JPH02246431A - Video audio multiplex system - Google Patents

Abstract

PURPOSE:To improve the quality of video image by assigning the transmission ratio of video and audio data in response to the presence of audio data. CONSTITUTION:An audio data generating section 2 detects the presence of the audio data, a transmission controller 3 sends a coded clock to a video data generating section 1 and an audio data generating section 2 depending on the data and a multiplex section 4 uses a multiplex control clock from the transmission controller 3 so as to multiplex the video data and the audio data. Then a bit assignment signal BAS generated from the transmission controller 3 is changed corresponding to the presence of the audio data and the changed signal is multiplexed by a multiplex section 5 and the resulting signal is sent to a receiver side. The receiver side varies the decoded clock of the video output generating section 10 and the audio output generating section 11 to decode the video data and the audio data. Thus, only the video information is sent in the absence of the audio data to improve the video quality.

Description

[Detailed Description of the Invention] [Summary] Regarding a method of encoding and multiplexing audio information and video information for transmission, the video quality is improved by allocating the transmission ratio of video data and audio data depending on the presence or absence of audio. The purpose is to detect the presence or absence of audio, generate a corresponding encoding clock, multiplex video data and audio data, and transmit the presence or absence of audio to the receiving side as a bit allocation signal. Accordingly, the receiving side is configured to generate a decoding clock depending on the presence or absence of audio.

[Industrial application field]

The present invention relates to a video/audio multiplexing system, and particularly to a system for encoding, multiplexing, and transmitting audio information and video information.

In recent years, with the expansion of communication networks and the increase in the amount of information generated, there has been a demand for high-efficiency encoding systems with low bit rates in order to make more efficient use of transmission channels. A highly efficient encoding method is also required when it is necessary to transmit both information and video information.

[Conventional technology]

FIG. 6 shows the configuration of the transmitting side of the conventional video/audio multiplexing system, which is composed of a video data generator 1, an audio data generator 2a, a timing generator 3a, and selectors 4 to 6. This will be explained using the operation time chart shown in FIG.

In the video data generation section 1, an input video signal is converted into a digital signal by an A/D converter 21, and this digital signal is compressed and encoded by a video encoding section 22, and is encoded by a clock from the video encoding section 22. It is temporarily stored in the buffer 23.

In the audio data generating section 2a, the input audio signal is converted into a digital signal by the A/D converter 24, and this digital signal is compressed and encoded by the audio encoding section 25. Buffer 2 by clock
6 is temporarily stored.

The data in the buffers 23 and 26 is first read out from the buffer 26 and input to the selector 4 during a period corresponding to the first 2 bits of one frame (8 bits) by the continuous audio clock A from the timing generator 3a. Thereafter, the video data is read out from the buffer 23 and input to the selector 4 during the next 5-bit period of the audio data by the video successive clock B.

The selector 4 selectively outputs audio data and video data using a clock D corresponding to the clocks A and B from the timing generator 3a. Therefore, this selector 4
This means that audio data and video data are multiplexed.

The remaining 1 bit of the above 8 bits is assigned as control data (hereinafter, BAS = old tAIlocat).
In order to allocate a signal (abbreviated as 1on Signal), the output data from the selector 4 is multiplexed by the selector 5 using the clock signal from the timing generator 3a and sent to the selector 6.

As shown in FIG. 8 (1) and (2), the RAS signal is control data that indicates which bits are assigned to audio data and video data, respectively, and is used for frame synchronization (hereinafter referred to as "frame synchronization") for obtaining frame synchronization. FA S*Frame
(abbreviated as Al1gn+went Signal)
This is data that is inserted into the 8th bit time slot along with the signal, and becomes 1'' only when the BAS signal, FAS signal, and AC signal are assigned, respectively.These control data are is Figure 8 (1)
e AC (Application
The Channel) signal can be used for any data.

Therefore, for the FAS signal, the selector 6 multiplexes the output signal of the selector 5 using the clock F from the timing generator 3a.

That is, when the BAS signal is assigned, the clock E
Multiplexing is performed at the timing of clock F, and when the FAS signal is assigned, multiplexing is performed at the timing of clock F.

