iPhone footage out of sync with itself

I just tried it with 4k 60pfs, transferred by airdrop and the issue is the same, except now the audio is 6 frames ahead  For what it's worth, the clips I have tested at 24p and 30p have been across 3 different Macs with FCPX and different versions. 

I think the only way to test it is with a distinct clap because with less distinct sounds it's pretty difficult to see. Can you confirm that with a clap it's 100% in sync inside FCP? 

flaminghick wrote: Wow thank you for testing that out! And did you find the sound was around 3 frames ahead of the video across the board?...

It varied a little from 2 to 3 frames.

flaminghick wrote: ...I guess my question now is...has this been happening for years and I only recently noticed or did it start happening at a certain point? 3 frames is easy to miss with "softer" sounds I find..

You're right -- one possibility is it's been here for a while and it wasn't noticed. Another possibility is it varies based on lighting, selected frame rate and version of iPhone.

In situations like PC/Mac screen capture or video conferencing, it's possible there are network fluctuations or the screen capture code path just isn't fast enough. Maybe they use variable frame rate as a "shock absorber" to compensate for the system's inability to produce constant frame rate without degrading the image.

But a modern iPhone definitely has the computational horsepower to produce true constant frame rate video, and there's no issue with data rate. They might be using variable frame rate for exposure control or other image processing.

flaminghick wrote: ...Can you confirm that with a clap it's 100% in sync inside FCP? 

When I tested 4k/24 material from my iPhone 11 Pro in both H264 and HEVC -- using a clap --  it's off a couple of frames as viewed in Quicktime Player and inside FCP, also inside Premiere Pro, and when played in VLC on Windows. 

I didn't test outside lighting conditions to see if that made any difference.

Oh, my clap test comment was meant for the guy who said their iPhone footage has been in sync for years and continues to be, but thanks for doing the test. It's looking to be a consistent issue across some devices anyway. 

Now that we know it's the iPhone and not FCP, I could probably go back in time through some older projects to see how far back it goes. 

Okay so I tried another test with Filmic Pro and Procam 8. 

Both of these apps are more in sync, but still slightly out...by around 1 frame, or 1.5 frames if that makes sense (like when there's a blurred frame in there). 

Just ran my own test and found 4K HDR at 60fps is fine (what I always shoot with) but with 30 or 24 there are 2-4 frames of lag. Go figure...

Thanks for testing. Well, seems we've uncovered an issue with the iPhone camera app. I put in a bug report. Hopefully they can fix this soon. If anyone else want to submit a bug report I think it would be helpful: 

www.apple.com/feedback/iphone.html

SAME HERE!! -- It's been for at least 6mo. I only edit single clips for actors auditions. (not complicated)
- They come in from various cameras, iPhones all different frame rates / audio rates etc... No matter what format audio is 2-4 frames behind when imported to FCP. (plays fine in Quicktime.)

I have an untested theory it's possibly to do with Compressor? Or the (new?) integration of LogicPro native plug-ins etc... ??
Killin me tho!! -- So impractical to convert to Constant Frame rate for EVERY single take of every single audition for every client just to trim up a bit, and send to casting. (used to take 10mins - now takes hours.)