Patent ID: 8009837

Claim:
An encoder for mixing a plurality of independent mono audio channels into a stereo recording, wherein said independent mono audio channels each comprise a first number of samples per unit time, and said encoder is arranged to mix said plurality of independent mono audio channels into a stereo recording by summing the plurality of audio channels and generating a restricted set of additional parameters used to master an audio track of a storage device, wherein the encoder is arranged to store each of the plurality of mono audio channels on the storage device in a summed channel having a second number of samples per unit time that is less than the respective first number of samples per unit time together with a restricted set of additional parameters, wherein the encoder includes an interpolating filter and the restricted set of additional parameters includes filter parameters of the interpolating filter, the interpolating filter being used to generate, by interpolation, immediate samples of said plurality of independent mono audio channels that were stored on the storage device by summing samples of one independent mono audio channel to intermediate samples of the other independent mono audio channels corresponding in time to said plurality of independent mono audio channels, such that the audio track can be played using an optical disk player and so that in a first mode said audio track including all of the plurality of mono audio channels which have been mixed by summing the plurality of audio channels are played as the stereo recording and in a second mode at least one of the plurality of mono audio channels is unmixed from said audio track by using said restricted set of additional parameters applied in the time domain and the stereo recording played with said mono audio channel removed.