JP2010093479A - Conference system and conference terminal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conference system and a conference terminal device that are composed of simple hardware by reducing a load required for distribution to a communication terminal operated by a person who sits in on a conference. <P>SOLUTION: A conference system has a host terminal M operated by a host among a plurality of speakers, speaker terminals A1 and A2 operated by other speakers, a speaker terminal A3 connected to the speaker terminal A1 in cascade and transmitting a conference moving image to the host terminal M through the speaker terminal A1, a distribution server SV receiving the conference moving image from the host terminal M and simultaneously distributing the image, and one or more terminals B of a person who sits in on a conference which receive the conference moving image simultaneously distributed from the distribution server SV by an operation of a person who sits in on a conference. The host terminal M synthesizes the conference moving image transmitted from the speaker terminal A1 with its own conference moving image to be transmitted to the speaker terminal A1 and the distribution server SV through an IP network NW. The distribution server SV transmits the conference moving image transmitted from the host terminal M to the terminal B of a person who sits in on a conference. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a conference system and a conference terminal device in which one or more listeners can observe a conference where a plurality of speakers speak.

  A conference system in which terminals arranged at multipoints are communicably connected to a network, and conference audio from a plurality of speakers transmitted from each terminal is synthesized by a server and distributed to the multipoint terminals. Has come to be used.

For example, in the multipoint conference system described in Patent Document 1, a conference call server that generates audio data obtained by mixing audio data from terminals belonging to a speaker group, and audio data mixed by the conference call server It has an audio distribution server for distributing to groups and terminals belonging to a listener group.
JP 2005-269347 A

  However, in the multipoint conference system described in Patent Document 1, the conference audio from the terminals of the speaker group synthesized by the telephone conference server is transmitted not only to all terminals to which the voice distribution server belongs to the speaker group, but also to the listener group. Since the conference audio is distributed to all the terminals belonging to the network, hardware that performs high-speed audio processing or high-speed distribution to the network is required.

  Accordingly, an object of the present invention is to provide a conference system and a conference terminal device that can be configured with simple hardware by reducing the load required for distribution to a communication terminal operated by a listener.

  The present invention relates to a first communication terminal operated by one of a plurality of speakers, at least one second communication terminal operated by another speaker, and from the first communication terminal. A distribution server that receives conference audio and broadcasts it, and one or more third communication terminals that are operated by an observer and receive conference audio broadcast from the distribution server and listen to the conference The first communication terminal is communicably connected to the network, and the first communication terminal synthesizes the conference voice transmitted from the second communication terminal and its own conference voice, and the conference synthesized by the synthesis means Transmitting means for transmitting voice to the distribution server and the second communication terminal via the network, the distribution server storing a third communication terminal as a transmission destination for broadcast distribution; Conference sound transmitted from the first communication terminal And it is characterized in that a distribution means for transmitting via the network to the third communication terminal stored destination in the storage means.

  In the present invention, the first communication terminal performs the conference voice synthesis and the transmission to the second communication terminal, thereby delivering the distribution server to the third communication terminal operated by the listener. By reducing the required load, it is possible to configure with simple hardware.

  The first invention of the present application is directed to a first communication terminal operated by one of a plurality of speakers, at least one second communication terminal operated by another speaker, and a first communication. A distribution server that receives conference audio from a terminal and broadcasts it, and one or more third communication terminals that are operated by a listener and receive the conference audio broadcast from the distribution server and listen to the conference Are communicably connected to the network, and the first communication terminal synthesizes the conference voice transmitted from the second communication terminal and its own conference voice, and the conference voice synthesized by the synthesizing means. Transmitting means for transmitting to the distribution server and the second communication terminal via the network, the distribution server storing a third communication terminal as a transmission destination for broadcast distribution, and the first communication terminal The meeting audio sent from Is obtained is characterized in that a distribution means for transmitting over the network to signal the destination of the third communication terminal.

  According to the first aspect of the present invention, the synthesizing means of the first communication terminal operated by one of the plurality of speakers operates the conference voice transmitted from the second communication terminal and the own conference voice. Since the synthesized voice is transmitted to the distribution server and the second communication terminal by the transmission means, the distribution server sends the third communication terminal stored in the storage means to the third communication terminal from the first communication terminal. Since the conference voice to be transmitted is transmitted from the distribution means, the distribution server is light in load required for distribution. Therefore, the first communication terminal has a function of synthesizing the conference voice transmitted from the second communication terminal and its own conference voice and transmitting the synthesized conference voice to the second communication terminal. For example, it is only necessary to add a distribution server to the transmission destination, and the distribution server does not require distribution to the first communication terminal or one or more second communication terminals, and the third communication operated by the listener. Since it only needs to be delivered to the terminal, high performance is not necessary. Therefore, the present invention can be configured with simple hardware by reducing the load required for distribution to the third communication terminal operated by the listener.

  According to a second invention of the present application, in the first invention, the synthesizing unit in the first communication terminal synthesizes the video in addition to the conference audio, and the distribution unit in the distribution server includes the conference audio synthesized by the synthesizing unit and The video is distributed as conference audio / video. According to the second invention, since the synthesizing unit synthesizes the video in addition to the conference voice, the first communication terminal can transmit not only the voice but also the video.

  A third invention of the present application is characterized in that, in the second invention, the third communication terminal has a streaming reproduction means, and the meeting audio / video distributed from the distribution server is reproduced by the streaming reproduction means. Is. According to the third invention, the listener who operates the third communication terminal can observe not only the voice but also the video in the conference.

  According to a fourth invention of the present application, in any one of the first to third inventions, the distribution server has a notification means for notifying the start of the conference to the third communication terminal stored in the storage means. It is a feature. According to the third invention, the listener who operates the third communication terminal can know the start of the conference by the notification by the notification means.

  According to a fifth invention of the present application, in any one of the first to fourth inventions, when the first communication terminal receives a conference participation request from a fourth communication terminal to newly join the conference, The second communication terminal accepts the conference participation request from the fourth communication terminal, and the second communication terminal permits the call, and receives the conference voice from the fourth communication terminal and its own voice. Are combined and transmitted to the first communication terminal. According to the fifth invention, even if the fourth communication terminal newly joins the conference, the first communication terminal may synthesize the conference voice transmitted from the second communication terminal and its own voice. Therefore, the number of conference voices does not increase.

