Patent ID: 7328160

Claim:
An encoding device for receiving and encoding an audio signal, the encoding device comprising: a transforming unit operable to extract a part of the audio signal at predetermined time intervals and to transform each extracted part to produce a plurality of window spectrums in each frame cycle, wherein the produced window spectrums are composed of short blocks and show how a frequency spectrum changes over time; a judging unit operable to: (a) judge whether there is a similarity of a predetermined degree among the produced window spectrums by comparing the produced window spectrums with one another; and (b) when there is the similarity between a first window spectrum of the produced window spectrums and a second window spectrum of the produced window spectrums, (1) specify, for each frequency, an average of high frequency parts of the first and second window spectrums so as to produce a new high frequency part composed of a plurality of specified averages, (2) replace the high frequency part of the second window spectrum with the new high frequency part, and (3) replace the high frequency part of the first window spectrum with a predetermined value, wherein the first window spectrum and the second window spectrum share the new high frequency part of the second window spectrum; a first quantizing unit operable to quantize each of the plurality of window spectrums to produce a plurality of quantized window spectrums after operation of the judging unit; a first encoding unit operable to encode the quantized window spectrums to produce first encoded data; and an output unit operable to output the produced first encoded data.