JPH0865646A - Moving picture image and sound transmission equipment - Google Patents

Abstract

PURPOSE: To shorten the delay time from input to output by transmitting image encoded data over an image transmission channel and a sound transmission channel in parallel when the code quantity of the image encoded data exceeds a specific value. CONSTITUTION: Sound information and image information which are converted into digital signals are compressed and stored temporarily in a sound code memory 103 and an image code memory 108. When the image changes in scene, an image encoding part 107 generates a scene change detection signal 111 and informs a control part 110 of it. According to this information, the control part 110 switches 1st and 2nd selectors 104 and 109 and the input of a sound transmitting buffer 105 and the input of an image transmitting buffer 113 are both connected to the output of the image code memory 108 by the switching. Therefore, the data in the image code memory 108 are sent to a reception side by an image data transmission part 132 and a sound data transmission part 131.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving image / sound transmission device, and more particularly to a device for simultaneously transmitting a moving image and a sound on different transmission paths such as a videophone and a video conference device.

[0002]

2. Description of the Related Art Recently, devices such as videophones and videoconference devices that simultaneously transmit moving images and audio have been widely used. In this case, the following two types of information transmission methods can be considered. (1) A method of physically preparing two transmission paths and allocating an audio signal and a moving image signal to each. (2) A system in which one transmission path is physically used and a voice signal and a moving image signal are multiplexed and transmitted.

As an example of the above (1), there is a videophone device that uses two B channels of the basic interface of ISDN, one for transmitting moving image data and the other for transmitting audio data. When the capacity of one usable transmission medium is not large as in this example, it is considered useful to transmit the moving image signal and the audio signal by different transmission media.

The operation of the conventional transmission system for transmitting the moving image signal and the audio signal through different transmission media will be described below with reference to FIGS. FIG. 7 is a block diagram showing a configuration of a transmission side in a conventional moving image / audio transmission system. FIG. 8 is a block diagram showing the configuration of the receiving side in the conventional moving image / audio transmission system. FIG. 9 is a diagram showing a transmission method of the moving picture audio transmission system shown in FIGS. 7 and 8.

In FIG. 7, the voice information converted into a digital signal by the voice input unit 501 is the voice encoding unit 5.
02 is compressed by the adaptive PCM coding method (ADPCM) or the like, delayed by the voice transmission buffer 503 for a predetermined time, and then transmitted to the reception side by the voice data transmission unit 521. On the other hand, the image converted into a digital signal by the image input unit 504 is compressed by the image encoding unit 505. At this time, an interframe predictive coding method is generally applied as a high-efficiency coding method used for a videophone device or the like. In the inter-frame predictive coding method, when the scene of an image changes significantly (this is called a scene change), only that image is encoded (this is called intra-frame encoding), and subsequent images are The difference from the previous frame is encoded (this is called interframe encoding). Therefore, the code amount of the image at the scene change is larger than the code amounts of the other images. The encoded data obtained by the image encoding unit 505 is written in the image transmission buffer 506 and transmitted by the image data transmitting unit 522 to the receiving side. The image transmission buffer 506
Is provided for smoothing the code amount different for each image frame and sending it to the image data transmitting unit 522 at a constant transmission rate. In addition, a signal 507 indicating the retention amount of encoded data in the image transmission buffer 506 is sent to the image encoding unit 50.
By feeding back to 5, the image coding unit 50
5 controls the generated code amount.

In FIG. 8, the voice coded data received by the voice data receiving unit 523 is the voice decoding unit 50.
8 and audio output unit 509 outputs the audio. The image coded data received by the image data receiving unit 524 is the image decoding unit 510 and the image display unit 51.
1, the image is displayed.

FIG. 9 shows a state of transmission when a scene change occurs between the image V1 and the image V6. However, it is assumed that no delay occurs in the image and audio encoding and decoding processes. V1
As an example, the code amount of 2 is 2 for normal time (V4, V5, etc.).
Therefore, it takes twice as long as the image frame interval from the input of V1 to the output of the image on the receiving side. Since the time interval of the input image and the time interval of the output image must be equal, the inter-coded image frame is also displayed after the time when the image is input, which is twice the image frame interval. There must be. Further, since the audio also has to be synchronized with the image, it is delayed by the audio transmission buffer 503 for a fixed time (in this case, twice the image frame interval). That is, the output time from the input of the image and sound on the transmission side to the output on the reception side is determined by the transmission time of the code of the image at the scene change.