  According to a sixth aspect of the present invention, in the fifth aspect, the first communication terminal is a fourth communication terminal that the second communication terminal permits a conference call when the second communication terminal is removed from the conference. Is present, the fourth communication terminal is used as a second communication terminal for a conference. According to the sixth invention, the first communication terminal synthesizes the conference voice from the fourth communication terminal and the other conference voice and transmits them to the fourth communication terminal instead of the second communication terminal. Even if two communication terminals leave the conference, the conference can be continued without any problem.

  According to a seventh aspect of the present invention, in the fifth aspect, when the fourth terminal detects a failure in the second communication terminal, the fourth communication terminal notifies the first communication terminal of the occurrence of the failure, and the first communication terminal Is characterized in that the fourth communication terminal is used as a second communication terminal for a conference. According to the seventh invention, the first communication terminal synthesizes the conference voice from the fourth communication terminal and another conference voice and transmits the synthesized voice to the fourth communication terminal instead of the second communication terminal. Even if the communication terminal 2 becomes unable to continue the conference due to a failure and leaves the conference, the conference can be continued without any problem.

  According to an eighth invention of the present application, in any one of the fifth to seventh inventions, the first communication terminal, the second communication terminal, and the fourth communication terminal are connected via an intranet, and the first communication terminal, The distribution server and the third communication terminal are connected by the Internet. According to the eighth invention, the first communication terminal, the second communication terminal, and the fourth communication terminal can be arranged in the same company or facility, and the distribution server and the third communication terminal are located in a remote place. Even if it exists, it can communicate via the Internet.

  In the ninth invention of the present application, the first communication terminal, the second communication terminal, the fourth communication terminal, and the distribution server are connected via an intranet, and the distribution server and the third communication terminal are connected via the Internet. It is characterized by being. According to the ninth invention, the first communication terminal, the second communication terminal, the fourth communication terminal and the distribution server can be arranged in the same company or facility, and the third communication terminal is located in a remote place. Can communicate via the Internet.

  According to a tenth aspect of the present application, in a conference terminal device operated by one of a plurality of speakers, a conference voice transmitted from at least one speaker terminal operated by another speaker, A synthesizing unit that synthesizes the conference audio, and the conference audio synthesized by the synthesizing unit is transmitted to the speaker terminal and broadcasted to one or more listener terminals that listen to the conference via the network. And a transmission means for transmitting. According to the tenth invention, as in the first invention, the conference terminal device of the present invention synthesizes the conference voice transmitted from the speaker terminal and its own conference voice, and the synthesized conference voice is given to the speaker. If it has a function to transmit to a terminal, it is only necessary to add a distribution server to the transmission destination. The distribution server does not require distribution to the conference terminal device of the present invention or one or more speaker terminals. High performance is not necessary because it only needs to be distributed to the listener terminal operated by the user. Therefore, it is possible to configure with simple hardware by reducing the load required for distribution to the observer terminal operated by the observer.

(Embodiment)
A conference system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of the entire conference system according to the embodiment of the present invention.

  As shown in FIG. 1, the conference system 1 mixes (mixes) audio and video of attendees of a conference and distributes them as conference audio / video. The conference system 1 includes an organizer terminal M (first communication terminal) operated by an attendant serving as an organizer, and a speaker terminal A (A1, A2: second communication) operated by an attendant speaking in a conference. A terminal, A3: a fourth communication terminal), a distribution server SV, and a listener terminal B (B1-Bn: third communication terminal) operated by a listener who observes the conference is an IP (Internet Protocol) network. Communication is established via the NW.

  In the present embodiment, the organizer terminal M functioning as a conference terminal device and the speaker terminals A1 to A4 are connected to an intranet N1 in the company, and the distribution server SV and the listener terminal B use the Internet N2 with them. Connected through. Hereinafter, the organizer terminal M, the speaker terminal A, and the listener terminal B may be simply referred to as “terminals”.

In FIG. 1, a hub, a router, and the like for connecting each terminal, distribution server SV, and IP network NW are not shown. Also, a multicast-compatible router that is arranged on a route through which the distribution server SV transmits IP packets by multicast is omitted.
(Configuration of organizer terminal M)
Next, the organizer terminal M will be described with reference to FIG. FIG. 2 is a block diagram illustrating a configuration of the organizer terminal that functions as a conference terminal device of the conference system illustrated in FIG. 1.

  The organizer terminal M has its own conference audio and video, and audio and video (hereinafter referred to as conference audio) including the conference audio and conference video sent from each speaker terminal A connected to the organizer terminal M. / Video), and returns to each speaker terminal A. In addition, the organizer terminal M transmits the synthesized conference audio / video to the distribution server SV in order to allow the observer operating the observer terminal B to observe the conference. The organizer terminal M includes an input / output unit 2, an AD / DA unit 3, an arithmetic processing unit 4, an encoding unit 5, a decoding unit 6, a channel data processing unit 7, a packet control unit 8, A call control unit 9, a communication unit 10, an information storage unit 11, and a communication control unit 12 are provided.

  The input / output unit 2 acquires attendee's voice (including ambient sounds) and video and outputs the voice signal and video signal to the AD / DA unit 3, and the audio signal and video from the AD / DA unit 3. Play the signal. The input / output unit 2 can be a microphone and a speaker for audio, and can be a camera and a display for video.

  The AD / DA unit 3 mutually converts the analog signal from the input / output unit 2 and the digital signal from the arithmetic processing unit 4 so that the analog signal is output to the input / output unit 2, and the digital signal is an uncompressed linear signal. The data is output to the arithmetic processing unit 4 as audio / video.

  The arithmetic processing unit 4 functions as a synthesizing unit that synthesizes audio / video from another terminal output from the decoding unit 6 and audio / video from the input / output unit 2 and outputs them to the encoding unit 5. To do. In addition, when the audio / video from another terminal is not received, the arithmetic processing unit 4 outputs the audio / video from the input / output unit 2 to the encoding unit 5 as synthesized data. When the arithmetic processing unit 4 synthesizes speech, the speech level is adjusted for each speech and synthesized. When the images are combined, the entire display size is divided according to the number to be combined under the control of the communication control unit 12 and is combined so as to fit in the whole. For example, in the case of compositing the video of the organizer terminal M and the speaker terminal A1, a video that is ½ the display size is arranged on the left and right to form one video.

  The encoding unit 5 encodes the input uncompressed linear data to generate a conference audio / video in which the entire data capacity is compressed, and outputs the conference audio / video to the channel data processing unit 7. If the encoding method is audio data, for example, G.P. 711. In the case of video data, H.264. 261, H.M. 263, H.I. However, any codec that can communicate with other terminals can be used.

