A data processing device is programmed to decode and transform a stream of data representing a plurality of subband encoded channels of audio data into one or more channels of PCM encoded data for reproduction by a speaker subsystem. An improved method for decoding and transforming utilizes downmix matrices...http://www.google.co.uk/patents/US5946352?utm_source=gb-gplus-sharePatent US5946352 - Method and apparatus for downmixing decoded data streams in the frequency domain prior to conversion to the time domain