FIG. 9 shows the configuration of the receiving side of a conventional video/audio multiplexing system, which includes a frame synchronization section 7, a BAs separation section 8, a timing generation section 9a, a video output generation section 10, and an audio output This will be explained with reference to the operation time chart shown in FIG. 10.

First, the frame synchronizer 7 detects the FAS signal of the multiplexed data from the transmission path, and a synchronization detection signal is sent to the timing generator 9a.

In the BAS separation section 8, the BAS signal in the time slot of the clock D generated by detecting frame synchronization is latched and separated, and sent to the timing generation section 9a.

Further, data from the transmission path is stored in buffers 33 and 36, respectively, at the timing of clocks A and B generated within the timing generator 9a based on the BAS signal.

The data in these buffers 33 and 36 is read out and decoded by the read clocks from the video decoding section 32 and the audio decoding section 35, respectively, and then sent to the D/A converter 31.
34 as analog video output and audio output, respectively.

In this way, the ratio of the information density between the audio signal and the video signal is 2:5.

[Problem to be solved by the invention]

When encoding the above video signal, high efficiency encoding is performed to reduce the transmission cost for videophones, etc.
Since the data is compressed to about /1000, the transmission bit rate is always low relative to the amount of generated information. The smaller amount results in a decrease in image quality and a decrease in the number of sheets to be transmitted.

On the other hand, there are "pauses" in real human conversation.
There is a silent state, and although there is a time slot for voice transmission, there is a time when nothing is actually transmitted.

Therefore, there is a problem in that the image and audio multiplexing method used in current videophone calls is not optimal depending on the amount of information generated.

Therefore, an object of the present invention is to improve video quality by allocating the transmission ratio of video data and audio data depending on the presence or absence of audio.

[Means to solve the problem]

In order to achieve the above object, in the video/audio multiplexing system according to the present invention, as shown in principle in FIG.
An audio data generation unit 2 that encodes an audio signal and detects the presence or absence of audio, a video encoding clock, an audio encoding clock, a video/audio multiplexing control clock, and a bit allocation signal corresponding to the presence or absence of audio. , a transmission controller 3 that generates a bit allocation signal multiplexing control clock, a frame synchronization signal, and a frame synchronization signal multiplexing control clock;
A multiplexing section 4 that outputs a multiplexed signal of the video data and the audio data or only the video data according to the video/audio multiplexing control clock, and output data of the multiplexing section according to the bit allocation signal multiplexing control clock. and the bit allocation signal, and further multiplexes the frame synchronization signal with the output signal of the bit allocation signal multiplexer using the frame synchronization signal multiplexing control clock and transmitting the frame synchronization signal to the transmission line. A frame synchronization signal multiplexing unit 6 is provided.

Furthermore, on the receiving side, there is a frame synchronization detection section 7 that detects the frame synchronization signal from the multiplexed signal from the transmission path, and a bit allocation signal separation section 8 that separates the bit allocation signal.
, a reception controller 9 that generates a separated clock to the bit allocation signal separation unit 8 based on the frame synchronization detection signal and a video decoding clock and an audio decoding clock based on the frame synchronization detection signal and the bit allocation signal; It includes a video decoding section 10 that decodes video data from the transmission path using a decoding clock, and an audio decoding section 11 that decodes audio data from the transmission path using the audio decoding clock. .

[For production]

On the transmitting side of the video/audio multiplexing system of the present invention shown in FIG. , a corresponding encoding clock is sent to the video data generation section 1 and the audio data generation section 2, respectively, and the multiplexing section 4 sends these video data and audio data to the multiplexing section 4 under multiplexing control from the transmission controller 3. Multiplexed by clock.

Therefore, when there is no audio, the encoding clock can be stopped, for example, and only the video data can be output from the multiplexing section 4 using the multiplexing clock accordingly.

Then, in response to the presence or absence of this audio, the transmission controller 3
The bit allocation signal BAS generated from the signal changes and can be multiplexed by the multiplexer 5 and transmitted to the receiving side.

