【作者】 陈雷；

【导师】 陈传波；

【作者基本信息】 华中科技大学 ， 软件工程， 2008， 硕士

【摘要】 随着智能手机、掌上电脑为代表的高端嵌入式终端产品的普及率也越来越高,嵌入式系统产品中对多媒体的应用也越来越多,而在这些多媒体的应用当中,要求对流媒体实时播放的支持显得越来越重要。主要目标是设计与实现在此类产品中支持3GPP标准流媒体文件的播放,以丰富产品的功能,增加产品的竞争力。在分析移动流媒体网络传输协议和H.264视频编码格式特点的基础上,充分考虑symbian操作系统的特点,重点研究了移动流媒体实时播放系统在Symbian平台的实现。根据Symbian平台的技术特点,系统使用活动对象实现各个功能模块,具体实现了网络模块,解码模块,播放模块和人机界面。其中网络模块采用RTP/RTCP/RTSP网络协议,实现了网络数据的请求与接收:实时传输协议通过UDP活动对象异步接收数据并拼成音频或视频帧;实时流协议利用TCP活动对象在应用层上控制数据的实时传输;实时传输控制协议通过UDP活动对象周期性地发送实时传输控制状态包以进行流量控制和拥塞控制。拼帧模块将UDP数据包中缺失和乱序的视频帧和音频帧还原为原始的音、视频数据。音视频解码模块将实时传输协议拼好的AAC/AMR-NB音频帧和H.264视频帧分别解码。音视频播放模块使用直接屏幕访问技术输出视频、多媒体框架输出音频,并根据时间戳信息调整视频播放速率以达到音视频同步。最后讨论了系统的界面设计上GUI的实现。更多还原

【Abstract】 With the wildly spread of the embedded terminal products such as Smart phone,and PDA in public,the application of Multimedia on embedded system has become more and more universal,and the real-time media stream play-back support based on 3GPP also become more and more important. The implementation of the play-back support to media stream file on embedded system is the main aim in this article.Referenced to 3GPP mobile streaming media system framework, bassed on analysis of the transport characteristic of wireless streaming media and h.264 video encoding and decoding technology, with the carefull consideration of symbian os, this project implements the real-time media stream play system on Symbian platform.The real-time stream media system is composed of network module, decoder, display module and Graphical User Interface, and these modules are implemented as Active Objects in Symbian OS.The network module uses RTP/RTCP/RTSP protocol to implement the request and receiving of network data: RTP receives and splices streaming data asynchronously by using UDP active object; RTSP uses TCP active object to control the real-time transmission in application layer; RTCP transmits status report periodically by means of UDP active object to control the flow and congestion. Syncretic module restores the lost and disorder video frame and audio frame from the UDP package and output the correct one.The audio-video decoding module decodes AAC/AMR-NB audio frame and H.264 video frame that syncretized by RTP. The direct screen access technology and multimedia framework technology are adopted by audio-video playback module to output audio and video, whose speed are adjusted according to timestamp to realize audio-video synchronization.Finally,it is discussed that fulfillment of all GUIs are also developed on different user interfaces .更多还原