maximum is 24 msec. Will be delayed. This is less than the ability of human beings to detect the synchronization deviation between video and audio, and is such that the synchronization is not noticed. Therefore, by using the digital signal encoding / decoding device according to the second embodiment, it is possible to obtain a decoded signal in which the video signal and the audio signal are almost in synchronization with each other even when the data is read from the middle of the data, though the circuit configuration is simple. You can

In the second embodiment, the apparatus for decoding the coded video data and the coded audio data recorded on the digital recording medium without causing the synchronization deviation has been described, but the recorded data is not limited to this. Not a thing. For example, audio signals from various musical instruments and vocal audio signals may be encoded individually and synchronized reproduction may be performed.

Further, although the second embodiment has explained the configuration for reading the coded multiplexed data from the digital storage medium, the present invention is not limited to this. For example, the encoded multiplexed data may be read from a communication medium such as a cable television.

Further, in the second embodiment, the configuration in which the video coded data and the audio coded data from the coded multiplexed data are separated by using the multiplexer outside the microcomputer has been described, but in the same microcomputer. You may divide by.

Example 3. Next, a case will be described in which the digital information encoding / decoding apparatus shown in the second embodiment incorporates a function of obtaining a decoded signal in which video and audio are almost synchronized even if the encoded multiplexed data is read from the middle. To do.

Incidentally, the digital information coding apparatus is shown in FIG.
It is assumed that the same digital information encoding device as the first embodiment shown in FIG.

FIG. 9 is a block diagram showing the structure of the digital information decoding apparatus according to the third embodiment. When FIG. 9 is compared with FIG. 5 of the first embodiment, it is the same as FIG. 5 except that the video decoder 14 is an improved video decoder 22.

The operation of the improved video decoder 22 will now be described. The data divided by the simple type demultiplexer and input to the improved video decoder 22 through the video buffer 12 and the video switching unit 13 is video encoded data as shown in FIG. The improved video decoder 22 starts decoding by inputting a sequence header with the sequence header as a start code in the data shown in FIG. 7. That is, when the data in the middle of the video coded data is received, the sequence header is first searched, and after the sequence header is found, the decoding of the data following the sequence header is started.

Now, the operation when data is read from a position in the middle of the digital storage medium 8 using the digital information encoding / decoding device shown above will be described.

In FIG. 8, consider the case where the data is read from point B, which is in the middle of the video coded data. At this time, the encoded video data read out from the middle is not judged as the encoded video data or the encoded audio data by the simplified demultiplexer 11 because there is no pack header / packet header and is discarded. next,
The video encoded data including the pack header / packet header is output to the video buffer 12 by the demultiplexer 11.

After that, the normally read audio coded data and video coded data are sequentially output to the audio buffer 16 and the video buffer 12.

The microcomputer 20 constantly monitors the data storage amount of the video buffer 12, and when the data storage amount of the video buffer 12 exceeds a predetermined threshold value, the video switching unit is closed and the video coded data is stored. Output from the video buffer 12 to the improved video decoder 22.

First, a part of the data of the first GOP in the coded video data shown in FIG. 8 is input to the improved video decoder 22. Here, the improved video decoder 22 starts decoding using the sequence header as a start code. for that reason,
Since the first input video encoded data does not have a sequence header, the video encoded data is skipped and is not decoded until the sequence header is input.
Then, when the second sequence header appearing next is input, the decoding of the video encoded data that follows is started. That is, in the improved video decoder 22,
When the data in the middle of the video coded data is input, the decoding is started from the head of the next GOP.

The audio coded data is normally read from the data whose time almost coincides with the second GOP data of the video coded data. At the same time that the improved video decoder 22 starts decoding, the audio decoder 18 also starts decoding. As a result, the same state as that read out from the second audio-encoded data and video-encoded data paired is obtained.

