JP2005311670A - Terminal, system and method for television conference, and program therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a television conference system capable of transmitting multimedia data including video image and voice by successively connecting a plurality of terminals in a communication network. <P>SOLUTION: A terminal TC for performing television conference among a plurality of terminals TA-TC connected through a network 1 generates two multimedia sessions 21, 22 in maximum for transmitting multimedia data including video image and voice to/from other terminals. The terminal TC transmits data received from the terminal TA through the one session 21 to the terminal TB through the other session 22, and also transmits data received from the terminal TB through the other session 22 to the terminal TA through the one session 21. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a video conference terminal, a video conference system, a video conference method, and a program for performing a video conference using a plurality of terminals connected via a network.

  When conducting a video conference by VoIP (Voice over Internet Protocol), it is necessary to deliver audio and video to all participants by mixing and transferring the audio and video of multiple people. . The process is expensive and cumbersome. Therefore, conventionally, a dedicated device using a board or the like for performing much of the processing by hardware is installed, and the processing is performed by the dedicated device. Further, conventionally, a method has been used in which a device that performs such processing is provided at one location in a communication network and processing is concentrated.

  However, in order to use such an apparatus for centralized management called an MCU (multi-point connection apparatus) or the like, it is first necessary to secure an installation place of such an apparatus. In addition, in order to perform communication between a plurality of terminals and their devices, it is necessary to prepare equipment such as a communication line having sufficient capacity.

  On the other hand, a video conference system has been proposed in which devices such as a multipoint connection device can be omitted. For example, Patent Document 1 describes a system in which a signal composed of a plurality of channels is transmitted on a transmission line formed in a loop shape, and video and audio signals are transmitted and received using each channel at each terminal.

  Patent Document 2 describes another system in which data communication such as video and audio is performed between terminals without using a multipoint connection device. In the system described in this document, the correspondence relationship between a user ID (identification information) and a network address such as an IP (Internet Protocol) address and a telephone number is managed by a directory server, and each terminal notifies from the directory server. Data communication such as video and audio is performed between each terminal (without going through the server) using the network address.

Patent Literature 3 describes another system that enables a video conference without using a multipoint connection device. In the system described in this document, a plurality of terminals are connected in a peer-to-peer format using two B channels of ISDN (Integrated Digital Communication Network), and each terminal is composed of images, sounds, and the like. Data is transmitted.
JP-A-8-32950 JP 2003-69969 A JP 7-177145 A

  In the system described in Patent Document 1, it is necessary to provide a dedicated loop transmission line to which a plurality of terminals are connected. In the system described in Patent Document 2, it is necessary to communicate data such as video and audio between terminals. For example, when a video conference is performed with three terminals A, B, and C, communication is performed between AB, between BC, and between AC. Therefore, when the number of terminals participating in the conference increases, the number of terminals that each terminal uses as a communication partner increases. Therefore, when the number of terminals increases, problems such as an increase in data amount and an increase in processing time due to communication overhead occur.

  Further, in a system such as that described in Patent Document 3, communication between a plurality of terminals is performed by connecting a plurality of terminals in a daisy chain (by daisy chain connection). Therefore, for example, when a video conference is performed with three terminals, if a terminal located in the middle stops transferring a signal, the other two apparatuses cannot communicate. Similarly, when a user during a conference exits on the way (a terminal disconnects communication), joins (connects), or puts it on hold, between other terminals In order not to affect communication, it is necessary to perform processing according to the operation after changing the connection state between the terminals or after changing the connection state.

  The present invention has been made in view of the above-described circumstances, and realizes a conference system using a technique for transferring multimedia data such as audio data and video data over an IP (Internet Protocol) network. In addition, the purpose is to improve the efficiency of the configuration related to the form of the transmission line. More specifically, the present invention relates to a system that realizes a conference function by transmitting multimedia data such as video and audio between a plurality of terminals over an IP network. It is an object of the present invention to provide a video conference system and a video conference method suitable for use in communicating multimedia data by connecting a terminal. Another object of the present invention is to provide a video conference terminal, a video conference system, a video conference method, and a program thereof that allow a user to easily perform operations such as joining, leaving, and holding when performing a video conference. And

  In order to solve the above-described problems, the present invention is a terminal for performing a video conference between a plurality of terminals connected via an IP (Internet Protocol) network, such as video, audio, etc. A multimedia session generating means for generating a maximum of two multimedia sessions for transmitting multimedia data of the user and one other multimedia session between the other second and third terminals are generated. The data received from the second terminal in one session is transmitted to the third terminal in the other session, and the data received from the third terminal in the other session is transmitted to the third terminal in the one session. And a data transfer means for transmitting to the second terminal.

