Synchronised clips are in sync in browser, out of sync in timeline

I have synchronised clips (from tentacle sync) that are in sync in the browser, but once pasted into timeline they are out of sync...

Increasing the weird: the clip is out of sync by the exact length of the used portion in the timeline...

Any thoughts?

Please give complete specs of the original media, video file and audio file, and complete project properties.

Media is X-AVC 4k, 25p

Audio is 32bit from a Zoom F6.

Project is vertical 1080X1920 23.98fps

 Audio file type. Sample rates please.They're critical.

lukeyo wrote:

Media is X-AVC 4k, 25p

Audio is 32bit from a Zoom F6.

Project is vertical 1080X1920 23.98fps

It's expected there will be a sync problem if you add 25 fps material to a 23.98 fps timeline. That material must be rate conformed and the NLE algorithm for that is a 4% rate change, with audio pitch correction. You can try retiming the Zoom audio 4% slower. When 24.0 fps films are shown on 25.0 fps broadcast systems they retime the 24.0 material about 4% faster and most viewers don't notice the difference.

Due to timebase drift and other factors you sometimes need to make retiming changes in fractions of a percent, such as 104.2% not 104%. In the retiming dialog, FCP does not reliably read the user-input digits with sufficient decimal precision. The software code is apparently casting the input or rounding it somehow. It appears you reliably have about 1% precision and maybe a bit better, but not 0.1% precision. DaVinci Resolve can retime it to 4 or 5 decimal digits of precision, so I've had to use that in certain situations, then after retiming it I'll export to ProRes and continue in FCP.

Also, if you have 23.98 video material from another camera that also needs the same Zoom audio, and if those clips are intercut with the above retimed 25.0 material, viewers might notice an audio pitch difference. You might instead be able to retime the video by itself. I thought it wouldn't work but I tested it and it seems to work OK.

If the video also has on-board "scratch" audio, you can adjust the timeline clip appearance to show waveforms better: support.apple.com/guide/final-cut-pro/ad...ance-verb8e5d346/mac If successive retiming changes are needed on a long audio clip, that helps when visually syncing the A/V and audio waveforms.

@Tom Audio is 48khZ 32bit

@Joema yes I think frame rate is the culprit here.

FWIW the fps was automatic after an XML import from PP via Send2X