AAC Triple Audio Decoders Based On ARM920T CPU In Blue-ray System

MPEG-2 AAC (Advanced Audio Coding) digital audio compressing standard has become the core algorithm of high quality audio coder of the MPEG national standard, which leads the trend of the perceptual audio coding technology. MPEG-2 AAC is one of the Hi-Fi audio coding standard, it contains many state-of-arts coding tools, including Modified Discrete Cosine Transform(MDCT), Time Domain Prediction, Temporal Noise Shaping, noiseless coding and so on. With the exploiting of psychoacoustic model of humanity auditory system and statistic theory, the encoding bit rate is reduced greatly while keeping the reconstruction quality as high as possible. A series of coding and decoding profiles are provided by MPEG2 AAC, so it can be used in different application areas and is adapted to different software environments and hardware architectures. As the blue-ray playing system is getting to be more and more widely used in consumer electronic areas, it's meaningful to research the implementation techniques of multimedia codes. This thesis analyses and optimizes the audio coding and decoding component of MPEG-2 AAC, and develops an audio decoding system which can decode 3-channel audio bit stream concurrently and is suitable for blue-ray system's application.The designed audio decoding system is an embedded software system based on SOC (system on chip), so it's important to select a suitable processor. As a result, this thesis chooses the ARM920T CPU which is widely used in consumer electronics and network router fields as the decoding CPU. This thesis introduces the architecture and pipeline of the instruction system of S3C2440 chip whose core is ARM920T. The main work of this thesis is to port the embedded operation systemμC/OS-Ⅱto ARM CPU and design the whole system software architecture of AAC-LC, in the mean while, the thesis induces the fast Huffman decoding algorithm for the decoding and mixing system to solve the hardware frequency limit issue.The designed system is verified on the S3C2440 evaluation board, and the test results are presented in the thesis. The results show that the designed audio decoding and mixing system meets the requirements of blue-ray system.