JPH03140052A - Video telephone message store and forward exchange system - Google Patents

Abstract

PURPOSE:To save the storage quantity of a message of video telephone message without reducing the transfer capability by using a level signal of a voice signal having an important roll of message transfer as a store control signal for a video telephone message. CONSTITUTION:The video telephone message store and forward exchange system consists of 1st and 2nd video telephone terminals 1, 2, a digital telephone network 3, and a message center 4 making message service. The message center 4 stores a voice signal for a voiced period in which a voice signal forming a video telephone message has a predetermined level or over, a video signal corresponding to the voiced period, voiced sound consecutive time information being the accumulated time of voiced periods, an unvoiced signal for a predetermined protection period in the unvoiced period in which the level of the voice signal does not reach the predetermined level in succession to the voiced period and the video signal corresponding to the protection period. Thus, the memory capacity for store and forward exchange is saved in a range not reducing the transfer capability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Four Fields of Industrial Application] The present invention relates to a storage and exchange system for videophone messages using an efficient information storage method and stored information reproduction method.

rPrior art] Videophone service is a two-way service that connects subscriber terminals via a switching network of broadband transmission lines, with the main purpose of transmitting moving images or still images including accompanying audio. be. In this videophone system, in addition to the videophone, a video button telephone device, a secretary television reception device, and the like are used as subscriber terminals. These subscriber terminals are accommodated in the exchange via subscriber lines such as balanced pair cables, and are connected to the trunk exchange via toll cables such as coaxial or microwave relay cables.

Traditionally, TV? In a store-and-forward system that provides a li-talk service, when a third-party center mediates a message to a communication partner, the sender's message is stored and forwarded as is.

The videophone service is described, for example, in "F Electronic Communication Handbook" published by Ohmsha Co., Ltd., March 30, 1971, pp. 1187-1188.

[Problems to be Solved by the Invention] Store-and-forward is a method in which destinations and information from an incoming line are temporarily stored in a buffer memory within an exchange, and then all messages are transferred to an outgoing line via a ring-by link according to the destination code. That is, by providing a buffer memory in the exchange, all links between terminals can be set up at the same time, and the information that has been accumulated is sequentially transferred and sent to the other terminal.

In this way, in the conventional method, messages from one sender are stored and exchanged as they are, so a large amount of memory is required when a large amount of information such as a videophone message is to be exchanged.

SUMMARY OF THE INVENTION An object of the present invention is to provide a videophone message storage/exchange system that can solve the above-mentioned conventional problems and reduce the memory capacity for storage/exchange without reducing transmission capability.

[Means for Solving the Problems] In order to achieve the above object, the videophone message storage and exchange system of the present invention provides the following features: Audio signal of the sound section and video 1 corresponding to the sound section
No. 3, sound duration information that is the cumulative time of the sound section, and a silence signal of a predetermined protection section following the sound section among the silent sections where the level of the audio signal does not reach a predetermined level. It is characterized by accumulating the video signal corresponding to the protected area. (b) If the video signal of the videophone message transferred from the first videophone terminal to the message center is transferred using a predictive coding method, the message center will be able to detect the change from a silent period to a voiced period. Another feature of the present invention is that it detects a point and requests the first videophone terminal to send a signal that is not interframe encoded. Furthermore, (c) the message center and the second videophone terminal are connected,
When transmitting a message from the message center to the second videophone terminal, the message center plays back the accumulated information as is in the sound section and the protection section behind the sound section, and in the silent section after the rear protection section. Then, for the audio signal, the sound section is restarted with no sound in the rear protection section of the sound section, and for the video signal, the video signal is made by freezing the video 1 & 2 after the rear protection section of the sound section, and the sound section is restarted. Another feature is that it can be played back up to and transmitted to the second videophone terminal.

[Function] In the present invention, a Bl channel for voice transmission and a B2 channel for video and data transmission are set by sending a call setting request signal between a videophone terminal and a message center, and the former The terminal then transmits digital information to the latter, thereby transmitting message information to other videophone terminals.

The message center detects the change point of the audio signal from a silent section to a sound section, and from a sound section to a silent section, and when a silent section is detected, a video signal that is not an interframe code is inserted from the videophone terminal. and send it.

The message center separates the digital information transmitted from each videophone terminal into an audio signal and a video signal, stores only the sound sections in each storage means, and then searches for a telephone message to be transmitted at an appropriate time. to play back the stored information,
Send digital information to the destination of the message. Note that the video information is protected by setting a protection section after the sound section among the silent sections.

