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005			20260818134507.0
008			090414s2006 th uu|m rtt 0| a1eng d
035			_a.b12052644
099		9	_aAIT Thesis no.ME-06-07
100	0		_aJessada Karnjana
245	1	0	_aImplementation of low delay, low bit-rate audio compression for wireless digital audio system
260			_aPathum Thani, Thailand : _bAsian Institute of Technology, _c2007
300			_a100 p. : _bill.
490	1		_aThesis ; _vno. ME-06-07
500			_aA thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Microelectronics, School of Engineering and Technology
502			_aThesis (M.Eng.) - Asian Institute of Technology, 2006
520			_aThe question to increase the compression rate while the reproduction quality to be still acceptable leads to the term of perceptual audio compression. Audio perceptual coding based on a psychoacoustic model which using to eliminate the irrelevant information. Psychoacoustic model is a mathematical model of human perceptual of sound. The goal of model is to develop functions that are related to hearing sensations of human auditory system. For real-time applications, e.g. wireless speaker, headphones, or internet telephony, these applications do not require high audio quality but require low coding delay. To achieve this fashion, I designed a system with low complexity to reduce the computational times but the quality does not much different from audio CD. I used MDCT filter banks as subband coding. The advantage of MDCT is its perfected reconstruction. For quantizing. I compare the coding performance both full-range and narrow-range. A full-range quantization gave poor dequantized signals compare to narrow-range quantization. But full-range is acceptable for a low bit-rate requirement. Adding Huffman coding after quantization improves compression ratio less than 5%. It depends on the nature of data to compress. Huffman coding is useless in the case of less identical data. Thus I designed the system to check the identical data before perform Huffman coding. This codec gave the average compression ratio about 2.71: I or 62.5%. The number of bits per sample reduced to 5.99 bits per sample b'om 16 hits per sample
650		0	_aPsychoacoustics
650		0	_aAuditory perception
700	1		_aAfzulpurkar, Nitin V., _eChairperson
700	0		_aPasin Israsena, _eCo-chairperson
700	0		_aChumnarn Punyasai, _eExamination committee
710	2		_aThailand Graduate Institute of Science and Technology, _eScholarship donor
810	2		_aAsian Institute of Technology. _tThesis ; _vno. ME-06-07
856			_3Full-Text _uhttp://203.159.5.9/ait-thesis/detail.php?q=B11063
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