Aac Decoder Based On The Hardware And Software Co-design, Development And Implementation

AAC audio coding standard is one of low bit-rate,high-fidelity coding standards having characteristic like high compression, good sound quality, supporting multi-channel and varying sample rate. Comparing to traditional standards like MP3,AC3,it can achieve the same quality with less bit-rate,hence reduces the bandwidth required by transferring. It is widely used in mobile multimedia broadcast,internet stream media and other applications.There are many ways to implement AAC decoder.The general approach is using commercial DSP with the advantage of flexible and fast time-to-market. However, this method is not always desirable since large power consumption and high cost. Another way is using pure ASIC approach, it has the advantage of high speed and less resource required, but flexibility is an important issue for this design. In this paper, we present a new solution to AAC audio decoder which put commercial processor and dedicated hardware accelerator together to develop the whole system design. By doing these, it can strike the right balance between efficiency and flexibility. General processor can easily deal with different audio codec while dedicated hardware can create the highly efficient utilization during the decoding process. In this paper, the work include the following four aspects:1. Analyzed the heart of tools in each step of AAC decoding, used high-level language to finish software source code corresponding to the algorithms, established the project of AAC audio decoder in software environment and realized real-time decoding in software.2. Established the blue print and architecture of"Dequantization and Scale operation"and"Filterbank", quantified the parameter of each module, built the simulation model based on Matlab software and finished the algorithms-level simulation according to the design plan.3. Wrote the source code of"Dequantization and Scale operation"and"Filterbank"by using Verilog-HDL, and then performed simulation and verification. 4. Modeled the"Play-Control"module in the AAC system which can be divided into software and hardware part. Software and hardware communicated through the decode control programs and SW-HW interface programs, meanwhile the hardware side realized data buffering operation.Adopted HW-SW Co-design method, built the"AAC Audio Decoder System"platform through PC and FPGA experimental board to realize real-time AAC audio decoding.