[Example] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a videophone message storage and exchange system showing one embodiment of the present invention.

Here, first, the first videophone terminal 1 is connected to the message center 4.
A case will be explained in which the videophone terminal 1 and the message center 4 are connected via the digital telephone network 3 by calling, and then the message information for the second videophone terminal 2 is sent to the message center 4 to request a message. do. Thereafter, the message information is transmitted from the message center 4 to the second videophone terminal 2.

In FIG. 1, 1 and 2 are first and second videophone terminals, 3 is a digital telephone network, and 4 is a message center that provides a message service.

In this switching system, a first videophone terminal l and a second
videophone terminals 2 each connect to a digital subscriber line 5.
, 6 and the digital telephone network 3, and the digital telephone network 3 and the digital subscriber line 7
It is connected to the message center 4 via. Digital subscriber line 5 between digital telephone network 3 and videophone terminal 1.2
, 6 are basic interfaces (2B+D), and the third digital subscriber line 7 between the digital telephone network 3 and the message center 4 is a primary group interface (23B+D). Here, the basic interface is a multiplex of two B channels of 64 bits/second and one D channel of 16 bits/second, and the primary group interface is a connection of one optical fiber, etc. By bundling one D channel and 23 B channels on a public line, large-capacity transmission can be achieved.

The first and second videophone terminals 1 and 2 have the same configuration, including an audio processing section 11 that converts analog audio signals and digital audio signals, and an image processing section 12 that encodes video signals with high efficiency. , a keyboard 13 for setting up a call and having a conversation with the message center 4, and a data control unit 14 having functions for assembling a transmission frame for keyboard input information and video information, and for separating video information and a pig signal from the transmission frame.
and an I-interface 15 having a digital telephone network termination function. Note that the audio processing unit 11
and an analog audio signal 17,
The analog video signal 19 is sent and received by a telephone (not shown) such as a video telephone.

The message center 4 also includes an audio processing unit 41 that detects the level of the audio signal transferred from the first or second videophone terminal 1 or 2, and a voice processing unit 41 that detects the level of the audio signal transferred from the first or second videophone terminal 1 or 2. a storage section 42 that accumulates audio and video signals transferred from the network, a data control section 43 that assembles and separates transmission frames for data and video signals, and an interface 44 that has a terminal function for a digital telephone network. It is made up of.

Next, as an operation of the system, the first videophone terminal l
Information transmission between the message center 4 and the message center 4 will be described.

Between the first videophone terminal 1 and the message center 4, there is an 81 for voice transmission between the two interfaces 15 and 44 in response to a call setting request signal 16 from the keyboard 13 in the terminal 1.
82 channels for video and data transmission will be established. The analog audio signal 17 from the videophone terminal is converted into a digital audio signal 18 via the μ-1aw converter Ill of the videophone terminal l, and the interface 1
5 is transmitted to the I interface 44 of the message center 4 as a signal on the Bl channel. On the other hand, an analog video signal 19 from a video phone is converted to a digital video signal 20 via an AD converter 121, and further converted to a digital video signal 20 by an encoder 12.
Predictive encoding is performed in step 2, resulting in a compressed video signal 21. This compressed video signal 21 is assembled into a transmission frame for 82 channels by the data control section 14, and is manually inputted to the interface 15. The transmission signal 22 for the B2 channel is
(2) At the interface 15, the signal is transmitted to the I interface 44 of the message center 4 as a signal on 82 channels.

In the message center 4, the interface 44 separates the Bl and B2 channel tn signals received from the first videophone terminal l into a digital audio signal 23 and an 82-channel reception signal 24, and the former is connected to the audio processing unit 41. The latter is input to the storage unit 42, and the latter is data Mtlfff.
J43 separates the compressed video signal 25 and stores it in the storage section 4.
Enter 2. Note that the storage section 42 includes an audio information convex ridge section 422 that stores the digital audio signal 23, a video information storage section 423 that stores the compressed video signal 25, and a video information storage section 423 that stores and plays the digital audio signal 23 and the compressed video signal 25. It is composed of an accumulated information control section 421 that performs control.

FIG. 2 is a time chart of videophone message storage and readout control in FIG. 1.

Where is the first TV? ItIiI! The operation related to storage and playback control of a videophone message consisting of a digital audio signal 23 and a compressed video signal 25 transmitted from an i-terminal 1 will be explained.

First, the digital audio signal 23 is input to the inverse μ-1aw converter 412 in the audio processor 41 in the message center 4, and is converted into an analog audio signal 26 as shown in signal A in FIG. Next, in the audio level detection section 411, this analog audio signal 26 is compared with the base 1 audio signal, and the signal B shown in FIG. 2 is outputted to the audio level detection signal line 27.

