Sync - Global Drift Early (Audio)
Audio sync with video becomes progressively earlier throughout the program. For example, the audio is in sync at the beginning, 2-seconds early in middle, 5-seconds early 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 early 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 the 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 is 23.98fps (the videos native framerate), but the secondary audio you have been supplied is conformed to a 25fps master that was used/distributed to a PAL territory.
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 early it is likely that you will have to perform a speed change and slow down the audio to bring it back in sync with the Netflix Proxy. Please note that doing so will reduce the pitch of the audio. If you are employing pitch correction ensure that no audio artifacts are introduced in the final deliverable.