JPH0993553A - Image communication equipment and image communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow the method to have provision for even revision of a delay time associated with a change in code quantity as well as permitting synchronization of an image with an audio signal accurately. SOLUTION: The equipment is provided with an image A/D converter 16, a frame counter 17 to obtain a frame number from an image data frame synchronizing signal, an image coding circuit 18 providing a frame number to an image code data, and an audio A/D converter 19, a number provision circuit 20 providing audio data to a frame number, an audio coding circuit 21, a frame number detection circuit 24 detecting an image frame number, a number detection circuit 25 detecting a frame number of audio data, a transmission delay control circuit 26 calculating a difference between the detected frame number and the detected number, a transmission delay memory 22 delaying the audio code data based on the difference and a multiplexer circuit 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image communication device and an image communication method for digitizing, encoding, transmitting or receiving, decoding and analogizing an image signal and an audio signal.

[0002]

2. Description of the Related Art The recent spread of digital communication networks and accompanying spread of multimedia-related systems is a market that is expected to expand in the future. In particular, thanks to the development of image coding technology, image communication has become easy in addition to conventional voice communication, and videophones, videoconference systems, etc. have become widespread.

One of the functions required in the image communication apparatus for communicating the image and the voice as described above is a so-called lip sync for synchronizing the output image and the voice. This is because the processing time is different between the image and the sound when the image and the sound are coded by the image coding circuit and the sound coding circuit and when they are decoded by the image decoding circuit and the sound decoding circuit, respectively ( Since an image has a larger amount of data than an audio and generally requires a long processing time), the movement of the displayed image and the audio may feel uncomfortable as it is. Therefore, the audio data is sent to synchronize with the image. It is a thing.

A conventional image communication apparatus will be described below. FIG. 5 is a block diagram showing a transmission device of a conventional image communication device. In FIG. 5, 1 is an image A / D converter that converts an input image signal into digital data, 2 is an image encoding circuit that encodes digital data of an image from the image A / D converter 1, and 3 is an input Audio A / D converter for converting the converted audio signal into digital data,
Reference numeral 4 is a voice encoding circuit that encodes voice digital data from the voice A / D converter 3, and 5 is a transmission delay memory that delays the voice code data from the voice encoding circuit 4 by a certain set time, 6 is a multiplexing circuit that multiplexes the coded data from the image coding circuit 2 and the transmission delay memory and sends it to the communication network, and 7 is a frame number TR that indicates the order of the images processed by the image coding circuit 2. A frame number detection circuit for detecting the
It is a transmission delay control circuit that sets the delay amount of the transmission delay memory 5 from the frame number TR from.

The operation of the conventional image transmitting apparatus of the image communication apparatus configured as described above will be described below. Regarding image coding, ITU-T (International Telecommunication Union Telecommunication Standardization Sector) Recommendation H.264. 261 is typical, and this will be described as an example. The input image signal v is converted into YUV data of luminance and color difference components by the image A / D converter 1 and input to the image encoding circuit 2. The image coding circuit 2 CIFs image data in order to perform coding processing.
(Screen format of 352 dots x 288 lines) or QCIF (screen format in which the vertical and horizontal directions of CIF are halved) is converted, DCT (discrete cosine transform) and quantization are performed in macroblock units, and output as image code data. To do. Although the screen format of CIF is 30 frames / second, the image encoding circuit 2 performs an encoding process while adding a frame number TR indicating the order of frames of an image. Needless to say, the decoding side (reception device) also performs the process of decoding the image while recognizing the frame number.

[0006] On the other hand, with respect to audio coding, ITU-
Recommendation G. 711, G.R. 722 etc. The simplest G.I. 711 is taken as an example, this is an audio signal of 64k.
This is a method of performing PCM conversion into a bps rate. 64 kbps with sampling rate of 8 kHz and data width of 8 bits
Becomes The input audio signal a is converted into digital data by the audio A / D converter 3 and input to the audio encoding circuit 4. The voice encoding circuit 4 performs PCM conversion according to the μ-law or the A-law and outputs it as voice code data. The voice code data output from the voice encoding circuit 4 is delayed by the transmission delay memory 5 for a set time and output to the multiplexing circuit 6. Transmission delay memory 5
For setting the delay time, the frame number detection circuit 7 detects the frame number TR from the image encoding circuit 2, and the interval between frames is determined from the value of the frame number TR counted in a certain unit time. Here, if the processing time of the image coding circuit 2 is long, the interval between frames becomes large, and conversely, if the processing time is short, the interval between frames becomes small. Of the image code data and the audio code data are synchronized by setting the processing time calculated from the interval between the frames in the transmission delay memory 5 in advance. Then, the data can be transmitted from the multiplexing circuit 6.

