Based On Audio-specific Dsp Core Ac-3 Decoder Design And Implementation

Digital Audio Compression Standard (AC-3) is the first perceptual encoding system which was designed for multi-channel digital audio signal. The AC-3 algorithm has high quality and low complexity. It has been widely applied in various fields, such as Digital Video Disc (DVD), HDTV (High Definition Television), DBS (Direct Broadcast Satellite), DVB (Digital Video Broadcasting), ATSC (Advanced Television System Committee), etc.The research of digital audio codec in China is later than in western countries. We can hardly find the slef-developped specific audio DSP for AC-3 decoding. Thus it is deserved to study and develop AC-3 decoder based on specific audio DSP.This thesis discusses the design and implementation of the AC-3 decoder based on audio specific DSP core. The main work includes:1. The audio-specific DSP core we used here is developed by ourselves, and there is no corresponding software development environment. The compiler greatly improved the efficiency of programming work.2. The program of AC-3 real-time decoding is performed by the instruction set of the audio soecific DSP core. The program includes the following parts: parsing bitstream information, exponent unpacking, bits allocation, mantissa unpacking, uncoupling, rematrixing, IMDCT, and downmixing. Finally we use the FPGA board to accomplish the emulation.3. The software and hardware co-verification can greatly improve the efficiency of haredware debugging. The AC-3 audio data is extracted by software and downloaded to the input buffer of the decoding system through PCI interface. The software and the PCI interface are 2 important sections of the whole software and hardware co-verification platform.4. As the compiler doesn't have automatic optimization function, the program optimization should be accomplished by the programmer. Program optimazation can improve the decoding efficiency and reduce the required memory volume. The optimizing methods include: reducing function calling, circulation optimization, using special instructions, removing redundant codes, flexiably using adressing mode, flexiably arranging the order of instructions, etc.