Next, in the transmission system having the configuration shown in FIGS. 7 and 8, the operation when a transmission error occurs in the image transmission channel will be described with reference to FIG. FIG. 10 shows the operation when there is no scene change in all the images and an error occurs during the transmission of the images V1 and V6. Since the encoded data of the image V1 and the image V6 is not transmitted, on the receiving side, the image V1 and the image V6 are transmitted.
Piece skipping will occur at the time when should be displayed.

[0009]

In the case of the above-mentioned conventional example, a transmission delay time which is twice the image frame interval is required from the input of the image and the audio on the transmitting side to the output of the image and the audio on the receiving side. are doing. As mentioned above, this transmission delay time depends on the transmission time of the code of the image at the scene change, but in the case of a moving picture audio transmission system used for dialogue such as a videophone, this transmission delay time If it is large, it will hinder the dialogue.

Further, as described above, when a transmission error occurs in the image data channel, frame skipping occurs on the receiving side, which deteriorates the received image.

Therefore, an object of the present invention is to provide a moving image / audio transmission apparatus in which the delay time from the input of the image and the audio on the transmitting side to the output of the image and the audio on the receiving side is small. Another object of the present invention is to provide a moving image / audio transmission apparatus capable of preventing frame skipping on the receiving side even if a transmission error or the like occurs.

[0012]

The invention according to claim 1 is
A moving image / sound transmission apparatus for transmitting moving image information and sound information using two transmission channels, namely, an image transmission channel and an audio transmission channel, wherein an input moving image signal is encoded to obtain a digital image encoding. Video signal encoding means for outputting data, audio signal encoding means for encoding the input audio signal to output digital audio encoded data, and image code output from the moving image signal encoding means Image data transmitting means for transmitting the encoded data using the image transmission channel, voice data transmitting means for transmitting the voice encoded data output from the voice signal encoding means using the voice transmission channel, and a moving image signal. When the code amount of the coded image data output from the coding means exceeds a predetermined value, the coded image data is converted into a video transmission channel and a voice transmission channel. And a switching means for switching the connection relationship between the moving image signal encoding means and the audio signal encoding means and the image data transmitting means and the audio data transmitting means so as to transmit using the two transmission channels. There is.

According to a second aspect of the present invention, in the first aspect of the invention, the switching means temporally corresponds to the image coded data transmitted next to the image coded data whose code amount exceeds a predetermined value. It is characterized in that the connection relationship between the moving image signal encoding means and the audio signal encoding means and the image data transmitting means and the audio data transmitting means is switched so that the encoded data is transmitted through the image transmission channel.

According to a third aspect of the present invention, in the first aspect of the invention, the audio signal encoding means inputs when the code amount of the image encoded data output from the moving image signal encoding means exceeds a predetermined value. It is characterized in that the compression rate by encoding the audio signal is increased.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the moving image signal coding means encodes the moving image signal using the interframe predictive coding method, and the switching means is the scene change. In order to transmit the coded image data output from the moving picture signal coding means in two using the two transmission channels of the image transmission channel and the sound transmission channel, the moving picture signal coding means, the sound signal coding means and the image are transmitted. It is characterized in that the connection relation between the data transmitting means and the voice data transmitting means is switched.

According to a fifth aspect of the present invention, there is provided a moving image / sound transmitting apparatus for transmitting moving image information and sound information by using two transmission channels, that is, an image transmission channel and a sound transmission channel. A moving picture signal coding means for coding a signal and outputting digital picture coded data, a sound signal coding means for coding an inputted sound signal and outputting digital sound coded data, and a moving picture. Image data transmitting means for transmitting the image encoded data output from the image signal encoding means using the image transmission channel, and audio encoded data output from the audio signal encoding means using the audio transmission channel. If the audio data transmitting means for transmitting and the encoded image data output from the moving image signal encoding means cannot be transmitted through the image transmission channel, the image code is transmitted. A switching means for switching the connection relationship between the moving image signal encoding means and the audio signal encoding means and the image data transmitting means and the audio data transmitting means is provided so that the data is transmitted using the image transmission channel. .