FIG. 6 is a block diagram showing a receiving apparatus of a conventional image communication apparatus. In FIG. 6, 9 is a separation circuit for separating data received from the communication network into image and audio code data, 10 is an image decoding circuit for decoding the image code data from the separation circuit 9, and 11 is image decoding. An image D for converting the image data from the circuit 10 into an analog image signal v
/ A converter, 12 is a voice decoding circuit for decoding the voice code data from the separation circuit 9, 13 is a reception delay memory for delaying the voice data from the voice decoding circuit 12 for a set time, and 14 is a reception Audio D / A for converting audio data from the delay memory 13 into an analog audio signal a
The converter 15 is a delay setting circuit for setting the delay time of the reception delay memory 13.

The operation of the conventional receiving apparatus of the image communication apparatus configured as described above will be described below. Decoding is the reverse procedure of the image and audio encoding described above. The image decoding circuit 10 performs inverse quantization and inverse DCT on the image code data to decode the image data, converts the image data into an analog image signal v by the image D / A converter 11, and outputs the analog image signal v. Further, the voice decoding circuit 12 performs inverse PCM conversion on the voice code data to decode the voice data, converts it into an analog voice signal a by the voice D / A converter 14 through the reception delay memory 13, and outputs it. Here, the delay setting circuit 15 sets the delay time from the difference value of the predetermined processing time between the image decoding circuit 10 and the audio decoding circuit 12 so that the image and the audio are synchronized with each other. ing. Unlike the case of encoding, the decoding side does not use the frame number TR to set the delay time of the reception delay memory 13, but the reason is that the received image code data and audio code data are transmitted. It is not always synchronized on the side. Therefore, on the receiving side (receiving device), in addition to the delay correction based on the difference in the decoding processing time between the image and the sound, the user finely adjusts the output image and the sound by feeling so that there is no discomfort. It will be.

[0009]

However, in the above-described conventional configuration, the delay time is preliminarily correlated on the transmitting side (transmitting device) from the frame interval based on the frame number TR detected from the image coding circuit 2. As a matter of fact, since it is a method of indirectly synchronizing the code data of the image and the voice, there is a problem that it is not always completely synchronized. Also, the receiving side (receiving device)
As described above, the synchronization between the received image data and the audio data requires the user to sense that the output image and the audio do not feel uncomfortable in addition to the delay correction of the decoding processing time of the image and the audio. Since it is fine-tuned, the accuracy is low and the delay time is fixed, so that there is a problem that the delay time cannot be changed due to the change in the code amount.

The present invention solves the above-mentioned conventional problems, and an image communication device and an image capable of accurately synchronizing an image and a sound and capable of changing a delay time due to a change in code amount. It is an object of the present invention to provide an image communication method capable of accurately synchronizing voices and adapting to changes in delay time due to changes in code amount.

[0011]

In order to achieve this object, an image communication apparatus according to claim 1 of the present invention comprises an image A / D converter for A / D converting an input image signal, and an image A / D converter. A frame counter that counts the frame synchronization signal of the image data from the D converter to obtain the frame number, and the image data from the image A / D converter to obtain the image code data, and to add the frame number to the image code data. Image encoding circuit and audio A / D that obtains digital audio data by A / D converting the input audio signal
D converter, numbering circuit for numbering the same frame number as the frame number of the image data obtained by counting by the frame counter to the digital audio data input at the same time as the image data counted by the frame counter, and numbering circuit A voice encoding circuit for encoding the voice data from, a frame number detecting circuit for detecting the frame number of the image from the image code data encoded by the image encoding circuit, and a voice encoded by the voice encoding circuit. A number detection circuit that detects the number given by the numbering circuit from the code data at the same time as the detection of the frame number, and the difference value between the frame number detected by the frame number detection circuit and the number detected by the number detection circuit is calculated. A transmission delay control circuit for controlling the voice code for a delay time set based on the calculated difference value. A transmission delay memory for delaying the voice code data from the encoding circuit, and a multiplexing circuit for multiplexing the image code data and the voice code data respectively output from the image encoding circuit and the transmission delay memory and transmitting them to the communication network. It has the composition which has.

