Software Design Of 3G Server Transcoder Based On DaVinci DSP

The wide application of video compression standards and mobile video technology accelerates the emergence and development of vide transcoding research. Video transcoding technology is the conversion of one kind of video compressed stream to another one, and the aim is to make the input stream in line with the requirements of receiving terminals. For these low-resolution display and the weaker performance of mobile devices (such as 3G mobile phones, mobile MP4), it is quite necessary to consider reducing the spatial resolution. The birth of new video compression standards also promotes the research on transcoding of different video formats. The 3G server is faced with a challenge, which is how to make various types of user terminals access and receive video information without any obstacle.The most straightforward transcoding architecture is to cascade the decoder and encoder directly. 3G server armed with this architecture can meet different types of transcoding. It is flexible but complex. However, significant complexity saving can be achieved while still maintaining acceptable quality, by reusing information contained in the original incoming bit stream, including motion vector, macroblock encoding mode and frequency domain information. In addition, the choice of a good performance platform is also essential. TI has introduced a series of DaVinci DSP processor, which is designed for the digital multimedia application. It has enormous advantages of video processing. This dissertation's design and optimization work was carried out based on the DaVinci DSP.This dissertation first discusses the principle of video compression and transcoding, and introduces the application of DSP and 3G server in the multimedia field.Then the dissertation presents the DaVinci technology and the features of the chip's structure, and focused on the key technologies and application frames of video transcoding. And the study on the MPEG-4 to H.263 transcoder to lower spatio-temporal resolutions is provided. The realization and optimization of software is discussed in detail from the algorithm level.Then the dissertation described how to implement the code base on DaVinci, including optimization of C code and Assembly code.The final part of the dissertation is about some conclusion and future work.