Patent ID: 8706508

Claim:
An audio decoding apparatus comprising: a memory configured to store a plurality of instructions; and a processor configured to execute the instructions, the instructions comprising, a signal acquiring instruction configured to receive a first audio signal that has a first number of channels and that is encoded; a dequantizing instruction configured to decode and dequantize the encoded first audio signal in each channel to calculate a first frequency spectrum; a spectrum converting instruction configured to divide the first frequency spectrum in each channel of the first audio signal in a time direction or in a frequency direction to calculate a first signal sequence having the same time resolution and the same frequency resolution in all the channels of the first audio signal; a down-mixing instruction configured to perform weighted addition on the signals at the same time and within the same frequency band included in the first signal sequence in all the channels to include a second signal sequence having channels of a second number different from the first number of channels; a spectrum inverting instruction configured to obtain one frequency spectrum value of the same frequency band from the signals within the frequency band included in each of the second signal sequences of a first predetermined number, which are continuous in the time direction, in each channel of the second signal sequence or obtain one frequency spectrum value from the signals within frequency bands of a second predetermined number, which are continuous in the frequency direction, in the second signal sequence to convert the second signal sequence into a second frequency spectrum having the second number of channels; and an audio recomposing instruction configured to convert the second frequency spectrum into a second audio signal in a time domain.