The section ``]'' where the signal level is higher than the reference audio signal is the sound section, and the section ``0'' where the signal level is lower than the reference audio signal.
is called a silent section. The stored information control unit 421 further generates a signal having a protection section after the sound section in which the signal B continues for a certain period of time from the start of the silent section.

On the other hand, the storage start command is transferred from the keyboard 13 of the first videophone terminal 1 to the data control unit 14 and interface 15 via the signal line 28, and further sent to the message center 4 via the digital telephone network 3. , from the I interface 44 of the message center 4 to the data control unit 43
is input to the stored information control section 421 via the data line 29.

As a result, the storage information controller 42 generates a signal C indicating the storage target section from the storage start command.

Next, take the OR logic of signal B and signal B, and further OR
The logic result signal and the signal C are ANDed and this signal is sent to the audio control line 30 and the video control line 31 as the signal E for controlling the accumulation of videophone message signals. Here, the signal is.

This is to protect the sound section when other information is inserted into the silent section of signal B.

The audio information M ridge section 422 and the video information storage section 423 store the digital audio information 23 of the section corresponding to B of the signal E.
and compressed video signal 25, and operates to discard the digital audio signal 23 and compressed video signal 25 corresponding to "O".

As a result, in the signal F representing the digital audio signal 23,
a2. a3. a5. a6. In No. 18 G, in which only B2. B3. B
5. B6. Only B8 is accumulated.

On the other hand, in the accumulated information control section 421, from 0' to l of the signal E,
When a change point to
A refresh request signal for an interframe encoded video signal is input to the input terminal. The data control unit 43 converts this refresh request signal into an 82-channel transmission signal 33 and transmits it to the first videophone terminal 1 . First TV M-talk terminal 1
Then, this refresh request signal is input to the data control unit 14 as the 82-channel reception signal 34. The data control section 14 inputs this refresh request signal to the encoding section 122 via the encoding section control line 35. Encoding part! In step 22, a video signal that is not interframe encoded is transmitted.

As a result, video information corresponding to silent sections where the audio level is below a certain level is not stored. In this case, even if the silent section changes to a sound section and the accumulation of video information is resumed, if the interframe coding method is used, in order to compress the amount of data to be transmitted, Only the difference information is transferred. As a result, even if the video information is played back, there is no starting video information, so if the video is played back as is, the video will be distorted. Therefore, in preparation for resuming storage, a signal that is not interframe encoded is transmitted.

The signals H1 and I in FIG.
This is a signal obtained by inserting another audio signal and a video signal into the silent section of the compressed video signal 25. Here, a3
．． a6, b3 and b6 are the inserted audio and video signals.

Further, signal J is a signal obtained by taking the AND logic of signal B and signal C, and is used as management information of message center 4.

FIG. 3 is an explanatory diagram of videophone message management information managed by the stored information control section of FIG. 1.

In MM information control #421 in the message center 4, the third
It has management information for videophone messages as shown in the figure. Information that can be used as search keywords for videophone messages such as "message contact number" and "readout memorization number J" is as follows:
It is assumed that the message from the first episode of TV'W is transmitted from the keyboard 13 of the first videophone terminal l prior to accumulation.

Also, TV Ili#,! Message 1, 2, 3.
...N is time management information for the sound section and silent section for the message of the message contact number, and the sound section duration time, the silent section duration time, and the sound section rear protection duration time are the first This is a time-series representation of the audio signal level of a videophone message input from the videophone terminal l. Specifically, it is a count of the time when the sound section rear protection IIX synchronization opening time number is 1', and the sound section duration is the AND logic of signal B and signal C. This is a count of the duration of l'.

Next, the reading of the ri-seki videophone message will be explained with reference to FIGS. 1, 2, and 3.

After calling the message center 4 from the second videophone terminal 2 and connecting to the message center 4, the first videophone terminal l
When a request to read a videophone message addressed to the second videophone terminal 2 (including the message contact number and readout PIN number) is input to the data control unit 43 of the message center 4, this readout request information is sent to the data line. 29 to the stored information control unit 421. M product information control unit 42
1, search and obtain the management information (information shown in Figure 3) of the corresponding videophone message from the message contact number,
For the sound section, calculate the difference between the silent section duration Ti and the sound section backward protection duration T,
If the value is positive, the first T seconds are l' and the remaining (Ti
-T) seconds is set to 0', and if it is negative, a signal E is generated with Ti seconds set to 1'. The stored videophone messages are played back in the following steps.