According to another aspect of the image communication device of the present invention, a separation circuit for separating data received from the communication network into image code data and voice code data, and image data obtained by decoding the image code data output from the separation circuit. , An image D / A converter for converting the image data from the image decoding circuit into an analog image signal, and a voice for decoding the voice code data output from the separation circuit to output voice data. A decoding circuit, a frame number detection circuit for detecting a frame number of an image given in advance to the image data from the image decoding circuit, and a number detection for detecting a number given in advance to the audio data from the audio decoding circuit Circuit,
A reception delay control circuit for calculating a difference value between the frame number detected by the frame number detection circuit and the number detected by the number detection circuit, and voice decoding for a delay time set based on the calculated difference value. A reception delay memory that delays the voice data from the circuit, and a voice D / that converts the voice data output from the reception delay memory into an analog voice signal.
And an A converter.

An image communication apparatus according to a third aspect is the image communication apparatus according to the first aspect.
The image communication device according to claim 2 and the image communication device according to claim 2 are included.

According to a fourth aspect of the present invention, there is provided an image communication method, wherein an image A / D conversion step for A / D converting an input image signal, and a frame number by counting a frame synchronization signal of image data from the A / D converter. A frame counting step for obtaining the image code data by encoding the image data and giving a frame number to the image code data, and A / D converting the input audio signal to obtain digital audio data. A number assigned to the digital audio data input at the same time as the image data counted in the frame counting step, and the same number as the frame number of the image data obtained by counting in the audio A / D conversion step and the frame counting step. A voice step for encoding the voice data numbered in the numbering step and the numbering step Encoding step, a frame number detecting step for detecting a frame number of an image from the image code data encoded in the image encoding step, and a numbering step assigned from the voice code data encoded by the voice encoding step A number detection step of detecting the number simultaneously with the detection of the frame number, and a transmission delay control step of calculating a difference value between the frame number detected in the frame number detection step and the number detected in the number detection step, A transmission delay step of delaying the voice code data encoded in the voice encoding step by the delay time set based on the difference value, and a delay time of the image code data encoded in the image encoding step and the transmission delay step. And a multiplexing step of multiplexing the voice code data and transmitting the same to a communication network. It has.

According to a fifth aspect of the image communication method, a separation step of separating the data received from the communication network into image code data and voice code data, and decoding the separated image code data and outputting the image data. An image decoding step, an image D / A conversion step of converting the image data decoded in the image decoding step into an analog image signal,
A voice decoding step of decoding the separated voice code data to output voice data, a frame number detecting step of detecting a frame number of an image previously given to the image data decoded in the image decoding step, Calculate the difference value between the number detection step that detects the number assigned in advance to the voice data decoded in the voice decoding step, and the frame number detected in the frame number detection step and the number detected in the number detection step. A reception delay control step, a reception delay step of delaying the voice data decoded in the voice decoding step for a delay time set based on the calculated difference value, and a voice data delayed in the reception delay step. And a voice D / A conversion step for converting into an analog voice signal.

The image communication method according to claim 6 is the method according to claim 4.
The image communication method described above and the image communication method according to claim 5 are included.

[0017]

With this configuration, it is possible to correct the deviation (difference value) in the delay time of the image and audio encoding processing, and therefore the image and audio codes output from the image encoding circuit and the audio encoding circuit, respectively. The data output times can be matched, that is, synchronized. Further, since it is possible to correct the delay time deviation of the image and audio decoding processing and the delay time deviation in the transmission stage, it is possible to correct the image and audio data output from the image decoding circuit and the audio decoding circuit, respectively. The output times can be matched, that is, synchronized. Further, it is possible to correct the delay time difference (difference value) between the image and audio encoding processing, and correct the delay time deviation between the image and audio decoding processing and the delay time difference in the transmission stage. Therefore, it is possible to match the output timings of the coded data of the image and the audio output from the image encoding circuit and the audio encoding circuit, respectively, and the images and the audio output from the image decoding circuit and the audio decoding circuit, respectively. The output timing of the data can be matched.

