| Streaming media technology is a network transmission technique which ensures that the processes of transmitting and playing audio or vedio on Internet can proceed concurrently.It can give user the same experience of playing the local media when user playing the remote media.Streaming media technology is the popular technology for research and application in communication networks nowadays.Integrating many network technolodies ,audio and video technologies.Straming media which has been widely used brings conveniency to peoples's work environment and daily life. Embedded system are application-oriented ,it has the characteristics of miniaturization, low power consumption, stable and reliable, easy to carry and so on.With the popularization of streaming media services and embedded system products are accepted by usr,embedded terminal equipment which support streaming media technology will have more widely market.This dissertation aims to study the relevant technologyies about streaming media and embedded system,and based on Intel PXA270 processor to realize a media player of embedded streaming system client.Firstly,this paper introduces some correlation technique of embedded streaming media,including audio and viedo compressed encoding,the transport protocols of streaming media.As the aspect of processor,we choose ARM processor as hardware platfrom and Linux which could support embedded as the operation system.In respect of real-time tramsmission protocol,RTP/RTCP and RTSP are chosen.Meanwhile,MPEG-4 and MP3 that fited for streaming transport have been chosen as multimedia standards,because of their high compression rate and low computational complexity relatively.Secondly,as resquested of PXA720 platform and embedded OS,we have been builted the embedded Linux.This paper divides the whole application program into two tasks,one of the tasks is the streaming media transport,the other is the streaming media player.The main work in this dissertation included two parts:(1)Realized streaming media protocol stack.Livemedia which is a library of open source is chosen to be a base for developing streaming media protocol stack.RTSP,RTP/RTCP and SDP protocols are integrated by Livemedia,and the streaming transmission of many types of media is supported by it.According to our system's demand,Livemedia is needed to be cut down and ported to the application programs of this system.(2)Realized the application program of receiving and decoding of audio and video streaming.The paper analyeses the general playing structure,expounded the receiving stream and decoding process,synchronization mechanism.According to the related features and ARM platform decoding algorithm,we optimized the corresponding program performance.Finally,we realized the basic function of embedded streaming media player, besides,the work has tested the application program and gived the improvement.The last,this paper summarizes the work done,pointed out the places and problems that still need further improvement. |