  The decoding unit 6 decodes the conference audio / video from the plurality of attendees output from the channel data processing unit 7 and outputs the decoded audio / video to the arithmetic processing unit 4.

  The channel data processing unit 7 supports the conference audio / video (compressed data) synthesized by the arithmetic processing unit 4 and encoded by the encoding unit 5 for each call channel of the transmission destination designated by the communication control unit 12. And output to the packet control unit 8. Further, the channel data processing unit 7 outputs the conference audio / video from the packet control unit 8 to the decoding unit 6 in association with each call channel of the transmission source.

  The packet control unit 8 divides the encoded conference audio / video from the channel data processing unit 7 into frames, and adds a header (including a codec type and a serial number (sequence number)) to the audio data used as a frame. RTP (Real-time Transport Protocol) packet is generated and transmitted to the IP network NW via the communication unit 10. Further, the packet control unit 8 extracts the conference audio / video from the RTP packet received via the communication unit 10 and outputs it to the channel data processing unit 7.

  Further, the packet control unit 8 transmits the call control message from the call control unit 9 as an IP packet, or extracts the call control message from the IP packet from the communication unit 10 and outputs it to the call control unit 9.

  The call control unit 9 controls operations such as a call to the communication partner, an incoming call from the communication partner, or a call with the communication partner based on SIP (Session Initiation Protocol).

  The communication unit 10 is a LAN (Local Area Network) physical layer interface such as IEEE 802.3 that transmits and receives IP packets to and from the IP network NW.

  The information storage unit 11 stores management information such as the IP address of the distribution server SV that is the destination of the conference audio / video, the IP address of the speaker terminal A participating in the conference, and various other information. Memory.

  The communication control unit 12 performs overall control of the organizer terminal M, performs permission control for a request for participation in the conference from the speaker terminal A, and performs synthesis control for the arithmetic processing unit 4. Further, the communication control unit 12 manages the speaker terminal A participating in the conference, and transmits the synthesized conference voice / video to the speaker terminal A participating, via the call control unit 9. To the packet controller 8. In the organizer terminal M according to the present embodiment, the communication control unit 12, the call control unit 9, the packet control unit 8, and the communication unit 10 constitute a transmission unit.

The operation unit 13 includes numeric keys for inputting a telephone number, various function keys, and a display screen. The operation unit 13 is operated to instruct setting, start of conference audio / video, and the like. The communication control unit 12 realizes various functions corresponding to the pressed function key of the operation unit 13.
(Description of the configuration of the speaker terminal A)
Next, the configuration of the speaker terminal A will be described with reference to FIG. FIG. 3 is a block diagram showing the configuration of the attendee terminal of the conference system shown in FIG.

  The input / output unit 2, the AD / DA unit 3, the arithmetic processing unit 4, the encoding unit 5, the decoding unit 6, the channel data processing unit 7, the packet control unit 8, the call control of the speaker terminal A shown in FIG. The unit 9, the communication unit 10, and the operation unit 13 have the same functions as the components of the organizer terminal M shown in FIG.

  The speaker terminal A transmits its own audio and video to the organizer terminal M when no other speaker terminal is connected. In addition, when another speaker terminal is connected, the speaker terminal A synthesizes the voice and video from the other speaker terminals connected to its own voice and video and transmits them to the organizer terminal M. To do. The information storage unit 11x of the speaker terminal A stores the IP address of the organizer terminal M that transmits its own conference audio and video or synthesized conference audio / video.

The communication control unit 12x performs overall control of the speaker terminal A as well as control of a conference participation request to the organizer terminal M, permission control for a conference participation request from another speaker terminal A, and the like. Is going.
(Configuration of distribution server SV)
Next, the distribution server SV will be described with reference to FIG. FIG. 4 is a block diagram showing the configuration of the distribution server of the conference system shown in FIG.

  Note that the packet control unit 8, the call control unit 9, and the communication unit 10 of the distribution server SV shown in FIG. 4 have the same functions as the components of the organizer terminal M shown in FIG. Omitted.

  The distribution server SV is provided with a multicast processing unit 14, a channel codec unit 15, and a storage device 16.

  The multicast processing unit 14 designates a plurality of listener terminals B by a multicast address, and multicasts conference audio / video to the multicast address.

  The multicast compatible router in the distribution route copies the conference audio / video according to the destination and broadcasts it to the multicast group. This multicast transmission is transmitted to the listener terminal B that has joined the multicast group using IGMP (Internet group management protocol).

  The channel codec unit 15 performs a packet loss compensation process. That is, the channel codec unit 15 has the same encoding and decoding functions as the encoding unit 5 and decoding unit 6 of the organizer terminal M and the speaker terminal A, and the conference audio / video from the packet control unit 8. And whether or not the audio data and the video data are normal is checked. If there is an abnormality in the data, the data is interpolated so that the influence can be reduced. The decoded and interpolated audio / video data is temporarily stored in the storage device 16. The channel codec unit 15 encodes the audio / video data once stored in the storage device 16 and passes it to the multicast processing unit 14. As the storage device 16, a high-capacity hard disk device that can be accessed at high speed so that conference audio / video can be transferred in real time is used.

  The distribution server SV is provided with an information storage unit 11y and a communication control unit 12y. In the information storage unit 11y, the IP address of the observer terminal B (B1 to Bn) that is the destination of the conference audio / video distributed by the distribution server SV, the affiliation of the observer operating the observer terminal B, and the name , Functions as a storage means for storing information including a telephone number and an e-mail address as a registration list.

The communication control unit 12y performs overall control of the entire distribution server SV, and also instructs the multicast processing unit 14 to distribute conference audio / video to the listener terminal B in response to a multicast request from the organizer terminal M. It has. In addition, the communication control unit 12y functions as a notification unit that notifies the start of a hearing by notifying the holding of the conference in advance when delivering the conference audio / video to the listener terminal B.
(Configuration of the listener terminal B)
Next, the listener terminal B will be described with reference to FIG. FIG. 5 is a block diagram showing a configuration of a listener terminal of the conference system shown in FIG.

  The channel data processing unit 7, the decoding unit 6, the call control unit 9, and the communication unit 10 of the listener terminal B shown in FIG. 5 have the same functions as those of the organizer terminal M shown in FIG. The description is omitted. The channel data processing unit 7x and the packet control unit 8x of the listener terminal B are provided with functions in only one direction of the channel data processing unit 7 and the packet control unit 8 of the organizer terminal M shown in FIG. Since there is, explanation is omitted.

