Patent ID: 7996233

Claim:
An acoustic coding apparatus comprising a processor comprising: a base layer coding section that encodes an input signal per base frame and obtains a base layer coded code; a decoding section that decodes the base layer coded code and obtains a decoded signal; a subtraction section that obtains a residual signal between the input signal and the decoded signal; a frame division section that divides the residual signal into a plurality of residual signals in units of an enhancement frame having a shorter time length than the base frame; an enhancement layer coding section performed by the processor that encodes the plurality of residual signals and obtains an enhancement layer coded code; and a multiplexing section that multiplexes the base layer coded code and the enhancement layer coded code to output a multiplexed code, wherein the enhancement layer coding section comprises: a frequency domain transform section that transforms the plurality of residual signals in the frequency domain and obtains a plurality of frequency domain transform coefficients represented on a two dimensional plane comprised of a time axis and a frequency axis; a domain divider that divides the plurality of frequency domain transform coefficients into a plurality of domains on the two dimensional plane such that each domain includes at least a plurality of frequency domain transform coefficients which are grouped continuously along a time axis; a quantization domain determining section that determines a part of the plurality of domains in each base frame to be quantization targets based on power spectrum values of the frequency domain transform coefficients within each domain and outputs domain information showing the part of the plurality of domains; and a quantization domain coding section that encodes the domain information and the frequency domain transform coefficients within the part of the plurality of domains shown by the domain information, and obtains the enhancement layer coded code.