Research And Implementation Of Video Compression And Transmission System Based On Embedded ARM Processor

Embedded technology is the center of interest in PC-after Era. In this dissertation, we designed and implemented a network video compression and transmission system base on embedded technology.In practice, as we know, the video data is too large to be transmited in the network application, so we need a compression coding method to achieve the video data pretreatment before the data's transmission. In our system, we choose JPEG2000 as the video compression coding method, which is implemented by ADV212 chips producted by ADI. ADV212 is a kind of high-powered compression coding chip, supporting 6 level 9/7 and 5/3 wavelet transform, lossy and lossless compression, and multiple bitstream rate controlling algorithms. In our system, embedded CPU PXA270 produced by Intel. It's the chief part of this video compression and transmission system. ADV212 and subsidiary circuit are the expansion components. Embedded Linux (Elinux) operating system runs on the embedded platform. In order to make Elinux to contact with the expanded component, we construct the device drivers for them. Device driver covers Zero-Copy technology, which assures that at one time, there is only one piece of compressed video steam in the system's physical memory without any copy. It not only improves the efficiency of the usage of memory, but also saves the CPU resource of copying the video stream. Futher -more, we designed a user application used for network transmission of multimedia data. RTP/RTCP transmission protocol is adopted to ensure the reliability and high-efficiency of the data transmission. To validate our system's performance and pacticability, a real application system, viz. a real time network video compression and transimission monitoring system, is designed based on it. The monitoring system is designed in embedded web way, so users can monitor the system just through an internet browser. Our experiment results demonstrate that this designed video coding system is feasible. The system can compress the PAL video signal into .j2c bitstream and put it out. Besides that, the bitstream rate can be adjusted to satisfy diferent demands.