  The output unit 2x provided in the listener terminal B is a speaker and a display for reproducing synthesized voice / video of the attendees of the conference from the DA unit 3x. The DA unit 3x converts uncompressed linear data, which is a digital signal from the streaming processing unit 17, into an analog signal.

  The streaming processing unit 17 functions as a streaming reproducing unit that outputs uncompressed linear data from the decoding unit 6 as streaming data to the DA unit 3x while buffering.

Various setting information is stored in the information storage unit 11z. The communication control unit 12z performs overall control such as resource management of the entire listener terminal B, and requests the distribution server SV to distribute conference audio / video.
(Conference system operation and usage status)
The operation and use state of the conference system according to the embodiment of the present invention configured as described above will be described with reference to FIGS.
(Registration of the listener terminal B)
First, the distribution request registration performed when the listener wants to observe the conference to be held will be described with reference to FIG. FIG. 6 is a sequence diagram for explaining registration of a listener terminal. In FIG. 6, the observer operates the operation unit 13 of the observer terminal B to register the distribution request to the distribution server SV. However, the observer may perform the registration operation from another personal computer.

  As shown in FIG. 6, the observer operating the observer terminal B activates an authentication program that operates on the observer terminal B to display an authentication screen, or accesses the distribution server SV via the web, The authentication screen transmitted from the distribution server SV is displayed on the browser operated in B, and identification information (for example, user ID and password) assigned to each listener is input. The observer terminal B transmits the input identification information to the distribution server SV (step S10).

  The distribution server SV determines whether or not the identification information transmitted from the observer terminal B is included in the registration list stored in the information storage unit 11y. In this registration list, information on the listener who is permitted to access the distribution server SV and hear the conference is registered, and the name, affiliation, telephone number, user ID, password, and listener terminal B of the listener are registered. IP address, delivery valid / invalid flag, and the like. If the user ID and password (identification information) input to the observer terminal B are included in the registration list, a notification of access permission is transmitted to the observer terminal B (step S11). When a new observer wants to obtain authentication, the new observer asks an administrator who has administrator authority over the distribution server SV. The administrator logs in identification information for authentication of the observer using the administrator authority ID and password to the distribution server, and registers information about the observer acquired in advance from the observer. Thus, the observer can operate the observer terminal B and can observe it.

  Next, the listener terminal B that has received the access permission from the distribution server SV transmits a distribution request indicating that he / she wishes to listen to the held conference (step S12).

  The distribution server SV registers the listener terminal B that validates the distribution valid / invalid flag associated with the IP address of the listener terminal B to which the distribution request is transmitted (step S13).

  When the registration of the observer terminal B is completed, the distribution server SV transmits a completion notification indicating that the registration is completed to the observer terminal B (step S14).

  The listener terminal B that has received the completion notification transmits a multicast distribution condition setting request indicating a distribution condition when the distribution server SV distributes conference audio / video by multicast. This multicast distribution condition setting request transmits, for example, settings such as sound quality of conference audio and slow playback as distribution conditions (step S15).

  When receiving the multicast condition setting request, the distribution server SV registers it in the information storage unit 11y as a condition for multicast transmission of conference audio / video (step S16).

Then, the distribution server SV transmits a notification of completion indicating that the registration of the observer terminal B is completed to the observer terminal B (step S17).
(Overall flow)
Next, the conference voice / video in which the organizer who operates the organizer terminal M and the attendee who operates the speaker terminal A1 have a meeting, and the listener who operates the listener terminal B (B1 to Bn). A series of flows to listen to will be described with reference to FIGS. FIG. 7 is a sequence diagram for explaining the overall flow of the conference by the conference system, and FIG. 8 is a diagram showing the conference system performing a two-party conference.

  In FIG. 7, when a session participation request and a conference call permission session are established between the speaker terminal A1 and the organizer terminal M, the speaker terminal A1 and the organizer terminal M are used in the present embodiment. However, the speaker terminal A1 may establish a session with the organizer terminal M via a SIP server (not shown).

  The attendee who speaks at the conference operates the speaker terminal A1 and makes a conference participation request to the organizer terminal M (step S20). The conference participation request is transmitted from the speaker terminal A1 to the organizer terminal M by the following operation.

  First, in the speaker terminal A1, when the communication control unit 12x detects that the function key of the conference participation request of the operation unit 13 is pressed, the address of the organizer terminal M stored in the information storage unit 11x is read and the call control unit 9 is instructed to transmit a conference participation request. In order to establish a session with the organizer terminal M, the call control unit 9 instructs the packet control unit 8 to transmit an INVITE message. The packet control unit 8 transmits the INVITE message as an IP packet to the organizer terminal M via the communication unit 10. The INVITE message includes SDP information, which is session information necessary for establishing a session for exchanging RTP packets between the speaker terminal A1 and the organizer terminal M.

  When the host terminal M receives an IP packet of the INVITE message from the IP network NW via the communication unit 10, the packet control unit 8 notifies the call control unit 9 of the INVITE message. The call control unit 9 notifies the communication control unit 12 that the destination address of the RTP packet is the speaker terminal A1 based on the SDP information. In response to this INVITE message, the call control unit 9 outputs a 100 Trying message indicating that the INVITE message has arrived to the packet control unit 8. The packet control unit 8 transmits the 100Trying message as an IP packet to the speaker terminal A1 via the communication unit 10. In addition, the call control unit 9 transmits a ringing tone at the organizer terminal M and outputs a 180 Ringing message indicating that the other party is being called to the packet control unit 8 to transmit it to the speaker terminal A1.

  If there is no problem when the organizer operating the organizer terminal M sees the other party who has transmitted the conference participation request, the off-hook button of the operation unit 13 is operated. By this operation, the conference call permission is transmitted to the speaker terminal A1 (step S21). This conference call permission is transmitted from the organizer terminal M to the speaker terminal A1 by the following operation.

  In the organizer terminal M, when the communication control unit 12 detects the operation of the off-hook button, the call control unit 9 is notified of permission for the conference call. The call control unit 9 transmits a 200 OK message as an IP packet to the packet control unit 8 in response to the conference call permission notification, thereby transmitting it to the speaker terminal A1.

