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According to top-down design process of big hardware design project and extreme complexity of decoding process make it impractical to directly design DOLBY ACS decoding hardware, that is why I devoted myself to successfully designing DOLBY AC3 decoder in system level. The successful design of this c language decoder gives a very good foundation for further design of hardware decoder, enhancing design and research capability of VLSI center in digital audio field.DOLBY ACS is a highly efficient and flexible digital audio compression standard, adopted in DVD and American HDTV audio systems, widely used in satellite digital broadcast, digital studio, home theatre as well as entertainment equipments. It supports a wide variety of audio mode: 1+1,1/0,2/0,3/0,2/1,2/2,3/2. Sample frequencies of 48khz, 44.1khz, 32khz are all supported. Bit rate can be as low as 32kbps,and as high as 640kbps. The use of perceptual coding exploiting the masking effect ensures high quality and great compression ratio .Features, frame structure, applications, decoding process and encoding process of DOLBY ACS are all presented in details. DOLBY ACS decoder system level implementation and verification have been passed .which is based upon good understanding of synchronization and error detection, unpack BSI, exponents decode, bit allocation, mantissas process, de-coupling, rematrixing, inverse transform, window overlap/add, downmixing, PCM output of decoding process. Design and verification in C language are now essential steps in designing complex hardware for many hardware designing companies. Successful design and verification in system level facilitate further design and give later designer sound foundation and guidance and confidence.Audio file in ACS format is not available either via internet or laser disk like DVD, a VOB file intended for testing acS decoder has been got, from which audio file in 5. 1 ACS format is extracted. Decoding this audio file with executable file got from my program produces PCM file, we obtain correct high quality sound when PCM file is played.- ii - "Features, configuration and application of AAC, MP3, and MPEG4 audio are also introduced in this paper.
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