PACKET LOSS CONCEALMENT FOR AUDIO CODEC

摘要

A speech signal is encoded as a sequence of consecutive frames. When a frame is lost, the loss is concealed at a receiver by reconstructing audio that would be contained in the lost frame based on other previously received frames. The frames contain a residual signal and linear predictive coding parameters representing a segment of audio data. For a lost frame the content of a previous frame is not copied, but is modified to make the reconstructed audio sound natural. The modification includes creating a weighted sum of a quasi-periodic signal derived from the latest two pitch cycles and a pseudo random sequence. The weights are selected based on a determination of whether the previous frame contains voiced or unvoiced utterances.