  In the speaker terminal A1, the call control unit 9 notifies the communication control unit 12x that the 200 OK message has been received. The call control unit 9 transmits an ACK message indicating a response to the 200 OK message by the packet control unit 8.

  The organizer terminal M recognizes that a session has been established with the speaker terminal A1 by receiving this ACK message. When the session is established, the communication control unit 12 secures a communication channel for the speaker terminal A1, or synthesizes conference audio / video between the own terminal and the speaker terminal A1 to the arithmetic processing unit 4. Or secure a call path.

  If a session is established between the organizer terminal M and the speaker terminal A1, a conference call is started (step S22). The conference call is performed using an RTP packet.

  The voice spoken by the attendee operating the speaker terminal A1 and the video of the situation are acquired from the input / output unit 2 of the speaker terminal A1, and output to the arithmetic processing unit 4 as voice / video by the AD / DA unit 3. The In this case, since there is no other audio / video to be synthesized, it is output to the encoding unit 5 as it is. The conference audio / video encoded and compressed by the encoding unit 5 is output to the packet control unit 8 as a conference audio / video to the organizer terminal M by the channel data processing unit 7. The packet control unit 8 transmits the conference audio / video as an RTP packet to the organizer terminal M to the IP network NW via the communication unit 10.

  In the organizer terminal M, when the RTP packet from the speaker terminal A1 is received via the communication unit 10, the conference audio / video is extracted by the packet control unit 8 and output to the channel data processing unit 7. The channel data processing unit 7 manages the conference audio / video from the speaker terminal A1 and outputs it to the decoding unit 6. In addition, the decoding unit 6 decodes the conference audio / video from the speaker terminal A1, and returns the audio data and video data as uncompressed linear data.

  The arithmetic processing unit 4 is controlled by the control from the communication control unit 12 so as to synthesize two voices and images of the organizer who operates the organizer terminal M and the attendee who operates the speaker terminal A1. . In other words, the voice spoken by the organizer and the video of the situation are acquired by the input / output unit 2 and converted into voice / video by the AD / DA unit 3, and the speaker terminal A1 output from the decoding unit 6 Audio and video are synthesized. Then, one of the synthesized audio / video is encoded by the encoding unit 5 toward the speaker terminal A1, and an RTP packet including conference audio / video is generated by the channel data processing unit 7 and the packet control unit 8. And transmitted from the communication unit 10. On the other hand, the audio / video synthesized by the AD / DA unit 3 is converted into an audio signal and a video signal, and the synthesized speech and video of the organizer and attendees are reproduced by the speaker and display of the input / output unit 2. The

  Here, when the organizer feels that the content of the conference needs to be understood by other parties, the operation unit 13 is operated to give permission to the other parties to listen (step S23). .

  The communication control unit 12 that has detected the pressing of the function key of the operation unit 13 that gives the permission to listen instructs the call control unit 9 to distribute the conference audio / video by multicast to the distribution server SV. Thus, an IP packet indicating a multicast request is transmitted from the packet control unit 8 (step S24).

  In the distribution server SV, the communication control unit 12y that receives the IP packet of the multicast request from the organizer terminal M via the packet control unit 8 and the call control unit 9 is included in the registration list stored in the information storage unit 11y. Then, the one in which the delivery valid / invalid flag is valid is read (step S25). Then, the distribution server SV transmits the name, affiliation, and telephone number of the listener in the read registration list to the organizer terminal M as information on the registration terminal (step S26).

  When the organizer terminal M receives the information of the registered terminal, the communication control unit 12 displays the information on the display of the operation unit 13. The organizer checks the list of listeners from the information of the registered terminal displayed on the display of the operation unit 13 (step S27). If there is no problem as a result of the check, the function key of the operation unit 13 indicating approval is pressed. The communication control unit 12 that has detected the pressing of the function key transmits a notification indicating approval to the distribution server SV (step S28).

  In the distribution server SV, when a notification indicating approval is received via the packet control unit 8 and the call control unit 9 and notified to the communication control unit 12y, a conference is held for the listener terminal B registered in the registration list. A notification indicating the start is transmitted (step S29).

  In the observer terminal B, when the notification indicating the start of the conference is received via the packet control unit 8 and the call control unit 9 and notified to the communication control unit 12z, a message indicating the start of the conference is displayed on the display of the operation unit 13. For example, it is displayed by a pop-up window. The observer can recognize that the conference is held by looking at the message indicating the start of the conference displayed on the display of the operation unit 13. Since the listener is prompted in advance to hold the conference, he can hear from the beginning of the conference even if he forgets that the conference will be held.

  The observer operates the operation unit 13 in order to observe the conference. The communication control unit 12z that has detected this operation transmits a notification indicating a request for listening to the conference as an IP packet to the distribution server SV (step S30). In addition, the communication control unit 12z transmits a notification indicating a request for hearing of the conference to the distribution server SV, and requests that the multicast-capable router of the local group to which the listener terminal B belongs participate in the multicast group. Send the indicated host membership report (IGMP Join message). By transmitting this host membership report, the listener terminal B can participate in the multicast group. Thereafter, the organizer terminal M starts unicast transmission of conference audio / video toward the distribution server SV (step S31a).

  When the distribution server SV receives the conference audio / video transmitted from the organizer terminal M by unicast, it is input to the channel codec unit 15 via the packet control unit 8. The channel codec unit 15 decodes the conference audio / video to form uncompressed linear data, and then stores it in the storage device 16. In parallel, the channel codec unit 15 performs packet loss compensation processing. When packet loss compensation processing is not performed, the channel codec unit 15 outputs the data as it is to the multicast processing unit 14 without decoding the conference audio / video.

  The multicast processing unit 14 instructs the packet control unit 8 to transmit the conference audio / video to a router (not shown) corresponding to the multicast located directly under the distribution server SV in the delivery route. The router performs multicast transmission toward the listener terminal B (B1 to Bn) by transmitting the conference audio / video (step S31b).

  In the listener terminal B, the conference audio / video received via the communication unit 10 is extracted from the IP packet by the packet control unit 8. Then, the data is decompressed by the decoding unit 6 via the channel data processing unit 7 and converted into uncompressed linear data to generate audio / video. The generated audio / video is buffered by the streaming processing unit 17 by a predetermined capacity. When the predetermined capacity is reached, the DA unit 3x converts it into an audio signal and a video signal, and audio is reproduced from the speaker of the output unit 2x and video is reproduced from the display. As shown in FIG. 8, the conference audio / video (a), which is the organizer's audio and video acquired by the organizer terminal M, and the conference audio / video, which is the audio and video of the speaker acquired by the speaker terminal A1. (B) is synthesized as conference audio / video (a + b) by the organizer terminal M and distributed by the distribution server SV, so that the listener can observe the state of the conference (step S32).