[0018]

【Example】

(Embodiment 1) An image communication apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an image communication apparatus according to an embodiment of the present invention, showing a transmitting apparatus. In FIG. 1, 16 is an image A / D converter that converts the input image signal v into digital data, and 17 is a frame counter that counts a frame synchronization signal of the image data from the image A / D converter 16 to obtain a frame number. , 18 is an image encoding circuit for encoding the image data from the image A / D converter 16, 19 is an audio A / D converter for converting the input audio signal a into digital audio data, and 20 is a frame counter 17 for counting. A numbering circuit for giving the same number as the frame number of the obtained image data to the digital audio data from the audio A / D converter 19 input at the same time as the image data counted by the frame counter 17, 21 is a number Application circuit 2
A voice encoding circuit for encoding voice data from 0, 22
Is a transmission delay memory for delaying the voice code data from the voice encoding circuit 21 by a set time, and 23 is image code data and voice code data output from the image encoding circuit 18 and the transmission delay memory 22, respectively. And a multiplexing circuit for multiplexing and transmitting to the communication network, 24 is a frame number detecting circuit for detecting a frame number TR indicating the order of image data processed by the image encoding circuit 18, and 25 is a voice encoding circuit 21. A number detecting circuit for detecting the number given to the audio data being processed by 26, and 26 calculating a difference value between the frame number detected by the frame number detecting circuit 24 and the number detected by the number detecting circuit 25, It is a transmission delay control circuit that determines the delay amount of the transmission delay memory 22 from the calculated difference value.

The operation of the image communication apparatus configured as described above will be described below with reference to FIGS. 1 and 2A to 2C. 2A is a timing diagram showing a frame synchronization signal, FIG. 2B is a data state diagram showing audio data, and FIG. 2C is a data state diagram showing assigned number data. As described in the section of the related art, regarding the image coding, ITU-T Recommendation H.264 is used. 261 is typical,
This will be described as an example. The input image signal v is the image A /
It is converted into YUV data of luminance and color difference components by the D converter 16 (image A / D conversion step) and input to the image coding circuit 18. The image encoding circuit 18 uses CIF (352 dots ××) for the image data in order to perform the encoding process.
288 line screen format) or QCIF (CI
Converted to a screen format in which the height and width of F are halved,
DCT (discrete cosine transform) and quantization are performed for each macroblock and output as image code data (image coding step). Although the screen format of CIF is 30 frames / second, the image encoding circuit 18 performs the encoding process while adding the frame number TR indicating the order of the frames of the image. Needless to say, the decoding side (reception device) also performs the process of decoding the image while recognizing the frame number.

On the other hand, with regard to audio coding, ITU-
Recommendation G. 711, G.R. 722 etc. The simplest G.I. 711 is taken as an example, this is an audio signal of 64k.
This is a method of performing PCM conversion into a bps rate. 64 kbps with sampling rate of 8 kHz and data width of 8 bits
Becomes The input audio signal a is converted into digital audio data by the audio A / D converter 19 (audio A / D
D conversion step), and is input to the voice encoding circuit 21 through the numbering circuit 20. The voice encoding circuit 21 performs PCM conversion according to the μ-law or the A-law and outputs it as voice code data (voice encoding step). The voice code data output from the voice encoding circuit 21 is delayed by the transmission delay memory 22 for a set time (transmission delay step) and output to the multiplexing circuit 23.

Here, the delay time of the transmission delay memory 22 is controlled as follows. First, frame counter 1
The frame number 7 obtained by counting the frame synchronization signal is introduced into the image encoding process as the frame number TR by the image encoding circuit 18, and at the same time, the audio data processed by the audio encoding circuit 21 by the numbering circuit 20. Are assigned as numbers (frame counting step, image coding step, numbering step).
Originally, unlike the image data, the audio data does not have a section such as a frame. Therefore, the audio data is a continuous data string and cannot be given a number as it is. However, the number can be given in the following manner.

An example of a method for assigning numbers to voice data will be described below with reference to FIG. Note that (a) is a timing diagram showing a frame synchronization signal, (b) is a data state diagram showing audio data, and (c) is a data state diagram showing assigned number data. The frame synchronization signal shown in FIG. 2A is a timing signal indicating a frame of an image encoded by the image encoding circuit 18, and the frame number TR is obtained by counting in synchronization with the frame synchronization signal. The voice data is the data sampled by the voice A / D converter 19 (8 kHz in the case of G.711) and encoded by the voice encoding circuit 21. Only the LSB bit in this is used for numbering. The other bits are assigned to be voice data (see voice data in FIG. 2B). LSB extracted in synchronization with the frame synchronization signal
Since the bit stream of 8 becomes serial data of 8 kbps, the header and audio number data (the same value as the frame number TR) is put here, and the extra portion is filled with fill data (additional number in FIG. 2C). See data). Such a format is determined in advance, encoded by the speech encoding circuit 21 and transmitted. As will be described later, the receiving side (receiving device) can take out the LSB bit according to this format and detect the number given to the audio data. When such a numbering system is not performed, all bits are switched to be assigned to audio data. In this numbering system,
G. It is possible to maintain timing compatibility between the standard method of voice encoding such as 711 and the clock rate. As described above, it is possible to give the voice code data a number synchronized with the frame of the image.