  In the present invention, the data transfer means identifies a data transmission source, and when the data transmission source is the own terminal, discards the data of which the transmission source is the own terminal and transfers it to another terminal. It is characterized by not. The present invention receives a multimedia session generation request from a new fourth terminal when the terminal is generating a multimedia session of one session between each of the second and third terminals. The second terminal is instructed to generate a multimedia session with the fourth terminal, and means for terminating the multimedia session between the terminal and the second terminal; And a means for generating a new multimedia session with the fourth terminal. In addition, the present invention allows the second terminal to receive a termination instruction from a user when the terminal generates a multimedia session of one session each with the second and third terminals. Means for instructing to generate a multimedia session with the third terminal, and terminates the multimedia session for each session generated between the terminal and the second and third terminals. And a means for performing.

  In addition, the present invention provides a conference function in which each terminal performs a conference between a plurality of terminals and a telephone function in which a call is performed between two terminals. When the operator to be instructed is operated by the user, a means for determining whether the provided function is a conference function or a telephone function, and a conference function is provided according to the determination result In the case where the input / output of the multimedia information at the terminal is stopped or the telephone function is provided while the process of transferring the data received from the other terminal is continued in the generated multimedia session. Comprises means for stopping transmission / reception of multimedia data.

  The present invention is also a system for conducting a video conference between a plurality of terminals connected via an IP (Internet Protocol) network, and transmits multimedia data such as video and audio to other terminals. When one multimedia session is generated between the multimedia session generating means for generating a maximum of two multimedia sessions for the purpose and the other second and third two terminals, Data received from the second terminal in the session is transmitted to the third terminal in the other session, and data received from the third terminal in the other session is transmitted to the second terminal in the one session A plurality of terminals having data transfer means are provided.

  The present invention is also a method for conducting a video conference between a plurality of terminals connected via an IP (Internet Protocol) network, and transmitting multimedia data such as video and audio to other terminals. A multimedia session generation stage for generating a maximum of two multimedia sessions to be performed, and when one multimedia session is generated between each of the other second and third terminals. Data received from the second terminal in the session is transmitted to the third terminal in the other session, and data received from the third terminal in the other session is transmitted to the second terminal in the one session And a data transfer stage.

  In addition, the present invention is a program for performing a video conference between a plurality of terminals connected via an IP (Internet Protocol) network, and transmits multimedia data such as video and audio to other terminals. A multimedia session generation stage for generating a maximum of two multimedia sessions to be performed, and when one multimedia session is generated between each of the other second and third terminals. Data received from the second terminal in the session is transmitted to the third terminal in the other session, and data received from the third terminal in the other session is transmitted to the second terminal in the one session It includes a description for causing the computer to execute the data transfer stage.

  According to the present invention, the multimedia session generating means generates a maximum of two multimedia sessions for transmitting multimedia data such as video and audio with other terminals, and the data transfer means When one multimedia session is generated between each of the second and third terminals, data received from the second terminal in one session is transmitted to the third terminal in the other session. And the data received from the third terminal in the other session is transmitted to the second terminal in the one session. As a result, when multiple terminals are connected in a daisy chain by a multimedia session, it is possible to transfer data such as audio and video input at each terminal to all other terminals, and the conference function Can be realized. Therefore, the efficiency of the configuration can be improved.

  According to the present invention, the data transfer means discards data whose source is the own terminal and does not transfer it to other terminals. Therefore, the problem that multimedia data circulates infinitely between a plurality of terminals can be avoided.

  According to the present invention, when the fourth terminal connects to the terminal and tries to participate in the conference when the second terminal is connected to the terminal and the third terminal is connected to the terminal. In addition, a new connection form of the second terminal, the fourth terminal, the terminal, the third terminal, and so on is automatically formed. Therefore, the user can participate in the conference by issuing a connection request to an arbitrary terminal participating in the conference regardless of the order of the daisy chain connection of each terminal.

  Further, according to the present invention, when the terminal is about to leave the conference when the terminal is connected to the second terminal, the terminal, the third terminal, and so on, the second terminal -A new connection form of the third terminal-is automatically formed. Therefore, the user can leave the conference in a state in which communication between other terminals is continued by giving an exit instruction to the terminal without being aware of the connection state of each terminal after the terminal has left. You can leave.

