KR19990053538A - Master / Slave Decision Method in Video Conference Terminal - Google Patents

Abstract

The present invention relates to a method for determining video conferencing terminals as a master or a slave when implementing a videoconferencing system using a non-vision network such as a LAN.

The present invention transmits a master / slave decision reject (MSD REJECT) message or a master / slave decision acknowledgment (MSD Ack) according to the state of the master / slave decision signaling entity (MSDSE) when a master / slave decision (MSD) message is received. Transmitting a message or generating an error indication signal; Generating a decision acknowledgment signal or an error indication signal and a reject indication signal according to a state of the master / slave decision signaling entity MSDSE when a master / slave decision acknowledgment (MSD Ack) message is received; And a processing step of generating an error indication signal and a rejection indication signal or transmitting a master / slave decision message according to the state of the master / slave decision signaling entity (MSDSE) when a master / slave decision rejection (MSD REJECT) message is received. .

Accordingly, the present invention can efficiently process access to limited resources by determining a master and a slave between the calling terminal and the called terminal when constructing a video conferencing system using a LAN such as the Internet.

Description

Method of determining master or slave terminals in visual conference system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to videoconferencing terminals, and more particularly, to a method for determining videoconferencing terminals as a master or a slave when implementing a videoconferencing system using a non-vision network such as a LAN.

As the Integrated Services Digital Network (hereinafter referred to as ISDN) and the Broadband ISDN (B-ISDN) are being actively researched, new communication services for video and data in addition to the existing voice communication service are also being conducted. The demand is increasing. The most representative examples of such new services are "visual telephone" and "visual conference system".

Such video telephony and video conferencing system is mainly known as ISDN technology and is widely known as a recommendation of the H.320 series in ITU-T. Recently, due to the expansion of the Internet, interest in video telephony and video conferencing system using the internet has been increasing. It is rising. In other words, the speed of use of the Internet has not been fast enough to meet the requirements of users, and the video and voice compression / restore technology suitable for the Internet environment is still insufficient, but the infrastructure of the national high-speed information communication network has been established. If high-speed information communication becomes possible in the world, video telephony and video conferencing systems using the Internet will become commonplace.

As such, ITU-T recommends a standard proposal for video conferencing systems as shown in Table 1 below.

Recommendation Recommended Title Video specification Audio standard Signaling standard H.320 Video terminal for narrowband ISDN H.261 G.711, G.723.1G.728 Q.2931, H.220 H.221, H.243 H.323 Video terminal for LAN H.261H.263 G.711, G.722G.723, G.728 H.225, H.245 H.324 Low speed multimedia communication terminal H.261H.263 G.723.1 H.223, H.245 T.120 T.122 / T.125 (MCS), T.124 (GCC), T.126, T.127

In Table 1, the video conferencing system in the Internet environment is known as the H.323 series, and data conferencing standards such as an electronic blackboard, file transfer, and the like are proposed in the T.120 series.

However, when implementing video conferencing terminals according to the H.323 protocol, when terminals belonging to the same call access resources at the same time, collisions occur. Therefore, each terminal needs to be set as a master or a slave to solve this problem.

Accordingly, the present invention has been proposed to meet the above necessity, and provides a method for determining video conferencing terminals belonging to the same call as a master or slave in a video conferencing system using a LAN. There is this.

In order to achieve the above object, in the method of the present invention, an originating terminal and a terminating terminal are connected through a LAN, and master / slave decision signaling entities (MSDSEs) are implemented in each terminal according to the H.245 protocol. In a video conferencing system, when a master / slave decision (MSD) message is received, a master / slave decision rejection (MSD REJECT) message is transmitted or a master / slave decision acknowledgment (according to the state of the master / slave decision signaling entity (MSDSE)). Processing a master / slave decision (MSD) message to send an MSD Ack) message or to generate an error indication signal; When a master / slave decision acknowledgment (MSD Ack) message is received, a master / slave decision acknowledgment (MSD Ack) message that generates a decision acknowledgment or error indication signal and a reject indication signal, depending on the state of the master / slave decision signaling entity (MSDSE). Processing step; And a master / slave decision rejection that generates an error indication signal and a rejection indication signal or transmits a master / slave decision message according to the state of the master / slave decision signaling entity (MSDSE) when a master / slave decision rejection (MSD REJECT) message is received. (MSD REJECT) message processing step.

