| 摘要 |
PURPOSE: Audio coder and decoder having a high speed analyzing filter and a composite filter are provided to reduce the number of times of multiplication by using the characteristics of a window coefficient. CONSTITUTION: An audio coder includes a mapping unit for sorting an input audio signal by a frequency band using a high speed band analyzing filter, a psycho-acoustics for allocating a bit to each frequency band by using the hearing psychology characteristics, a quantizing and coding unit for performing a quantization and a coding on the mapped signal according to the bit number allocated to each frequency, and a frame packing unit for forming a bit stream from the signal outputted from the quantizing and coding unit. An audio decoder includes a frame unpacking unit for unpacking the signal from the coded and inputted bit stream, a decoding and inverse-quantizing unit for performing a decoding and an inverse-quantization on the quantized signal, and an inverse mapping unit.
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