Stability of the synthesis filter in stereo linear prediction

A scheme for stereo audio coding is proposed consisting of a 2-channel linear prediction stage in combination with a single rotator. It is argued that it combines different attractive features of existing stereo coding mechanisms. It is experimentally shown that for unequal orders of auto- and cross-predictors, the stability of the synthesis system cannot always be guaranteed. For equal orders, the Block-Levinson algorithm is applicable, which is the basis for the proof of the stability of the synthesis filter. It is shown that the forward and the backward error signal vectors appearing in a 2-channel lattice filter implementation are coupled via a 2-channel allpass filter. This latter finding can be used as the basis for an alternative proof of the stability of the synthesis system.