KR100216576B1 - Asymmetric Multimedia Signal Multiplexing / Demultiplexing Method - Google Patents

Abstract

The present invention reduces the bandwidth required for the entire multi-point communication by assigning and assigning the bands allocated to the transmitter and the receiver differently in the configuration of the H.221 multiplexer / demultiplexer to multi-point through the broadband ISDN multi-point controller The present invention relates to an asymmetric multimedia signal multiplexing / demultiplexing method, which allows a user who performs multimedia communication to use less bandwidth, thereby bringing an economic advantage due to circuit reduction.

Description

Asymmetric Multimedia Signal Multiplexing / Demultiplexing Method

The present invention utilizes a multipoint control unit (MCU: Multipoint Control Unit, ITU-T H231, ITU-T H243 Recommendation, hereinafter referred to as MCU) to provide multipoint communication services such as multipoint multimedia conferencing and distance education in broadband ISDN. Asymmetric multimedia signal multiplexing / demultiplexing method for constructing.

H.221 is a standard that recommends a frame composition method and procedure for multiplexing / demultiplexing audio, video, data and control information recommended by ITU-T. It was mainly used as a multiplexed frame for narrowband ISDN. . 1 illustrates an example in which multiple terminals are connected to a multi-point multimedia communication conference in a broadband ISDN using an MCU. As shown in FIG. 1, a multimedia terminal currently recommended as a standard terminal on a wideband ISDN is an H.321 terminal, which is a configuration form in which an H.320, which is a standard video terminal in a conventional narrowband ISDN, is matched to a wideband ISDN. Have As can be seen from the configuration of the H.321 terminal of FIG. 2, the end-to-network call processing portion 101 is changed from Q.931 to Q.2931 for wideband ISDN, and instead of the ISDN network matching unit, an ATM adaptation layer, AAL. (ATM Adaptation Layer) Type 1 and AAL-5 and ATM, and the physical layer, but the rest of the H.221 multiplexer / demultiplexer is the same as the configuration of narrowband ISDN.

Audio, video, data and control information 102, 103, 104 and 105 of FIG. 2 are multiplexed via an H.221 multiplexer and input to the MCU via an access point 201 with the control device shown in FIG. The multiplexed multimedia signals 202, the result of which the terminal is connected, are separated into the original audio, video, and data signals through the H.221 demultiplexer. These signals are sent to the media signal processing units 207, 208, 209, 210, 211 and 212 via buses 203, 204, 205 and 206. Each media signal processed by audio mixing and video switching in each signal processor is multiplexed by an H.221 multiplexer and sent to each H.321 terminal. In other words, the basic procedure and signal flow may be the same as the conventional multi-point ISDN in terms of processing the media signal and using the same transmission band as the multi-point communication between the narrow-band ISDN. The typical signal flow of multipoint communication in broadband ISDN using MCU and H.321 terminals is as mentioned above.

The present invention is an apparatus conforming to the H.221 multiplexer / demultiplexer (ITU-T H.221 standard) which is a method of multiplexing individual audio, video, data and control information used in the international standard IUT-T H.321 multimedia standard terminal. When applying the structure of) to broadband ISDN MCU, it is focused on the fact that even if the flow of multimedia signal is asymmetric, no quality degradation occurs in multi-point multimedia communication.

As described above, FIG. 1 illustrates a form in which an H.321 multimedia terminal is connected to a wideband ISDN multipoint control apparatus for multipoint multimedia communication through a wideband ISDN. Demultiplex the multimedia signal according to the generated H.221 multiplexed frame and mix the audio signal and send it to all connected terminals, and the video signal sends the screen of the currently speaking speaker to the remaining participants except the presenter. The screen is sent to the terminal corresponding to the presenter. By the operation of the basic multi-point control device, in the case of the video signal, the actual multi-point control device processes only signals corresponding to two speakers including the presenter and the previous speaker, and ignores the video signals of the remaining access terminals. In such a case, when a circuit is connected like a narrowband ISDN, when the transmission and reception use the same band, it is inevitable. However, in the broadband ISDN based on ATM, the transmission band and the reception band can be allocated differently.

Accordingly, the present invention reduces the bandwidth required for the entire multi-point communication by configuring the H.221 multiplexer / demultiplexer by differently assigning and assigning bands allocated to the transmitter and the receiver. It is an object of the present invention to provide an asymmetric multimedia signal multiplexing / demultiplexing method that enables users of branch multimedia communication to use less bandwidth, thereby bringing economical benefits due to circuit reduction.