  When the meeting by the organizer and the attendee is finished, the function is terminated at the meeting partner by pressing the function key of the operation unit 13 indicating the end of the meeting on either the organizer terminal M or the speaker terminal A1. Is transmitted (step S33).

  When the conference is ended, the communication control unit 12 of the organizer terminal M transmits a notification indicating a request to end the multicast to the distribution server SV (step S34).

  The distribution server SV receives a notification indicating a request to end multicasting, thereby transmitting a message indicating that the request has been accepted to the organizer terminal M (step S35) and canceling multicast transmission (step S36).

Thus, the organizer terminal M combines the conference audio / video transmitted from the speaker terminal A and its own audio / video, and adds the synthesized conference audio / video to all the speaker terminals A. The distribution server SV does not need to be distributed to the organizer terminal M or one or more speaker terminals A, and only distributes to the listener terminal B operated by the listener. Because it is good, high performance is not necessary. Therefore, it is possible to configure with simple hardware by reducing the load required for distribution to the communication terminal operated by the listener.
(Participation in the meeting)
Next, when the organizer terminal M and the speaker terminals A1 and A2 are holding a three-party conference, the procedure for the speaker terminal A3 to further participate and hold the four-party conference is based on FIGS. 9 to 13. I will explain. FIG. 9 is a diagram showing a conference system performing a three-party conference, FIG. 10 is a sequence diagram for explaining the transition from a three-party conference to a four-party conference, and FIG. 11 is a conference terminal A3 participating in the conference FIG. 12 is a diagram showing a conference system when a request is transmitted to the organizer terminal M to join the conference. FIG. 12 shows the conference system when the speaker terminal A3 re-notifies the conference participation request according to an instruction from the organizer terminal M. FIG. 13 is a diagram illustrating a conference system in which a four-party conference is performed.

  In the present embodiment, it is assumed that the organizer terminal M can synthesize audio / video from up to two speaker terminals A.

  As shown in FIGS. 9 and 10, first, the organizer who operates the organizer terminal M and each speaker who operates the speaker terminal A1 and the speaker terminal A2 have a meeting. In this case, the organizer terminal M sponsors the conference audio / video (a), the conference audio / video (b) from the speaker terminal A1, the conference audio / video (c) from the speaker terminal A2, The conference audio / video (a + b + c) synthesized by the listener terminal M is distributed by multicast to the listener terminals B1 to Bn by the distribution server SV. In addition, the conference audio / video (a + b + c) synthesized at the organizer terminal M is played back by the organizer terminal M, and is also distributed and played back to the speaker terminal A1 and the speaker terminal A2 (step S40). ).

  It is assumed that a speaker who operates the speaker terminal A3 desires to participate in the conference. The speaker operates the operation unit 13 of the speaker terminal A3 to input a conference participation request. By this operation, as shown in FIG. 11, the speaker terminal A3 transmits a conference participation request to the organizer terminal M (step S41).

  In the organizer terminal M, since the communication control unit 12 is currently in a conference between the speaker terminal A1 and the speaker terminal A2, the number of connected terminals is maximized. It is determined that conference audio / video synthesis is not possible. Based on this determination, the communication control unit 12 reads the speaker terminal A having a meeting from the information storage unit 11, selects one of the speaker terminals A, and joins the selected speaker terminal A in the conference. An instruction is sent back to the speaker terminal A3 to send the request.

  In this embodiment, as shown in FIG. 12, when the speaker terminal A1 is selected, the speaker terminal A3 is notified of a reply to an instruction to transmit a conference participation request to the speaker terminal A1 (step S1). S42). When the organizer terminal M receives the conference participation request from the speaker terminal A3, the communication control unit 12 indicates that the speaker terminal A3 is connected to the information storage unit 11 under the speaker terminal A1. Store information.

  The speaker terminal A3 transmits a conference participation request to the speaker terminal A1 by a reply from the organizer terminal M (step S43).

  At the speaker terminal A1, since there is currently no connection to the other speaker terminal A, a conference call permission notification is transmitted to the speaker terminal A3 (step S44). This is determined by comparing the number of other speaker terminals A to which the communication control unit 12x is currently connected with the number of connections that are allowed to be connected.

  The speaker terminal A3 transmits the audio and video acquired by the conference call permission notification from the speaker terminal A1 as conference audio / video (d) to the speaker terminal A1 as shown in FIG. In the four-party conference, as with the speaker terminal A3, the speaker terminal A2 that transmits the audio and video acquired by itself as the conference audio / video (c) to the organizer terminal M, and the conference voice synthesized with the speaker terminal A3 / Conference audio / video (a + b + c + d) synthesized with / video (b + d) is distributed to the listener terminal B via the distribution server SV. In addition, the conference voice / video (a + b + c + d) synthesized at the organizer terminal M is played back at the organizer terminal M, and is also distributed to the speaker terminal A1 and the speaker terminal A2, and to the speaker terminal A3. Is also delivered via the speaker terminal A2 (step S45).

  The conference audio / video IP packet is synthesized with the conference audio / video of the speaker terminal A1 and transmitted to the organizer terminal M from the speaker terminal A3, so that each speaker terminal A physically has the network NW. The speaker terminal A3 communicates as if it were connected in cascade with the organizer terminal M through the speaker terminal A1.

  The transition from the three-party conference to the four-party conference can be similarly performed in the five-party conference in which the participation of another speaker terminal A is further added from the four-party conference. In this case, according to the allowable number of speaker terminals A, a new speaker terminal A can be cascaded to the speaker terminal A1 or cascaded to the speaker terminal A3.

By connecting the speaker terminals A in this way, the organizer terminal M allows the conference audio / video and its own audio to be transmitted from the speaker terminal A1 even if the speaker terminal A3 newly joins the conference.・ Since video is synthesized, the number of synthesized conference audio does not increase. Accordingly, it is possible to increase the number of speaker terminals A that can participate without increasing the load on the organizer terminal M.
(Exit from meeting)
Next, a procedure for forming a three-party conference by the speaker terminal A1 leaving the conference during the four-party conference will be described with reference to FIG. FIG. 14 is a sequence diagram for explaining a state when the speaker terminal A1 leaves the conference and shifts from the four-party conference to the three-party conference.

