| Due to the increasing interests in digital TV, video telephony and multimedia communication, there has been tremendous progress in video compression coding technology. Based on different applications, many international video compression standards have been established by different international organizations. As a video compression standards recommended by ISO/IEC, MPEG-2 has been applied in fixed multimedia communications widely. However, with the growing of request, MPEG-2 is not adapted in many situation, such as mobile multimedia communications, wireless video conferencing etc. Comparing with MPEG-2, MPEG-4 has higher compression rate, wider range of code rate. So it can support more multimedia applications, especially adapt to mobile multimedia communications. Having been applied for many years, MPEG-2 has huge accumulations at hardware, software and multimedia storage. Meanwhile, MPEG-2 is coding standard of digital TV and will continue being used for a long time. For fully using existing multimediaresource, the transcoding from MPEG-2 video stream to MPEG-4 video stream is available. Aim at applying video stream transcoding technology to end product, the implementation of transcoding arithmetic on hardware is needed. One of implementation approachs is feasible by programmable DSP. Based on TMS320C6416 DSP, this paper discussed the implementation method of MPEG-2/MPEG-4 video stream transcoding on hardware.This paper is composed of following parts:Firstly, the principle of MPEG-2 video stream decoding and MPEG-4 video stream encoding is introduced.Secondly, analyze DSP chip structure characteristic and sum up the DSP software optimization techniques.Finally, based on TMS320C6416 DSP hardware platform, after adopt ing cascaded space-domain transcoding scheme and solving the bottleneck problem of high-speed data exchange between PC and DSP by PCI mode, near real-time implementation of MPEG video stream transcoding is achieved. Major optimization techniques are also given.
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