Based On The Dvb Standard Mpeg Audio Decoder Design

As an International standard, MPEG Audio finds its wide applications in HDTV, multimedia technology and DAB. Aiming at designing of an audio decoder in the HDTV source decoder, this paper conducts an in-depth research of audio algorithm and its standard, and design two kinds of audio decoder: One is based on fixed point DSP, and the other is a purely hardware design.There are many audio compressing standards in-use, such as MPEG-1, MPEG-2, MPEG AAC and AC-3, among which MPEG-2 audio Layerl and LayerII is used in DVB standard, AC-3 and E-AC-3 are used in ATSC standard. This paper researches the DVB audio standard, and points out the shortcomings of the sub-band synthesis filter suggested by MPEG audio standard. By observing the symmetry of dewindow coefficient table in MPEG standard the storage of this table is cut by half. By simplifying the process of filter bank, the storage of temp variables are reduced by more than half. This paper compares between the 32-point DCT decomposition method and the property of cosine function to find the latter more efficient for DCT fast algorithm. Besides, the degrouping process suggested by the audio standard contains frequent divisions that consume much resource. This paper designs an interative method to replace the division module.Being a high performance processor, DSP is widely applied in multimedia designs. This paper introduces the flow of designing an audio decoder that is based on Ti DM642 DSP. Firstly it describes the audio decoder with full precision, and then transfers it to fixed-point description with limited precision. Based on the test of some representational audio streams, we evaluate the SNR of the fixed-point algorithm. Afterwards, it presents the architecture of the DM642 EVM board and the process of developing an audio decoder on the board. Finally the real-time audio decoder is successfully designed and tested.After accomplishing the software design, this paper present the development of audio decoder of MPEG SoC chip which is based on DVB standard. It starts with the definition of the objective decoder, divides the modules of audio decoder and designs the circuit diagram of the modules. Then it codes the design into verilog hardware description. After simulating the code with VCS and Modelsim, we download the design to Altera FPGA board, where we cover the conformance test and successfully play the TV programs on Asia No. 3 satellite. Lastly this paper brings forward some schemes for future compatibility of AC-3 streams.