  Further, according to the present invention, when an operation for placing a hold state is performed, when a conference function is provided, a process for transferring data received from another terminal in a generated multimedia session is continued in the terminal. Input / output of multimedia information such as video and audio is stopped, and transmission / reception of multimedia data is stopped when a telephone function is provided, and input / output of multimedia information such as video and audio on the terminal is stopped . Therefore, even when a terminal that relays multimedia data is put on hold, multimedia information of other terminals can be transmitted. Further, since the operator for instructing the hold state can be shared by the conference function and the telephone function, the user can easily operate.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram for explaining the configuration of an embodiment of a video conference system according to the present invention. The video conference system shown in FIG. 1 includes a network 1 and three terminals TA, TB, and TC connected to the network 1.

  The network 1 is a communication network composed of one or a plurality of communication networks of the Internet, a public communication network, and a non-public communication network. Examples of the public communication network include a wired telephone network, a mobile phone network, and a public wireless LAN (Local Area Network), and examples of the non-public communication network include a dedicated communication line, an in-house WAN (Wide Area Network), and a private LAN. . The network 1 is configured as an IP network that uses IP (Internet Protocol) in the network layer and transfers data by a packet switching method. An IP address is assigned to each device connected to the network 1.

  Terminals TA, TB, and TC are realized by a computer such as a personal computer and its peripheral devices, and a program executed by the computer. Components of the computer and its peripheral devices include a display, a camera, a speaker, a microphone, a mouse, and the like.

  Here, with reference to FIG. 2, a display example of the display of the terminals TA, TB, and TC will be described. FIG. 2 shows a display example of the screen 10 of the display of any one of the terminals TA, TB, and TC participating in the conference. On the screen 10, a video window 11 for displaying a photographed image (video) of a user (user) of another terminal and an operator window 12 configured in the same manner as a telephone are displayed. The operator window 12 includes a monitor box 13 for displaying a destination address number, a call mode (conference / phone), a call time, a dial key group 14 including a plurality of dial keys, and a disconnect key (disconnect button) 15. , A call key (call button) 16, a conference mode button 17, a hold button 18 and the like are provided. For example, when starting a conference, the address of the connection destination terminal is input, and when the call key 16 is clicked while the conference mode button 17 is pressed, connection request processing in the conference mode is performed on the connection destination terminal. Is started.

  In the embodiment shown in FIG. 1, multimedia data such as audio data and video data is transferred between the terminals TA, TB, and TC using the VoIP technology. In this case, the transfer of multimedia data is performed using multimedia sessions 21 and 22 formed between each terminal TA, TB, and TC on a peer-to-peer basis.

  The multimedia sessions 21 and 22 are sessions defined by, for example, RTP (Real-time Transport Protocol). RTP is a transmission protocol for streaming reproduction of multimedia data such as audio data and video data. It is a UDP (User Datagram Protocol) type protocol, and communication control information using RTCP (RTP Control Protocol) for data transmission / reception control. Is used. In the present embodiment, each terminal TA, TB, and TC can generate a maximum of two multimedia sessions with another terminal by using a maximum of two RTP ports. It shall be.

  In the example of FIG. 1, the terminal TA used by the user A uses one RTP port, the terminal TC used by the user C uses two RTP ports, and the terminal TB used by the user B Two multimedia sessions 21 and 22 are generated between terminals TA, TB, and TC using one RTP port. In this case, each of the terminal TA and the terminal TB can further generate one multimedia session by using an unused RTP port. Here, the multimedia data transmitted from each of the terminals TA, TB, and TC is given identification information indicating the transmission source terminal by SSRC (Synchronization source) in the RTP header of the RTP packet that constitutes the divided data. It shall be.

  In the multimedia session 21 between the terminal TA and the terminal TC, data such as voice and video input at the terminal TA is transmitted from the terminal TA to the terminal TC, and at the terminal TC from the terminal TC to the terminal TA. The input audio and video data and the audio and video data input at the terminal TB are transmitted. The data such as audio and video input at the terminal TB transmitted in the multimedia session 21 is the data directly transferred from the terminal TB by the terminal TC in the multimedia session 22. On the other hand, in the multimedia session 22 between the terminal TC and the terminal TB, data such as voice and video input at the terminal TB is transmitted from the terminal TB to the terminal TC, and the terminal TC transmits the data to the terminal TB. Data such as audio and video input at the TC and data such as audio and video input at the terminal TA are transmitted. The data such as audio and video input at the terminal TA transmitted in the multimedia session 22 is the data transferred from the terminal TA by the terminal TC in the multimedia session 21 as it is. Each terminal TA, TB, and TC mixes audio data received from other terminals and outputs it from a speaker or the like, and displays video data captured by each terminal separately for each terminal.

