JPH09214561A - Multimedia communication system, inter-work equipment and multimedia communication terminal equipment used for the system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate a multi-point communication by giving the information of a multimedia communication attribute of a line connected to a multimedia communication terminal equipment to a communication terminal equipment connecting to either a public line network or a LAN line. SOLUTION: An inter-work equipment 1 receives an incoming call from a multimedia communication terminal equipment 41 on a public line network to a multimedia communication terminal equipment 21 on a LAN line 2. Then an incoming call is informed to the terminal equipment 21 on the line 2 and the connection of the line is set. Then a protocol is converted so that inter- terminal communication of control information is made between the terminal equipment 21 on the line 2 and the terminal equipment 41 on the public line network (N-ISDN). A capability information exchange sequence is conducted between the terminal equipments 21, 41 to allow them to device at least one of the voice coding mode, the video coding mode and an application transmission rate or the like, preferably all of the communication modes and the result information is given also to the inter-work equipment 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multimedia communication system, an interworking device and a multimedia communication terminal, and in particular, it is possible to multiplex multimedia information such as video / audio / data to mutually communicate. LAN (Local arca netwo) for multimedia communication terminals typified by various videophones and conference systems.
rk) multimedia communication terminal connected to the line,
The present invention relates to a multimedia communication system for enabling mutual communication with a multimedia communication terminal connected to a public line network such as PSTN / ISDN line via an interwork device.

[0002]

2. Description of the Related Art In recent years, due to rapid increase in speed, increase in capacity, increase in function, and reduction in price of personal computers (hereinafter referred to as PCs), ITU-T / ISO and the like have successively recommended and standardized them. Is being promoted, and full-scale spread of multimedia communication services such as video information, audio information, and data has been promoted.

In particular, narrow band ISDN lines (hereinafter referred to as NI
It is referred to as SDN) ITU-T Recommendation H. The multimedia communication based on the 320 series is expected to rapidly spread as a practical standard for various PC conference systems.

At the same time, broadband ISD, which is a future communication network
A used as a communication protocol over N (hereinafter referred to as B-ISDN) or a higher-speed LAN line
ITU-T as multimedia communication based on TM communication
Recommendation H. 310 series and ITU-T Recommendation H.264 for multimedia communication application to PSTN lines. The 324 series, etc. are also being specified in order.

In addition, LAN facilities as a corporate network are rapidly spreading due to the spread of PCs, and
Is used by being connected to a LAN such as Ethernet. In addition, ITU-T Recommendation H.264 is applied to the application of multimedia communication to ISV LAN and the like with guaranteed bandwidth. 322
Although the series is being defined, there is no provision for recommendations to be applied to multimedia communication on a LAN that is usually provided as a corporate LAN and is not guaranteed in bandwidth.

In order to perform multimedia communication between a PC connected to a corporate LAN and a PC connected to a public network, a device for interworking the LAN and a public network such as PSTN / ISDN, that is, Generally, an interwork device called a gateway or a router is required.

In the above interworking device, LA
Protocol conversion between N communication protocol and various communication protocols of public network such as PSTN / ISDN, control for absorbing speed difference between LAN / public network, and in some cases, audio / video information coding conversion processing And so on.

ITU-T currently defined as a standard
Recommendation H. In the 320 series, ITU-T Recommendation H.264 is used. 221 defines a multimedia multiplexing frame structure. FIG. 5 shows N-ISDN 64 kbps.
H.x on 1 × 1 channel. It is a figure which shows a 221 frame structure, and the numbers 1-8 of a horizontal axis are bit numbers. Also,
The numbers from 1 to 80 on the vertical axis are octet numbers, and NI
One frame is composed of 80 octets transmitted on the 1B channel on the SDN.

FAS (frame synchronization signal) in FIG.
By this, control of frame synchronization / multi-frame synchronization, communication quality monitoring function, alarm information notification, and the like are performed.
ITU-T H242. Then in-channel BAS
Communication procedures such as capability information exchange sequence and mode switching sequence using (bit allocation signal) are defined. ITU-TH. 230 specifies various control and notification signals necessary for multimedia communication.