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the switching means temporally corresponds to the image coded data transmitted next to the image coded data transmitted by the voice transmission channel. It is characterized in that the connection relationship between the moving image signal encoding means and the audio signal encoding means and the image data transmitting means and the audio data transmitting means is switched so that the encoded data is transmitted through the image transmission channel.

According to a seventh aspect of the present invention, in the fifth aspect of the invention, when the audio signal encoding means cannot transmit the image encoded data output from the moving image signal encoding means through the image transmission channel, It is characterized in that the compression rate of an input audio signal is increased.

[0019]

As described above, the delay time from the input of the image and the sound on the transmission side to the output on the reception side is determined by the transmission time of the image coded data having a large code amount such as at the scene change. Therefore, if the transmission time can be shortened, the delay time can be shortened.

Further, if it is possible to transmit the image coded data that cannot be transmitted due to an error of the image transmission channel by another method, it is possible to prevent frame skipping on the receiving side.

Therefore, in the invention according to claim 1,
When the code amount of the coded image data output from the moving image signal coding means exceeds a predetermined value, the coded image data is transmitted in parallel using two transmission channels, that is, an image transmission channel and an audio transmission channel. Thus, the transmission time is shortened, and the delay time from the input of the image and the sound on the transmission side to the output on the reception side is reduced.

According to the second aspect of the present invention, the audio coded data temporally corresponding to the image coded data to be transmitted next to the image coded data having a code amount exceeding a predetermined value is transmitted via the image transmission channel. As a result, there is no delay in voice transmission.

According to the third aspect of the present invention, when the code amount of the coded image data output from the moving image signal coding means exceeds a predetermined value, the compression rate by coding the voice signal is increased, and The transmission time is shortened so that the voice transmission is not delayed.

In the invention according to claim 4, when the moving image signal is encoded by using the inter-frame predictive encoding method, the code amount of the image encoded data at the time of the scene change increases, so that the scene change Image coded data at the time of occurrence is transmitted using two transmission channels, an image transmission channel and an audio transmission channel.

According to the fifth aspect of the present invention, when the image coded data cannot be transmitted through the image transmission channel due to a transmission error or the like, the image encoded data is transmitted through the image transmission channel so that the receiving side So I try not to skip pieces.

In the sixth aspect of the invention, the audio coded data temporally corresponding to the image coded data transmitted next to the image coded data transmitted by the audio transmission channel is transmitted by the image transmission channel. As a result, there is no delay in voice transmission.

In the invention according to claim 7, when the image coded data output from the moving image signal coding means cannot be transmitted through the image transmission channel, the compression rate by encoding the audio signal is increased, The audio transmission time is shortened so that the audio transmission is not delayed.

[0028]

【Example】

(First Embodiment) FIG. 1 is a block diagram showing the configuration of the transmitting side of a moving picture / audio transmission system according to the first embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the receiving side of the first embodiment. The configuration and operation of the first embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, the voice information converted into a digital signal by the voice input unit 101 is the voice encoding unit 1.
02 is compressed by the adaptive PCM coding system (ADPCM) or the like, and is temporarily stored in the voice code memory 103.
Similarly, the image information converted into a digital signal by the image input unit 106 is compressed by the image encoding unit 107 and temporarily stored in the image code memory 108.

In a normal state in which no scene change has occurred, the control unit 110 causes the first and second selectors 104 and 109 to make the input of the audio transmission buffer 105 the output of the audio code memory 103 and the image transmission buffer 1
13 inputs are respectively connected to outputs of the image code memory 108. The data in the voice code memory 103 is transmitted to the receiving side by the voice data transmitting unit 131 via the voice transmitting buffer 105. Similarly, the data in the image code memory 108 is transmitted to the receiving side by the image data transmitting unit 132 via the image transmitting buffer 113.

When a scene change occurs in the image,
The image encoding unit 107 generates a scene change detection signal 111 and notifies the control unit 110 of it. Accordingly, the control unit 11
0 switches the first and second selectors 104 and 109, thereby connecting both the input of the audio transmission buffer 105 and the input of the image transmission buffer 113 to the output of the image code memory 108. Therefore, the image code memory 10
The data in 8 is transmitted to the receiving side by the image data transmitting unit 132 and the audio data transmitting unit 131.