On the receiving side, the reception controller 9, which has been informed that frame synchronization has been detected by the frame synchronization detection section 7, sends a separated clock of the bit allocation signal BAS to the separation section 8 to separate it, and separates it in response to this bit allocation signal BAS. By making the decoding clocks of the video output generating section 10 and the audio output generating section 11 variable, it is possible to decode the video data and audio data of the multiplexed data from the transmitting side.

In this case, when the bit allocation signal BAS indicates that there is no audio, the audio decoding process is stopped, and only the video signal is output.

In this way, only video data can be multiplexed and transmitted when there is no audio, and the image quality of the video signal can be improved.

〔Example〕

FIG. 2 shows an embodiment of the transmitting side of the video/audio multiplexing system of the present invention shown in FIG. D converter 2
The digital output of No. 4 and the darkness value are compared for a certain period of time, and a sound presence/absence detection signal is generated as a result of the comparison. Further, the transmission controller 3 is composed of a timing generation section 30 and selectors 31 and 32, and the timing generation section 30 generates clocks A to F shown in FIG. 3, of which clocks A to D are The clock E is sent to the selector 31.
, F are each sent to a selector 5.6 as a multiplexing section. Based on the audio presence/absence detection signal from the comparator 27, the selector 31 selects the clock A and the "0" signal from among these clocks A to D, selects the clocks B and C, and selects the clock D and the "0" signal. The signal is configured to select the signal. In addition, the selector 32 selects the BAS■ signal and the BAS■ signal.
The signal is also selected based on the audio presence/absence detection signal from the comparator 27. In addition, the BAS■ signal is a BAS signal (for example, "rollolloo") during voice transmission.
), and the BAS■ signal is the BAS signal (
For example, "rololoool").

The other configurations are the same as the conventional example shown in FIG.

Next, the operation of this embodiment on the transmitting side will be explained with reference to the time chart of FIG.

First, the comparator 27 determines that audio is "present" only when the data after A/D conversion of the audio input exceeds a threshold value and that value continues for a certain period of time. At this time, the selector 31 selects clocks A, B, and D, respectively, and buffer 26.
23 and the selector 4, and the selector 32 selects the BAS■ signal during audio transmission and sends it to the selector 5, thereby performing the same operation as in the conventional example.

On the other hand, when the comparator 27 determines that there is no audio, the selector 31 selects II OII instead of clock A.
Clock C is selected instead of clock B, and "θ" is selected instead of clock D.

As a result, the buffer 26 is not provided with successive clocks, so no audio data is output. Instead, the clock C is provided to the buffer 23, and as shown in FIG.
The video data will be read from. At this time, since the control clock to the selector 4 also becomes a "0" signal, only the video data output from the buffer 23 is directly passed through the selector 4 and sent to the selector 5.

Also, in the selector 32, the BAS■
The signal is selected and sent to the selector 5, and the selector 5 multiplexes this BAS■ signal into the 8th bit based on the clock pulse and sends it to the selector 6.

The relationship between selectors 5 and 6 is as described in the conventional example, and B
Either the AS signal or the FAS signal will be multiplexed and sent to the transmission path.

FIG. 4 shows an embodiment of the receiving side of the video/audio multiplexing system of the present invention shown in FIG. It is configured.

The timing generation section 90 uses the frame synchronization detection section 7 to perform FAS.
The signal is detected for one multiframe (therefore, data until one multiframe is received becomes an error), and in response to this synchronization detection signal, a clock D for separating the BAS signal shown in FIG. 5 is generated. In addition, after detecting the BAS signal separated by the separating unit 8 and detecting the presence or absence of audio, the corresponding clocks A to C are generated and the selector 9
I am sending it to 1. The selector 91 is the timing generator 90
Clock A and “0” upon receiving the audio presence/absence detection signal from
The clock B and clock C are switched and provided to buffers 36 and 33, respectively. Also, the audio decoding unit 3 of the audio output generating unit 11
5 is also given a voice presence/absence detection signal. The rest of the configuration is the same as the conventional example shown in FIG.

Next, the operation of this embodiment on the receiving side will be explained with reference to the time chart of FIG.

