Audio Drift

Hello,

I have a 23.98 bunch of multicam video clips and a 25fps audio recording, so there is an inevitable audio drift.
What's the best/easiest way to overcome this in FCPX? Any help greatly appreciated thank you.

Dean

Actually, its not timecode, but sample rate of the audio. What is the sample rate of your clips, what is the sample rate of your Multiclip, and what is the sample rate of the Project you're editing in? I've mixed different frame rates in a multiclip and not had issues before, so I'm guessing there is a difference in audio sample rates. Verify everything is at 48kHz, as a starting point.

Thank you Ben, appreciate that, it's actually a mix of 48 and 44.1.. The main audio I am synching to is 48, some of the video clips are at 44.1, some are 48.

Audio sync issues are 9 out of 10 times due to differences in sample rates. You can use Compressor or some other transcode app to conform the 44.1 audio to 48kHz (and conform frame rates while you're at it).

Thanks Ben, I just noticed even on the main audio (44.1khz) and a video file (44.1khz) they still go out of sync by around 5 seconds by the end of the 1hr 15mins... Will going to 48khz on both change that? Or is this just something separate?

Silly me, worked it out, im in a 48Khz project, sorry!

FCPX will count audio samples and time them to the setting of the Project/Compound/Multiclip you drop them in to. So a 44.1 clip in a 48 timeline will play back at an incorrect rate, and you get drift over time. It won't play 44,100 samples in the first second of playback, it will play 48,000 sample in that first second. So the second second starts 3900 samples off (virtually undetectable). The third second starts 7800 samples off (barely noticeable if you have trained ears). The fourth second starts off 11,700 samples off and gets noticeable. Further and further out of sync over time.

Audio sample rates; can't live with 'em, can't shoot 'em.

I just noticed they still go out of sync, going to try and resample both to 48khz see if that makes any difference perhaps?

Couple questions,

- Is there camera audio? I've found that even if the audio longer or shorter than the audio of the video file. FCPX seems to shrink or expand the audio file to fit when synchronizing.

- Second, did you make the multicam clips with the audio as well?

"I just noticed they still go out of sync, going to try and resample both to 48khz see if that makes any difference perhaps?"

Didn't I say transcode it all to 48?

It is very simple, don't overly complicate this.

Ben, both audio and video/audio at 48khz in a 48khz project still out of sync by around 3 seconds by the end.

Yes to both Darren thanks

What is the video frame rate of your project?

- Ronny

Ronny it's 23.98 same as video file, audio file says same in inspector.

Okay, and why did you say the audio was "25fps"? Do you mean it was subtracted from a 25fps movie ?

If that's the case it is quite logical that the audio will not be in sync with the 23.98 fps video. You will have to retime the audio by 4% to make it sync up with the video on a 23.98fps timeline, or you will have to edit in a 25fps project timeline and apply Automatic Speed to the 23.98fps video to sync it up with the audio.

- Ronny