In this case, as shown in FIG. 6, a pair of encoded audio data and encoded video data is encoded by audio encoded data at a time of one frame or less of the encoded audio data, that is, a deviation of 24 msec or less. Is ahead of time. Therefore, if you start decoding these data at the same time, 24msec
The audio signal output is delayed due to the following synchronization deviation. Audio signal output delay of 24 msec
It is below the detection limit, and synchronization deviation is unknown. From the above, it is possible to obtain a reproduction signal whose synchronization is not known.

As described above, according to the third embodiment, when the encoded multiplexed data is read from the middle to obtain the decoded signal in which the video and the audio are synchronized, the paired audio It is not necessary to read accurately from the beginning of the encoded data and video encoded data, but if the approximate position of the beginning of the audio encoded data and video encoded data is known, read from an appropriate position slightly before that position. You can put it out.

In the third embodiment, the improved video decoder 22 has been described to start decoding with the sequence header as the start code, but the present invention is not limited to this, and the sequence header may be replaced with a GOP header or a picture header.

In the third embodiment, the apparatus for decoding the video coded data and the audio coded data recorded on the digital recording medium without causing the synchronization deviation has been described, but the recorded data is not limited to this. Not a thing. For example, audio signals from various musical instruments and vocal audio signals may be encoded individually and synchronized reproduction may be performed.

Further, although the third embodiment has explained the configuration for reading the coded multiplexed data from the digital storage medium, the present invention is not limited to this. For example, the encoded multiplexed data may be read from a communication medium such as a cable television.

Further, in the third embodiment, the configuration in which the video coded data and the audio coded data are separated from the coded multiplexed data by using the multiplexer outside the microcomputer has been described, but in the same microcomputer. You may divide by.

Example 4. Next, a case will be described in which the digital information encoding / decoding device shown in the third embodiment incorporates a function capable of synchronizing video and audio even if the encoded multiplexed data is read from an arbitrary position.

As the digital information decoding device, the same digital information decoding device as that of the third embodiment shown in FIG. 9 is used.

FIG. 10 is a block diagram showing the structure of the digital information coding apparatus according to the fourth embodiment. Comparing FIG. 10 with FIG. 1 of the first embodiment, it is the same as FIG. 1 except that the simplified multiplexer 7 is an improved multiplexer 21.

Here, the operation of the improved multiplexer 21 is performed by dividing the video coded data and the audio coded data shown in FIG. 6, the structure of the video coded data shown in FIG. 7, the pack header and the packet header shown in FIG. The configuration is the same as that of the simplified multiplexer 7 shown in FIG. 1 of the third embodiment. However, the structure of the data following the packet header is different from that of the simplified multiplexer 7. The structure of the data created by the improved multiplexer 21 will be described with reference to FIG.

Here, the first coded video coded data for one GOP starts with the sequence header shown in FIG. 7, is followed by the GOP header and the picture data for 15 pictures, and finally the sequence of the next GOP. Including headers. Then, the 1 that is output after the second
In video coded data for GOP, it starts with a GOP header, followed by 15 pieces of picture data, and finally the next G
It shall include up to the OP sequence header.

Now, the operation when data is read from an arbitrary position on the way of the digital storage medium 8 using the digital information encoding / decoding device shown above will be described.

In FIG. 11, consider the case where the data is read from point B, which is in the middle of the same video coded data as in the third embodiment. At this time, since the second sequence header is read out, it is possible to obtain a decoded signal in which the video and the audio are almost synchronized from the second GOP, as in the third embodiment.

Next, in FIG. 11, let us consider a case where the data is read from point C which is in the middle of the audio encoded data. At this time, since the pack header / packet header has not been read in the audio data read from the middle, the simplified demultiplexer 11 discards it as data that is neither video coded data nor audio coded data.

Next, the video coded data is read,
Video buffer 1 by simplified demultiplexer 11
2 and the audio coded data and the video coded data that follow are sequentially sent to the audio buffer 16 and the video buffer 12 by the simple demultiplexer 11.

