Recently I recorded a quick video to talk about why footage from your iPhone, mobile device, or gaming system may be bogging down your computer system when you try to edit it.  

We’ll go over what Variable Frame Rate footage is, why it slows your computer down, and a solution to the problem.

Check it out.

This video has been transcribed in case you’d prefer to read through the text quickly.

In this video I want to talk about something called VFR, or Variable Frame Rate.  Not to be confused with Panasonic’s version of slow motion on their cameras, which they also in the menu call Variable Frame Rate.  I’ll go into that in a second, but if you’ve been filming on your iPhone or other mobile device, and you put it on your computer, and you try to edit with it and it just plays back slow, it’s laggy, it bogs your system down…VFR, or Variable Frame Rate is most likely the culprit.

So what we’ll talk about is what that is, why it’s like that, and then of course…a solution.

Let’s start with the basics.  Variable Frame Rate on a Panasonic camera is not the same thing as variable frame rate on a clip from something like an iPhone.

These Panasonic cameras are still shooting at a constant frame rate, but say you’re shooting at 23.98 frames per second…in the menu you can go (and you want to shoot slow motion) and you go to variable frame rate, and you turn it on.  You can choose the frame rate like, say, you scroll to 60 frames per second and you hit set, or select.  You’re still shooting at the base frame rate of 23.98 but the camera is interpreting 60 frames per second to 23.98 frames per second which results in a speed of about 40%.

But it’s still shooting at a constant frame rate.  It’s still recording at 23.98 frames per second for the entire duration of the clip.

On an iPhone or other mobile devices (I’m going to keep saying iPhone because that’s what I’m using and I have in my hands right now), you can click on settings, then you scroll down through the apps until you get to camera.  Click on camera, and then you’ll see here it says Record Video.  Click on that and it says 4K at 24fps.  Or you can choose 30 or 60 frames.  I leave mine at 24 fps because that’s more like the film look, but that’s not really representative of what always happens.  If you shoot a short clip, or you shoot something that doesn’t have a lot of visual information in it, it may film at 24 frames per second the whole time.  However, if you film a longer clip, or if you film something that has a lot of visual information (lots of colors, lots of detail), then there’s a good chance it’s actually going to change the frame rate throughout the duration of the clip.  The frame rate is going to vary.

I’ll show you here real quick, I’m going to bring in this clip I have.  Now this was set to 4k at 24 on my iPhone.  But you can see right here, it says 30.01.  So that tells me that this clip is a variable frame rate clip.

Another thing you can do to quickly check to see if a clip is variable frame rate, is just right click on it, then go up to properties, select that, and then you’ll see at the bottom here “variable frame rate detected.”  And then you can just close that out when you’re done.

A lot of people are using apps like Filmic Pro.  Awesome app.  Unfortunately even if you set that to 24 frames per second, you’re most likely still going to get a variable frame rate clip.  Like I said, if you’re shooting a short clip, there’s a good chance it’ll shoot 24 frames per second, but if you’re recording longer content, or you’re recording content with a lot of detail…you’re inevitably going to run into variable frame rate clips.

If you have a lot of these, trying to edit this stuff together is probably going to drive you nuts.

Now I’ve heard…that Final Cut may handle variable frame rate clips better than Adobe Premiere.  Avid, a lot of the time you’re going to be transcoding down to a proxy or something anyways.  That’s more television based.  For me, I use Premiere and I use Avid.  I don’t really use Final Cut that much.  Nothing against it, it’s just not really what I use in my industry and for my line of work.

So in Adobe Premiere you can really bog down your system doing this.  

The reason for variable frame rate on something like an iPhone or mobile device, is because they’re not built like cinema cameras.  Cinema cameras are built to record, and so they can handle recording at a constant frame rate throughout the clip.  iPhones are not built like that.

So they do it to compensate for what you’re recording and for compression.  But the trade off is once you put that on your system and you’re trying to edit it, especially if you have a lot of these clips that are variable frame rate, is that it takes a lot more processing power from your computer.  So it can really bog down your system and make your playback laggy.  We don’t want that.  I don’t want that for you, so let me offer you a quick solution.  

What I’m going to do here is I’m going to pop-up Adobe Media Encoder.  

The easy solution for this is to just re-transcode all of your footage.  Convert it all to something that’s a constant frame rate.  

You can go in, and I’ve got this same clip dropped in here and I chose a quicktime.  If I open it up, it’s an Apple ProRes 422 Proxy (that’s the Media Encoder preset setting).  Phones don’t record where I need to do something like a 422 HQ on a clip like this.

So something like a proxy is fine.  Even if you want to do something that is just lightweight but is a good codec for Premiere.  Like, a .MXF format, or Quicktime works great in Premiere.  So if you want to do something like that and then link back to your RAW footage at the end of your edit, that’s a typical proxy workflow (NOTE: if you transcode to a high enough quality file, there’s really no reason to link back to the RAW files, and it may cause issues).  

That should help eliminate a lot of the headache.  

I’m going to give you another tip here.  The clip I had was 30.01 frames per second.  So I don’t know what amount of the clip was recorded at 30 frames per second, so I don’t necessarily want to drop down to 23.98 unfortunately.  If it’s just going to web or something you can still do 29.97 or 30p, but if I’m doing a lot of this footage and I notice a lot of it is listed at 30 frames per second…when you transcode and you drop it down and you’re pulling frames out because you’re going from 30 frames to 23.98, that’s when it can start to change the look.  

You typically don’t want to go down in frame rate.  You can go up.  You can go from 23.98 to 29.97 and it’ll still look okay, but you don’t want to go from 29.97 or 59.94 down to 23.98.

So what I would do since I have a 30.01 variable frame rate clip here, is just transcode at 29.97 or 30p.

So once I transcode all this footage, I hit okay, I set my destination, I would do it for all the iPhone clips that I’m going to be editing with, and then when I bring them into Premiere they should playback way better.  It should be way smoother of a process, and hopefully that should help fix your problems.  

So to recap:

  • Variable frame rate when talking about recording clips on an iPhone or mobile device means that it’s actually recording the clips at variable frame rates.  It’s varying the frame rate to help with compression and storage space.  
  • The drawback to this is when you bring variable frame rate clips onto your computer and you start editing with them, some editing programs (probably most of them) don’t play well with variable frame rate clips.  So the trade-off is that it takes a lot more processing power on your computer to edit with these clips. 
  • The solution is to put them into an application and transcode them to something that is a constant frame rate.  Now be careful.  Depending on what software you’re using, if you’re using a free app or something to transcode your footage, make sure that it’s actually transcoding it to a constant frame rate (you might see it listed as CFR) and not spitting it back out to another variable frame rate because then you’ll just be dealing with the same problem again.

So that’s that.  I hope this helps because there’s a lot of people out there filming on iPhones and stuff like that right now with Covid going on.

So I hope this helps alleviate any headaches when filming on a mobile device and then trying to edit it.

And let’s face it, mobile devices aren’t going anywhere anytime soon.  People are constantly recording millions of video clips all of the time.  So if you’re running into trouble once you bring them in and you’re trying to edit with them I hope this helps.

Thanks for watching.


Dragonfly 44 Productions is a video Production and Post Production company in Sacramento, CA that creates impactful content for clients all over.

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Disclaimer: These tutorials are created to help folks, however, it is always the viewers responsibility to make the best decisions for themselves and their situation.