1 is a schematic diagram of multimedia communication through a multipoint controller in a broadband ISDN;

2 is an internal configuration diagram of an H.321 multimedia communication terminal;

3 is a configuration diagram of a connection with a multi-point control device of a multimedia communication terminal;

4A and 4B are a general configuration diagram of an H.221 multiplexed frame,

5A and 5B are H.221 multiplexed frame structures according to 2xB and H0, H11, H12,

6A to 6C are asymmetric H.221 frame and symmetric H.221 frame configuration diagram,

7 is a schematic diagram of multi-point multimedia communication using an asymmetric H.221 multimedia multiplexer / demultiplexer,

8 is a block diagram of an asymmetric H.221 multiplexer / demultiplexer bandwidth control device;

9A and 9B are flow charts of multipoint communication using an asymmetric multimedia signal / multiplex demultiplexer.

The present invention comprises the steps of attempting end-to-network call processing (ITU-T Q.2931) between a terminal connected to a multimedia communication conference and a wideband ISDN multipoint controller; Attempting end-to-end call processing (ITU-T H.242) between a terminal connected to a multimedia communication conference and a broadband USDN multipoint controller; Setting a speaker and an incubator in an initial state and initiating multi-point multimedia communication by completion of band allocation of the speaker, the incubator and the general attending terminal among the connected multimedia terminals; Determining a method of selecting a speaker or a speaker by speaker recognition or conference coordinator; And detect the change of coin and incubator that can change continuously, if there is no change, proceed to earth communication mode, and if the speaker is changed, H.242 and MLP between multi-point control device and terminal according to the change. (T.120) Reassignment of bands by means of end-to-end signaling procedures.

Hereinafter, the present invention will be described in detail.

FIG. 4 illustrates a general H.221 multiplex frame configuration. The control information including FAS, BAS, and ECS of the user area is multiplexed by occupying a portion of a subchannel of the figure. The multiplexed frame can be of two types as shown in FIG. When two lines of 64 Kbit / s (corresponding to two virtual channels having 2xB channels in narrowband ISDN and 64Kbit / s in wideband ISDN) are used, the frame as shown in FIG. Is multiplexed, and when using 64 Kbit / s, one multiplexed frame as shown in FIG. 4A is used. When using bandwidths according to the bands of H0 (384 Kbit / s), H11 (1536 Kbit / s), and H12 (1920 Kbit / s), FAS, BAS, and ECS are respectively shown in the frame form of FIG. The first 8 subchannels (including 8 subchannels correspond to the bandwidth of one B channel on 64Kbps narrowband ISDN) are added with 5xB, 23xB and 29xB channels without FAS, BAS and ECS. Will have a form. When a plurality of H.321 multimedia communication terminals as shown in Figure 6 (C), (D) is allocated a line transmission and reception bandwidth of as much as H12 (1920 Kbit / s) to the multi-point control device for multi-point multimedia communication In addition, the audio signal of 48Kbit / s and the data of 14.4Kbit / s in the first channel 64Kbit / s of the bandwidth corresponding to each H12 by H.242 end-to-end signal negotiation procedure of H.321 terminal and MCU (800 bits / s, 1.6 Kbit / s are allocated to the FAS and BAS without using the ECS) and the remaining 29x 64 Kbit / s is occupied by the video signal.

The operation at this time is as follows. In FIG. 1, if the multimedia communication terminal 1 is set as the presenter and the multimedia communication terminal n-1 is set as the telephone, the multi-point control apparatus displays the screen of the communication terminal n-1 according to the operation of the current multi-point control device. The screen of the communication terminal 1 is transmitted to all the connected multimedia communication terminals including the communication terminal n-1. In the case of the voice signal, all the voices are mixed or only a specific speaker is selectively mixed. Accordingly, each multimedia communication terminal demultiplexes an H.221 multiplexed frame transmitted by the multi-point access device, an audio signal of 48 Kbit / s, 144.4 Kbit / s data, 1.6 Kbit / s control information, and the remaining 29 x. Extract and process 64Kbit / s video signal. However, while the receiver of the connected multimedia communication terminal must receive all bands corresponding to the H12 band, the transceiver does not need to use the H.12 band. As in the case of Figure 1, since the multi-point control device selected the multimedia communication terminal 1 and n-1 as the presenter and the telephone, the video signal of the remaining communication terminals 2, 3, ... n is multi-point control It is discarded by the device. Such a configuration is inevitable in a network environment in which a circuit must use the same band for both transmission and reception, such as a narrowband ISDN. However, in a broadband ISDN based on ATM, the transmission and reception bands can be allocated asymmetrically. Do. Accordingly, the multimedia communication terminals 1 and n-1 of FIG. 1 use the H.12 band for both transmission and reception, and the transmission speed of the other multimedia communication terminals is 64 Kbit / s. There is no obstacle in offering. Since the actual presenter and the telephone person can be dynamically changed according to the multi-point communication situation, if the presenter and the telephone person are changed from the terminal 1 and n-1 to the terminal 2 and the terminal n, they correspond to the previous presenter and the telephone person. The band corresponding to the video signal is removed from the H.221 transmitter of the terminal, and the frame corresponding to (B) of FIG. 5 including the video band of 29 x 64 Kbit / s is included in the multiplexed frame of the terminal 2 and n. And send it. In this case, the transmission / reception band required for all multipoint multimedia communication can be reduced from nx (transmitter H12 band + receiver H12 band) to ((2 x transmitter H12) + nx (receiver H12 band)). . The asymmetric type H.221 multiplexing / demultiplexing unit described above is a multiplexing / demultiplexing unit of H.221 so that 64Kbit / s of lines can be multiplexed only by the receiving unit in a structure in which the conventional transmission / reception direction is multiplexed in the same way. It can be easily implemented by changing some functions.