Image data and audio data having the same number are input to the image encoding circuit 18 and the audio encoding circuit 21, respectively, to be encoded and output as image and audio encoded data. As described in the section of the technology of (1), the respective encoding processing times are different (the image encoding processing time is generally longer), and therefore the frame number detected by the frame number detection circuit 24 and the number detection A difference value occurs in the number detected by the circuit 25 (frame number detecting step, number detecting step). That is, this difference value causes a difference in processing time between the image encoding circuit 18 and the audio encoding circuit 21, and accordingly the transmission delay control circuit 26 corrects the delay time of the audio code data in the transmission delay memory 22. By controlling (transmission delay control step), the code data of the image and the audio are synchronized at the time of multiplexing by the multiplexing circuit 23 (multiplex step). Since the above control is performed for each frame, even if the processing time changes midway, the delay amount changes accordingly, so that accurate synchronization is always performed.

As described above, according to this embodiment, it is possible to correct the delay time difference (difference value) between the image and audio encoding processes, so that the image encoding circuit 18 and the audio encoding circuit 21 can be used. The coded data of the image and the audio that are output can be temporally matched in the multiplexing circuit 23, and the image and the audio can be accurately synchronized.

(Second Embodiment) An image communication apparatus according to a second embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram showing an image communication apparatus according to the second embodiment, showing a receiving apparatus.
In FIG. 3, 27 is a separation circuit for separating the data received from the communication network into image code data and audio code data.
8 is an image decoding circuit which decodes the image code data output from the separation circuit 27 and outputs the image data, 29 is an image D / A converter which converts the image data from the image decoding circuit 28 into an analog image signal, 30 is a separation circuit 27
A voice decoding circuit that decodes voice code data output from the voice output circuit and outputs voice data, 31 is a voice decoding circuit 30.
A reception delay memory for delaying the audio data from the audio data by a set time, 32 is an audio D / A converter for converting the audio data from the reception delay memory 31 into an analog audio signal, and 33 is audio data from the audio decoding circuit 30. A number detecting circuit for detecting a number from the image decoding circuit 28
A frame number detecting circuit for detecting the frame number of the image data from 35, a receiving delay control 35 for controlling the delay time of the receiving delay memory 31 from the difference value of the numbers respectively detected by the number detecting circuit 33 and the frame number detecting circuit 34. Circuit.

The operation of the conventional image communication apparatus receiving apparatus configured as described above will be described below. Decoding is the reverse procedure of the image and audio encoding described above. The data received through the separation circuit 27 is separated into image and audio code data and output to the image decoding circuit 28 and the audio decoding circuit 30 (separation step). The image decoding circuit 28 performs inverse quantization and inverse DCT on the image code data to decode the image data (image decoding step),
The image D / A converter 29 converts it into an analog image signal (image D / A conversion step) and outputs it. The voice decoding circuit 30 performs inverse PCM conversion from voice code data to decode voice data (voice decoding step),
Audio D / A converter 32 through reception delay memory 31
Is converted into an analog audio signal (audio D / A conversion step) and output.

The control of the delay time of the reception delay memory 31 will be described below. As shown in the first embodiment,
When the image data is encoded on the transmitting side, the frame number TR of the image gives the frame number TR to the image code data in advance, and the voice data input at the same time as the image data also has the same number given in advance. ing. Therefore, from the image decoding circuit 28 to the frame number detection circuit 34, the frame number TR of the image is detected.
Are detected from the audio decoding circuit by the number detecting circuit 33 to the audio (frame number detecting step and number detecting step). Since the processing times are different, when the image and audio code data received by the separation circuit 27 are synchronized, that is, even when the respective numbers before decoding match, the frame number detection circuit 34 and the number detection are performed. The numbers detected by the circuit 33 are different from each other. Therefore, the reception delay control circuit 35 calculates this difference value (reception delay control step), and the reception delay memory 31 is output from the image D / A converter 29 and the audio D / A converter 32 according to the difference value. It is possible to correct the time lag between the image signal v and the audio signal a (reception delay step). Further, according to this method, correction can be performed even when the code data of the image and the voice received by the separation circuit 27 are not synchronized, that is, even when the image and the voice of the transmission side are not synchronized. Further, similar to the encoding, the above control is performed for each frame, so that even if the processing time changes in the middle, the delay amount changes accordingly, so that accurate synchronization is always performed.

