
Some Mathematics Behind MultiChannel PredictionInternal Technical Memo, Sept. 1994 Heiko Purnhagen Universität Hannover, Institut für Theoretische Nachrichtentechnik und Informationsverarbeitung IntroductionMultichannel prediction is a technique to exploit redundancy between different channels of a multichannel audio signal. Thus, the coding of these signals can be improved. The basic idea is to calculate an estimate z^(n) for the signal z(n) in a channel z based on the signals x(n) and y(n) in the channels x and y. If desired, the prediction can also be based on only a single signal x(n). When using prediction, instead of the signal z(n) only the predictor error signal e(n) = z(n)z^(n) has to be transmitted. The parameters describing the applied predictor (predictor coefficients etc.) have to be transmitted as sideinformation. In the decoder, x(n), y(n) and the transmitted predictor parameters are used to calculate z^(n) as in the encoder. Together with the transmitted predictor error signal e(n), the original signal $z(n)$ can be reconstructed. Prediction can be applied independently for several channels z1, z2, ... if desired. If a subbandbased coding scheme is used, prediction can (and should) be applied independently in the different subbands.