The improved video decoder 22 first reads a series of data starting with the second GOP header shown in FIG. However, since there is no sequence header, the encoded video data is skipped until the sequence header appears, and decoding is not performed. Then, when the third sequence header that appears next is received, decoding of the video encoded data that follows is started. That is, the improved video decoder 22 starts decoding from the third GOP data.

The audio coded data is normally read from the data whose time matches the third GOP data of the video coded data. At the same time that the improved video decoder 22 starts decoding, the audio decoder 18 also starts decoding. As a result, the same state as that read out from the third audio coded data and the video coded data which are paired is obtained. In this case,
As shown in, the pair of encoded audio data and encoded video data is such that the encoded audio data precedes the encoded audio data temporally by a time of one frame or less of the encoded audio data, that is, a deviation of 24 msec or less. Has become. Therefore, if the decoding of these data is started at the same time, the audio signal output will be delayed by a synchronization shift of 24 msec or less. The delay of the audio signal output of 24 msec or less is less than the detection limit, and the synchronization deviation is unknown. From the above, it is possible to obtain a reproduction signal whose synchronization is not known.

As described above, according to the digital information coding / decoding device of the fourth embodiment, even if the digital storage medium 8 is read from any position on the digital storage medium 8 with a simple circuit configuration, there is almost no synchronization shift between video and audio. A decoded signal that does not exist can be obtained.

In the fourth embodiment, the improved video decoder 22 has been described to start decoding using the sequence header as the start code, but the present invention is not limited to this, and the sequence header may be replaced with a GOP header or a picture header.

In the fourth embodiment, the apparatus for decoding the video coded data and the audio coded data recorded on the digital recording medium without causing the synchronization deviation has been described, but the recorded data is not limited to this. Not a thing. For example, audio signals from various musical instruments and vocal audio signals may be encoded individually and synchronized reproduction may be performed.

In the fourth embodiment, the coded multiplexed data is read from the digital storage medium, but the present invention is not limited to this. For example, the encoded multiplexed data may be read from a communication medium such as a cable television.

Further, in the fourth embodiment, the configuration in which the video coded data and the audio coded data from the coded multiplexed data are separated by using the multiplexer outside the microcomputer has been described, but in the same microcomputer. You may divide by.

Example 5. Next, an example in which the demultiplexer is improved in the digital information encoding / decoding device shown in the fourth embodiment will be described. The digital information coding apparatus is the digital information coding apparatus of the fourth embodiment shown in FIG.

FIG. 12 is a block diagram showing the structure of the digital information decoding apparatus according to the fifth embodiment. Comparing FIG. 12 with FIG. 9 of the fourth embodiment, the simplified demultiplexer 11
9 is an improved demultiplexer 23 except that FIG.
Is the same as

The operation of the improved demultiplexer 23 will be described below. The coded multiplexed data as shown in FIG. 11 is input to the improved demultiplexer 23 as in the fourth embodiment. In the case of the multiplexing structure as shown in FIG. 11, when read from the head of the pack header of the data containing the encoded audio data, that is, point D, the audio encoded data that is read first is decoded. , The video encoded data that follows is not decoded because there is no sequence header, and as a result, the synchronization between the video signal and the audio signal in the decoded signal is 1G.
The phenomenon that it shifts by OP will occur.

Therefore, in the fifth embodiment, the operation of the improved demultiplexer 23 is set as shown in the flowchart of FIG. First, when video encoded data is input at the start of reading, a decoded signal in which a video signal and an audio signal are synchronized can be obtained by performing a normal operation. Next, when the audio encoded data is input at the start of reading, that is, when the encoded multiplexed data is read from the head or read from the point D, the input audio encoded data is output to the audio buffer 16. After that, the head of the input video coded data is confirmed, and if the sequence header is present, that is, if it is confirmed that the data is read from the head of the coded multiplexed data, normal processing is performed. If the sequence header does not exist, it is determined that the sequence header has been read, and the audio buffer 16 is instructed to discard all the data currently held. With the above processing, a synchronized decoded signal can be obtained regardless of the position of the encoded multiplexed data read.