As described above, according to the present embodiment, the reception delay control circuit 35 can correct the delay time deviation of the image and audio decoding processing and the delay time deviation in the transmission stage, so that the image decoding is performed. Conversion circuit 28 and speech decoding circuit 3
Image data and audio data respectively output from 0 are D /
The A converters 29 and 32 can be matched in time, and the image signal and the audio signal can be accurately synchronized.

(Embodiment 3) An image communication apparatus according to a third embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a block diagram showing an image communication apparatus according to the third embodiment. In FIG. 4, 16 is an image A /
D converter, 17 is a frame counter, 18 is an image encoding circuit, 19 is an audio A / D converter, 20 is a numbering circuit, 21 is an audio encoding circuit, 22 is a transmission delay memory, 23 is a multiplexing circuit, and 24 is Frame number detection circuit,
Reference numeral 25 is a number detection circuit, 26 is a transmission delay control circuit, 27 is a separation circuit, 28 is an image decoding circuit, 29 is an image D / A converter, 30 is a voice decoding circuit, 31 is a reception delay memory, and 32 is a voice D. A / A converter, 33 is a number detection circuit, 34 is a frame number detection circuit, and 35 is a reception delay control circuit. Since these are the same as those in FIGS. 1 and 3,
The description is omitted. A is a transmitting device that constitutes an image communication device, B is a receiving device that constitutes an image communication device, 36 is a camera that outputs an image signal, 37 is a microphone that outputs an audio signal, and 38 is an image based on the image signal. monitor,
39 is a speaker for outputting a sound based on a sound signal, 40
Is a line circuit that connects the multiplexing circuit 23 and the demultiplexing circuit 27 to a communication network, 41 is an operation unit for the user to operate the device, and 42 is a control unit that controls the entire device.

The operation of the image communication apparatus configured as described above will be described. As shown in FIG. 4, in this embodiment, the camera 36 is connected to the input terminal (not shown) of the image signal of the transmitter A and the microphone 37 is connected to the input terminal (not shown) of the audio signal in the first embodiment. Are connected, and the operation content is the same as that of the first embodiment. In the second embodiment, the monitor 38 is connected to the image signal output terminal (not shown) of the receiving apparatus B, and the speaker 39 is connected to the audio signal output terminal (not shown). Example 2
Is the same as The line circuit 40, to which the multiplexing circuit 23 and the demultiplexing circuit 27 are connected, is connected to a communication network to send and receive data to and from the other image communication device. The control unit 42 performs control based on an operation of the image communication device performed by the user using the operation unit 41, connection and disconnection operation with a communication network, control of an image and audio encoding / decoding circuit, and the like.

As described above, according to this embodiment, the transmission delay control circuit 26 can transmit the multiplexed data in which the image and the sound are accurately synchronized in the transmission, and the reception delay control circuit 35 can receive the the multiplexed data in the reception. After the image and sound are accurately synchronized, the display on the monitor 38 and the speaker 39 are performed.
It is possible to output the sound in.

[0035]

As described above, the present invention provides an image A / D converter for A / D converting an input image signal and an image A / D converter.
A frame counter that obtains a frame number by counting a frame synchronization signal of image data from the / D converter;
An image encoding circuit that encodes the image data from the image A / D converter to obtain the image code data and gives a frame number to the image code data, and the input audio signal is A / D converted to digital audio data. An audio A / D converter for obtaining, and a numbering circuit for giving the same number as the frame number of the image data obtained by counting by the frame counter to the digital audio data inputted at the same time as the image data counted by the frame counter. A voice encoding circuit for encoding voice data from the numbering circuit,
A frame number detecting circuit that detects a frame number of an image from image code data encoded by the image encoding circuit, and a frame number that is a number assigned by a number assigning circuit from the voice code data encoded by the voice encoding circuit. The number detection circuit that detects simultaneously with the detection of the frame number, the transmission delay control circuit that calculates the difference value between the frame number detected by the frame number detection circuit and the number detected by the number detection circuit, based on the calculated difference value. A transmission delay memory that delays the voice code data from the voice encoding circuit by a set delay time, and the image code data and the voice code data that are respectively output from the image encoding circuit and the transmission delay memory are multiplexed. By having a multiplexing circuit for transmitting to the communication network, the delay time difference (difference value) between the image and audio encoding processing can be reduced. It is possible to positively, it is possible to realize an image communication apparatus capable to take accurate synchronization between images and audio code data output from the image coding circuit and the audio encoding circuit.