On the other hand, ITU-TH. In 261, px
It stipulates encoding / decoding of moving image information at a speed of 64 kbps (p = 1 to 30). ITU-T
H. Reference numeral 320 denotes a system aspect of the entire multimedia communication using N-ISDN. The voice coding G series recommendation to be applied in other multimedia communication and MLP (Multi Layer) as data communication system control.
The T120 series recommendations, etc. to be adopted under the Red Protocol) are also being specified in sequence.

The existing interworking device for multimedia communication for interworking between ISDN and LAN controls interworking between ISV LAN and ISDN, and LAN side has a large capacity communication of video / audio information. Many have assumed a special LAN for use. In addition, it supports some popular LAN such as Ethernet,
Some products that tried to perform their own interwork control have become available.

[0012]

However, in the above-mentioned conventional multimedia communication system, since the LAN side is a LAN different from the LAN for the OA network, it can be used from a PC connected only to the normal OA network. I couldn't. Therefore, conventionally, L
Since the AN had to be installed separately and was expensive, it did not spread widely.

Further, the protocol conversion / encoding conversion on the interwork device has not been considered optimally.
In addition, considering that multipoint communication between a plurality of terminals connected to a LAN line and a public network terminal can be easily performed without a large-scale multipoint control device, communication on the public network and LAN is considered. An interworking device, which takes into consideration the difference in speed and the like so as not to waste communication traffic on the LAN, has not yet been obtained.

The present invention has been made in view of the above problems, and makes it possible to easily realize interworking between a multimedia communication terminal on a LAN line and a multimedia communication terminal on a public line network. Is the first purpose.

A second object is to enable interworking with a multimedia communication terminal on a public line network from each PC / WS connected to a computer network for OA.

Further, it is possible to easily enable multipoint communication between a plurality of multimedia communication terminals connected to a LAN line and a multimedia communication terminal connected to a public line network. A third object is to be able to carry out the traffic connected to the network without unnecessarily increasing the traffic.

[0017]

The interworking device of the present invention enables mutual communication between a multimedia communication terminal connected to a LAN line and a multimedia communication terminal connected to a public line network. In an interworking device capable of performing, a connection line multimedia communication attribute with a multimedia communication terminal connected to one of the public line network and the LAN line is set to one of the public line network and the LAN line. It is characterized by having a communication attribute notifying means for notifying a multimedia communication terminal connected to the other.

Another feature of the present invention is that
It is characterized by further comprising a conversion means for converting the communication control information between the public line network and the LAN line.

Further, the multimedia communication terminal of the present invention, when the connection line communication attribute with the multimedia communication terminal connected to the public line network is notified, based on the notified connection line communication attribute, It is characterized by having a communication mode selection means for selectively controlling at least one communication mode of a voice encoding system, a video encoding mode, and an applicable transmission rate during mutual communication with a multimedia communication terminal on a public line network.

The multimedia communication system of the present invention converts analog voice information from analog to digital,
Audio information encoding means for encoding in accordance with a specified encoding method, audio information output means for decoding the encoded audio information and digital-to-analog converting and outputting as analog audio information, and analog video information Video information coding means for analog-to-digital conversion of the above and coding according to a designated coding method, and video information output for decoding the above-mentioned coded video information and performing digital-to-analog conversion to output as analog video information Means, multimedia information transmitting means for multiplexing the multimedia information composed of the encoded audio information and video information, and transmitting the multiplexed information via the LAN line; and, when receiving the multiplexed multimedia information, Multimedia information for separating the multiplexed multimedia information and decoding each information Similarly to the multimedia communication terminal connected to the LAN line having a communication means and the multimedia communication terminal connected to the LAN line, multimedia information is encoded / decoded / multiplexed to mutually communicate. A multimedia communication terminal connected to a public line network including PSTN / ISDN, and the above LA
A multimedia communication system comprising an interworking device for interworking between a multimedia communication terminal connected to an N line and a multimedia communication terminal connected to the public line network, A communication attribute notifying unit for notifying the multimedia communication terminal connected to the LAN line of the communication line communication attribute with the multimedia communication terminal connected to the network; and the connection line communication attribute notified by the communication attribute notifying unit. And a communication mode selection means for selectively controlling a communication mode including a voice coding method, a video coding mode, and an applicable transmission rate when performing mutual communication with the multimedia communication terminal connected to the public line network based on the above. Is characterized by.

