DIGITAL AUDIO SYNCHRONIZING SYSTEM WITH MUTE TIME SWITCHING FUNCTION

摘要

A digital audio synchronizing system resynchronizes the audio signal of a video signal by storing the audio signal in a memory and reading it out from the memory after a time period which is related to the time by which the video signal is delayed as a result of being synchronized to a reference video signal. In order to prevent a discontinuity in the audio signal waveform caused by variations in the video delay between the video signal and the reference signal, the digital audio signal is read out as a first and a second output from memory addresses which correspond to the previous video delay and to a new updated video delay value. A synchronized audio signal is obtained by switching from the first output to the second output when the muting times of the first and the second outputs are coincident with each other. When the both muting times are not coincident with each other within a predetermined time from the variation in the video delay, the first and the second outputs are cross-faded with each other over a predetermined time period and the cross-faded output is produced as the synchronized audio signal for the predetermined time period, and after cross-fade operation, the second output is produced as the synchronized audio signal.