Study Of MP3 Code And Decode System Based On Digital Signal Processor

This paper mainly researches MPEG I Layer III algorithm and mp3 decode algorithmic realization based on fixed-point digital signal processor, which involved in the integration of digital camera and mp3 player. As a part of the project from Information Industry bureau of Chongqing , named "the Study of Digital Camera' Key Technology".The head of this paper introduces audio code and decode theoretics and process. Mp3 compress ratio can reach 1:12 mainly because of its lossy compress method depended on psycho acoustic model. Mp3 code technology can reduce most data quantity without influence audio quality because of man's physiologic acoustic mask effect (time mask and frequency mask). The body of this paper, the main research, is realization of mp3 decode procedure and mp3 player system. We realize two scheme to implement mp3 decode system: one is hard chip decoded system, which decode mp3 file in STA013 chip controlled by mcrochip; the other system decode by software base fixed-point digital signal processor- TMS320VC5416. The later is the core application. Float operation implements in fixed-point DSP by software simulation, so its speed is very slow. The float operation must be fixed for fixed-point DSP, and, the paper has bring forward some optimized procedure for special mp3 decode module. These optimized procedures have been implemented in DSP system.As a whole, this paper introduces audio compress algorithmic in the international still image compress standard MPEG I Layer III, mp3 file format, soft validating of the algorithmics, and transplanting the algorithmic to digital signal processor, the realization of fixation for float procedure and optimization for some special mp3 decode module, the realization of software mp3 decode system based on DSP and system hardware. In addition, the realization of mass data store and transfer for digital consumer is significant. The interface between microchip and DSP has been implemented, the combination of DMA and MCBSP in DSP chip control mp3 data play.The mp3 decode software depended on DSP can be easily transplanted to other system which have DSP processor to implement mp3 play function with low cost. For example, digital camera with mp3 play function will be popular. For the procedure implements based on C language with inefficient compiler, the procedure must be handwork compiled. The success of this research will accelerate the combination of digital camera and mp3 player.