  As described based on FIG. 13, the speaker terminal A3 is connected in cascade to the speaker terminal A1 with respect to the organizer terminal M, so that the organizer terminal M and the speaker terminals A1 to A3 have four parties. A meeting is held (step S50 shown in FIG. 14). It is assumed that a speaker operating the speaker terminal A1 desires to leave the conference. The speaker operates the operation unit 13 of the speaker terminal A1 to input a conference end notification. By this operation, the speaker terminal A1 transmits a conference end notification to the organizer terminal M and the speaker terminal A3 that is directly transmitting the conference audio / video to the speaker terminal A1 (step S51).

  In the organizer terminal M, the communication control unit 12 reserves for the conference with the speaker terminal A1 by recognizing that the speaker terminal A1 is out of the conference by the conference end notification from the speaker terminal A1. The resources are released and the conference is terminated (step S52). Then, the conference call permission is notified to the speaker terminal A3 that has transmitted the conference audio / video to the speaker terminal A1 (step S53).

  In the speaker terminal A3, the conference audio / video that has been transmitted to the speaker terminal A1 so far by the conference end notification from the speaker terminal A1 and the conference call permission notification from the organizer terminal M is transmitted to the speaker terminal M1. By directly transmitting to, the transition from the four-party conference to the three-party conference shown in FIG. 9 is completed (step S54).

In the four-party conference, the conference audio / video of the speaker terminal A3 is transmitted to the organizer terminal M together with the audio / video acquired by the speaker terminal A1, and the conference audio / video synthesized by the organizer terminal M is transmitted to the speaker terminal. The message is transmitted to A3 via the speaker terminal A1, but in a three-party conference in which the speaker terminal A1 is removed from the conference, the speaker terminal A3 transmits directly to the organizer terminal M, and the organizer terminal M It is transmitted to the speaker terminal A3 in place of A1. Thereby, even if the speaker terminal A1 interposed between the organizer terminal M and the speaker terminal A3 is removed from the conference, the conference can be continued without any trouble.
(Failure of speaker terminal A)
Next, when a failure occurs in the speaker terminal A1 during the four-party conference and the conference voice / video cannot be relayed from the speaker terminal A3, the speaker terminal A1 is disconnected and becomes a three-party conference. This will be described with reference to FIGS. FIG. 15 is a sequence diagram for explaining a state when a transition from a four-party conference to a three-party conference occurs due to a failure of the speaker terminal A1, and FIG. 16 is a conference system when a failure occurs in the speaker terminal A1. FIG. 17 is a diagram showing a conference system when notifying the occurrence of a failure from the lower speaker terminal A3 to the upper organizer terminal M, and FIG. 18 shows the conference system when the three-party conference is restored. FIG.

  As described based on FIG. 13, the speaker terminal A3 is connected in cascade to the speaker terminal A1 with respect to the organizer terminal M, so that the organizer terminal M and the speaker terminals A1 to A3 have four parties. A meeting is held (step S60 shown in FIG. 15).

  As shown in FIG. 16, it is assumed that a failure occurs in the speaker terminal A1, and it becomes impossible to synthesize conference audio / video or receive or transmit IP packets. Therefore, the conference audio / video (c) obtained by synthesizing the conference audio / video (c) acquired by the speaker terminal A2 and the conference audio / video (a) acquired by the organizer terminal M is included in the speaker terminal A2. (A + b) is transmitted from the organizer terminal M, but the speaker terminal A3 cannot receive the conference audio / video (step S61).

  In the speaker terminal A3, when the communication control unit 12x detects that the conference audio / video IP packet from the speaker terminal A1 is not transmitted even after a predetermined time has passed, or the packet from the speaker terminal A1. When it is detected that there are many check code errors such as FCS (Frame Check Sequence) added to the URL, or there are many packet drops, it is determined that the speaker terminal A1 has a fault. As shown in FIG. 17, the communication control unit 12x of the speaker terminal A3 transmits a failure detection notification of the speaker terminal A1 to the organizer terminal M when detecting the failure of the speaker terminal A1 (step S62).

  Upon receiving the failure detection notification from the speaker terminal A3, the sponsor terminal M transmits a conference call permission notification to the speaker terminal A3 that is the transmission source (step S63). In this notification, the address of the conference audio / video transmission destination transmitted by the speaker terminal A3 is also transmitted. In the present embodiment, since the upper terminal of the speaker terminal A1 is the organizer terminal M, the IP address of the organizer terminal M is notified as the conference audio / video transmission destination address.

  The speaker terminal A3 directly transmits the conference audio / video that has been transmitted to the speaker terminal A1 up to now to the organizer terminal M in response to the conference call permission notification from the organizer terminal M, as shown in FIG. Thus, the organizer terminal M shifts from the four-party conference to the three-party conference by directly transmitting the synthesized conference audio / video to the speaker terminal A3 instead of the speaker terminal A1, and recovers from the failure. Is completed (step S64).

  Thus, in the four-party conference, the conference audio / video of the speaker terminal A3 is transmitted to the organizer terminal M together with the audio / video acquired by the speaker terminal A1, and the conference audio / video synthesized by the organizer terminal M is transmitted. Is sent to the speaker terminal A3 via the speaker terminal A1, but if the speaker terminal A1 fails and cannot deliver the conference audio / video, the speaker terminal A3 directly Since the organizer terminal M transmits to the speaker terminal A3 instead of the speaker terminal A1, the conference can be continued without any trouble.

  In the present embodiment, a case where a failure occurs in the speaker terminal A1 in which only the speaker terminal A3 is cascade-connected is described, but other speaker terminals A are cascaded in the speaker terminal A in several stages. However, it can be recovered in the same procedure. Specifically, from the organizer terminal M, the address of the speaker terminal A that is one level higher than the speaker terminal A in which the failure has occurred is used as the destination address, and the speaker terminal that is one level lower than the speaker terminal A in which the failure has occurred Notify A. By doing so, the speaker terminal A, one level lower than the speaker terminal A in which the failure has occurred, transmits the conference audio / video to the transmission destination address. Then, the speaker terminal A, which is one level higher, transmits the synthesized conference audio / video toward the speaker terminal A that is transmitting the conference audio / video. By adopting such a procedure, even if a failure occurs in the middle of the speaker terminals A connected in cascade, the conference can be continued without any problem.