  In the present embodiment, generation (establishment or start), modification (change), and termination (disconnection) of the multimedia sessions 21 and 22 are executed by software processing (program processing) using SIP (Session Initiation Protocol). The SIP is an application layer control (signaling) protocol for creating, modifying, and terminating multimedia sessions (or simply sessions) with one or more parties. Specifies the encryption function as well as the creation, modification, and termination functions of multimedia sessions. In SIP, the data communication procedure of the multimedia session can be defined by other protocols such as SDP (Session Description Protocol) in addition to the RTP described above.

  The process of generating a multimedia session by SIP is also called call connection. In this embodiment, the number of multimedia sessions that can be generated by each terminal TA, TB, and TC is limited to two, but this limit is the number of terminals that each terminal can call-connect in SIP. Can be realized by limiting the maximum number of terminals to two.

  In the configuration shown in FIG. 1, the number of terminals is three, but the number of terminals can be further increased by daisy chain connection. In this case, one call connection is established between the terminals, and one multimedia session is generated. Accordingly, the two terminals at the extreme end of the plurality of terminals generate one multimedia session with each other adjacent terminal, and the other terminals in the remaining intermediate part each have two adjacent terminals. One multimedia terminal and one multimedia session (two in total) are generated.

  FIG. 3 shows a multimedia data transmission path when five terminals 31 to 35 are connected in a daisy chain in that order. In FIG. 3, the transmission path | route of the multimedia data output with the terminal of the terminal 35 (user E) is shown. The multimedia data input at the terminal 31 (user A) is transmitted as the RTP packet 41 to the terminal 32 (user B). The terminal 32 (user B) transmits the multimedia data input at its own terminal as the RTP packet 42 to the terminal 33 (user C) and transmits the same multimedia data as the received RTP packet 41. The RTP packet 43 is transmitted to the terminal 33 (user C). Although the source address of the RTP packet 43 is the terminal 32, it can be identified as the information of the terminal 31 similar to the RTP packet 41 by the SSRC included in the RTP header.

  Similarly to the terminal 32 (user B), the terminal 33 (user C) also transmits the input information at the terminal and the received information to the terminal 34 (user D). The terminal 34 (user D) transmits the multimedia data input at its own terminal as an RTP packet 44 to the terminal 35 (user E), and receives the information received from the terminal 33 (user C) as RTP. Packets 45 to 47 are transmitted to terminal 35 (user E). Then, the terminal 35 (user E) reproduces the audio data and the video data input from the terminals 31 to 34 based on the RTP packets 47 to 44, and outputs the audio information 51 and the video information 52. To do. Here, the audio information 51 is a signal obtained by mixing the audio signals input from the terminals 31 to 34, and the video information 52 is reproduced from the video signals input from the terminals 31 to 34 individually in separate windows. Is.

  In the configuration shown in FIG. 1, SIP servers such as a proxy server, a registration server, and a redirect server that are generally used in SIP are not shown. Also in this embodiment, these servers can be provided in the network 1. For example, the redirect server uses a location service to provide a function for acquiring an address (one or a plurality of addresses) at which the called terminal may exist on the calling side.

  Next, a processing procedure of each function provided by the configuration shown in FIG. 1 will be described with reference to FIGS.

  First, with reference to FIG. 4, a processing procedure when a conference is started among the terminal TA, the terminal TB, and the terminal TC with the configuration shown in FIG. 1 will be described. In the initial state, the call connection is not established among the terminal TA, the terminal TB, and the terminal TC. In this state, the terminal TA and the terminal TB start the call connection in the conference mode to the terminal TC at almost the same time (request ).

  FIG. 4 shows a processing procedure in the terminal TC. The terminal TC first establishes a call connection with the terminal TA (step S101), and then places the line with the terminal TA on hold in order to perform processing for the terminal TB (S102). Next, a call connection is made with the terminal TB (S103), and then the line with the terminal TB is put on hold (S104). Next, the transfer processing of the audio / video data between the terminal TA and the terminal TB in the terminal TC is started (a startable state is set) (S105). When the preparation for the transfer process is completed, the line holding with the terminal TB is released (S106), and the line holding with the terminal TA is released (S107). Thereafter, as shown in FIG. 1, data transmission by two multimedia sessions 21 and 22 is performed between the terminals TA, TB, and TC.

  Here, the contents of the data transfer process in the terminal TC will be described with reference to FIG. FIG. 5 shows a processing procedure in the terminal TC of FIG. When the terminal TC receives data from the terminal TA (step S201), the received data is checked (S202). If there is no problem, the audio / video data is decoded (S203), and the audio signal and the video are received. A signal is output from a predetermined output device (S204). Further, it is confirmed whether or not the data checked in step S202 can be transferred (S205), and if it is possible (“OK” in S205), it is transmitted to the terminal TB (S206). In addition, the audio input at the terminal TC and the captured video are encoded (S207), transmitted to the terminal TB (S206), and transmitted to the terminal TA (S212).

