The Research Of MPEG-2 AAC Decoding Algorithms And The Realization On DSP

As a new generation audio coding standard, MPEG-2 AAC provides many useful characteristics, including high compression rate, good quality, modularization of codec and flexible configuration of channels. And it has been widely used in the field of digital audio storage, multimedia transmission on Internet and digital audio broadcast. Thus, the research on and realization of MPEG-2 AAC is very important.However, the complicated algorithm of MPEG-2 AAC results in great computation and storage consumption. Diamond 330HiFi audio processor, developed by Tensilica, is a DSP system that targets at audio processing. With its specific configuration and instructions, it can provide a good application environment for the real-time realization of AAC decoder.The dissertation is to implement an efficient real-time MPEG-2 AAC decoder. First, the core algorithms in MPEG-2 AAC standards are introduced, and a detail analysis of some modules with the high complexity is presented. Then some improvements on the reference decoder are introduced from aspects of decoding speed and memory cost according to the analyzed result.The decoder realization on Diamond 330HiFi Audio Engine focuses on the feature of the processor instructions. The crucial modules like Huffman decoding and filters with IMDCT are rewritten with AE instructions. The special instructions are quite effective in improving the decoding speed, especially for the computation-intensive codes.Finally, according to the test result, the real-time AAC decoder requires 86.13MHz on Diamond 330HiFi Audio Engine platform. The result of this dissertation is useful for the spread and application of AAC standard.