Based On The Pc And Dsp, Mpeg-4 Codec Design And Realization

In order to achieve video compression and high-performance video transmission, a series of video compression standards continue to emerge and MPEG-4 arises at the historic moment. As a general video compression standard, MPEG-4 supports very low bit rate (64kb/s or less) applications, and was released by ISO/IEC in 1999. In this paper, video encoder and decoder based on MPEG-4 standard are studied.This paper introduces some characteristics of MPEG-4 standard in Profile, level and bit-stream structure. According to the principle of MPEG-4 coding, some function modules are analyzed including discrete cosine transform, quantization, DC and AC prediction, zigzag scanning, run-length coding and entropy coding, motion estimation and compensation, rate control etc. The encoder and decoder are debugged and run after their main functions were written. The effect of compression is studied by changing single parameter of the encoder and watching decoding effect. According to the different effect of compression of each parameter, the suitable parameter combination is tested so as to realize the best compression effect of encoder based on PC.In order to realize the video codec based on DSP, the paper adopts DM642 development board for development. After fully understanding the working principle of the DM642 chip and other devices on the board, Two examples are analyzed, a kind of program realizes image collection, treatment and display based on single thread, Another kind realizes image collection, treatment and display based on the multi-thread. The encoder and decoder are realized in a main function so as to verify input, encoding, decoding and output. And then encoder and decoder singly packaged are separately moved into two example programs in the CCS, The single-threaded and multi-threaded video codec based on DSP are realized ultimately by modifying the relevant interface parameters.