Research And Application On QoS Of Real-time Video Based On Internet

Due to the explosive growth of the Internet and increasing demand for multimedia information on the web, real-time multimedia streaming over the Internet has received tremendous attention from academia and industry. Transmission of real-time video typically has bandwidth, delay, and loss requirements. However, the current best-effort Internet does not offer any quality of service (QoS) guarantees to real-time multimedia streaming. Real-time video streaming over Internet poses even more challenges, as it has more delay requirement. To address this challenge, this paper covers three areas of real-time video streaming over Internet: protocols for streaming real-time video, video compression and Application-layer QoS control. In areas of protocols and Application-layer QoS control, we first have a study of RTP/RTCP protocols, then we present a mechanism based on RTF for dynamic adjustment of QoS . As in the area of video compression, we have a research of the theory of Wavelet Transform and Multi-Resolution Analysis. Basing on the theory of Multi-Resolution, we compress the raw video sequence into layered video: lower layers which can be independently coded and provide coarse visual quality, higher layers which can also be independently coded and provide better visual quality. The quality adaptation mechanism adds and drops layers of the video stream according to the fluctuating of the bandwidth. If all the . . layers are forward-lifted to client buffer, we will have the highest quality video. That is the ideal situation. Usually a choice will be made between higher quality photos and continues video according to the bandwidth and the demand of client.