The Research Of Audio And Video Communication Mechanism Under Constrained Bandwidth

Multimedia has become the trend of modern network communication systems, and the demand of audio and video multimedia services have grown rapidly.Compared to other data services on the network, audio and video services have a higher requirement of the network bandwidth, but nowadays the low bandwidth and fluctuation are common and cause the problems such as high packet loss, mosaics and screen pause which affect the quality seriously. In order to solve these bandwidth-constrained problems, mechanisms are proposed by this thesis and an audio and video data communication system which ensures the QoS is constructed. The main features are: (1) For the bandwidth fluctuation, by applying FGS scalable coding, error control and FTFRC (FGS-based TCP-Friendly Rate Control Protocol) rate adjustment algorithm proposed in this thesis, a transmission mechanism is presented. FTFRC improves the TFRC algorithm which is widely used and enables the audio and video streaming rate to match the network bandwidth better. (2) For the low bandwidth of wireless communication, a region of interest based asynchronous transfer mechanism is proposed. By processing image to extract key information of interest so that the packet size is reduced and the transmission is achieved timely. In a word, this thesis provides a valuable technology to solve the problem that audio and video communication systems can not adapt to the network conditions so that the quality of service is reduced.The thesis documented the communication mechanism, algorithm module design and system implementation. Actual test data show that the system has basically reached the design requirements, the main modules have been applied in Jinhua network system of China telecom mega eyes and Yiwu bus station advertising system.