Lip Sync issues occur when the timing of the Audio and Video track are out of sync. MC allows you to adjust A/V sync correction in milliseconds to address Lipsync issues when playing back video.
Manually Setting A/V Correction by Zone
Under "Tools --> Options --> Video --> Advanced" there are two options to adjust A/V Sync correction on a per zone basis, one for when the display is in 24hz mode and one for other frequencies. You can manually add values (both +'ve and -'ve) to advance or retard the the Lipsync till it is in sync.
Adjusting the A/V Correction during Playback of a File
In addition, MC will allow you to modify the lipsync during playback of a video using keyboard shortcuts (SHIFT+COMMA and SHIFT+PERIOD). When doing lip-sync adjustment using keyboard shortcuts, the final result is saved in the PlaybackInfo tag of the file and these values will be used in subsequent playback.
Adjusting a Zones A/V Correction during Playback of a Calibration File
If the file has Media Subtype of "System" (i.e. a calibration file) then the final result is saved in "Tools --> Options --> Video --> Advanced" for the particular display type (i.e. 24 Hz display vs. other displays)
Link to Calibration Files
Link to Interact Thread