Keeping PreComp Audio In Sync With a Master Layer’s Audio In After Effects

Zack Lovatt posts a little writeup on how to hold a preComp’s audio channel in place while you are moving the layer around in After Effects, keeping it in sync with another layer.

Zack shares an Expression for After Effects that uses the linear() command to make certain that the audio of the pre comp remains synchronized with the master audio in the same composition. As Zack notes, this can be useful for swapping out audio from scratch to final audio. There most likely will be times when the two clips will no longer share the same timings between rough and final. This can also be very useful for adding alternate audio to a composition, for versioning or to accommodate different language versions that may be needed.


This expression looks at what time both the whole precomp and the audio layer specifically starts in the master comp, then looks at the start and end points of the audio layer inside of the precomp, and remaps the inner start & end points to match that of the master audio layerZack Lovatt –

How the Expression Works

The expression will look at what time the audio specifically starts for the both the preComp and the audio layer in the master composition in After Effects. It then will look at the start and end points of the audio layer that is inside the preComp. The expression will then remap the start and end points to match the audio of the master layer. You can now move the preComp around and watch the audio hold still as you are shifting the layer around in the timeline.

Head on over to Zack’s site for the complete article, and You can check out the expression as well as Zack’s thoughtful explanation here: linear() – Syncing Precomp Audio to Main.

Going Further With After Effects Audio Sync

Felt Tips recently had some great tutorials covering how to keep audio in check in after effects with Synchronize Your Audio Across After Effects Compositions With Expressions – showing you how to how to use expressions in After Effects to sync audio across your nested compositions.

We have also had a look at synchronizing audio in AE using the TypeMonkey Script which will allow you to quickly synchronize your animations – Quickly Sync Kinetic Type to Music With TypeMonkey for After Effects.

And a technique for using Adobe Premiere as an intermediary to create audio sync with Automatically Sync Voice Overs in After Effects With TypeMonkey and the Help of Premiere Pro

Lastly, David Legion also had a look at swapping out scratch audio with final audio in After Effects and keeping it all in sync with Switching Out Voice Overs Using Auto Lip Sync