Blackmagic Forum

Hi all,

I've got an iPhone 15 Pro, recording Apple Log HEVC 23.976. Blackmagic Camera App version 2.0.000016
The issue is that while playing these files back in Resolve, there is a duplicate frame every second or so. The clips show up as 23.976 fps in the Media Pool as expected.

Playing the files in Apple Compressor or Quicktime doesn't show duplicate frames. However, if I transcode out of Compressor to Prores, those files will also have duplicate frames every second.

Recording in 24fps on the Blackmagic Camera App does not have this issue. Attached is a MediaInfo report on one of the clips affected.

That's not CFR (constant frame rate), so some issues are to be expected.
Quite typical for phones. Don't use the internal stabilizer, but mechanical means instead.

Ryan Schroeder wrote:Hi all,
I've got an iPhone 15 Pro, recording Apple Log HEVC 23.976.

This is the effect of variable frame rate that is very common in smartphones. I "fix" it using Shutter Encoder using the Conform function.
And I avoid using a phone for recording important videos because od this. A phone is the last resort for me.

Even if the image from a good phone might be quite impressive, it's definitely not a 'real' camera (yet?).

Just dropping by to note that this is still an issue in the latest Blackmagic Camera App 2.1

Yes, I know this is VFR footage, but usually one can conform them for 23.976fps playback. Unfortunately, Resolve reports these clips as already being 23.976. If they were reported accurately, there would be the option to conform the frames to 23.976, but since they're already reported at such, there's no way to adjust them.

I pick the camera that is right for the job. I could grab my Epic or Komodo if I wanted to. However, if I need a very small camera on me in the wilderness, an iPhone can do a great job, and little issues like this can certainly be fixed.

Did you try without any stabiliser active? On my iPhone 15 Pro Max the variation of the frame rate is so small then that I don't experience any issues like yours. I have to admit, though, that I use only 25 or 30 fps.

Yes, the issue occurs with the stabilizer turned off.
I have an iPhone 15 Pro.
The issue does not occur when filming in 24fps; only 23.976.

I've been told by Blackmagic support that the app receives support through the forum and the developers have been made aware of the issue, so that's why I'm posting about it here.

Ryan Schroeder wrote:Yes, the issue occurs with the stabilizer turned off.
I have an iPhone 15 Pro.
The issue does not occur when filming in 24fps; only 23.976.

I've been told by Blackmagic support that the app receives support through the forum and the developers have been made aware of the issue, so that's why I'm posting about it here.

I posted about this months and months ago. Disappointing to see it’s not fixed and sad that people are defending this as expected behaviour. I’ve never seen a camera app that can’t manage to write frames to disc without doubling them up. And it only happens with a certain combination of settings is what I found.


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I don't think the frames are actually doubled, as playing back these clips in Quicktime/Compressor doesn't show duplicate frames. I think it's the way the frame rate is encoded and then interpreted by NLE's that is the problem, so hopefully this is an easier fix than it may seem to be...

Ryan Schroeder wrote:I don't think the frames are actually doubled, as playing back these clips in Quicktime/Compressor doesn't show duplicate frames. I think it's the way the frame rate is encoded and then interpreted by NLE's that is the problem, so hopefully this is an easier fix than it may seem to be...

Either way I’ve been unable to use it. Also we are never going to get timecode support for my Ultrasync units due to BM’s animosity towards Atomos


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Yes. I need 23.976 because some other cameras I'm using (DJI Action 5) can only shoot 23.976; otherwise I'd just use 24p. The only workaround I can think of for now is to shoot 24p on the iPhone and conform to 23.976 before the edit, which is OK for short b-roll clips. Long clips the audio will go out of sync.

Ryan Schroeder wrote:The issue does not occur when filming in 24fps; only 23.976.

Well, definitely a bug, then.

Ryan Schroeder wrote:Long clips the audio will go out of sync.

I don't think so. Did you try?
Don't use the Clip Attributes, but speed up in the timeline. You can even get pitch correction. I doubt that's audible, though.

I did try.

Speeding up in the timeline would be fairly annoying for a length editing session; always having to speed up clips when cutting them in would be a frustrating editing experience. However, I could see doing a pass after picture lock to precisely conform the frame rate to the timeline via a speed change, and you're right, the tiny amount of pitch correction wouldn't be noticeable.