1 is a schematic structural diagram of a terminal according to the H.323 standard connected on a LAN;

2 shows the primitives and messages of MSDSE in H.245 protocol,

3 is a state transition diagram of MSDSE in the H.245 protocol,

4A is a flowchart of a signal for determining a master / slave when the remote terminal is determined to be a master in the H.245 protocol;

4b is a flowchart of a signal for determining a master / slave when the remote terminal is determined to be a slave in the H.245 protocol;

4C is a flowchart of a signal for determining a master / slave when determined to be a master in a second attempt in the H.245 protocol,

5 is a flowchart of a procedure for processing a master / slave decision message according to the present invention;

6 is a flowchart of a procedure for processing a master / slave decision acknowledgment message according to the present invention;

7 is a flowchart of a procedure for processing a master / slave decision reject message according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the videoconferencing terminal according to the H.323 protocol and the H.245 protocol will be briefly described to facilitate understanding of the present invention.

1 is a schematic structural diagram of a terminal according to the H.323 standard. The H.323 standard is an ITU-T Recommendation for enabling video conferencing in a communication environment where QoS (Quality Of Service) is not guaranteed, such as the Internet based on TCP / IP and UDP. As shown in FIG. 1, a video codec (111) connected to a video input / output device (I / O) 101 and an audio codec connected to an audio input / output device (I / O) 102 are provided. Codec: 112, the reception path delay unit 113, the system control user interface 104 is connected to the system control unit 114 to perform a variety of control, the audio and video stream and the data stream and control stream to synchronize the packet processing It consists of a real-time protocol (RTP) processing unit 115, the real-time protocol (RTP) processing unit 115 is connected to a LAN (LAN) such as the Internet through a network (LAN) matching unit 120. The system controller 114 includes an H.245 controller 114a, a call control 114b, and a RAS controller 114c.

The video codec 111 compresses and encodes the transmission video input from the video input / output device 101 according to the H.261 or H.263 protocol, and decodes the video received through the network according to the H.261 or H.263 protocol. To the video input / output device 101. The audio codec 112 compresses and encodes the transmission audio input from the audio input / output device 102 according to the G.711 or G.722, G.723, G.728, and G.729 protocols, and transmits the encoded audio through a LAN. The received audio is decoded according to the G.711 or G.722, G.723, G.728, and G.729 protocols and output to the audio input / output device 102.

The real-time protocol (RTP) processor 110 multiplexes and demultiplexes a video stream, an audio stream, a control stream, and the like according to RTP and RTCP.

Referring to the general operation of the H.323 terminal, a signal for starting a conference is exchanged using protocols such as conference create, invite, and join in a call setup step. In H.323, even in a multi-party conference, you do not call several participants at the same time, but first create a conference between two people, and then others join or join. As a result of the call setup, the H.245 session is established to send and receive H.245 protocols, and then the protocol for H.245 conference setup procedures is performed. H.245 sessions run over TCP, which first establishes a master / slave to play a leading role in establishing a multiparty conference.

When the capacities of audio and video channels that can be used in the conference are determined by the master terminal according to H.245, an RTP session is established for each media accordingly. RTP sessions reside on UDP and use IP multicast.

If a multi-party meeting is required, a meeting between the first two people is established, and services such as invite and join are performed to extend the multi-party meeting. It also exchanges necessary protocols with gatekeepers or other terminals to increase network bandwidth during conferences. If call termination is required, close the RTP / RTCP session for the audio and video that was in use, and close the H.245 session.

