Blackmagic Forum

I've been trying to raise attention to the issue of VFR in the camera app, it's pretty apparent it's an Apple issue and not BMD. The only way we will ever be able to bypass this is if enough of us raise the concern with Apple directly through the Feedback app or website form. I have created a template we can send them but you can change it to say why CFR is important to you.

VFR will cause issues with audio desyncing and on a "Pro" device it should absolutely not be using it. There really is no excuse and I hope this is just an oversight by Apple that can quickly be resolved.

Online form: https://www.apple.com/feedback/iphone/

Template

ProRes is in variable frame rate when it should be constant.

ProRes log encodes video with a variable frame rate (VFR) instead of a constant frame rate (CFR). This is an issue when working with “Pro” workflows that require external audio, the "missing" or "extra" frames will cause audio to desync.

My suggestion is to simply allow the camera API to give us constant frame rates as an option. Alternatively, just get rid of variable frame rate altogether if shooting in ProRes.

Also, here is what I've sent in the Feedback app if you have that available to you:

To throw into the ring, I wonder if some of the issues for VFR have to deal with the White Balance, Shutter and ISO. I have seen these issues crop up on Android, mainly with my experience with Samsung.

Also, has what if we were to also whomever have Apple Developer accounts file it off as a bug report as well? Because I can see it from a few sides including that its likely the phone can't flush the buffer fast enough to the internal drive and since BMD hasn't put in external recording yet, that it could be the cripple point there.

Just a suggestion but why don't you make a quick video explaining the problem because there must be many people who don't realize it exists and post it on YouTube . You'll get more traction that way.

And it's a general smartphone issue. How many of you have a smartphone that records CFR?

Uli Plank wrote:And it's a general smartphone issue. How many of you have a smartphone that records CFR?

All my H264 and H265 clips from the BMD camera app have been CFR. iPhone Xs max.

*Update*
They are playing at a constant frame rate but are actually tagged as VFR. My apologies!

Same here Peter. As I posted in a different thread. Resolve reports them all as 24FPS.

Steve.

DR doesn't report VFR, Media Info (free) does.
You may not run into problems with short clips, but there are many reports of issues with longer ones. It's definitely something to get rid of or at least keep in mind before being too euphoric about those smartphones.

Not ready for prime time IMHO.

Well Uli, Media Info reports all at 24.0 FPS as well.

Steve.

You may be looking at the wrong tab. Unfortunately, the problem lies deeper.
What does it say in the second tab?
This is what a proper clip should show (30 fps in this case, but 24 should work just as well):

This is from footage a client sent me for testing that I just loaded into Media Info. Is it actually CFR, or is Media Info reporting it incorrectly?

As others reported, sometimes it is CFR, but you can't rely on it.

Thanks Uli, Just checked that second tab and all are variable! Hmm.

Steve.

The sync is an existing issue with Filmic Pro and, in a separate thread I wrote:

"I've had a prompt reply from Filmic and they are aware of the issue, one that affects most mainstream video edit programs, to varying degrees. It is also an issue for their own competitors' apps. Only the native Apple apps don't seem to be affected. They're in contact with Apple, whilst working on their own mitigation efforts.

My own workaround options, if I encounter the problem again, include:
1) Record in the native iOS Camera app - OK for some video but FilmicPro has finer control over settings, and also a really useful image stabilisation setting.
2) Edit in iMovie - OK for simple work.
3) Convert .mov to .mp4 - may not work with all conversion apps and it may have other effects on quality, but well worth trying as it should allow the better recorder to be used with the better editor.
4) Pre-process audio to manually sync - extra work, probably the option if the others don't work."

It looks like it's not something BM will be able to fix - but I don't think BM released the app so iPhones can replace their cameras. It's a useful tool that, like all tools, has its limitations. For me, it's useful if it does something I need better than the native camera, and it would be nice if it didn't have the problem, but nobody is forcing me to use it.

Uli Plank wrote:As others reported, sometimes it is CFR, but you can't rely on it.