Another feature of the present invention is that
First information exchanging means for exchanging capability information with the multimedia communication terminal connected to the LAN line, and second information exchanging means for exchanging capability information with the multimedia communication terminal connected to the public line network. A communication mode selecting means for selecting a communication mode that minimizes a processing load in the interwork device, and a multimedia communication terminal connected to the public line network for the communication mode selected by the communication mode selecting means, And communication mode notifying means for notifying the multimedia communication terminal connected to the LAN line, and conversion processing means for performing protocol conversion processing and encoding conversion processing according to the communication mode notified by the communication mode notifying means. It is characterized by that.

Another feature of the present invention is that the multipoint communication is performed between the multimedia communication terminal connected to the LAN line and the multimedia communication terminal connected to the public line network. Communication for selecting a communication mode so as to minimize the processing load on the interwork device according to the capabilities of the communication control means for controlling the communication and the plurality of multimedia communication devices participating in the multipoint communication. It is characterized by having a mode selection means.

Further, another feature of the present invention is that multipoints are provided between a plurality of multimedia communication terminals connected to the LAN line and the multimedia communication terminals connected to the public line network. It is characterized by having a transmission rate control means for controlling the transmission rate on the LAN line or the public line network so that the applied transmission rate control at the time of intercommunication is adjusted to the slowest transmission rate.

[0024]

Since the present invention comprises the above technical means, it is easy to realize interworking between a multimedia communication terminal connected to an ordinary LAN line as an OA network and a multimedia communication terminal on a public line network. Therefore, it is possible to provide an interworking system in which the interworking processing load of the interworking device that realizes the above interworking is extremely small.

According to another feature of the present invention, a LAN
It is possible to inexpensively construct a multimedia communication system capable of interworking between a plurality of multimedia communication terminals on a line and a multimedia communication terminal on a public line network.

According to another characteristic of the present invention, L
To establish a multipoint multipoint multimedia communication interwork between a plurality of multimedia communication terminals on an AN line and a multimedia communication terminal on a public line network without unnecessarily increasing the traffic on the LAN line. Is possible.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a multimedia communication system of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram showing an embodiment of a multimedia communication system according to the present invention.

In FIG. 1, 1 is a LAN line which is a computer network communication line, and PSTN / ISD.
It is an interworking device that controls interworking with a public network such as N. The interworking device 1 of the present embodiment is for enabling mutual communication between a multimedia communication terminal connected to the LAN line and a multimedia communication terminal connected to the public line network. The connection line communication attribute with the multimedia communication terminal connected to the public line network is set to the LAN.
It has a communication attribute notifying means for notifying the multimedia communication terminal connected to the line.

Reference numeral 2 is a LAN line such as Ethernet / talk ring / FDDI / ATM / LAN which is installed as a private computer network connection communication line.
Reference numerals 21, 22, and 23 are multimedia communication terminals connected to the LAN line 2, and are constructed based on a PC (personal computer) or the like.

The multimedia communication terminals 21 to 23 connected to the LAN line 2 convert the voice information from analog to digital and encode the voice information according to a designated encoding method, and the voice information. And audio information output means for decoding the audio information coded by the information coding means and for performing digital / analog conversion and outputting as analog audio information.

Further, the video information coding means for analog-digital converting the analog video information and coding it according to a designated coding method, and the video information coded by the video information coding means are decoded to digital. -It has a video information output means for performing analog conversion and outputting as analog video information.

Further, multimedia information transmitting means for multiplexing and transmitting the multimedia information including the encoded audio information and video information via a LAN line,
And a multimedia information receiving means for separating the multiplexed multimedia information and decoding each information when receiving the multiplexed multimedia information.

31 and 32 are PSTN / N-ISDN / B
-A public network such as ISDN. Reference numerals 41 and 42 denote multimedia communication terminals connected to the public line network.
The multimedia communication terminal connected to the public line network, like the multimedia communication terminal connected to the LAN line, encodes / decodes / multiplexes multimedia information to communicate with each other.

