JP2908270B

A novel apparatus, capable of adaptively encoding input digital audio signals from N number of channels, comprises N number of subband filters arranged in parallel for filtering the input digital audio signals, respectively, on a subband-by-subband basis; an estimator for estimating perceptual parameters for each subband, each frame and a frame group including NxM number of current and previous frames for the total N number of channels, which corresponds to the estimated perceptual entropies; a bit allocation unit for adaptively determining bits for the respective subbands of the frame group based on the estimated signal-to-mask ratio data, perceptual entropies, and mean and standard deviation parameters and for generating bit allocation information corresponding to the determined bits for the respective subbands of the frame group; N number of quantizers arranged in parallel for quantizing the filtered subband audio signals for the N number of channels in response to the corresponding bit allocation information generated for the respective subbands of the frame group; and a circuit for formatting the quantized digital audio signals together with the bit allocation information.