As such, when a video conference system is set up according to the H.245 protocol, an H.245 message is exchanged between the calling terminal and the called terminal. In this case, elements for processing the message of H.245 include a master slave decision signaling entity (MSDSE), a characteristic exchange signaling entity (CESE), and a logical channel signaling entity (LCSE).

The Master / Slave Decision Signaling Entity (MSDSE) is used to determine one of the two terminals to conduct video conferencing as the master and the other as the slave. The master terminal has priority over resource usage over the slave. The feature exchange signaling entity (CESE) is used to convey the performance supported by the terminal. In this case, performance refers to the type of audio / video codec available and the screen size. The logical channel signaling entity (LCSE) is called when a new one-way logical channel is to be created between two connected systems.

FIG. 2 is a primitive and message of a Master Salve Determination Signaling Entity (MSDSE) in the H.245 protocol, and FIG. 3 is a state transition diagram of the MSDSE in the H.245 protocol.

Referring to FIG. 2, the MSDSE receives a DETERMINATION.request primitive from an MSDSE user or sends a DETERMINE.confirm, DETERMINE.indication, or REJECT.indication primitive to an MSDSE user. MSDSE and Master / Slave Determination, Master / Slave Determination Ack, Master / Slave Determination Reject, and Master / Slave Determination Release messages It sends and receives the ERROR.indication primitive to the management layer. Here, each primitive is a signal transmitted between upper and lower layers, and is one of a request (* .request), a confirmation (* .confirm), and an indication (* .indication), and a message is information data transmitted between the same layers.

Referring to FIG. 3, the state of the MSDSE includes an INCOMING AWAITING RESPONSE (2), an idle (IDLE: 0) state, and an OUTGOING AWAITING RESPONSE (1) state. After sending the DETERMINE.request in the idle state, it transitions to the OUTGOING AWAITING RESPONSE state. In the outgoing response wait state, the rejection indication primitive (REJECT.indication) or the DETERMINE .confirm) transitions to the idle state (0) after sending the primitive. Sends the decision indication primitive (DETERMINE.indication) in the outgoing response wait (1) and idle state (0), then transitions to the encapsulating response wait state (2), and rejects the primitive indication primitive in the inking response wait state (2). Transmit to idle state (0) after sending (REJECT.indication) or reject confirmation primitive (DETERMINE.confirm).

4A shows the master slave decision flow when the remote MSDSE is set to master, FIG. 4B shows the master slave decision flow when the remote MSDSE is set as slave, and FIG. 4C shows the second attempt after the first attempt failed. It shows the flow when the master slave is determined by.

Referring to FIG. 4A, upon receipt of a DETERMINE.request primitive, the originating MSDSE forwards a master / slave decision (MSD) message to the destination MSDSE, whereby the destination MSDSE indicates a decision indication (DETERMINE.indication). The primitive is notified to the user and a master / slave message is sent to the calling MSDSE. The originating MSDSE delivers a DETERMINE.confirm (SLAVE) primitive to the user when the MSD Ack (slave) message is received, and forwards the MSD Ack (master) message to the destination MSDSE. The destination MSDSE issues a DETERMINE.confirm (MASTER) primitive to its parent. At this time, the sending MSDSE starts the timer T106 at the same time as sending the MSD message, and stops the timer T106 when the DETERMIN.confirm primitive is received. When the MSDSE is received, the destination MSDSE transmits an MSD Ack (slave) message and starts the timer T106. When the MSDSE is received, the terminating MSDSE stops the timer T106 when the DETERMIN.confirm primitive is received.

Referring to FIG. 4B, upon receipt of a DETERMINE.request primitive, the originating MSDSE forwards the MSD message to the destination MSDSE, whereby the destination MSDSE sends a DETERMINE.indication primitive to its user. At the same time as the notification, it sends an MSD Ack (master) message to the calling MSDSE. The originating MSDSE delivers a DETERMINE.confirm (MASTER) primitive to the user when the MSD Ack (master) message is received, and forwards the MSD Ack (slave) message to the destination MSDSE. The destination MSDSE issues a DETERMINE.confirm (SLAVE) primitive to the parent user. At this time, the sending MSDSE starts the timer T106 at the same time as sending the MSD message, and stops the timer T106 when the DETERMIN.confirm primitive is received. When the MSD message is received, the destination MSDSE transmits an MSDAck (master) message and starts the timer T106, and stops the timer T106 when the DETERMIN.confirm primitive is received.