  In addition, when receiving data from the terminal TB (step S209), the terminal TC checks the received data (S210). If there is no problem, the terminal TC decodes the audio / video data (S203), and receives the audio signal. The video signal is output from a predetermined output device (S204). Further, it is confirmed whether or not the data checked in step S210 can be transferred (S211). If it is possible (“OK” in S211), the data is transmitted to the terminal TA (S212).

  In addition, each process enclosed with the broken line in FIG. 5 is each process step characterized by this embodiment. The flowchart of FIG. 5 shows the processing performed at the terminal TC. By considering the processing described as the terminal TA and the terminal TB as processing for the other two terminals connected to a certain terminal, the processing other than the terminal TC is performed. It can be seen as a general flowchart in the middle terminal connected in a daisy chain. Note that the two terminals at the end of the daisy chain connection (terminals TA and TB in FIG. 1) do not perform data transfer processing (processing to transfer received data to other terminals), but from other terminals. Only the data reception process and the input data transmission process of the terminal itself are performed.

  Next, processing contents of the reception data check (S202 and S210) in FIG. 5 will be described with reference to FIG. In addition, each process enclosed with the broken line in FIG. 6 is each process step characterized by this embodiment. In FIG. 6, step S301 corresponds to the process of step S201 or S209 of FIG. The processing in step S304 corresponds to the processing in steps S205 and S206 or S211 and S212. And the process of step S309 and S310 respond | corresponds to the process of step S203 and S204. 6 is executed in units of RTP packets, and it is assumed that identification information indicating a transmission source terminal is attached to the SSRC in the RTP header in the RTP packet.

  When data is received (step S301), first, loop determination is performed based on identification information of the SSRC transmission source terminal (S302).

  When terminals at both ends in daisy chain connection are mistakenly connected, the transmission path has a loop configuration. In that case, the RTP packet of the own terminal transmitted to one connection partner arrives from the other connection partner and goes around the loop infinitely (see FIG. 7). Therefore, in this embodiment, when an RTP packet sent from the terminal arrives, it is determined that the transmission path has a loop configuration, and the packet data is discarded (S303). The SSRC set in the RTP header part is used for identification of own terminal data. SSRC is an identifier that allows a transmission path for RTP packets to be uniquely specified between connected terminals, and is selected from a 32-bit random value. Note that FIG. 7 shows a state in which three terminals T1 to T3 are connected in a loop via lines P1 to P3.

  If it is determined in step S302 that the loop configuration is not established (transmission source = other terminal), the received data is transferred to the other of the two terminals connected by call (S304). Next, it is determined whether or not the number of transmission source terminals has increased (S305). If the transmission source of the RTP packet subject to reception check is a new transmission source (not a terminal that is currently outputting), it means that the transmission source has increased. It is determined whether or not (S306). For example, when there is an unused output device (output window) for 5 seconds or more, the terminal assigned to the device is changed to a new transmission source terminal (S308). If there are a plurality of unused output devices for more than 5 seconds, the least recently used output device (output window) is set as a change target by the LRU (Least Recently Used) algorithm, The allocated terminal is changed to a new transmission source terminal (S308).

  The output device (output window) to be determined in step S306 is, for example, the video window 11 on the screen 10 shown in FIG. In this embodiment, it is assumed that each terminal TA to TC can display images for six terminals, and more than six terminals are connected in a daisy chain, and data is transmitted continuously for 5 seconds. If there is no terminal that has not been received, it is determined that there is no output device that can be used (“NO” in S306), and the data is discarded (S307). However, in step S307, for example, only video data may be discarded and audio data may be output.

  In the present embodiment, the exit from a video conference by a terminal that is not adjacent is not notified to each terminal. However, if there is a terminal that has left, it is necessary to detect this, release resources such as the video window 11 used to output the corresponding terminal data, and prepare for new terminal participation. Therefore, when the RTP data reception of a certain terminal is interrupted for a predetermined time (5 seconds), it is determined that the terminal has left, and when newly added terminal data is received, the resources for the leaving terminal are reused. It is said.

  When the packet source is an existing source (terminal to which an output device is assigned) (“existing source” in S305), or it is determined that there is an output device that can be used even if it is a new source. If it is found (“Yes” in S306), an output device for video or the like is determined (S308), and decoding processing (S309) and data output (S310) are executed using that device as the output destination.

