Image Number 11 for United States Patent #5588024.
The invention provides a frequency subband encoding apparatus wherein the amount of comparison operation processing of a bit allocator is minimized. A subband filter divides a PCM signal into and outputs a plurality of frequency subbands. A SMR calculator calculates, for each of the frequency subbands, an SMR which is a ratio between a signal level and a mask level. A bit allocator calculates a reference NMR which is a value obtained by subtracting, from an SMR of the entire frequency band, a S/N ratio calculated from a reference bit number to be allocated to one of the frequency subbands which exhibits a maximum SMR, and adjusts the reference NMR to perform bit allocation to the frequency subbands.