Patent ID: 7835904

Claim:
A process for encoding an audio signal, comprising the process actions of: using a computing device for: inputting an audio signal and obtaining a base layer bitstream of the audio signal; using the base layer bitstream of the audio signal and the input audio signal to obtain a residue; determining a psychoacoustic mask of an enhancement layer bitstream; encoding the enhancement layer bitstream using the psychoacoustic mask and the residue; and producing a scalable bitstream that improves perceptual audio quality of the audio signal using the encoded base layer bitstream and encoded enhancement layer bitstream, wherein the psychoacoustic mask of the enhancement layer is used to guide the order of coding bits of the scalable bitstream, comprising the process actions of: (a) inputting the psychoacoustic mask obtained from the coded base layer bitstream; (b) dividing the residue of the enhancement layer bitstream into individual bits; (c) encoding a set of bits that correspond to smaller psychoacoustic mask levels of the input psychoacoustic mask; (d) encoding a set of bits that correspond to larger psychoacoustic mask levels of the input psychoacoustic mask; and (e) repeating process actions (c) and (d) until a prescribed bitrate or distortion level is reached or all bits have been encoded.