Thinking about this, I wonder if part of the issue is that we don’t have the ability to disable proxies. It could very well be taxing the SoC because it’s technically rendering two videos at once and we all know that H265 can be hungry on a GPU/CPU on resources to encode. The dual encoding in combination with the reporting that Apple is aware of the SoC running hotter than expected, we could be seeing the issue of thermal throttling that is affecting the performance and thusly the frame rate. I think that would explain that shorter clips seem to be at 24fps to generally be CFR,

I’ve been able to consistently get at least with shorter clips, CFR at 24fps and my 30FPS, I tend to generally get 30fps with VFR at 31, but it can vary between 28-31fps. I do think that a 30fps CFR is possible, but would love to see a toggle in the app to disable proxies for if we choose to.

In mediainfo the default info tab will say 24fps. When you click on the tabs in the upper right of the medinfo window you get more detailed metadata info and yes some clips say constant and some say variable. Like its been said its an apple thing and I hope everyone pushes apple to deal with it.

It’s a smartphone issue. Generally, smartphones have no adjustable aperture, so they are trying to adapt exposure via ISO and shutter. The latter is causing variations in fps.

As of now your options are apple compressor, Handbrake and FFmpeg to convert. maybe Blackmagic with their constant innovating can come up with a solution.

I've been using Shutter Encoder as you can just drag and drop then press render and everything will be forced to CFR.

joe_scotto wrote:I've been using Shutter Encoder as you can just drag and drop then press render and everything will be forced to CFR.

Yes, I donated because its a great program.

Something to watch out for is that the Blackmagic app lets you record prores 4k 60p internally when apple says you need an external drive to do this. Aside from possible overheating issues that may arise I tested to see if VFR issue goes to the extreme when recording internal in that format and that frame rate in the Blackmagic app. Media info says variable with minimum frame rate 54.545fps and maximum frame rate 66.667fps. shooting internally and almost similar when using an external drive except minimum frame rate is 60fps.

Mike Los wrote:Something to watch out for is that the Blackmagic app lets you record prores 4k 60p internally when apple says you need an external drive to do this. Aside from possible overheating issues that may arise I tested to see if VFR issue goes to the extreme when recording internal in that format and that frame rate in the Blackmagic app. Media info says variable with minimum frame rate 54.545fps and maximum frame rate 66,667fps.

That's the same minimum and maximum I get going externally. I'm fairly certain the "limitation" is that Apple doesn't want people filling their phone up in 10 minutes.

Mike Los wrote:... Media info says variable with minimum frame rate 54.545fps and maximum frame rate 66.667fps. showing internally and almost similar when using an external drive.

Doesn’t that make it a non-starter in a professional workflow?

rick.lang wrote:

Mike Los wrote:... Media info says variable with minimum frame rate 54.545fps and maximum frame rate 66.667fps. showing internally and almost similar when using an external drive.

Doesn’t that make it a non-starter in a professional workflow?

Rick just like all the footage shot on any phone the VFR exists and from my time spent with this you've just got to go through an extra step where you look for the footage to see what's not a constant frame rate make a folder of those VFR's and batch conform the folder to a constant frame rate. And from my testing I don't see any issues other that the time it takes to do this.

Understand you have good results with Shutter Encoder, but I wonder how the playback motion after conforming looked with such wonky frame rates as input.

Does anyone know of a phone that can record video in CFR (Constant Frame Rate) instead of VFR (Variable Frame Rate)?

that's what I was looking for, tnx.

Hi,

I would like to ask a question to blackmagic developpers.

I had recorded some videos with shutter locked, fixed iso and framerate set to 29.97 - I can tell with mediainfo that VFR stands between 29.940 & 30.000 (which i believe is a small variation but still, VFR)

by that time, i turned to record videos with exposure set to auto (that triggered shutter and iso to automatic [with exposure increase or decrease step to 0.1 which is better than apple stock camera app with 0.3 step]) - Those videos sent to mediainfo show a VFR between 28.958 to 29.014.

-First, that is far from 29.97
-Second, i'm seeing shutter and iso value that i'm not able to set manually, for instance : iso 26 & shutter 1/1096. And sometime shutter speed is beyond the shortest 1/8000 available (i had 1/10989)

My question : Does the frame rate must be proportional or multiple to the shutter speed ? Or does an odd shutter speed prevent to reach a predefined frame rate ?

Thank you for your time, thank you for your essential app and at last thank you for not collecting data from user (almost unique behavior from company and very appreciable!).

Device : Iphone 15 pro.
App : blackmagic camera app 2.3.000047