I studied the framework of the H.323 protocol yesterday afternoon and evening. It seems that using this protocol framework fully meets the needs of the X project. However, this protocol should be performed accordingly.
ITU's multimedia communication series standard H.32X is a standard for video conferencing in existing networks; where H.323 is a standard for multimedia communication in existing packet network PBN. If it combines with the existing IETF resource reservation protocol, multimedia communication in the IP network can be implemented. H.323 includes technical requirements for multimedia communication on a network without service quality assurance.
The H.263 protocol is compressed to the video code stream; H.225 is formatted by data, audio, control, etc., and accepts data from the network, which is mainly encapsulated by RTP, RTCP. The end-to-end signaling is encapsulated, and the H.245 protocol (multimedia communication control protocol) that guarantees the normal communication of the H.323 terminal, defines request, response, signaling, and instruction information; the control of the entire system is h. 245 Control Channel, H.225.0 Call channel, RAS channel is provided; H.225.0 implements the mechanism for packaging packets and synchronous transmission of stream media.
Unreliable channels for registration, approve, and state communication are called RAS channels. At the beginning, the call party first sends an authentication request message, then send an initial establishment message, which is ended at the end of the connection message. When the reliable H.245 channel is established, various channels of transmission can be established, and the settings of the multimedia can be set here;
So how do you guarantee the quality of communications in different transmission instances? Because H.225.0 can use different transmission addresses, audio and video data are transmitted and accepted in different RTP instances, ensuring the serial number of different media frames and the quality of each media; what to pay attention is, the current manufacturer is generally It is a different network address to transmit audio and video data; the communication has a process of performance exchange. The performance exchange process includes the media signals can be accepted, that is, tell the sender's own decoding ability; send performance to the reception party define the selection collection of the operation mode, which makes the same terminal to process multiple roads simultaneously signal;
