The Research And Implementation Of MP3 Digital Audio Codec Algorithm

With MP3 audio codec algorithm popularized in internet music, a wide variety hardware decoders appear. The SOC design of low-speed CPU with MP3 hardware decoder module is the most cost-effective way of many implementations, which is the reason why this method is chosen.Focusing on the research of standard of the encoding algorithm for MPEG-I audio layer III, the major modules in the compression algorithm, including encoding of subband filter bank, MDCT and alias reduction, psychoacoustics model, non-uniform quantization , huffman coding and bit-frame group,is analysed in detail. The principle of MP3 decoder is introduced on the basis of the theory of MP3 coding above. In addition, a number of algorithms and improvements in the logic which accelerate the speed of decoding hardware and reduce the amount of caculation, such as subband cut-off approach, are applied to various modules in the decoding process.Following the research and optimization of the MP3 decoding standard of ISO/IEC 11172-3, parallel technology is applied to the main modules: Huffman decoder, scalefactor decoder, requantizer and etc. The advantage of parallel technology is that decoding is carried out in each clock cycle, and isn't influented by the code length. The increases in hardware complexity accelerate the decoder. The VHDL is used to achieve the design of the main module, and all modules of MP3 decoder are simulated and verified. The theory of FPGA is introduced finally, and the test programme is proposed.