中文摘要：

手机电视系统必须能够适应网络和客户端的异构性、无线信道的多变性等特点．提出一种手机电视系统SMTVS，流媒体服务器在不同码率的H．264视频流之间进行切换以适应网络状况的变化；代理服务器之间构成一个内容分送网络，视频数据通过应用层组播的方式传输到各个代理服务器，降低了服务器的负载，提高了网络资源利用率；代理服务器接收到视频数据之后，针对无线链路的状况对数据进行处理后再发送到客户端，以适应最终用户的不同需求；客户端根据网络状况来动态调整播放速率，避免显示缓冲区下溢和上溢．通过流媒体服务器、代理服务器以及客户端的协作，实现了视频数据在无线信道上的自适应传输．

英文摘要：

Mobile TV system should adapt to the heterogeneity of the networks, clients and the dynamic of the wireless links. In this paper, we present SMTVS,a mobile TV system based on H. 264 video coding standard. In SMTVS,the streaming server switches among H. 264 bitstreams with different rate to adapt to the dynamic of the network condition. The proxy servers construct a content delivery network, and transfer the video data from streaming server to the proxy servers through application level multicast. This scheme alleviates the streaming server＇s load and improves the utilization of the network resources. The proxy servers transcode and shape the rate of the received video data then relay to the clients,which implements the adaptation to the heterogeneity of the clients. To avoid the overflow and underflow of the playout buffer,clients dynamically adjust the rapidity of the playout according to the playout buffer＇s condition. Through the cooperation between the streaming server,the proxy servers and clients,SMTVS implements the adaptive transmission of video data over wireless links.