FIG. 3 is a diagram showing a state of transmission when a scene change occurs in the image V1 and the image V6 in the first embodiment. However, it is assumed that no delay occurs in the image and audio encoding and decoding processes. Hereinafter, the transmission operation will be described more specifically, focusing on the scene change of V1.

The code amount of V1 is normally (V4, V5, etc.)
The transmission time is halved by transmitting this simultaneously on the audio transmission channel and the image transmission channel, and the output time from the input of the image and the audio on the transmitting side to the receiving side of the image and the audio is 1 time of the image. It is the same time as the frame interval. The image coded data may be distributed to the two transmission channels alternately in small block units, or may be distributed to the first half and the second half of the image.

Next, the first and second selectors 104 and 109 reconnect the input of the audio transmission buffer 105 to the output of the audio code memory 103 and the input of the image transmission buffer 113 to the output of the image code memory 108, respectively. . As a result, the audio encoded data A1 is transmitted by the audio data transmitting unit 131, and the image encoded data V2 is transmitted by the image data transmitting unit 132.

By the way, since half of the image coded data V1 is transmitted through the voice transmission channel, the voice coded data A
If 2 is transmitted via the voice transmission channel, it will not be possible to respond again to the subsequent scene change. Therefore, the voice coded data A2 is transmitted through the image transmission channel. That is,
The second selector 109 connects the input of the image transmission buffer 113 to the output of the voice code memory 103,
The transmission code amount on both channels is smoothed so that it can be used for subsequent scene changes.

As described above, as shown in FIG.
By transmitting audio coded data and image coded data using two transmission channels, it is possible to reduce the delay time from the input of the image and the audio on the transmitting side to the output of the image and the audio on the receiving side. You can

On the other hand, on the receiving side, the voice data receiving section 13
3 and the data type of the two transmission channels received by the image data receiving unit 134 (whether it is audio or video) is detected by the audio receiving buffer 114 and the video receiving buffer 119, and based on the detection result, the control unit 121 By appropriately switching the third and fourth selectors 115 and 120, the voice coded data is stored in the voice code memory 116 and the image coded data is stored in the image code memory 122. Then, the voice is the voice decoding unit 117.
Is output by the audio output unit 118, and the image is output by the image decoding unit 123 and the image display unit 124.

In the first embodiment, the moving image V1
In order to be able to cope with the next scene change (moving image V6) after a scene change occurs, the audio encoded data A2 is transmitted to the receiving side using the image transmission channel. By increasing the compression rate of part or all of A2 to A5 to shorten the transmission time, it may be possible to deal with the next scene change. In this case, the voice coded data A2 is transmitted to the receiving side using the voice transmission channel like the other voice coded data A1 and A3 to A5.

In the first embodiment, when the scene change occurs, the coded image data is transmitted using the two transmission channels of the image and the sound. However, the present invention is not limited to this. When the code amount of a moving image to be transmitted exceeds a predetermined value for some reason, the encoded image data may be transmitted using two transmission channels of image and sound.

(Second Embodiment) FIG. 4 is a block diagram showing the structure of the transmission side of a moving picture / audio transmission system according to the second embodiment of the present invention. FIG. 5 is a block diagram showing the configuration of the receiving side of the second embodiment.

Referring to FIGS. 4 and 5, the second embodiment is different from the above-described first embodiment (FIGS. 1 and 2) in structure, instead of control unit 110 of FIG. The only difference is that the controller 1100 of FIG. 4 is provided. That is, the control unit 110 of FIG. 1 performs the switching operation of the first and second selectors 104 and 109 based on the scene change detection signal 111, whereas the control unit 1100 of the present embodiment is operated by the image data transmission unit 132. The switching operation of the first and second selectors 104 and 109 is performed based on the transmission error detection signal 311. Other configurations in the second embodiment are similar to those in the first embodiment described above, and corresponding parts are designated by the same reference numerals and the description thereof will be omitted.

