What should be seamless videos in FCP timeline, are not seamless

Try this test:

open your video clip in browser and put a marker at an audible and visible starting point. Put another marker at the end at an audible and visible point.

Do the same process to your audio for those same corresponding audio points.

Add the marked video clip in timeline (audio set to 48 kHz in project settings), connect the marked audio synched with start marker. See if the start and end markers are aligned. I suspect that your audio will be shorter than your video. If so, open the retimer for audio clip and drag the audio end point to align the end marker to the video one.

"...when I overlay the independent/external audio track starts ok but by minute 2.5 or so, it is off by a few frames..."

Separate audio and video recorders are not guaranteed to stay in sync over long periods, but when they drift out of sync over a few minutes, the most likely cause is rate conforming in the NLE.

E.g., if you have a 24.0 fps clip on a 25.0 fps timeline (or vice versa), it will be automatically rate-conformed, causing a small retiming change. That will cause audio to drift out of sync fairly soon. The solution is don't do that. If you shoot at 24.0 fps or 25.0 fps, use that as your timeline frame rate.

I think the same thing can happen with 29.97 fps material on a 30.0 fps timeline and vice versa.

How to examine this: In FCP, select a clip, then open the inspector to view the frame rate. Then select the project (aka timeline) icon in the Event Browser and look at the inspector for its frame rate. They should be exactly the same.

Sync drift is not typically caused by a 44.1 Khz vs 48 Khz sample rate difference. FCP resamples all audio, so that aspect makes no difference.

Have you tried "Save As" to another video format prior to importing into your Final Cut Project?

You can always change the frame rate within a project; however, that may not yield the same results.

Smiliñ 😎 Brian

Have you deleted the preferences as I suggested?

When FCP alters its behaviour unexpectedly, deleting the preferences can often help.

As it only takes seconds it is something that should be tried earlier rather than later.

One quick thing you could try with FCP is to delete the preferences.

Please explain with screenshots the sampling rates of the audio clips and the project. It's hard to understand from just words.

Hi(bonjour),

Does the sample rate in H4 is the same as your project setting ( say 44.1 vs 48 kHz)?

Michel

No it does not do continual sync drift compensation. The only tool I know of which did that was Plural Eyes.

I have watched your concert video and I think FCP is somewhat overkill for it.

You would get exactly the same quality with iMovie, so should FCP become temperamental you could just swap to iMovie.

The only time you would need to use FCP would be if you were doing a multi camera shoot but it doesn't look as though you use that technique.

There is a misconception that FCP will give better quality video than iMove. This is completely incorrect as they both provide the same up to 4K.

All FCP does is provide you with extra editing capabilities but it doesn't look as though you need those for the type of film you are making.

iMovie has at least one big advantage over FCP in that you can customise the bit rate.

For 1080p movies both apps have a default setting of 20 Mbps but iMovie has a custom option where you can change the rate from 3.33 Mbps up to 26.66 Mbps . . . . you need to use Compressor or some third party app if you want to use a different bit rate with FCP.

No problem.

By the way, you can delete the iMovie preferences the same way.

Are you using FCP's automatic "Synchronise Clips" feature with the external audio as that should work perfectly?

Auto Sync External Video