Further, a separation circuit for separating the data received from the communication network into image code data and voice code data, and an image decoding circuit for decoding the image code data output from the separation circuit and outputting the image data. , An image D / which converts the image data from the image decoding circuit into an analog image signal
A converter, a voice decoding circuit that decodes the voice code data output from the separation circuit and outputs the voice data, and a frame number that detects the frame number of the image given in advance to the image data from the image decoding circuit A detection circuit, a number detection circuit for detecting a number given in advance to the voice data from the voice decoding circuit, and a difference value between the frame number detected by the frame number detection circuit and the number detected by the number detection circuit. A reception delay control circuit that calculates the delay time, a reception delay memory that delays the voice data from the voice decoding circuit for a delay time that is set based on the calculated difference value, and the voice data that is output from the reception delay memory by analog By having an audio D / A converter for converting into an audio signal, the delay time difference between the image and audio decoding process and the transmission stage can be improved. It is possible to correct the deviation of the delay time, it is possible to realize an image communication apparatus capable to take accurate synchronization between picture and sound to be outputted from the image decoding circuit and the audio decoding circuit.

Further, by configuring the image communication apparatus to be the image communication apparatus according to the above two inventions, it is possible to realize an image communication apparatus that produces the effects of the above two inventions together.

Further, an image A / D conversion step of A / D converting the input image signal, a frame counting step of counting a frame synchronization signal of the image data from the A / D converter to obtain a frame number, and an image An image encoding step of encoding data to obtain image encoded data and giving a frame number to the image encoded data, and an audio A / D conversion step of A / D converting an input audio signal to obtain digital audio data. In the numbering step and the numbering step, the same number as the frame number of the image data obtained by counting in the frame counting step is given to the digital audio data input at the same time as the image data counted in the frame counting step. An audio encoding step for encoding the audio data with a number, and an image code. The frame number detection step of detecting the frame number of the image from the image code data encoded in the encoding step, and the frame number detection of the number assigned in the number assigning step from the voice code data encoded by the voice encoding step. A number detection step that is detected at the same time, a transmission delay control step that calculates the difference value between the frame number detected in the frame number detection step and the number detected in the number detection step, and setting is performed based on the calculated difference value. A transmission delay step of delaying the voice code data encoded in the voice encoding step by the delay time, the image code data encoded in the image encoding step, and the voice code data delayed in the transmission delay step. By having a multiplexing step of multiplexing and transmitting to a communication network It is possible to correct the deviation of the delay time of the processing (difference value), an image communication method capable of synchronizing the output image code data and outputs the voice code data accurately can be realized.

Further, a separation step of separating the data received from the communication network into image code data and voice code data, an image decoding step of decoding the separated image code data and outputting image data, and an image decoding An image D / A conversion step of converting the image data decoded in the encoding step into an analog image signal, a voice decoding step of decoding the separated voice code data and outputting voice data, and an image decoding step. A frame number detecting step of detecting a frame number of an image given in advance to the decoded image data; a number detecting step of detecting a number given in advance to the voice data decoded in the voice decoding step; A receiver that calculates the difference between the frame number detected in the number detection step and the number detected in the number detection step. A delay control step, a reception delay step for delaying the voice data decoded in the voice decoding step for a delay time set based on the calculated difference value, and the voice data delayed in the reception delay step are converted to analog voice. By including the audio D / A conversion step of converting into a signal, it is possible to correct the delay time deviation of the image and audio decoding processing and the delay time deviation in the transmission stage. It is possible to realize an image communication method capable of accurately synchronizing with a signal.

Further, by making the image communication method the image communication method according to the above-mentioned two method inventions, it is possible to realize the image communication method which produces the effects of the two method inventions together.

[Brief description of drawings]

FIG. 1 is a block diagram showing an image communication device according to an embodiment of the present invention.

FIG. 2 is a diagram showing timing and the like indicating a frame synchronization signal.

FIG. 3 is a block diagram showing an image communication device according to a second embodiment.

FIG. 4 is a block diagram showing an image communication device according to a third embodiment.

FIG. 5 is a block diagram showing a transmission device of a conventional image communication device.

FIG. 6 is a block diagram showing a receiving device of a conventional image communication device.

