Research And Implementation Of Transmission System For EVDO Wireless Video Based On Embedded Linux

In today's world, technology of digital video and technology of wireless network isdeveloping rapidly, which make the video application having digital, networking andwireless characteristic. Nowadays, we are stepping into 3G days. And thus, videotransmission based on 3G network and the research on relative products is currentlypaid more attention. In this background, using video coding standard (H.264) andreal-time transport protocol (RTP), this paper works on the video transmission based onEVDO network, and designed a video transmission system for which theimplementation and verification has been done.Firstly, the related theoretical content is expounded, which includes some targetedstudy on QoS characteristic of real-time transmission. Then all the work is carried outon the board of Mini2440, and the video transmission system is completed with thesequence of setting up the software platform before design and verification and portingthe protocol stack and driver before programming the application. For the developmentof this video transmission system, details involves in: realized the driver of MC8630module, making the communication through USB between Mini2440 and MC8630possible; ported PPP program and written dialing script, making the Internet availablefor Mini2440; optimized the output of X264 encoder, making the efficiency of videotransmission raised; designed the packaging structure and arithmetic for video streamaccording to H.264 standard; developed the video transmission software withcombining of encoding and transmission, and verified it on the platform.Experiments show that, this system can compress raw video data of YUV format,and pack them according to designed packaging structure and arithmetic, then send toPC client. And H.264 code stream is store temporarily to some RAM zones, waitingfor being read by the packaging process. By analysis, the real-time performance ofvideo transmission mainly depends on the efficiency of encoding, so low processingcapacity of a processor may affect the client's decoding and playback.