FIG. 2 is a block diagram showing an outline of the multimedia communication terminal of this embodiment. 201 in FIG.
Is a video input unit such as a camera / VTR, and 202 is a display unit such as a display monitor for displaying video information and data information. Reference numeral 203 is a voice input unit such as a microphone, and 204 is a voice output unit such as a speaker.

Reference numeral 205 denotes an operation unit such as a keyboard / mouse for inputting operations of the multimedia communication terminal and inputting data and the like. Reference numeral 206 denotes A / D conversion / D of a video signal for converting an analog video signal and a digital video signal.
An A / A conversion function and a video interface unit for selecting / switching input / output video signals.

Reference numeral 207 is a voice signal A / D conversion / D / A conversion function for converting an analog voice signal and a digital voice signal, and a voice interface unit for selecting / switching input / output voice signals. Reference numeral 208 denotes an image synthesizing unit that performs image synthesizing processing of the self-image / receiving partner image and data information to be displayed displayed by the system control unit.

Numeral 209 is a video information coding / decoding means for carrying out the processing of coding the digitized video signal in the designated coding mode and the processing of decoding the received coded video information. .

Reference numeral 210 is a voice encoding / decoding means for performing the process of encoding the digitized voice information in the designated encoding mode and the process of decoding the received encoded voice information.

Reference numeral 211 denotes multimedia demultiplexing control means, which is encoded video information output from the video encoding / decoding means 209, encoded audio information output from the audio encoding / decoding means 210, and a system. Control unit 213
Multimedia multiplexing means for multiplexing multimedia information such as data instructed further, and multimedia multiplexing information received from the LAN line control means 212 are separated into video information, audio information, data, etc. It has an encoding / decoding unit 209, a speech encoding / decoding unit 210, and an output unit for outputting to the system control unit 213.

Reference numeral 212 is a LAN line control means for controlling connection with the LAN line 2 and actual information transmission / reception control.
The LAN line control means 212 is the LAN line control means in the case of the multimedia communication terminals 21, 22, 23, but the multimedia communication terminal 4 connected to the public line network.
In the case of 1 and 42, each multimedia communication terminal 4
Depending on the public line to which 1 and 42 are connected, it becomes a PSTN line control means or an ISDN line means.

A system control unit 213 controls the entire multimedia communication terminal, and controls the overall operation such as input / output control of data information, control means and instruction control of each unit. A storage unit 214 stores multimedia information and various control information, and includes a memory and an H
D and the like.

FIG. 3 shows the LAN line 2 and the public line network 3 in the multimedia communication system of this embodiment.
It is a block diagram which touches the schematic structure of the interworking apparatus which interworkes with 1, 32, and 33.

In FIG. 3, reference numeral 101 denotes LAN line control means for controlling communication on the LAN line side, reference numeral 102 denotes multiplexed transmission of multimedia information on the LAN line 2, and the LAN.
This is a LAN-compatible multimedia demultiplexing control means for demultiplexing the received multimedia multiplexed information on the line 2.

Reference numeral 103 is a video encoding / decoding control means for encoding / converting video information as necessary, 104 is an audio encoding / decoding control means for encoding / converting audio information as necessary, and 105 is data or It is a data encoding / decoding means for converting control information as necessary.

Reference numeral 116 is a video selection / synthesis means for selectively switching and switching video information from a plurality of multimedia communication terminals, and 117 is a selective switching for audio information from a plurality of multimedia communication terminals. , Voice selection / synthesis control means for performing voice synthesis processing.

Reference numeral 106 denotes a protocol conversion means for converting the communication protocol on the LAN line and the communication protocol on the public line network. N-ISDN-compatible demultiplexing means 107 is an N-ISDN line-compatible multimedia multiplexer, for example, ITU-T Recommendation H.264. 221 for controlling demultiplexing of multimedia information.

Reference numeral 108 denotes PSTN demultiplexing means,
Multimedia multiplexing for STN lines, eg ITU
-T Recommendation H. 223 for controlling multimedia demultiplexing.

Reference numeral 109 is a B-ISDN demultiplexing control means, which is a B-ISDN line compatible multimedia multiplexing unit.
For example, ITU-T Recommendation H.264. It performs multimedia demultiplexing control according to 222. 110 is N-ISDN
It is a line control means and controls communication with the N-ISDN line.