Further, the process of instructing the audio buffer 16 to discard the data currently held should be replaced with a process in which the improved demultiplexer 23 does not output the audio encoded data to the audio buffer 16. You can also

As described above, according to the digital information encoding / decoding apparatus of the fifth embodiment, a reproduced signal having no synchronization deviation can be obtained with a simple circuit configuration even if the digital storage medium 8 is read from any position. To be

In the fifth embodiment, the improved video decoder 22 has been described to start decoding using the sequence header as the start code, but the present invention is not limited to this, and the sequence header may be replaced with a GOP header or a picture header.

In the fifth embodiment, the apparatus for decoding the video coded data and the audio coded data recorded on the digital recording medium without causing the synchronization deviation has been described. It is not limited. For example, audio signals from various musical instruments and vocal audio signals may be encoded individually and synchronized reproduction may be performed.

Further, although the fifth embodiment has explained the configuration for reading the coded multiplexed data from the digital storage medium, the present invention is not limited to this. For example, the encoded multiplexed data may be read from a communication medium such as a cable television.

In the fifth embodiment, the video coded data and the audio coded data from the coded multiplexed data are separated by using a multiplexer external to the microcomputer. However, the same microcomputer is used. You may divide in.

Further, in the fifth embodiment, the configuration in which the series of processes for discarding the audio encoded data is performed by the improved demultiplexer outside the microcomputer has been described, but it may be performed in the same microcomputer. .

[0117]

According to the first aspect of the present invention, the digital information encoding / decoding device having a simple structure can be configured with a small memory.

According to the second aspect of the present invention, in the digital information encoding / decoding device having a simple structure, when decoding is performed from the middle of the encoded multiplex signal, even if the synchronization shift between the video and the audio occurs, it is below the detection limit. Since it is a delay, the synchronization deviation is unknown.

According to the third aspect of the invention, in the digital information encoding / decoding device having a simple structure, when decoding is performed from the middle of the encoded multiplexed data, even if the reading start position is not accurately specified, the synchronization is performed. It is possible to obtain a decoded signal with almost no deviation.

According to the invention of claim 4, a digital information coding / decoding device having a simple structure can obtain a decoded signal with almost no synchronization deviation even if it is decoded from an arbitrary position in the middle of the coded multiplexed data. You can

According to the fifth aspect of the present invention, in the digital information encoding / decoding device having a simple structure, it is possible to obtain a decoded signal with almost no synchronization deviation even if it is decoded from an arbitrary position in the middle of the encoded multiplexed data. Obtainable.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a digital information encoding device according to first to third embodiments of the present invention.

FIG. 2 is a diagram for explaining a state of division of video encoded data and audio encoded data according to the first embodiment.

FIG. 3 is a diagram showing a structure of encoded multiplexed data according to the first embodiment.

FIG. 4 is a diagram showing configurations of a pack header and a packet header according to the first, second and fourth embodiments.

FIG. 5 is a block diagram showing a configuration of a digital information decoding device according to the first and second embodiments.

[Fig. 6] Fig. 6 is a diagram for explaining a state of division of video coded data and audio coded data according to Examples 2 to 4.

FIG. 7 is a diagram showing a structure of video encoded data according to Examples 2 to 4.

FIG. 8 is a diagram showing a structure of encoded multiplexed data according to Examples 2 to 4.

FIG. 9 is a block diagram showing a configuration of a digital information decoding device according to Examples 3 and 4.

FIG. 10 is a block diagram showing a configuration of a digital information encoding device according to Examples 4 and 5.

FIG. 11 is a diagram showing the structure of coded multiplexed data according to Examples 4 and 5.

FIG. 12 is a block diagram showing the configuration of a digital information encoding device according to a fifth embodiment.

FIG. 13 is a flowchart illustrating an initial operation of the demultiplexer according to the fifth exemplary embodiment.

FIG. 14 is a diagram showing the structure of encoded multiplexed data in a conventional example.

