Optimize H.264 Encoder And Implement It On DM642

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 main work of this paper can be divided into four parts:1. As the number of intra prediction mode is more than other standard, the complexity of forecasting significantly increase. In this paper, we made a fast intra mode decision algorithm based on the characteristics of the macroblock. Intra16×16 is suitable for flat areas, while Intra4×4 is suitable for complex region. So in intra-frame mode, the texture characteristic is adopted to judge the best intra-frame prediction mode defore coding, which avoids calculating all modes during the coding process.2. Inter mode of H.264 use multi-mode to improving the prediction accuracy, but at the same time the complexity of calculating significantly increase. In this paper, we made a fast inter mode decision algorithm based on statistical properties of macroblock that Inter 16×16 is majority. In inter-frame mode, the half stop rule is decided by comparing the sum of the absolute difference (SAD) with a threshold after the motion estimation. The other blocks is splited in to 4×4 mode, after that calculating motion vectors of the block. If the motion vectors of the small block is the same, merging into large blocks.3. we optimize the encode algorithm based on the feature of DSP platform. First, we optimize chip memory and make a rational allocation of storage space; Second, we make C language-level optimization, including optimizing the cycle, Uniting aim and using intrinsic functions. Third, according to the results of performance analysis, we rewrite more time-consuming function with linearcompilation.4. we complete a network video surveillance system with RF5 and NDK of TI based on optimazed H.264 encoder. In this surveillance system, we use UDP to 5. send image data, while we use TCP to transimit the information of controlling. The system further verify capability of optimazed H.264 encoder, and has some practical value.Experimental results show that the coding rate has reched 18-20fps, with little degradation of the video quality on both subjective and objective views.