US Patent 7155383 Quantization matrices for jointly coded channels of audio

Quantization matrices facilitate digital audio encoding and decoding. An audio encoder generates and compresses quantization matrices; an audio decoder decompresses and applies the quantization matrices. For example, the audio encoder includes a multi-channel transformer operable to output multi-channel audio data in jointly coded channels and a program module for generating a single quantization matrix for weighting all of the jointly coded channels. In one such example, the program module computes the single quantization matrix from an aggregation of pattern information for all of the jointly coded channels, and the aggregation of pattern information is an aggregate excitation pattern. In another example, an audio encoder switches between different quantization matrix generation techniques based upon whether the first and second channels are jointly coded or independently coded, using a single quantization matrix for two jointly coded channels or using first and second quantization matrices for two independently coded channels. Decoders are described for decoding various encoder outputs.