  Next, with reference to FIG. 8, a processing procedure in the case of ending a conference among the terminal TA, the terminal TB, and the terminal TC with the configuration shown in FIG. 1 will be described. FIG. 8 shows a processing procedure in the terminal TC. In this case, it is assumed that call connection by daisy chain connection is established among the terminal TA, the terminal TB, and the terminal TC as shown in FIG. It is assumed that the terminal TC has received an instruction to end the conference.

  The terminal TC sends an instruction to hold the line to the terminal TB (step S401), and ends the audio / video transfer process of the terminal TA-terminal TB (S402). Next, the call with the terminal TA is disconnected (S403), and then the call with the terminal TB is disconnected (S404). With the above processing, all multimedia data transmission processing in the conference mode between the terminals TA to TC is completed.

  Next, with reference to FIG. 9, a description will be given of a processing procedure in a case where a terminal participating in the conference is put on hold (a state in which input and output of multimedia data is stopped on the terminal while the call connection is put on hold). To do. Prior to the description with reference to FIG. 9, matters to be noted in the hold process will be described with reference to FIG.

  FIG. 10 is an explanatory diagram assuming a case where the hold processing by the telephone function is performed in the terminal C located in the middle of the five terminals A to E connected in a daisy chain in the present embodiment. In the hold processing by the telephone function, there is a case where the call connection is put on hold and all data communication in the multimedia session is stopped. In this case, a hold signal is transmitted to the opposite terminal at the time of terminal hold during one-to-one communication. As a result, the opposite terminal interrupts RTP data transmission to the own terminal. In a video conference according to the present embodiment, a terminal that performs transparent transfer between terminals (transfer that changes only the destination and does not change the contents) transmits a hold signal to an adjacent terminal in the same manner as in one-to-one communication. If this happens, all RTP data transmission to the terminal stops. As a result, as shown in FIG. 10, the communication in the video conference is divided. In FIG. 10, a cross indicates a multimedia session in which data transfer is interrupted. Therefore, the hold during the video conference does not transmit the hold signal, but stops only the transmission / reception of the RTP data of the own terminal.

  As shown in FIG. 9, when terminals A to E are daisy chained in that order as shown in FIG. 10, the user presses the hold button 18 of FIG. When putting communication on hold by clicking or the like, first, the terminal determines the connection form (step S501). If it is determined that the connection is a one-to-one connection (connection by a telephone function for making a call between two terminals) ("one-to-one connection" in S501), a hold signal is transmitted to another terminal. Thereafter (S502), data input / output (audio / video data input / output) at the terminal is stopped (S503). On the other hand, if it is determined that the connection state is due to a conference function for performing a conference between a plurality of terminals (“conference connection” in S501), data input / output (in the terminal) without sending a hold signal ( Audio / video data input / output) is stopped (S503). Then, the media type is determined (S504), and if the terminal is outputting video, a hold image is output, and if only audio output is being performed, a hold sound is output (S505). With this process, when the conference function is used, the input / output of the multimedia information at the terminal is stopped while the process of transferring the data received from the other terminal is continued in the generated multimedia session. When the telephone function is used, a hold signal is transmitted to another terminal, and transmission / reception of multimedia data is stopped.

  Next, with reference to FIG. 11 and FIG. 12, a processing procedure in which another terminal participates in a video conference already being executed will be described. Here, as shown in FIG. 11, a process when a new terminal E connects to and participates in the terminal A at the end of the four terminals A to D connected in a daisy chain will be described.

  In this case, as shown in FIG. 12, when a call is made from terminal E to terminal A (step S1), an incoming call response is made from terminal A to terminal E (S2), and the participation process is completed. That is, the terminal E that has transmitted to the terminal A at the end of the daisy chain completes the connection in the same procedure as in the one-to-one communication. Thereafter, RTP data for all terminals participating in the conference (terminal A to terminal D) can be received from the opposite terminal A. Note that the content of the data transfer process in the terminal A or the like is the same as that described with reference to FIG.

  Next, with reference to FIG. 13 and FIG. 14, a processing procedure when the terminal E connects to and participates in a terminal in the middle of the daisy chain (referred to as terminal B in FIG. 13) will be described. In this case, since terminal B is already connected to two terminals, it cannot receive further incoming calls. Therefore, when there is an incoming call from the newly participating terminal E (step S11 in FIG. 14), the terminal B transfers the data transfer destination from the terminal B to the terminal E with respect to one adjacent terminal (referred to as terminal C). A transfer instruction to change is made (S12). Here, the terminal C transmits to the terminal E (S13), and when the incoming call response is made from the terminal E to the terminal C, the connection between the terminal C and the terminal E is established (S14). Here, the terminal C notifies the terminal B that the transfer preparation is completed (S15).

