Research on Key Technologies of MPEG-4 Decoding Based on Media DSP
|Course||Information and Communication Engineering|
|Keywords||MPEG-4 IDCT Huffman decoding Media digital signal processor Data scheduling Real-time decoding|
With the continued enhancement of DSP processing power based on DSP platform video codec video compression technology applications. MPEG-4 video in part because of its high compression efficiency, reasonable implementation complexity, has a large number of applications in multimedia communications while mobile, portable player, wireless video surveillance. Currently, many organizations are engaged in applied research and product development of the MPEG-4 technology on the DSP platform This article has a real-time MPEG-4 decoding key technology research based on independent research and development of Information and Communication Engineering Institute of Zhejiang University Media System-on-Chip MediaSOC322xA important practical significance. Based on DSP video codec to achieve the key issues meet resource constraints, to maximize the performance of the codec. Therefore, first of all for the limited processor resources, the idea of ??hierarchical optimization is proposed based on the macroblock decoding strategy, the overall structure of the decoder is optimized. Secondly, a key module optimization. 1. From the data parallel processing and improve the utilization of memory bandwidth, data-intensive module in the decoding process optimization, dramatically reducing the cost of data preparation and calculation. 2. Combination of statistical and mathematical methods, compute-intensive module-IDCT process of decoding, Huffman decoding optimized. Wherein the optimization of the Huffman decoding module on the basis of the study of the statistical characteristics of the variable length codeword, the decoding method in a parallel step-by-step look-up table; IDCT module optimization analysis of the distribution of DCT coefficients of the sparsity proposed A new fast algorithm based on the statistical characteristics of the IDCT. The module optimization of a combination of the SIMD instruction, to further improve the decoding performance. Finally, the implementation of real-time decoding, optimized decoder data scheduling, media data flow control: based on two-dimensional DMA, optimize the structure of the program, take full advantage of parallel data processing and data handling, reducing the processor overhead; waiting for data preparation and control strategy based on data-driven, alternative control strategies based on time-driven, eliminating the overhead of the processor polling timer. Optimized by the above two aspects, the processor can further reduce the operating frequency. Optimize storage allocation, key modules (IDCT, Huffman decoding) algorithm, control strategy, the decoder MediaSOC322xA 81MHz can complete the real-time decoding of MPEG-4.