FIDELITY-OPTIMISED VARIABLE FRAME LENGTH ENCODING

摘要

Polyphonic signals are used to create a main signal, typically a mono signal , and a side signal (Xside). A number of encoding schemes (81) for the side signal (Xside) are provided. Each encoding scheme (81) is characterised by a set of sub-frames (90) of different lengths. The total length of the sub- frames (90) corresponds to the length of the encoding frame (80) of the encoding scheme (81). The encoding scheme (81) to be used on the side signal (Xside) is selected dependent on the present signal content of the polyphoni c signals. In a preferred embodiment, a side residual signal is created as the difference between the side signal and the main signal scaled with a balance factor. The balance factor is selected to minimise the side residual signal. The optimised side residual signal and the balance factor are encoded and provided as encoding parameters representing the side signal.