  Next, a disconnection instruction is sent from the terminal B to the terminal C (S16), and a disconnection response is sent from the terminal C to the terminal B when the disconnection process is performed (S17). Next, terminal B connects to terminal E, and an incoming call response is sent from terminal B to terminal E (S18).

  With the above processing procedure, a daisy chain connection is established in the order of terminal A-terminal B-terminal E-terminal C-terminal D. Note that control signals such as connection requests and incoming call responses between the terminals can be transferred by a route independent from the already established multimedia session by SIP.

  Next, with reference to FIGS. 15 to 17, a processing procedure in a case where a terminal participating in a conference exits without ending the conference will be described. First, as shown in FIG. 15, when terminal A to terminal E are daisy chain connected in that order, processing when terminal A at the end is withdrawn will be described. In this case, as shown in FIG. 16 and FIG. 17, when the terminal at the end of the daisy chain leaves, processing for terminating the connection with the adjacent terminal is performed in the same procedure as in the one-to-one communication. That is, a disconnection instruction is transmitted from terminal A to terminal B (step S21), and then a disconnection response is transmitted from terminal B to terminal A (S22). Here, the terminal A leaves and the terminal B becomes the terminal at the end, and the processing is continued.

  Next, referring to FIG. 18 to FIG. 20, when terminal A to terminal E are daisy chained in that order as shown in FIG. 18, processing when terminal C located in the middle leaves Will be described. In this case, as shown in FIGS. 19 and 20, it is necessary to connect the two adjacent terminals and maintain the daisy chain before terminating the connection between the two terminals B and D of the terminal C to leave. Therefore, the leaving terminal C gives a connection instruction to one adjacent terminal (terminal D) with the other adjacent terminal (terminal B) (step S31). Terminal D transmits to terminal B and requests connection (S32). Further, in the signals transmitted from the terminal C to the terminal D and from the terminal D to the terminal B in steps S31 and S32, information indicating that the terminal B and the terminal C are disconnected is included.

  Next, an instruction to disconnect between terminal B and terminal C is sent from terminal B to terminal C (S33). Then, when disconnected, a disconnection response is sent from terminal C to terminal B (S34). Here, the connection between the terminal B and the terminal C is disconnected.

  Next, after terminal B and terminal D are connected, an incoming call response is sent from terminal B to terminal D (S35). Next, a notification that transfer preparation is completed is sent from terminal D to terminal C (S36). Here, the terminal C sends a disconnection instruction to the terminal D (S37). When the terminal C is disconnected, a disconnection response is transmitted from the terminal D to the terminal C (S38). As described above, the terminal C leaves, a new connection is established between the terminal B and the terminal D, and the daisy chain connection state between the other terminals is maintained.

  As described above, according to the present embodiment, the number of multimedia sessions can be limited to a maximum of two at each terminal, so that a video conference can be easily realized only by software. Therefore, it is not necessary to provide a dedicated device, and a video conference can be easily performed. Also, the cost is reduced. In addition, since the data is relayed, it is possible to connect a plurality of people and hold a video conference. In addition, the software that can be seen by the user is only two lines, and the effect that it looks good is also obtained.

  According to the present embodiment, when a conference system is realized using technology for transferring multimedia data such as audio data and video data over an IP network, a transmission path is configured by daisy chain connection. Thus, the number of multimedia sessions between terminals can be reduced to a maximum of two to improve the efficiency of the transmission path. In addition, since the processing of joining, leaving, holding, etc. of each terminal connected to the daisy chain is automatically performed so that the daisy chain connection can be instructed, the user can easily perform the instruction operation. .

  Note that the embodiment of the present invention is not limited to the above, and it is possible to appropriately change the processing by the protocol to another, for example, using SDP instead of RTP. Further, the processing procedure of the present invention is not limited to the above, and the sending direction of signals related to call connection or the like may be reversed or the order may be changed as long as the same processing function can be maintained. It is possible as appropriate. Further, the program (software) constituting this embodiment can be recorded on a computer-readable recording medium or distributed via a communication line.

