MPEG-1 Layer III (MP3)語音編碼是最近幾年流行的標準，而一較高品質的標準Advanced Audio Coding(AAC)也已被提出與使用當中，AAC是由Moving Picture Experts Group(MPEG)所發展，並已於1997年4月成為國際標準。 在MP3與AAC中，量化和反量化是一不可缺少的部分，且影響音訊的好壞，關於量化和反量化，此篇論文提出一新的演算法和硬體架構，並且以ARM 920T處理器完成嵌入式MPEG AAC 解碼系統。 而整個AAC 解碼使用ARM的920T發展平台，而為了即時的展示，設計了一個數位轉類比的介面電路在ARM的Logic Module LM-XCV2000E上，它接收來自Core Module的音訊PCM資料，並傳到DAC電路而輸出類比音訊。 MPEG-1 Layer III (MP3) audio coding has been the most popular standard for these years. Moreover, a new higher quality audio coding standard “Advanced Audio Coding (AAC)” has been proposed and widely used now. AAC is a high-quality perceptual audio coder developed by Moving Picture Experts Group (MPEG). It has been standardized as ISO 13818-7 in April 1997. The quantization/re-quantization is an essential block in both MP3 and AAC and can affect the coding quality significantly. This paper presents a new high accuracy estimation algorithm and corresponding hardware for MP3 and MEPG-2/4 AAC audio coding. And this paper proposes the techniques to implement MPEG AAC decoding algorithm using the ARM 920T 32-bit RISC processor. We also apply the high quality quantization algorithm to increase the quality and performance. The whole AAC decoding system is designed based on an embedded system with ARM’s Core Module 920T and the Integrator/AP ASIC Development Motherboard. In order to make a real time demonstration, we designed a DAC (Digital to Analog Converter) interface in the Xilinx FPGA chip on the ARM’s Logical Module LM-XCV2000E. It receives the audio PCM data from the Core Module and transfers to the DAC chip for output the audio signal.