Referring to FIG. 4C, upon receipt of a DETERMINE.request primitive, the originating MSDSE forwards the MSD message to the destination MSDSE, and the destination MSDSE rejects the master / slave decision (MSD Reject) unless it can determine. Deliver the message to the calling MSDSE. After receiving the MSD Reject message, the calling MSDSE sends another MSD message to request the decision. Accordingly, the destination MSDSE notifies the user with a DETERMINE.indication primitive and sends an MSD Ack (slave) message to the source MSDSE. The originating MSDSE delivers a DETERMINE.confirm (SLAVE) primitive to the user when the MSD Ack (slave) message is received, and forwards the MSD Ack (master) message to the destination MSDSE. The destination MSDSE issues a DETERMINE.confirm (MASTER) primitive to its parent. At this time, the sending MSDSE starts the timer T106 at the same time as sending the MSD message, and stops the timer T106 when a decision confirmation (DETERMIN.confirm) is received. When the MSD message is received, the destination MSDSE transmits an MSD Ack (master) message and starts timer T106, and stops timer T106 when a DETERMIN.confirm primitive is received.

5 is a flow chart of a procedure for processing a Master / Slave Decision (MSD) message in accordance with the present invention. Referring to FIG. 5, in step 501, a master / slave decision message is received and processed according to the current state. That is, if the current state is 'IDLE', steps 511 to 515 and 525 to 528 are processed. If the current state is an outgoing response wait state, steps 521 to 528 and steps 531 to 537, 544, and 545 are processed. Steps 541 to 545 are processed if the current state is the waiting for the encapsulation response.

If the current state is IDLE in step 511, the determination state is identified in step 512. If it is determined as master or slave in step 513, steps 525 to 528 are performed. In case of indeterminate state, rejection of master / slave decision in step 514. After transmitting the (MSD REJECT) message to the counterpart, the terminal maintains the idle state (515). If it is determined in step 513 that it is a master or slave, in step 525 a master / slave decision acknowledgment (MSD Ack) message is sent to the other party, and in step 526 a decision indication signal is sent to the local user. In step 527, the timer T106 is set, and in step 528, the state transitions to the waiting for enqueuing response.

If the current state is an outgoing response wait state in step 521, the timer T106 is reset in step 522, and the decision state is discriminated in step 523. If in step 524 the decision status is determined to be master or slave (i.e., according to the contents of SV_STATUS), then in step 525 a master slave decision acknowledgment (MSD Ack) message is sent to the other side, and in step 526 a decision indication signal is sent to the local user. send. In step 527, the timer T106 is set, and in step 528, the state transitions to the waiting for enqueuing response. If it is determined in step 524 that it is determined in step 531 that the number of pending determinations (ie, SV_NCOUNT value) has reached the predetermined set value (N100), if it is reached, an error indication signal is generated in step 537, and then a rejection indication signal is sent in step 544. Transmit, and transition to idle state in step 545. If the predetermined value has not been reached in step 531, a random number is written to the variable SV_SDNUM in step 532, and an undetermined count value is increased by one in step 533. In step 534, a master / slave decision (MSD) message is transmitted. In step 535, timer T106 is set, and then in step 536, the outgoing response wait state is transferred.

In step 541, if the current state is waiting for an encapsulation response, the timer T106 is reset in step 542, an error signal is generated in step 543, the reject signal is transmitted in step 544, and the idle in step 545 is transmitted. ) Transition to the state.