The stored information control unit 421 transmits the signal E generated as described above via the audio control line 30 and the video control line 31. The audio information storage section 422 stores the stored digital audio information during the period when the signal E is 1', and stores the stored digital audio information during the period when the signal E is 0'. No. 13 of the protected area of nJ is repeatedly inserted. Thereafter, when the signal 11 (digital audio information 36) in which the stored digital audio information continues is outputted to the 1 interface 44. On the other hand, regarding video information, in the video information storage section 423, the signal E is
The compressed video information multiplied by rJ is sent, and while the signal E is 0', video information obtained by making the video information of the immediately preceding protection section still is repeatedly inserted. Thereafter, when the signal becomes Il+, a signal (2) (compressed video information 37) in which the stored video information continues is outputted to the interface 44 via the data control section 43. Here, as a method for freezing the video information, if the encoding method is interframe predictive encoding, it is sufficient to continue transmitting a signal with a difference of O. The videophone message thus reproduced is transmitted from the I interface 44 of the message center 4 to the I interface of the second videophone terminal 2, and output to the display or telephone of the videophone terminal 2.

As described above, in the present invention, since the level signal of the audio signal, which plays an important role in message transmission, is used as the videophone message storage control signal, it is possible to reduce the amount of messages stored. In addition, since the information of the section with low audio level was deleted, the interframe “f”
- When using the measurement coding method, the quality deteriorates when the video after deletion is played back, but by sending a refresh request signal synchronized with the M product restart signal from the message center side, the video quality can be improved. deterioration can be prevented.

[Effects of the Invention] As explained below, according to the present invention, it is possible to reduce the amount of accumulated message videophone messages without reducing the message transmission ability, thereby making it possible to transmit videophone messages economically. Store and exchange can be realized. Furthermore, even if information about sections with low audio levels is deleted, it is possible to prevent deterioration of video quality.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a videophone message storage and exchange system showing an embodiment of the present invention, FIG. 2 is a time chart for controlling storage and readout of videophone messages in FIG. 1, and FIG. FIG. 2 is an explanatory diagram of videophone message management information managed by the stored information control unit of FIG. 1; l: first videophone terminal, 2: second videophone terminal, 3: digital telephone network, 4: message center, 5, 6, 7
: Digital subscriber line, 11: Audio processing section, 12: Image processing section, 13: Keyboard, 14: Data control section, 15
．． 44+1 interface, 27: Audio level detection signal line, 28: Keyboard signal line, 29,327 data line,
30: audio control line, 31: video control line, 35: encoding section control line, 41: audio processing section, 42: storage section, 43: data control section,! +1: μ-1aw conversion unit, 121: AD conversion unit, 122: encoding unit, 411: audio level detection unit,
412: inverse μ-1aw conversion unit, 422: audio information storage unit, 423: video information storage unit, 421: storage information control unit. +0 0

Claims (3)

[Claims] (1) From the first videophone terminal to the message center,
When a videophone message consisting of video and audio addressed to the second videophone terminal is transmitted via an independent information channel of the digital telephone network, the message center stores the received videophone message and transmits the videophone message to the second videophone terminal. In the videophone message storage and forwarding method, which reads the stored videophone message and transmits the message to a second videophone terminal after the terminal and the message center are connected, the message center An audio signal of a sound section in which the audio signal constituting the telephone message is at a predetermined level or higher, a video signal corresponding to the sound section, and sound duration time information that is the cumulative time of the sound section; A silent signal of a predetermined protected section following the sound section among the silent sections in which the level of the audio signal does not reach the predetermined level, and a video signal corresponding to the protected section are stored. Features videophone message storage and exchange system. (2) If the video signal of the videophone message transferred from the first videophone terminal to the message center is transferred using a predictive coding method, the message center 2. The videophone message storage and forwarding system according to claim 1, wherein the videophone message storage and forwarding system detects a change point to the first videophone terminal and requests the first videophone terminal to send a signal that is not interframe encoded. (3) When the message center and the second videophone terminal are connected and a message addressed to the second videophone terminal is transmitted from the message center, the message center In the protection interval behind the sound interval, the accumulated information is played back as is, and in the silent interval after the rear protection interval, the silence in the protection interval behind the sound interval is played for the audio signal, and the sound is played back for the video signal. Claim (1) characterized in that the video signal in which the last video of the rear protection section of the section is frozen is played back until the sound section is restarted and transmitted to the second videophone terminal. Videophone message store-and-forward method described.