Optimization Of H.264 Decoder And Research Of Adaptive Rate Control

Entering 21 Century , the adoption of digital video has been fuelled by the development of many video coding standards in many applications , which are targeted in different application areas.There are many video protocols such as H.26x and MPEG-x . However the requirements for video transmission are increasing with the prevalence of Internet, so the video protocols are not applicable nowadays. Therefore ITU-T put forward and released anew standard for video compression------H.264. It has many different features and its efficiencyis improved by adding flexibility and functionality.But accroding to the analysis,we find that H.264 codec gain the performance by increasing the complication of calculation.and can not coding or decoding in real-time. So it is a hot point to improve the implementing of real-time coding or decoding.In this paper ,the basic stucture of H.264 decoder is introduced first and then the flow is analyzed deeply.Accroding to the analysis, we optimized some important parts of the decoder with MMX,such as intra prediction decoding,inter prediction decoding,transform coefficient decoding and deblock filter .And to reduce the multiply operations of quarter pixel interpolation , we replaced them with table . At the same time ,we studied the rate control of H.264 encoder and proposed an adaptive RC scheme for GOP-level.Compare with the primal decoder , the new one shortened the decoding time without any loss of performance . And the output of the coder with the enhenced RC method is more exact. We gain some increase on PSNR simultaneity.