First, the frame synchronizer 7 detects the FAS signal from the multiplexed data from the transmission path, and the timing generator 90 detects the FAS signal.
When informed of this, the timing generator 90 generates a clock D for BAS signal separation, and the RAS separation unit 8
As a result, the BAS signal is separated from the received data and is provided to the timing generator 90.

The timing generating section 90 generates B based on this RAS signal.
Clock A, B, and B for audio transmission of AS■ signal
The selector 91 selects clocks A and B when the AS■ signal is not transmitting audio, and the selector 91 selects clocks A and B when the BAS■ signal is present, that is, when there is audio.
33 respectively, and the decoding units 32 and 35 perform the same decoding operation as in the conventional example, but when the BAS■ signal is present, that is, when there is no audio, 0'' is selected instead of the clock A.
By switching to select clock C instead of clock B, the write operation of the buffer 36 is stopped, and data, that is, video data, is written only to the buffer 33 and decoded to output a video signal.

When the audio decoding unit 35 receives a signal without audio from the timing generating unit 90, it can avoid decoding old data by stopping the successive clocks to the buffer 36. ] As described above, according to the present invention, the presence or absence of audio is detected, a corresponding encoding clock is generated, video data and audio data are multiplexed, and the presence or absence of audio is detected using a bit allocation signal. By transmitting this information to the receiving side, the receiving side can generate a decoding clock according to whether there is audio or not, so only video information can be transmitted when there is no audio, thereby improving the video quality. At the same time, it becomes possible to efficiently utilize the transmission path.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the principle configuration of the video/audio multiplexing system according to the present invention, Fig. 2 is a block diagram showing an embodiment of the transmitting side of the inventive system, and Fig. 3 is an embodiment of the transmitting side of the present invention. 4 is a block diagram showing an embodiment of the receiving side of the present invention, FIG. 5 is a time chart of the receiving side embodiment of the present invention, and FIG. 6 is a block diagram of the transmitting side of the conventional example. A block diagram showing one embodiment. Fig. 7 is a time chart diagram of the transmitting side embodiment of the conventional example. Fig. 8 is a format diagram of a video/audio multiplexed transmission frame. Fig. 9 is a diagram of the receiving side of the conventional example. A block diagram showing one embodiment, FIG. 10 is a time chart diagram of a conventional receiving side embodiment,
It is. In FIG. 1, 1... Video data generation section, 2... Audio data generation section, 3... Transmission controller, 4-6... Multiplexing section, 7... Frame synchronization detection section, 8 . . . Bit allocation signal (BAS) separation unit, 9 . . . Reception controller, 10 . . . Video output generation unit, 11 . In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A video data generator (1) that encodes a video signal, an audio data generator (2) that encodes an audio signal and detects the presence or absence of audio, and a video coder that corresponds to the presence or absence of audio. a transmission controller (3) that generates a coding clock, an audio encoding clock, a video/audio multiplexing control clock, a bit allocation signal, a bit allocation signal multiplexing control clock, a frame synchronization signal, and a frame synchronization signal multiplexing control clock; a multiplexing section (4) that outputs a multiplexed signal of the video data and the audio data or only the video data according to the video/audio multiplexing control clock; a bit allocation signal multiplexing section (5) that multiplexes output data and the bit allocation signal, and further multiplexing the frame synchronization signal on the output signal of the bit allocation signal multiplexing section using the frame synchronization signal multiplexing control clock. A video/audio multiplexing method comprising: a frame synchronized signal multiplexing unit (6) that converts the signal into a frame synchronized signal and sends the converted signal to a transmission path. (2) A frame synchronization detection unit (7) that detects the frame synchronization signal from the multiplexed signal from the transmission path, and a bit allocation signal separation unit (8) that separates the bit allocation signal.
), a reception controller (9) that generates a separated clock to the bit allocation signal separation unit (8) based on the frame synchronization detection signal, and a video decoding clock and an audio decoding clock based on the frame synchronization detection signal and the bit allocation signal. ), a video decoding section (10) that decodes the video data from the transmission path using the video decoding clock, and an audio decoding section that decodes the audio data from the transmission path using the audio decoding clock. 2. The video/audio multiplexing system according to claim 1, further comprising: (11).