new audio file not aligning with existing project

So we are producing a music video in FCP, synchronizing multiple clips with an audio file. After several days of work, we are pretty much done, but I just received the mastered version of the song.

We thought we would easily be able to replace the audio file we had been using in the timeline with the mastered version, since they line up perfectly with each other. To our dismay, when we dragged it into the project, there was slight latency, or a delay, which increased gradually over the course of the song. In fact, if we drag in a copy of the same audio file we used to make the video, it won’t line up with the project.

The audio files have the standard 44kHz sample rate, while the sample rate in FCP is set to 48kHz. Changing it to 44kHz at this point doesn’t help.

Is there any way to get the new file to line up with the project? Otherwise we will have to start from scratch. Any insight or guidance on this subject will be appreciated!

Simply ask the audio guy to supply a 44.1kHz master original for you, and you'll be fine. Mismatched sample rates cause drift over time.

How did you get a 44.1kHz copy to film with?

44.1kHz is not standard for video. You should have been shooting at 48kHz, and should have had the mastered original at 48kHz before shooting anything, but yes, everything should be video standard 48kHz.

The standard for CDs is 44.1kHz, that's not standard for video. Video, 48kHz, across the board.

Thanks for the good news. This was new info to me I asked him for a 48kHz master original, which I assume is what you meant, not 44.1.

The 44.1 was the pre-mastered, mix file. It was taking time to get the master from the engineer and we wanted to start shooting.

So we slipped in the 48K audio file, and unfortunately, it’s still not lining up with the project.
What’s the next course of action?
Thanks guru.

Please see the attached screenshot to give you a visual of what the project looks like...

Create a new Project with 48kHz sample rate.
Copy/paste from an older project where ALL files in the Timeline are 48kHz sample rate.
If there is still audio drift, something else is going on also. You shouldn't ever mix audio sample rates in a Timeline.

Thanks guru... Well I guess the issue is that we started editing the music video by lining up with a 44.1k audio file, though I’m not 100% sure this wouldn’t have happened if we had started with a 48k file.

Isn’t the 44.1k audio file intertwined with all the clips now? Is it possible to select everything but that, then copy and paste?

Just so you have all the background info, what we have here is a bunch of clips shot in 4K with my friend’s camera, which lined up perfectly with my audio file, the same file we were playing aloud while shooting. We also added several YouTube clips, which should be 48k also, since all video is 48k.

All the video was lining up perfectly with the 44.1k final mix. I just need the master audio file to be used, not the final mix file. The final mix and the master files line up with each other in any other context, but the master does not line up with the final mix audio in the timeline in FCP, after it’s been worked on, clips added to it, etc.

The drift is very minor, but I need them to align the same way they do when you play them simultaneously side by side in Logic, with zero drift.

If you line them up in a 44.1 LPX project, export the one you need from there as 44.1.

You can also convert and retime in Compressor.

Hey, thanks. The problem is solved. We replaced the audio with the 44.1k master, and then used the audio from the video for synchronization, and it lined up just right. Your help is much appreciated.

Pre-Production is the most vital part of a project... glad you got it working.