The H.264Codec Based On ARM-Linux

With the rapid development of information technology, as the information carrier, video and audio play more and more important role in various fields of social life. However, as there are plenty of redundant information in digital video and audio information, and the redundant information in digital videos and audios which are always take up great amount of storage space restrict the development of multimedia technology. In this case, as its higher compression ration and better image quality, the H.264, which is the new video compression standard formulated by JVT(Joint Video Team)——comes into existence from the VCEG(Video Coding Expert Group) of ITU-T and the MPEG(Motion Picture Expert Group) of ISO/IEC, has became the most mainstream video processing standard. Using MC/MP to eliminate video temporal redundancy, DCT to eliminate spatial redundancy of the difference image, VLC to eliminate the statistical redundancy of the quantized coefficients, H.264gets a high-performance compression efficiency. As its computational complexity, developers always use SoC(System on Chip)+ASIC(Application Special Integrated Circuit) or DSP(Digital Signal Process) to implement the H.264Encoding/Decoding.As the performance of H.264compression efficiency raises at the cost of the growth of the algorithm complexity, and people care more about the real-time decoding in practical use. The existing algorithms are based on PC general-purpose processors. Although in recent years, the ARM processor and embedded technologies are developing rapidly, limited in processing ability and storage capacity, the existing H.264algorithms must be transplanted and optimized to meet the actual needs.The paper first introduced the H.264standard and its new features in detail, analyzed the time-consuming functions and modules in the decoder. And then described the Linux system, bootloader, transplant of the kernel as well as the production of the root file system over friendly arm mini2440. Transplanted X264, ffmpeg and other reference software based on the H.264standard to the ARM platform after cross-compile, and made compiler optimization as well as the code-level optimization. The compiler optimization is to select the appropriate cross-compile environment and configure the best compilation parameters to generate better target software,while in the code-level optimization, including the removal of redundant code, rewrite the loop structure and the assembly optimization.Finally, completed the decode and play, and gave the experimental result as well as the evaluation. The experimental result shows that at the resolution of qcif, the real-time decoding and playing can make success.