Patent ID: 7895034

Claim:
A method of encoding an audio signal, comprising: (a) obtaining a sampled audio signal which is divided into frames; (b) identifying: (i) at least a portion of a transient within one of the frames, the transient including an attack followed by a fall and the identified portion including the attack or the fall, (ii) a first portion of said frame that includes samples before said identified attack or fall, and (iii) a second portion of said frame that includes samples after said identified attack or fall; (c) generating transform data samples by performing multi-resolution filter bank analysis on the frame data, including filtering the first portion at a different resolution than the second portion; (d) generating quantization data by quantizing the transform data samples using variable numbers of bits based on a psychoacoustical model; (e) grouping the quantization data into variable-length segments based on magnitudes of the quantization data; (f) assigning a code book to each of the variable-length segments; and (g) encoding the quantization data in each of the variable-length segments using the code book assigned to set the variable-length segment.