Audio is out of sync with Video when imported into FCP 11.1.1 Timeline

You could try optimizing a short clip that exhibits the issue. Optimizing (right-click on the clip in the browser and choose Transcode) will create a very large ProRes file that is easier for FCP to work with. Historically FCP hasn't been happy with variable frame rate video which the iPhone shoots (or can shoot, I haven't worked with iPhone footage in a while so I don't know if it's still the default) .

I don't know if is related, but the standard audio sample rate for video is 48 kHz, not 44.1 kHz.

ARRJAYONE wrote:

Well, actually, the audio that comes in from the iPhone 16 Pro is 44.1 kHz. But I did try your suggestion and imported the footage into a new timeline with the audio set to 48 kHz. Unfortunately, I have the same out-of-sync audio issue.

I was wondering about this, and I checked a short clip I recorded in my iPhone 16 (not Pro); this one was 48 kHz. It may be a setting somewhere, or may be different in different camera apps, I’ll have to see that. In any case, whatever the sample rate, it should of course not miss any audio nor have it out of sync.

You could try transcoding the file in Finder (control-click, Encode Selected Video Files) and see if the transcoded file has the same problem.

ARRJAYONE wrote:

Thanks for the suggestion. I gave that a shot but the optimized clip still has the out-of-sync audio issue.

Does it play in sync in Finder or Quicktime Player? Does it play in sync in FCP browser, and only out of sync in the timeline?

To verify, iPhones have always recorded video at 48kHz, not 44.1. If you have actual iPhone footage that has 44.1kHz audio then something is seriously wrong, because iPhones don't record 44.1kHz audio with video. Unless you have a third party app that can do it. Thus, an iPhone clip in an FCP 48kHz Timeline should play just fine.

Video standard audio has been 48kHz for decades. Only the stray, odd camera or device recorded video audio at 44.1. So no, 2023, broadcast/video standard had already been 48kHz for a very long time. Even my Canon GL1 cameras back in 2005 shot 48kHz audio. Established broadcast standard, set in stone for many, many, many years now. It is far from new.

It might be older video. In 2023 they were still shooting 44.1 would you believe. Took a lot of nagging to get that to change.

Indeed it has, but not on the iPhone. It took until then 23 or 24 before the built in camera caught up with 40 year old technology.

iPhone 11 started to shoot 48kHz audio for video. Actually, in that model you could switch between 48 and 44.1. And that was 2011.