Research Of Video Technique On The Ethernet Applied To Subway

The metro multimedia information system, as an indispensible part of subway industry, provides various information resources for the passengers. However, with the improvement of peoples'living standard, the traditional analog signal transmission gradually fails to meet the rising demand of high-quality video service for subway. Along with the development of information era, the synthesis of embedded system, internet, communication and multimedia technology proved to be the future trend of mobile TV. Therefore, this article carries out a research of the transmission and video decoding in embedded system, based on semi-physical network control platform applied to subway.Having studying the video processing technology of embedded system, this article proposed a digital video system which followed the concept of DM368 platform created by TI as a series product of Da Vinci. This digital video system mainly consisted of three parts:transmission modules, decoding module and image display module. Furthermore, HDMI was added on its original hardware for advanced image display in future. This digital video system applied open source embedded Linux of which the driver was configured according to hardware, as its OS. Based on this, a cross-compiling environment with arm_v5t_le tools chain was set up as the preparation of the application software development. In order to enable the system implement the functions of real-time transmission and display, this article studied the technical application of RTP to the embedded media stream, as well as the techniques of video codec of embedded system. Finally, this article also completed the software design that was comprised of the following tasks:transplanting oRTP library onto embedded Linux OS, achieving the real-time transmission of streaming media in the network, applying FFmpeg which was an open source cross-platform solution for audio and video to decoding video stream and completing the function of image display by Video Processing Back End of DM368.This article analyzed the programs of each module respectively and highlighted the key issues of programming as well. Finally, it gave some suggestions of improving the system, such as upgrading the video decoding function to create high definition of video output.