FIG. 15 is a block diagram showing a configuration of an encoding device in a conventional example.

FIG. 16 is a block diagram showing a configuration of a decoding device in a conventional example.

[Explanation of symbols]

1 video A / D converter, 2 video encoder, 3
Video buffer, 4 audio A / D converter, 5 audio encoder, 6 audio buffer, 7 simplified multiplexer, 8 digital storage media, 9
Buffer, 10 switcher, 11 simplified demultiplexer, 12 video buffer, 13 video switcher, 14 video decoder, 15 video D / A converter, 16 audio buffer, 17 audio switcher, 18 audio decoder, 19 audio D / A converter, 20 microcomputer, 21 improved multiplexer, 22 improved video decoder.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noritaka Kishida No. 1 Baba Institute, Nagaokakyo City Video Systems Development Laboratory, Mitsubishi Electric Corporation (72) Masafumi Kodama No. 1 Baba Institute, Nagaokakyo Mitsubishi Electric Corporation In-house Kyoto Works (72) Inventor Tomoaki Ryu No. 1 Nagaokakyo Baba-Zousho Mitsubishi Electric Co., Ltd. In-house Kyoto Works (72) Inventor Kiyotaka Yamamoto 2-5-1 Inadera, Amagasaki Mitsubishi Electric Mykon Equipment Software Co., Ltd. In the company

Claims (5)

[Claims] 1. In a video coded data string and an audio coded data string in which the heads of data are at the same time, the audio coded data string is arranged before the video coded data string to create coded multiplexed data. A digital information encoding / decoding device comprising a multiplexer, a video decoder and an audio decoder for simultaneously starting the decoding of respective head data of the video encoded data sequence and the audio encoded data sequence. 2. In a video coded data string and an audio coded data string in which the heads of data are at the same time, the audio coded data string is the same as the division of the video coded data string, or there is a synchronization deviation between video and audio. A multiplexer that creates encoded multiplex data by dividing each divided data string in vertical columns by an earlier time difference that is not detectable by humans, and each of the above-mentioned video encoded data string and audio encoded data string A digital information encoding / decoding device comprising a video decoder and an audio decoder for simultaneously starting decoding of head data. 3. In a video coded data string and an audio coded data string in which the heads of data are at the same time, the audio coded data string is the same as the division of the video coded data string, or there is a synchronization shift between video and audio. By dividing at a time that is too early for humans to detect, a multiplexer that creates encoded multiplexed data by arranging each divided data string in columns and by receiving the start code in the video coded data string A digital information encoding / decoding device comprising: a video decoder for starting decoding, and an audio decoder for starting decoding at the same time when the video decoder starts decoding. 4. In a video coded data string and an audio coded data string in which the heads of data are at the same time, the audio coded data string is the same as the division of the video coded data string or there is a synchronization shift between video and audio. Encoding is performed by dividing at an earlier time by a time difference that cannot be detected by humans, arranging each divided data string in columns, and arranging the start code in the video encoded data immediately before the audio encoded data at the same time. A multiplexer for generating multiplexed data, a video decoder for starting decoding by receiving a start code in the video coded data string, and an audio decoder for starting decoding at the same time when decoding of the video decoder is started. Digital information encoding / decoding device 5. In a video coded data string and an audio coded data string in which the heads of data are at the same time, the audio coded data string is the same as the division of the video coded data string, or there is a synchronization shift between video and audio. Encoded multiplexed data by dividing at an earlier time by a time difference that cannot be detected by humans, arranging each divided data string in columns, and arranging the start code in the video coded data immediately before the audio data at the same time. When the audio coded data string is input first and the start code does not exist at the beginning of the video coded data string immediately after that, the first input audio coded data string is discarded. Demultiplexer,
A digital information encoding / decoding device comprising a video decoder for starting decoding by receiving a start code in the video encoded data string, and an audio decoder for starting decoding simultaneously with the start of decoding by the video decoder. .