Sync - Global Drift Late (Audio)
Audio sync with video becomes progressively later throughout the program. For example, the audio is in sync at the beginning, 2-seconds late in middle, 5-seconds late by the end).
Audio out of sync will become more noticeable during playback, ultimately resulting in dialogue and effects falling significantly out of sync and create a poor customer experience.
Audio drifts late compared to on-screen action and dialogue.
How to Prevent:
Lock tracks when not working on audio in order to avoid accidental slips. Check sync points before any export.
Reposition elements to sync with video.
This issue can be caused by conforming the audio to a video master that runs at a framerate different than the video that we hold.
For example, the video we have might be 25fps, but the secondary audio you have been supplied is conformed to a 24fps master that was distributed/used for the theatrical release.
When processing Secondary Audio assets for Netflix, always ensure that the final checks for sync are performed against the Netflix proxy that should be available within the Source Request on Backlot.
If the audio drifts late it is likely that you will have to perform a speed change and speed up the audio to bring it back in sync with the Netflix Proxy. Please note that doing so will increase the pitch of the audio. If you are employing pitch correction ensure that no audio artifacts are introduced in the final deliverable.