Reference numeral 111 is a PSTN line control means for controlling communication with the PSTN line, and 113 is B-ISDN line control means for controlling communication with the B-ISDN line. Reference numeral 114 is a system control unit that controls the entire interworking apparatus, and 115 is a memory / H that stores various information.
A storage unit such as D.

FIG. 4 shows the LAN line and NI of this embodiment.
It is a figure which shows the data flow which shows an example of protocol conversion / coding conversion at the time of interworking with an SDN line.

In FIG. 4, reference numeral 501 denotes V (video information), A1 (audio coded information) and D, which are transmitted on the LAN line 2.
It is a packet in which (data information) and C (control information) are multiplexed and transmitted.

Reference numeral 502 is video coded information V, and 503 is the first.
Voice encoding information A1 and 504 is data information D and 505.
Is control information C, which is information separated by the LAN demultiplexing control means 102.

Reference numeral 506 is a video information coding / converting means, 507.
Is a voice information coding / converting means, 508 is a data information coding / converting means, and 509 control information converting means, and is a conversion process when it is necessary to convert the coded information when multiplexing the above various information to N-ISDN. Is for doing.

Reference numeral 510 indicates the second voice coded information A2 on the ISDN, and reference numeral 511 indicates H.264. Control information BAS on 221
, 512 also indicates control information on the MLP.
Here, the speech coded information is converted from the first speech coded information A1 to the second speech coded information A2 by the speech information conversion means.
And that the control information C has been converted into the control information BAS511 on the H221 and the control information 512 on the MLP.

Of course, the second received from the ISDN line side
Of the speech coded information A2 is converted into the first speech coded information A1, and the control information BAS and the control information on the MLP are LA.
It is converted into control information C on the N line. Here, it is indicated that the video coding information V and the data information D have not been converted.

N-ISDN compatible demultiplexing control unit 107
Is the video coding information V and the second audio coding information A described above.
2, the data information D, the control information BAS, and the MLP are multiplexed, and H.264 shown in 513. The multimedia information is multiplexed into the 221 frame structure and transmitted. On the contrary, N-ISD
The frame 513 received from N is separated and output to each media information. Of course, the above is an example for simplifying the description, and various other combined controls are conceivable.

FIG. 6, FIG. 7 and FIG. 8 are flowcharts showing the operation procedure of this embodiment. Hereinafter, the first embodiment will be described in detail with reference to the flowchart of FIG. First,
In step S101, the interwork apparatus 1 receives an incoming call from the multimedia communication terminal 41 on the public line network to the multimedia communication terminal 21 on the LAN line 2.

Next, in step S102, the LAN line 2
Notify the corresponding communication terminal 21 of the incoming call, set the connection on the LAN line 2, and
It is an N-ISDN incoming call and the applicable transmission rate is 64 kbp.
Notify that it is s / 128 kbps.

Next, in step S105, the LAN line 2
Protocol conversion is performed between the upper communication terminal 21 and the communication terminal 41 on the public network (N-ISDN) so that communication between the terminals of control information can be performed, and the communication terminal 21 and the communication terminal A capability information exchange sequence is performed with 41 to determine at least one, preferably all communication modes such as a voice coding mode, a video coding mode, and an applicable transmission rate.

Next, in step S106, the multimedia communication terminal 21 on the LAN line 2 also notifies the interwork device 1 of the communication mode determined in step S105.

Next, in step S107, it is determined whether an additional connection is required in the communication mode. Then, as a result of the above determination, if an additional connection is required, the process proceeds to step S108 to set the additional connection. ITU-T Recommendation H.264. According to the 320 series, the calling side of the first connection also calls the required additional connection. If the additional connection is no longer needed, the process proceeds to step S109 to actually determine and start the multimedia communication to which the communication mode determined previously is applied.

Contrary to the above description, step S1
As shown in 03, when the multimedia communication terminal 21 on the LAN line 2 makes a call request to the communication terminal 41 on the public line network (N-ISDN line network), the process proceeds to step S104. Work device 1 is applicable terminal 4
Make a call to 1 and set the connection,
The setting result is notified to the communication terminal 21 that made the call request.

