1. An audio and video data processor, comprising: a selector for selecting at least a portion of an audio data stream, said audio data stream being synchronized with a video data stream; an audio feature analyser for abstracting from said selected portion of said audio data stream a stream of time-varying features and for abstracting corresponding time-varying features from an input audio data stream; a timing analysis and waveform editing processor adapted to determine timing differences between said stream of time-varying features and said corresponding time-varying features and to utilize said timing differences to edit said input audio data stream; and a playback control module adapted to control running of said synchronized audio data and video data streams with said edited input audio data stream replacing said selected portion.