Patent ID: 8447597

Claim:
An audio encoding device, comprising: a storage unit which stores information indicating a frequency width of each of a plurality of bands of audio data comprised of a plurality of first frequency bands, in association with a set number of bits respectively, wherein the set number of bits increases with respect to a central frequency of at least one of the frequency widths on a lower-frequency side; a discrete transformation unit that discretely transforms the audio data from a real-time domain to a frequency domain by acquiring the audio data and calculating quantized values indicating audio strength for each frequency; a maximum value acquisition unit that separates the discretely transformed frequency domain audio data into the plurality of first frequency bands having the respective frequency widths, and acquires a maximum value of quantized values for each of the separated first frequency bands; a determining unit that, for each of the first frequency bands, determines whether or not a number of bits necessary for expressing the corresponding maximum value acquired by the maximum value acquisition unit exceeds the corresponding set number of bits stored in the storage unit; an adjustment unit that, for each of the first frequency bands, when the determining unit determines that the necessary number of bits exceeds the set number of bits, adjusts the audio strength by conducting a right shift operation of the quantized values so that the corresponding acquired maximum value is within the corresponding set number of bits; a re-quantizing unit that, for each of a plurality of second frequency bands having a predetermined band width, re-quantizes quantized values calculated by the discrete transformation unit, or alternatively, quantized values adjusted by the adjustment unit, at a precision decided in advance such that the re-quantization precision increases with respect to at least one of the plurality of second frequency bands on the lower-frequency side; and an encoding unit that encodes and outputs quantized values calculated by the re-quantizing unit.