7 illustrates a practical example of a multipoint multimedia communication conference using an asymmetric media multiplexing / demultiplexing scheme. In this case, a multipoint multimedia conference is controlled by a conference coordinator. As shown in the figure, the multi-point conference host selects terminal 2 as the current speaker and selects terminal n-1 as the previous speaker. The screen switching method is possible to use the video switching method by the speaker recognition and the conference controller, which are basic functions described in the ITU-T H.231 and H.243 MCU related recommendations. In this case, the latter method is taken as an example. Under these conditions, all participants who are connected to the MCU receive the first speaker and MCU, including audio, data, video and control information, as shown in order to receive the video and mixed voice of the current speaker and the previous speaker. All bands in accordance with the capability bargaining shall be used. However, as shown in FIG. 3, the image signals are input to the image signal processing apparatus 207 through the image signal bus 203, and a specific image is selected under the control of the system manager 212. The images selected here are terminals 2 and (n-1) as described above, and when the speaker processing unit switches the images, the images other than terminals (2) and (n-1) have no value as information in the MCU. There is no. Therefore, the bandwidth according to the video transmission of the remaining (n-2) people can be considered completely wasted under the current operating conditions. In addition, considering that the bandwidth occupied by the video signal is most of the overall bandwidth, the loss on the user side can be very large.

In order to solve this problem, the present invention changes some functions of the existing symmetric H.221 multiplexer / multiplexer and uses the asymmetrical allocation of the band according to transmission and reception, which is an advantage of broadband ISDN. . Referring to the example of FIG. 7, the terminal for transmitting a video signal performs the existing H.221 symmetrical communication using the same band for both transmission and reception. The receiver of the terminal that does not need to transmit other images uses the same band as the previous terminal, but the transmitter uses the minimum band. Here, the minimum band means a transmission band through which an audio signal of an attendee can be transmitted. As shown in the configuration of the audio signal processing apparatus in the wideband ISDN multi-point control apparatus of FIG. 8, the attendee's audio signal is used as information for screen switching when there is no conference moderator, and the audio signal processing apparatus of FIG. This is because multiple audio signals can be converted to a common format like a linear PCM signal and then mixed. Therefore, the present invention uses 64 Kbps corresponding to the B channel as the minimum band of the asymmetric communication of FIG. The 64 Kbps full bandwidth must include FAS and BAS control signals in addition to the audio signal, and all other terminals have the same bandwidth for low speed data (LSD) or MLP (Multi-Layer Protocol) information in the initial channel. If you choose to use it as a data signal can be included. The reason that the BAS signal must be included here is that when the speaker of the multipoint communication changes, the bandwidth of the line must be reset accordingly, and the path that enables this is the H.242 end-to-end signaling procedure through the BAS signal. Because it is. In other words, if the present presenter and the previous presenter are changed from the terminal (2), (n-1) to (2), (n) in FIG. 7, the H.221 of the (2) and (n) is transmitted at the current 64 Kbps. It should be converted into the band including the video and the transmitter of (2) and (n-1) should delete the video band. The following asymmetrical band allocation of terminal and MCU is possible through MLP path in addition to H.242 signal. Such an asymmetric H.221 multiplexer / demultiplexer is composed of two conventional H.221 chips to separate transmission / reception multiplexing / demultiplexing paths and asymmetric transmission / reception band allocation in the H.221 frame structure. It can be easily implemented by enabling configuration.

9 is a flowchart illustrating multi-point multimedia communication using an asymmetric multimedia signal multiplexer / demultiplexer. In order to initiate multipoint multimedia communication using a multipoint control device on a wideband IDSN, as shown in FIG. 9, a single-to-network call processing procedure for a line connection between a terminal and a multipoint control device (ITU-T Q.2931) And a line connection is established between a plurality of multimedia communication terminals and a digital point control device.