Since the above description has been made with respect to the mutual communication with the terminal on the N-ISDN line, the applicable transmission rate is 64 kbps / 128 kbps. But,
In the case of PSTN, the transmission rate negotiated by the connection between modems is notified.

After step S109, according to the communication mode determined as described above, the interwork apparatus 1 does not perform any encoding conversion on the encoded video / audio / data, etc. Interworking is done just by converting. For control information, L
Since the control information on the AN line 2 and the control information transmitting means on the N-ISDN are different, code conversion is also performed.

In the case of PSTN or B-ISDN,
ITU-T Recommendation H. It is considered that the communication procedure is similarly defined by H.245, but since the communication procedure on the LAN line 2 has not been determined, code conversion is also required for the time being.

(Second Embodiment) Next, the second embodiment of the present invention will be described in detail with reference to the flowchart of FIG. First, in step S201, the interwork device 1 receives an incoming call from the multimedia communication terminal 42 on the public line network to the multimedia communication terminal 22 on the LAN line 2.

Next, in step S202, the multimedia communication terminal 22 on the LAN line 2 is notified of an incoming call and a connection is set, and at the same time, the multimedia communication terminal 22 is provided with the capability of encoding and decoding. get. Proceeding to step S205, the interworking device 1 performs the capability exchange sequence on behalf of the multimedia communication terminal 42 on the public line network, and both the multimedia communication terminals 2 obtained by the capability information exchange sequence.
The final applicable coding mode, the applicable transmission rate, etc. are determined so that the processing load on the interworking device 1 is reduced in consideration of the capabilities of Nos. 2 and 42 and the capability of the interworking device 1.

Next, in step S206, it is determined whether or not there is an additional connection. For example, in the case where the communication line is an N-ISDN line and additional connection setting is required, the process proceeds to step S207 to set and establish the additional connection. Call control conditions are N-ISD
The case of N is as described in the first embodiment.

Next, in step S208, the communication mode determined above is notified to the terminal 22 on the LAN line 2. In step S209, multimedia multiplex communication in the applicable communication mode is executed while performing protocol conversion / encoding conversion in the interwork device 1 as necessary.

On the contrary, in step S203, L
When the call request to the multimedia communication terminal 42 on the public line network is received from the multimedia communication terminal 22 on the AN line 2, the process proceeds to step S204. The interwork device 1 establishes a connection with the corresponding multimedia communication terminal 42 and acquires the capability of the calling multimedia communication terminal 22 on the LAN line 2. After that, the process proceeds to step S205, and the same operation as described above is performed.

For example, as shown in FIG. 4, the LAN line 2
Above is packet communication in the form of voice coded information A1,
H.264 on the N-ISDN line. The speech coding conversion processing means 507 performs coding conversion so that the 221 frames are mutually communicated in the format of the speech coding information A2.

Similarly, the control information C is communicated on the LAN line 2 in a packet format, but on the N-ISDN, it is H.264. In order to code as BAS information on 221 or as control information on MLP, the data coding conversion processing means 509 performs coding conversion processing. The selection of the voice coding A1 and the N-ISDN voice coding information A2 on the LAN line 2 is determined by the interworking device 1 by selecting the optimum coding due to its processing load.

In the above embodiment, only the interworking between the N-ISDN and the LAN line 2 is described, but the same processing can be performed between the LAN line 2 and other public networks such as PSTN / B-ISDN. .

(Third Embodiment) Next, the third embodiment will be described in detail with reference to the flowchart of FIG. First, in step S301, a connection is set up for multimedia communication between the multimedia communication terminals 21 and 22 on the LAN line 2.

Next, in step S302, the LAN
An appropriate communication speed is determined based on the current traffic on the line 2 and various actual communication modes are determined. next,
In step S303, multimedia communication according to the video coding mode, the audio coding mode, and the applied transmission rate according to the communication mode determined above is performed between the communication terminals of the LAN line 2.

Next, in step S304, it is monitored via the interwork apparatus 1 whether or not a request for participation in the multimedia communication is made from the multimedia communication terminal connected to the public network. As a result of the monitoring in step S304, when it is detected that the participation request incoming call is made, the process proceeds to step S305, and the interworking device 1 is capable of communicating with the calling terminal connected to the public network on the LAN line 2. To exchange capability information.