6 is a flowchart of a procedure for processing a Master / Slave Decision Acknowledgment (MSD Ack) message in accordance with the present invention. Referring to FIG. 6, after receiving the master / slave decision acknowledgment message in step 601, if the current state is the waiting for an encapsulating response or the waiting for an outgoing response, steps 602 to 609 are processed. That is, in step 602, if the enqueue response wait state or the outgoing response wait state in step 603, the timer T106 is reset in step 604, and in step 605, it is determined whether the master slave decision acknowledgment matches the state. That is, in step 605, it is determined whether the decision variable of the MasterSlave Determination Ack matches the SV_STATUS, and if it matches, step 606 is performed.

After the decision acknowledgment signal is transmitted in step 606, the processor transitions to the idle state in step 609. If the master slave decision acknowledgment does not match the state in step 605, an error indication signal is generated in step 607, the reject indication signal is transmitted in step 608, and then transitions to an idle state in step 609.

7 is a flowchart of a procedure for processing a Master / Slave Decision (MSD REJECT) message in accordance with the present invention. Referring to FIG. 7, in step 701, a master slave decision rejection message is received, and if the current state is an outgoing response waiting state or an encapsulating response waiting state, the timer T705 is reset in step 705. Subsequently, in step 706, it is determined whether the SV_NCOUNT value has reached the predetermined set value N100, and if it is not reached, a random number is substituted into the variable SV_SDNUM in step 707. Increment the value of (SV_NCOUNT) by 1. In step 709, a master / slave decision (MSD) message is transmitted. In step 710, the timer T106 is set, and in step 711, the terminal transitions to the outgoing response waiting state.

If the unresolved count (SV_NCOUNT) value reaches the predetermined set value (N100) in step 706, an error indication signal is generated in step 712, and a rejection indication signal is transmitted in step 713, and then in idle state in step 714. To transition to.

As described above, when the video conferencing system is constructed using a LAN such as the Internet, the present invention determines the master and the slave between the calling terminal and the called terminal to efficiently handle access to limited resources. It can be effective. In particular, in performing the processing procedure, the current state can be determined and processed according to the state, thereby reducing the amount of source code when implemented in software and improving the processing speed when executing the program.

Claims (2)

In a video conferencing system in which a calling terminal and a called terminal are connected through a LAN, and each terminal is implemented with master / slave decision signaling entities (MSDSEs) according to the H.245 protocol. When a master / slave decision (MSD) message is received, either send a master / slave decision reject (MSD REJECT) message or send a master / slave decision acknowledgment (MSD Ack) message, depending on the state of the master / slave decision signaling entity (MSDSE). Processing a master / slave decision (MSD) message to generate an error indication signal; When a master / slave decision acknowledgment (MSD Ack) message is received, a master / slave decision acknowledgment (MSD Ack) message that generates a decision acknowledgment or error indication signal and a reject indication signal, depending on the state of the master / slave decision signaling entity (MSDSE). Processing step; And When a master / slave decision rejection (MSD REJECT) message is received, the master / slave decision rejection generates an error indication signal and a rejection indication signal or transmits a master / slave decision message according to the status of the master / slave decision signaling entity (MSDSE). MSD REJECT) message processing step, characterized in that the master / slave determination method for a videoconferencing terminal. The method of claim 1, wherein the processing of the master / slave decision (MSD) message generates a master / slave decision reject message and generates an idle state if the state of the master / slave decision signaling entity (MSDSE) is idle and the message content is undecided. Maintaining; Generating a master / slave decision acknowledgment message, setting a timer T106, and transitioning to an enqueuing response waiting state if the state of the master / slave decision signaling entity (MSDSE) is idle and the message content is determined; If the state of the master / slave decision signaling entity MSDSE is outgoing response wait state and the message content is determined state, generating a master / slave decision acknowledgment message, setting the timer T106 and transitioning to the enqueue response wait state; Repeating the determination process only up to a predetermined count value if the state of the master / slave decision signaling entity MSDSE is an outgoing response wait state and the message content is undetermined; And generating an error indication signal and transmitting a reject indication signal when the status of the master / slave decision signaling entity (MSDSE) is in the waiting state for the response of the sending.