FIG. 6 is a diagram showing how the image V1 and the image V6 are transmitted when an error occurs during the transmission in the second embodiment. The transmission operation when an error occurs will be described below with reference to FIG. Now, it is assumed that an error occurs in the transmission of the image coded data V1 while transmitting the voice coded data A1 through the voice transmission channel and the image coded data V1 through the image transmission channel. At this time, the image data transmission unit 132 detects a transmission error of the encoded image data and outputs a transmission error detection signal 311 to the control unit 1100. Accordingly, the control unit 1100 determines that the first
The selector 104 is switched, and the input of the audio transmission buffer 105 is connected to the output of the image code memory 108. As a result, the audio data transmitting unit 131 stops the transmission of the encoded audio data A1 on the way and instead transmits the encoded image data V1 to the receiving side using the audio transmission channel. Subsequent operations are the operations after the scene change in the above-described first embodiment (in FIG. 3, the voice coded data A
2 to A5 and the operation when transmitting the encoded image data V2 to V5). The same operation as above is performed when an error occurs in the transmission of the image V6.

[0043]

According to the first aspect of the present invention, when the code amount of the coded image data output from the moving image signal coding means exceeds a predetermined value, the coded image data is transmitted through the image transmission channel and the voice transmission. Since the transmission is performed in parallel using the two transmission channels, the transmission time of the image coded data is shortened, and as a result, from the input of the image and audio at the transmitting side to the output at the receiving side. The delay time can be reduced.

According to the second aspect of the present invention, the audio coded data temporally corresponding to the image coded data to be transmitted next to the image coded data whose code amount exceeds the predetermined value is transmitted via the image transmission channel. Therefore, even if the image coded data having the code amount exceeding the predetermined value is simultaneously transmitted through the two transmission channels, it is possible to prevent the delay in the voice transmission.

According to the invention of claim 3, when the code amount of the coded image data output from the moving image signal coding means exceeds a predetermined value, the compression rate by coding the audio signal is increased. Therefore, even if image coded data whose code amount exceeds a predetermined value is simultaneously transmitted through two transmission channels,
Since the voice transmission time is shortened, it is possible to prevent delay in voice transmission as a result.

According to the fourth aspect of the present invention, when the moving picture signal is coded by using the inter-frame predictive coding method, the code amount of the coded image data at the time of the scene change increases, so that the scene change By transmitting the image coded data at the time of occurrence using two transmission channels, that is, an image transmission channel and an audio transmission channel, the delay time from the input of the image and the audio at the transmitting side to the output at the receiving side is reduced. I am trying.

According to the fifth aspect of the invention, when the image coded data cannot be transmitted through the image transmission channel due to a transmission error or the like, the image coded data is transmitted through the image transmission channel. It is possible to prevent frame skipping on the receiving side.

According to the invention of claim 6, the audio coded data temporally corresponding to the image coded data to be transmitted next to the image coded data transmitted via the audio transmission channel are transmitted via the image transmission channel. Therefore, even if the image coded data is transmitted through the audio transmission channel, it is possible to prevent a delay in the subsequent audio transmission.

According to the invention of claim 7, when the coded image data is transmitted through the voice transmission channel, the compression rate by coding the voice signal is increased, so that the coded image data is transmitted through the voice transmission channel. Even if it is transmitted, it is possible to prevent a delay in voice transmission.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a transmitting side of a moving image / audio transmission system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a receiving side of the moving picture audio transmission system according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a state of transmission when a scene change occurs in image V1 and image V6 in the first embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a transmitting side of a moving image / audio transmission system according to a second example of the present invention.

FIG. 5 is a block diagram showing a configuration of a receiving side of a moving image / audio transmission system according to a second example of the present invention.

FIG. 6 is a diagram showing a state of transmission when an error occurs during transmission of the images V1 and V6 in the second embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a transmission side of a conventional moving image / audio transmission system.

FIG. 8 is a block diagram showing a configuration of a receiving side of a conventional moving image audio transmission system.

FIG. 9 is a diagram showing a state of transmission when a scene change occurs in an image V1 and an image V6 in a conventional moving image audio transmission system.

FIG. 10 is a diagram illustrating a case where an error occurs during transmission of the images V1 and V6 in the conventional moving image audio transmission system,
It is the figure which showed the mode of transmission.