Next, in step S306, the communication mode in which the load of the protocol conversion / encoding conversion process on the interwork device is optimal is determined based on the result of the capability information exchange, and the communication mode on the LAN line 2 is determined. A request for changing the communication mode of multimedia communication is notified to the communicating terminal.

Next, in step S307, the LAN
It is monitored whether the terminal-to-terminal communication mode on the line 2 is ready to be changed to the notified new communication mode. And when you are ready to change to the new communication mode, next,
Progressing to step S308, multipoint multimedia communication including terminals on the public network is started.

In the above description, the applicable transmission rate during the communication mode may be matched to the terminal to which only the slowest speed can be applied. For example, a terminal on the PSTN line network can handle only 28.8 kbps, but the transmission rate on the LAN line 2 remains high and the interwork device adjusts the transmission rate. The communication mode of the multimedia communication terminal for performing multipoint communication is controlled so as not to continue the communication mode that increases the extra processing of.

Of course, if the public line network is capable of applying a higher transmission rate than the ordinary Ethernet LAN line 2 in the B-ISDN, conversely, by limiting the transmission rate on the public line network side, , B-ISDN can be controlled so as not to increase the traffic unnecessarily.

In the above description, only the interworking between the LAN line 2 of the private network and the public line networks 31 and 32 such as PSTN / ISDN has been described. However, the present invention is not limited to PSTN / N-ISDN.
The present invention is also applicable to interworking between public line networks such as / B-ISDN, etc. and exactly the same as interworking with CATV and the like.

[0082]

As described above, the present invention realizes interworking between a multimedia communication terminal on a LAN line and a multimedia communication terminal on a public line network without making a large-scale and expensive investment. A multimedia communication system can be provided. In particular, each PC / WS connected to the OA computer network can interwork with a multimedia communication terminal on a public line network, and can communicate with a plurality of multimedia communication terminals on a LAN line. LA is a means for easily performing multipoint communication with a multimedia communication terminal on a public line network.
It becomes possible to provide the traffic on the N line without unnecessarily increasing the traffic, and the PC-based multimedia communication connected to the ordinary LAN line as the OA network and the multimedia communication terminal on the public line network. Interworking can be easily realized.

Further, according to another feature of the present invention, it is possible to provide an interwork system in which the interwork processing load of the interwork device for realizing the above interwork is extremely small.

According to another feature of the present invention, L
It is possible to inexpensively construct a multimedia communication system capable of interworking between a plurality of multimedia communication terminals on an AN line and a multimedia communication terminal on a public line network.

According to another feature of the present invention, L
Multipoint-to-point multimedia communication interwork between a plurality of multimedia communication terminals connected to an AN line and a multimedia communication terminal on a public network without increasing the traffic connected to a LAN line unnecessarily. Can be built.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a multimedia communication system of the present invention.

FIG. 2 is a block diagram showing an embodiment of a multimedia communication terminal.

FIG. 3 is a block diagram showing an embodiment of an interworking device.

FIG. 4 is a diagram showing an example of a data flow for explaining an embodiment of interworking of multimedia multiplexed communication on a LAN line and an ISDN line.

FIG. 5: ITU-T Recommendation H.264 over narrowband ISDN. 22
It is a 1-frame block diagram.

FIG. 6 is a flowchart showing the first embodiment.

FIG. 7 is a flowchart showing a second embodiment.

FIG. 8 is a flowchart showing a third embodiment.

