Patent ID: 7330555

Claim:
A coding device for mixing a plurality of channel signals every predetermined regular zone and for coding a resulting mixed output signal, a predetermined zone being a segment of time having a length separating successive peaks in the plurality of channel signals or a length separating successive zero-crossing positions in which each of the plurality of channel signals intersects with a zero level, the coding device comprising: a channel signal mixing unit for mixing the plurality of channel signals based on at least one predetermined channel mixture ratio and outputting at least one mixed output signal; a first processing unit for setting an output coefficient calculated by using a correlation coefficient of the plurality of channel signals, which is determined for a previous zone, as an output coefficient of the mixed output signal for a current zone; a second processing unit for setting an output coefficient calculated by using a correlation coefficient of the plurality of channel signals, which is determined for the current zone, as the output coefficient of the mixed output signal for the current zone; a first quantizing unit for quantizing a spectrum signal obtained by performing spectrum transform on the mixed output signal using the output coefficient supplied from said first processing unit; a second quantizing unit for quantizing a spectrum signal obtained by performing spectrum transform on the mixed output signal using the output coefficient supplied from said second processing unit; a selection control unit for controlling the selection of an output of said first quantizing unit and an output of said second quantizing unit based on a result of comparing a quantization error in said first quantizing unit with a quantization error in said second quantizing unit; and a coding unit for coding the output of said first quantizing unit or the output of said second quantizing unit selected by said selection control unit.