[Explanation of symbols]

 101 ... Voice input unit 102 ... Voice coding unit 103, 116 ... Voice code memory 104, 109, 115, 120 ... First to fourth selector 105 ... Voice transmission buffer 106 ... Image input unit 107 ... Image coding unit 108, 122 ... Image code memory 110, 121, 1100 ... Control part 111 ... Scene change detection signal 113 ... Image transmission buffer 114 ... Audio reception buffer 116 ... Audio code memory 117 ... Audio decoding part 118 ... Image decoding part 119 ... Image reception Buffer 123 ... Audio output unit 124 ... Image display unit 131 ... Audio data transmitting unit 132 ... Image data transmitting unit 133 ... Audio data receiving unit 134 ... Image data receiving unit 311 ... Transmission error detection signal

Claims (7)

[Claims] 1. A video / audio transmission apparatus for transmitting video information and audio information using two transmission channels, an image transmission channel and an audio transmission channel, by encoding an input video signal, Moving picture signal coding means for outputting digital picture coded data, sound signal coding means for coding inputted sound signal and outputting digital sound coded data, said moving picture signal coding means Image data transmitting means for transmitting the image coded data output from the audio transmission channel using the image transmission channel, and audio coded data output from the audio signal encoding means using the audio transmission channel When the code amount of the image coded data output from the audio data transmission means and the moving image signal coding means exceeds a predetermined value, the image coded data So as to be transmitted using the two transmission channels of the image transmission channel and the audio transmission channel, the moving image signal encoding means, the audio signal encoding means, the image data transmitting means, and the audio data transmitting means. And a switching means for switching the connection relationship between the moving image and audio transmitting apparatus. 2. The switching means transmits audio coded data temporally corresponding to image coded data to be transmitted next to image coded data having a code amount exceeding a predetermined value through the image transmission channel. 2. The moving image according to claim 1, wherein the connection relationship between the moving image signal encoding means and the audio signal encoding means and the image data transmitting means and the audio data transmitting means is switched. Audio transmission device. 3. The audio signal coding means, when the code amount of the coded image data output from the moving image signal coding means exceeds a predetermined value, sets the compression rate by coding of the input audio signal. The moving picture audio transmission device according to claim 1, wherein the moving picture sound transmission device is enhanced. 4. The moving picture signal coding means codes a moving picture signal using an interframe predictive coding method, and the switching means outputs from the moving picture signal coding means at a scene change. The moving picture signal coding means, the sound signal coding means, the picture data transmitting means, and the moving picture signal coding means so that the coded picture data can be transmitted using two transmission channels of the picture transmission channel and the sound transmission channel. The moving picture audio transmission apparatus according to claim 1, wherein a connection relationship with the audio data transmission means is switched. 5. A moving picture audio transmission apparatus for transmitting moving picture information and audio information using two transmission channels, an image transmission channel and an audio transmission channel, by encoding an inputted moving picture signal, Moving picture signal coding means for outputting digital picture coded data, sound signal coding means for coding inputted sound signal and outputting digital sound coded data, said moving picture signal coding means Image data transmitting means for transmitting the image coded data output from the audio transmission channel using the image transmission channel, and audio coded data output from the audio signal encoding means using the audio transmission channel If the encoded image data output from the audio data transmitting unit and the moving image signal encoding unit cannot be transmitted through the image transmission channel, Switching the connection relationship between the moving image signal encoding means and the audio signal encoding means and the image data transmitting means and the audio data transmitting means so that encoded data is transmitted using the image transmission channel. A moving image / audio transmission apparatus comprising: a switching unit. 6. The switching means transmits, on the image transmission channel, voice encoded data that temporally corresponds to image encoded data transmitted next to the image encoded data transmitted on the audio transmission channel. 6. The moving image according to claim 5, wherein the connection relationship between the moving image signal encoding means and the audio signal encoding means and the image data transmitting means and the audio data transmitting means is switched. Image and audio transmission equipment. 7. The audio signal encoding means enhances the compression rate of the input audio signal when the image encoded data output from the moving image signal encoding means cannot be transmitted through the image transmission channel. The moving image / audio transmission apparatus according to claim 5, wherein