TY  - SER
AU  - Jessada Karnjana
AU  - Afzulpurkar,Nitin V.
AU  - Pasin Israsena,
AU  - Chumnarn Punyasai,
ED  - Thailand Graduate Institute of Science and Technology,
TI  - Implementation of low delay, low bit-rate audio compression for wireless digital audio system
T2  - Thesis
PY  - 2007///
CY  - Pathum Thani, Thailand
PB  - Asian Institute of Technology
KW  - Psychoacoustics
KW  - Auditory perception
N1  - A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Microelectronics, School of Engineering and Technology; Thesis (M.Eng.) - Asian Institute of Technology, 2006
N2  - The 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
UR  - http://203.159.5.9/ait-thesis/detail.php?q=B11063
ER  -