[Explanation of symbols]

 A transmitter B receiver 16 image A / D converter 17 frame counter 18 image encoding circuit 19 audio A / D converter 20 numbering circuit 21 speech encoding circuit 22 transmission delay memory 23 multiplexing circuit 24 frame number detecting circuit 25 number Detection circuit 26 Transmission delay control circuit 27 Separation circuit 28 Image decoding circuit 29 Image D / A converter 30 Audio decoding circuit 31 Reception delay memory 32 Audio D / A converter 33 Number detection circuit 34 Frame number detection circuit 35 Reception delay control circuit 36 Camera 37 Microphone 38 Monitor 39 Speaker 40 Line Circuit 41 Operation Section 42 Control Section

Claims (6)

[Claims] 1. An image A / D converter for A / D converting an input image signal, a frame counter for counting a frame synchronization signal of image data from the image A / D converter to obtain a frame number, and An image encoding circuit that encodes the image data from the image A / D converter to obtain the image code data and gives the frame number to the image code data, and the digital audio data by A / D converting the input audio signal. A / D converter that obtains
A numbering circuit for giving the same number as the frame number of the image data obtained by counting by the frame counter to the digital audio data input at the same time as the image data counted by the frame counter; and the numbering circuit. A voice encoding circuit for encoding the voice data from, a frame number detecting circuit for detecting the frame number of the image from the image code data encoded by the image encoding circuit, and an encoding by the voice encoding circuit. A number detection circuit that detects the number assigned by the numbering circuit from the voice code data at the same time as the detection of the frame number, a frame number detected by the frame number detection circuit, and a number detected by the number detection circuit. A transmission delay control circuit that calculates a difference value between and, set based on the calculated difference value A transmission delay memory for delaying the voice code data from the voice encoding circuit by a predetermined delay time, and the image code data and the voice code data respectively output from the image encoding circuit and the transmission delay memory are multiplexed. And a multiplexing circuit for transmitting the data to a communication network. 2. A separation circuit for separating data received from a communication network into image code data and audio code data, and an image decoding circuit for decoding the image code data output from the separation circuit and outputting image data. And an image D for converting the image data from the image decoding circuit into an analog image signal.
/ A converter, a voice decoding circuit that decodes voice code data output from the separation circuit and outputs voice data, and detects a frame number of an image given in advance to the image data from the image decoding circuit A frame number detecting circuit, a number detecting circuit for detecting a number given in advance to the voice data from the voice decoding circuit, a frame number detected by the frame number detecting circuit and a number detected by the number detecting circuit. A reception delay control circuit for calculating a difference value with the number, a reception delay memory for delaying the voice data from the voice decoding circuit for a delay time set based on the calculated difference value, and the reception delay memory And an audio D / A converter for converting audio data output from the device into an analog audio signal. 3. An image communication apparatus comprising the image communication apparatus according to claim 1 and the image communication apparatus according to claim 2. 4. An image A / D conversion step of A / D converting an input image signal to obtain image data; a frame counting step of counting a frame synchronization signal of the image data to obtain a frame number; Image coding step of coding image data to obtain image code data and giving the frame number to the image code data, and audio A / D conversion for A / D converting the input audio signal to obtain digital audio data And a numbering step of assigning the same number as the frame number of the image data obtained by counting in the frame counting step to the digital audio data input at the same time as the image data counted in the frame counting step. , A speech coding step for coding the speech data numbered in the numbering step. A frame number detecting step of detecting a frame number of an image from the image code data encoded in the image encoding step, and a number assigning step of the voice code data encoded in the voice encoding step. Number detecting step of detecting the detected number simultaneously with the detection of the frame number, and a transmission delay control step of calculating a difference value between the frame number detected in the frame number detecting step and the number detected in the number detecting step. A transmission delay step of delaying the voice code data encoded in the voice encoding step by a delay time set based on the calculated difference value, and an image code encoded in the image encoding step. Data and voice code data delayed in the transmission delay step are multiplexed and transmitted to a communication network. Image communication method characterized by having a multiplexing step that. 5. A separation step of separating data received from a communication network into image code data and audio code data, an image decoding step of decoding the separated image code data and outputting image data, An image D / A conversion step of converting the image data decoded in the image decoding step into an analog image signal; a voice decoding step of decoding the separated voice code data to output voice data; A frame number detecting step of detecting a frame number of an image given in advance to the image data decoded in the decoding step, and a number detecting a number given in advance to the audio data decoded in the audio decoding step. A detecting step, a frame number detected in the frame number detecting step, and a number detected in the number detecting step; A reception delay control step of calculating a difference value, a reception delay step of delaying the voice data decoded in the voice decoding step for a delay time set based on the calculated difference value, and the reception delay step. And a voice D / A conversion step of converting the voice data delayed by 1. into an analog voice signal. 6. An image communication method comprising the image communication method according to claim 4 and the image communication method according to claim 5.