After the line connection is established, the bandwidth of the connected line is multiplexed between the terminal and the multi-point control device by using a certain number of bands of some kind of multimedia signal, and the method of the individual Miltimedia signal (audio, video encoding method and data transmission and reception). Communication protocol). This is done by the ITU-T H.242 end-to-end signaling procedure. Other decision of the speaker and the incubator can be made by the above-described end-to-end signaling procedure or by the multipoint conference host or the conference organizer registering a particular speaker in the multipoint control device.

After this procedure is completed, the initial multi-point multimedia communication is started, and in order for the real-time multi-point multimedia communication to dynamically allocate bands as the presenter and the incubator change dynamically, coins as shown in FIG. The method of determining whether the change of the party and the incubator is decided by the frequency and frequency of the voice signal of the participant who participated in the multi-point multimedia communication meeting or by the speaker recognition and the host conducting the meeting should be decided.

The end-to-network signaling procedures accompanying this scheme may follow the schemes in ITU-T's H.242 and T.120 Recommendations. After the above method is decided, the actual multipoint multimedia communication conference is held. During the multi-point multimedia communication session, the multi-point control device detects the change of the main speaker and the incubator that can change continuously. If there is no change, the multi-point control device proceeds to the original communication mode. The band is reallocated by the H.242 and MLP (T.120) end-to-end signaling procedure between the point control device and the terminal. In this case, according to the scheme proposed by the present invention, the presenter and the incubator allocate the same band to the input and output, and multiplex / demultiplex to deliver the speaker's multimedia signal to the remaining multipoint multimedia communication participants. . Of the remaining attendees whose video signals are not distributed to all attendees, the output signals include voice signals and low-speed data and MLPs (where low-speed data and MLP information is essential for multipoint multimedia communications), in which case the remaining bands It can be filled with voice signal) and multiplexed to 64Kbps including FAS and BAS information. Since the input channel must receive the video signals of the main speaker and the incubator, the input channel is allocated to receive all the multimedia signals such as audio, video, and data in the same way as the input of the main speaker and the incubator.

Accordingly, the multimedia signals of the attendees except the main speaker and the incubator are allocated asymmetrically. That is, this asymmetric multimedia signal multiplexing / demultiplexing method is always performed dynamically during a multipoint multimedia communication session, which can be controlled by the procedures according to H.242 and T.120, which are currently recommended. The above-described method has not been considered because the multi-point controller has been used in a narrowband ISDN environment using the same input / output band to date. However, in the wideband ISDN, the input / output band can be allocated separately. It will bring about the effect of saving the line fee following the line bandwidth reduction.

H.221 multiplexer / demultiplexer based on narrowband ISDN uses the same transmit / receive band due to the characteristics of circuit switching. This may be one-to-one communication, but in case of multi-point communication through MCU, many bands are wasted. Therefore, in the present invention, when multi-point multimedia communication through the MCU in the broadband ISDN, the frame configuration of H.221 is changed asymmetrically to reduce the bandwidth. This is to take full advantage of the advantage that the broadband ISDN can allocate the transmission and reception bands separately, and when such a device is applied to both the H.321 terminal and the MCU, when receiving the multi-point multimedia communication conference service through the MCU on the broadband ISDN, It will provide users with the economic benefits of bandwidth savings and provide the network with the opportunity to reduce unnecessary load. This asymmetric H.221 multiplexing / demultiplexing method can be maximized as the image bandwidth occupies a large part of the total bandwidth used, which means that it is suitable for high quality multimedia multi-point communication. In addition, even if the screen processing of the MCU adopts the screen division method instead of switching, if this method divides the participant's video that is limited, the effect will be substantial.

Claims (1)

Attempting end-to-network call processing (ITU-T Q.2931) between a terminal connected to a multimedia communication conference and a wideband ISDN multipoint controller; Attempting end-to-end call processing (ITU-T H.242) between a terminal connected to a multimedia communication conference and a broadband USDN multipoint controller; Setting a speaker and an incubator in an initial state and initiating multi-point multimedia communication by completion of band allocation of the speaker, the incubator and the general attending terminal among the connected multimedia terminals; Determining a method of selecting a speaker or a speaker by speaker recognition or conference coordinator; And Detects the change of the main character and the incubator that can change continuously, if there is no change, proceeds to the normal communication mode, and if the speaker is changed, H.242 and MLP between the multi-point control device and the terminal according to the change. T.120) An asymmetric multimedia signal multiplexing / demultiplexing method comprising reallocating bands by an end-to-end signaling procedure.