The Implementation And Verification Of AAC Codec

MPEG-2 AAC(Advanced Audio Coding) standard is a high tone quality audio coding standard. It has a features of multi-channel(48 main channel, 16 low-frequency-channel),high compression ratio(Compression ratio is 11:1),more sampling rate(support 8KHz to 96KHz) and high tone quality(every channel will achieve high definition when the data rate is 64kbps).On the one hand, High sampling rate and multi-channel makes it very suitable for DVD-Audio.On the other hand,the feature of high tone quality at low bit rate makes it also suitable for mobile communication,online radio,Internet phone,etc.In this paper,the research object is MPEG-2 AAC and we propsed the design of AAC codec.This paper studies the implement of AAC codec.In the part of implementation of codec,this paper will show the basic block diagram of encoding and decoding,and introduce the function,structure and state machines of every module in the coder and decoder,then this design optimize some module to make the AAC codec more faster.The AAC codec in this paper is a singlechip which support the MPEG-2 and MPEG-4 standard.There are about 18K gates in this codec and the codec has a 176k bits RAM,meanwhile without ROM.The number of gates in coder is about 8K and it use a 166K bits RAM while the number of gates is 14K and use a 110K RAM in decoder.The coder and decoder share a 110K RAM and other module such as Cordic,FFT,ALU1 and ALU2.Finally,this paper has a simple verification of AAC codec,we verify the coding and decoding function of AAC codec in the IP verification and verify the AAC codec with FPGA in the actual environment.After constantly analysis and optimization, makeing the AAC codec achieve better effect.