US Patent 7313520 Adaptive variable bit rate audio compression encoding

An adaptive variable bit rate audio encoder and method that examines audio level information and detects various information in the audio data in a psychoacoustic model to create a quantization value and assign a mode tag to a single frame of audio. A bit rate is assigned according to one of three modes, a self-adaptive mode which is free-running and takes direction only from the characteristics of the incoming audio signal, a managed mode which is controlled by rules set from a statistical multiplexer, and a combination of self-adaptive and managed in which control rules from the statistical multiplexer act to maintain limits on the self-adaptive mode.