  In the present embodiment, as shown in FIG. 1, in the conference system 1, the organizer terminal M and the speaker terminals A1 to A3 are connected via the intranet N1, and the organizer terminal M and the distribution server SV By connecting with the listener terminal B via the Internet N2, the organizer terminal M and the speaker terminals A1 to A4 can be placed in the same company or facility, and the distribution server SV and the listener Even if the terminal B is at a remote location, the conference audio / video can be distributed via the Internet N2.

  For example, in the conference system 1x shown in FIG. 19, in addition to the organizer terminal M and the speaker terminals A1 to A4, the distribution server SV is arranged in the intranet N1, and the distribution server SV, the listener terminal B, and the Internet N2 are connected. Arranged to connect through. By being arranged in this way, the distribution server SV can be used within the facility, and the conference audio / video can be distributed via the Internet N2 even if the listener terminal B is at a remote location.

  In the present embodiment, the organizer terminal M that functions as a conference terminal device is operated by the organizer that hosts the conference. However, it is only necessary that one speaker can be operated among a plurality of speakers who speak in the conference. A speaker other than the organizer may operate instead.

  Since the present invention can be configured with simple hardware by reducing the load required for distribution to a communication terminal operated by a listener, one or more listeners can hold a conference where a plurality of speakers speak. It is suitable for a conference system and a conference terminal device that can be heard.

The figure which shows the structure of the whole conference system which concerns on embodiment of this invention. The block diagram which shows the structure of the sponsor terminal which functions as a conference terminal device of the conference system shown in FIG. The block diagram which shows the structure of the attendee terminal of the conference system shown in FIG. The block diagram which shows the structure of the delivery server of the conference system shown in FIG. The block diagram which shows the structure of the observer terminal of the conference system shown in FIG. Sequence diagram for explaining registration of the listener terminal Sequence diagram for explaining the overall flow of the conference by the conference system The figure which shows the conference system which has the two-party conference The figure which shows the conference system which has 3 party conference Sequence diagram for explaining the transition from a three-party conference to a four-party conference The figure which shows a conference system when a speaker terminal transmits a meeting participation request to an organizer terminal, and joins a meeting. The figure which shows the conference system when a speaker terminal re-notifies a meeting participation request by the instruction | indication from a sponsor terminal. The figure which shows the conference system which is performing the four-party conference Sequence diagram for explaining a state when a speaker terminal leaves the conference and shifts from a four-party conference to a three-party conference Sequence diagram for explaining a state when transitioning from a four-party conference to a three-party conference due to a failure of a speaker terminal Diagram showing the conference system when a failure occurs in the speaker terminal The figure which shows the conference system when notifying a failure occurrence from the lower speaker terminal to the upper organizer terminal Diagram showing the conference system when restored to a three-party conference The figure which shows the conference system which concerns on other embodiment of this invention.

Explanation of symbols

A, A1 to A3 Speaker terminal B, B1 to Bn Listener terminal M Organizer terminal N1 Intranet N2 Internet NW network SV distribution server 1, 1x Conference system 2 Input / output unit 2x Output unit 3 AD / DA unit 3x DA unit 4 Arithmetic processing unit 5 Encoding unit 6 Decoding unit 7, 7x Channel data processing unit 8, 8x Packet control unit 9 Call control unit 10 Communication unit 11, 11x, 11y, 11z Information storage unit 12, 12x, 12y, 12z Communication control Unit 13 operation unit 14 multicast processing unit 15 channel codec unit 16 storage device 17 streaming processing unit

Claims (10)

A first communication terminal operated by one of a plurality of speakers, at least one second communication terminal operated by another speaker, and conference audio from the first communication terminal are received. And a distribution server that broadcasts and a network that can be communicated with an at least one third communication terminal that receives a conference voice broadcast from the distribution server and listens to the conference. Connected to
The first communication terminal includes a synthesizing unit that synthesizes the conference voice transmitted from the second communication terminal and its own conference voice, a distribution server for the conference voice synthesized by the synthesizing unit, and the second Transmitting means for transmitting to the communication terminal via the network,
The distribution server stores a third communication terminal as a transmission destination for broadcast distribution, and a conference voice transmitted from the first communication terminal as a third destination stored in the storage means. And a distribution means for transmitting to the communication terminal via the network. The synthesizing unit in the first communication terminal synthesizes video in addition to conference audio, and the distribution unit in the distribution server distributes the conference audio and video synthesized by the synthesizing unit as a conference video. The conference system according to claim 1, wherein: 3. The conference system according to claim 2, wherein the third communication terminal includes a streaming playback unit, and the streaming playback unit plays back the conference video distributed from the distribution server. 4. The conference according to claim 1, wherein the distribution server includes a notification unit that notifies the third communication terminal stored in the storage unit of the start of the conference. 5. system. When the first communication terminal receives a conference participation request from a fourth communication terminal that is about to newly join the conference, the first communication terminal instructs the second communication terminal to request the conference participation,
When the second communication terminal receives the conference participation request from the fourth communication terminal, the second communication terminal permits a call, and synthesizes the conference voice from the fourth communication terminal and its own voice to combine the first voice. The conference system according to claim 1, wherein the conference system transmits to a communication terminal. When the second communication terminal is disconnected from the conference and the fourth communication terminal is permitted to the conference call by the second communication terminal, the first communication terminal The conference system according to claim 5, wherein the conference is performed using the terminal as the second communication terminal. When the fourth terminal detects a failure in the second communication terminal, the fourth terminal notifies the first communication terminal of the occurrence of the failure,
6. The conference system according to claim 5, wherein the first communication terminal performs a conference using the fourth communication terminal as a second communication terminal. The first communication terminal, the second communication terminal, and the fourth communication terminal are connected via an intranet, and the first communication terminal, the distribution server, and the third communication terminal are connected via the Internet. The conference system according to claim 5, wherein the conference system is provided. The first communication terminal, the second communication terminal, the fourth communication terminal, and the distribution server are connected via an intranet, and the distribution server and the third communication terminal are connected via the Internet. The conference system according to claim 5, wherein: In a conference terminal device operated by one of a plurality of speakers,
Synthesizing means for synthesizing the conference voice transmitted from at least one speaker terminal operated by another speaker and the conference voice;
Transmitting means for transmitting the conference voice synthesized by the synthesizing means to the speaker terminal and transmitting via a network to a distribution server that broadcasts the conference to one or more listener terminals. A conference terminal device characterized by that.

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