Management Of Audio-visual Real-time Transmission On Internet

Audio-visual transmission concerns two following aspects—multimedia and network communication, it must satisfy the requirement of quality of service to some degree, and thus, it is necessary to study the multimedia technology which is suitable for communication and right communication technology.This paper addresses the current situation on audio-visual transmission and then gives a detailed analysis of codec technology and real-time transmission of audio and video. As for audio-visual codec, this paper first studies the architecture of MPEG-4, and then turns my focus on hierarchical structure, which is designed for transmission, finally analyzes the MPEG-4 payload format of audio and video. As far as transmission is concerned, the article addresses the technology of the three layers: IP layer, Transport layer and Application layer. It deals with such related technologies on IP QoS as IntServ,DiffServ and MPLS,which begin with the network architecture. What's more, based on existing Internet technology, it expounds some technologies about multimedia network. These technologies involve congestion control and avoidance,queue management and RTP protocol. In queue management, the article introduces Random Early Detection (RED) Algorithm in detail. RTP protocol is designed for multimedia real-time transmission by IETF, and the article goes into detail the RTP packet format and RTCP packet format,RTP implementation components and the rules and algorithms of RTP transmission control. Further, it addresses RTP dynamic bandwidth adjustment algorithm based on AIMD policy. As it has advantage of saving network bandwidth which is in scare state, multicasting is widely applied on audio and video delivery. Since layered coding and layered delivery keep a close relation, the following part of the article deals with Receiver-driven Layered Multicast (RLM) algorithm, and give an introduction to Adaptive Layered Transmission (ALT) algorithm based on RLM and RTP dynamic bandwidth adjustment algorithm.Based on the above work, firstly, the article further presents AVRTM framework whose core is AVRTM ALT algorithm, which derive from modified ALT by making modification to AIMD algorithm–change from constant value to the one that the increment/decrease value is inversely propotional to current rate or bandwidth. By doing that, On one hand, it is adaptive and TCP-Friendly, on the other hand it makes rate or bandwith adjustment smoother in peak situation. In addition, AVRTM introduces a third-party controller whose function is monitoring and controlling the quality of audio and video delivery and thus improving the situation of delay and jitter. At the same time, the article conceives and designs the manager in terms of control theory and middleware model (Cobra). Secondly, the article addresses the...