Implementation And Optimization Of H.264/AVC Encoder Based On DSP Platform

Multimedia terminals have been becoming more and more popular in a variety of fields, such as video conference, video phone, video surveillance, PDA, digital TV and so on. Thus, an efficient and smart embedded video compression system is not only significant to the academia, but also helpful to the industry.Nowadays, the performance that the latest video coding standard H.264/AVC achieves is more outstanding than any other former standards did. However, its additional complexity challenges the real-time implementation and optimization. Thanks to the rapid development of microprocessors, the capability of DSP has been upgraded sharply. The high-performance digital media processor TMS320DM642, manufactured by Texas Instrument, is one of the most powerful DSP available to date. And it is the ideal platform to implement H.264 encoder. The work of this paper is focused on the H.264 algorithm and DSP optimization:The research on the fast intra mode prediction algorithm, based on histogram and autocorrelation: In intra-frame mode, the texture characteristic is adopted to judge the best intra-frame prediction mode before coding, which avoids calculating all modes during the coding process.The design of the fast inter mode prediction algorithm, based on the pretreatment of motion search and the analysis of texture difference: In inter-frame mode, the half stop rule is decided by comparing the sum of absolute difference (SAD) with an auto-adapted threshold after the motion estimation. As to other macro–blocks, combining the predisposing method and the analysis of texture difference, a novel fast inter mode prediction algorithm is proposed. Optimization based on the feature of DSP platform: Firstly, according to the structure of DM642 and the characteristic of H.264 encoder, the on-chip memory is reallocated reasonably. Meanwhile, the EDMA is adopted to ease the bottleneck of data accesses. Secondly, the time-consuming ANSI C codes are optimized. Finally, the linear assembly is introduced to accelerate the performance of the certain program.After the optimization on H.264 algorithms as well as DSP platform, the performance of the encoder is improved dramatically. Experimental results show that the coding rate has reached 16.55 fps in average, with little degradation of the video quality on both subjective and objective views.