It is a system diagram for demonstrating the structure of embodiment of this invention. It is a figure which shows the example of a display of the display of each terminal TA-TC of FIG. It is explanatory drawing for demonstrating the transmission form of the data in this invention. It is a flowchart which shows the process sequence at the time of starting a conference function with the structure of FIG. It is a flowchart which shows the procedure at the time of performing a data transfer process with the conference function by the structure of FIG. FIG. 6 is a flowchart for explaining processing contents of reception data check (S202, S210) of FIG. 5; It is explanatory drawing for demonstrating the loop determination process of step S302 of FIG. It is a flowchart which shows the process sequence at the time of complete | finishing a conference function with the structure of FIG. It is a flowchart which shows the procedure at the time of performing a hold process with the structure of FIG. It is explanatory drawing for demonstrating the subject of the pending | holding process of FIG. It is explanatory drawing for demonstrating the process sequence at the time of making a new terminal participate in a meeting in this Embodiment. It is a flowchart for demonstrating the process sequence at the time of making a new terminal participate in a meeting in this Embodiment. It is explanatory drawing for demonstrating the process sequence at the time of making a new terminal participate in a meeting in this Embodiment. It is a flowchart for demonstrating the process sequence at the time of making a new terminal participate in a meeting in this Embodiment. It is explanatory drawing for demonstrating the process sequence at the time of leaving a terminal during a meeting in this Embodiment. It is explanatory drawing for demonstrating the process sequence at the time of leaving a terminal during a meeting in this Embodiment. It is a flowchart for demonstrating the process sequence at the time of making a new terminal participate in a meeting in this Embodiment. It is explanatory drawing for demonstrating the process sequence at the time of leaving a terminal during a meeting in this Embodiment. It is explanatory drawing for demonstrating the process sequence at the time of leaving a terminal during a meeting in this Embodiment. It is a flowchart for demonstrating the process sequence at the time of making a new terminal participate in a meeting in this Embodiment.

Explanation of symbols

1 ... Network, TA, TB, TC ... Terminal, 11 ... Video window, 18 ... Hold button, 21, 22 ... Multimedia session

Claims (8)

A terminal for performing a video conference between a plurality of terminals connected via an IP (Internet Protocol) network,
Multimedia session generating means for generating a maximum of two multimedia sessions for transmitting multimedia data such as video and audio to and from other terminals;
When one multimedia session is generated between each of the other second and third terminals, data received from the second terminal in one session is transmitted to the third terminal in the other session. And a data transfer means for transmitting data received from the third terminal in the other session to the second terminal in the one session.   The data transfer means identifies the data transmission source, and when the data transmission source is the own terminal, discards the data of which the transmission source is the own terminal and does not transfer to another terminal. The video conference terminal according to claim 1. When the terminal generates a multimedia session for each session with the second and third terminals, the second terminal receives a request for generating a multimedia session from the new fourth terminal. Instructing the terminal to generate a multimedia session with the fourth terminal, and terminating the multimedia session between the terminal and the second terminal;
The video conference terminal according to claim 1, further comprising: means for generating a new multimedia session between the terminal and the fourth terminal. When the terminal is generating a multimedia session of one session each with the second and third terminals, when the terminal receives an end instruction from the user, the third terminal Means for instructing to create a multimedia session with the terminal;
4. The apparatus according to claim 1, further comprising: means for terminating a multimedia session of each session generated between the terminal and the second and third terminals. Video conferencing terminals. Each terminal provides a conference function for performing a conference between a plurality of terminals and a telephone function for performing a call between two terminals,
Means for determining whether a function provided is a conference function or a telephone function when an operator operating a communication suspension provided in a terminal is operated by a user;
If the conference function is provided according to the determination result, input / output of multimedia information at the terminal while continuing the process of transferring data received from other terminals in the generated multimedia session. The video conference terminal according to any one of claims 1 to 4, further comprising: means for stopping transmission / reception of multimedia data when the communication function is stopped or a telephone function is provided. A system for conducting a video conference between a plurality of terminals connected via an IP (Internet Protocol) network,
Multimedia session generating means for generating a maximum of two multimedia sessions for transmitting multimedia data such as video and audio between other terminals;
When one multimedia session is generated between each of the other second and third terminals, data received from the second terminal in one session is transmitted to the third terminal in the other session. And a data transfer means for transmitting data received from the third terminal in the other session to the second terminal in the one session, a video conferencing system comprising a plurality of terminals . A method for conducting a video conference between a plurality of terminals connected via an IP (Internet Protocol) network,
A multimedia session generation stage for generating a maximum of two multimedia sessions for transmitting multimedia data such as video and audio to and from other terminals;
When one multimedia session is generated between each of the other second and third terminals, data received from the second terminal in one session is transmitted to the third terminal in the other session. And a data transfer step of transmitting data received from the third terminal in the other session to the second terminal in the one session. A program for conducting a video conference between a plurality of terminals connected via an IP (Internet Protocol) network,
A multimedia session generation stage for generating a maximum of two multimedia sessions for transmitting multimedia data such as video and audio to and from other terminals;
When one multimedia session is generated between each of the other second and third terminals, data received from the second terminal in one session is transmitted to the third terminal in the other session. And a data transfer step of transmitting data received from the third terminal in the other session to the second terminal in the one session, and including a description for causing the computer to execute And a video conferencing program.

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