[Explanation of symbols]

1 Interworking device 2 LAN line 21, 22, 23 Multimedia communication terminal connected to LAN line 31, 32 Public line network 41, 42 Multimedia communication terminal connected to public line network 101 LAN line control means 102 LAN line Corresponding multimedia demultiplexing means 103 Video coding / decoding control means 104 Audio coding / decoding control means 105 Data coding / decoding control means 106 Protocol conversion means 107 N-ISDN compatible demultiplexing means 108 PSTN compatible demultiplexing means 109 B -ISDN compatible demultiplexing means 110 N-ISDN line control means 111 PSTN line control means 113 B-ISDN line control means 114 System control section 115 Storage section 116 Video selection / synthesis means 117 Audio selection / synthesis means 201 Video input section 20 Display unit 203 Audio input unit 204 Audio output unit 205 Operation unit 206 Video interface unit 207 Audio interface unit 208 Image synthesis processing unit 209 Video encoding / decoding control unit 210 Audio encoding / decoding control unit 211 Multimedia demultiplexing control unit 212 LAN line control means 213 system control unit 214 storage unit

Claims (7)

[Claims] 1. An interworking device that enables mutual communication between a multimedia communication terminal connected to a LAN line and a multimedia communication terminal connected to a public line network, Connection line between multimedia communication terminal connected to either public line network or LAN line Notify multimedia communication terminal connected to either the public line network or LAN line of multimedia communication attribute An interworking device having a communication attribute notifying means for performing the communication. 2. The interworking apparatus according to claim 1, further comprising a conversion unit that performs code conversion of communication control information between the public line network and the LAN line. 3. A multimedia communication terminal on the public line network based on the notified connection line communication attribute when the connection line communication attribute with the multimedia communication terminal connected to the public line network is notified. A multimedia communication terminal comprising communication mode selection means for selectively controlling at least one communication mode of an audio encoding system, a video encoding mode, and an applicable transmission rate during mutual communication with the communication terminal. 4. A voice information coding means for analog-digital converting analog voice information and coding it according to a designated coding method, and decoding and digital-analog converting the coded voice information. Audio information output means for outputting as analog audio information, video information encoding means for performing analog / digital conversion of analog video information and encoding according to a specified encoding method, and decoding the encoded video information. A video information output means for digital / analog converting and outputting as analog video information, and a multimedia information transmitting means for multiplexing the multimedia information including the encoded audio information and video information and transmitting the multiplexed information via the LAN line. And when the multiplexed multimedia information is received, the multiplexed multimedia information is received. A multimedia information receiving means for separating information and decoding each information
A multimedia communication terminal connected to an N line and a terminal that performs mutual communication by encoding / decoding / multiplexing multimedia information, like the multimedia communication terminal connected to the LAN line. PSTN / ISD
Interwork communication between a multimedia communication terminal connected to a public line network including N, a multimedia communication terminal connected to the LAN line, and a multimedia communication terminal connected to the public line network In a multimedia communication system constituted by an interwork device, a communication attribute notification for notifying the multimedia communication terminal connected to the LAN line of the connection line communication attribute with the multimedia communication terminal connected to the public line network Means, and a voice coding method, a video coding mode, and applicable transmission for mutual communication with the multimedia communication terminal connected to the public line network based on the connection line communication attribute notified by the communication attribute notifying means. Communication mode selecting means for selectively controlling a communication mode including a rate. -Media communication system. 5. A first information exchanging means for exchanging capability information with the multimedia communication terminal connected to the LAN line, and a second information exchanging means for exchanging capability information with the multimedia communication terminal connected to the public line network. Information exchange means, communication mode selection means for selecting a communication mode that minimizes the processing load on the interwork device, and the communication mode selected by the communication mode selection means is connected to the public line network. Multimedia communication terminal,
And communication mode notifying means for notifying the multimedia communication terminal connected to the LAN line, and conversion processing means for performing protocol conversion processing and encoding conversion processing according to the communication mode notified by the communication mode notifying means. The multimedia communication system according to claim 3, wherein: 6. A communication control means for controlling multipoint communication performed between the multimedia communication terminal connected to the LAN line and the multimedia communication terminal connected to the public line network, and the communication control means. Communication mode selecting means for selecting a communication mode so as to minimize the processing load on the interworking device according to the capabilities of a plurality of multimedia communication devices participating in point-to-point communication. The multimedia communication system according to claim 3. 7. An applicable transmission rate control for multipoint communication between a plurality of multimedia communication terminals connected to the LAN line and a multimedia communication terminal connected to the public line network. 6. The multimedia according to any one of claims 3 to 5, further comprising a transmission rate control means for controlling the transmission rate on the LAN line or the public line network so as to match the slowest transmission rate. Communications system.