Post Production

Understanding iPhone framerates for shooting, editing & distribution

Learn how to deal with iOS’s VFR (variable frame rate) for shooting, editing and distribution.

When you shoot video on iOS (including iPhone, iPad and iPod Touch), framerates don’t work the way they do on conventional camcorders, which use CFR (constant frame rate). That’s because iOS video recording uses VFR (variable frame rate) with only targets, not exact framerates. This is true, whether you shoot on iOS with FiLMiC Pro or MoviePro. The way framerates work when editing video on iOS is also different, although when you share (export) from an app like LumaFusion, they can go back to the traditional way of handling things as CFR. Ahead you’ll learn how to handle iOS footage, whether or not you edit and grade your iOS footage on a traditional computer or on iPad/iPhone/iPod Touch.

Framerate workflow for iOS

 

Shoot with an app like FiLMiC Pro or MoviePro in the approximate target framerate.

As I have covered in great detail in many past articles (including Video framerates and the Tower of Babel: a translation guide, illustrated above), exact rates like 30.000 and 60.000 haven’t been standard since before 1953. Many standalone cameras and apps unfortunately round the standard 29.97 and 59.94 (also rounded numbers, but precise enough for our purposes) to the closest integers, “30” and “60”. In the case of physical cameras, those rounded numbers usually refer to 29.97 and 59.94. In the case of apps in iOS devices, to my knowledge, all iOS camera apps including the iOS camera app, FiLMiC Pro and MoviePro shoot at VFR (variable framerate) for efficiency’s sake, and the framerate you choose before shooting is only a target, not a final framerate. Generally speaking, any shooting app that doesn’t offer you any framerate choice has a target of ±30 fps only. Both true 24.000 and 23.976 (aka “23.98”) are indeed standards today, and it’s important to know which to use when exporting (sharing), less so when shooting with iOS devices.

FiLMiC Pro and MoviePro have targets for ±24, ±25, ±30, ±50, ±60 and more. (I wish both developers would add the ± symbol in front of each to clarify this.) So for this and many other benefits these apps offer, you should be shooting with FiLMiC Pro or MoviePro or some other professional app.

  • If you want your final product to be 23.976 fps, shoot with ±24 in your desired shooting app. Of course, set the audio to 48 kHz.
  • If you want your final product to be 24.000 fps, shoot with ±24 in your desired shooting app. Of course, set the audio to 48 kHz.
  • If you want your final product to be 25 fps, shoot in ±25 fps in your desired shooting app. Of course, set the audio to 48 kHz.
  • If you want your final product to be 29.97 fps, shoot with ±30 fps in your desired shooting app. Of course, set the audio to 48 kHz.

Unless you are shooting and editing specifically for a 720p TV station, I recommend avoiding the use of 50p or 59.94p as a final delivery framerate, since its distribution beyond 720p TV stations is quite limited, with multiple millions of iOS and Android devices in use that can’t play more than 30 fps. Only a few of the latest devices can handle playback up to ±60 fps or more. So if you innocently were to produce a final product of 50 fps or higher, most of your viewers will end up seeing half of your intended framerate, and the shutter speed you used when shooting will no longer match, and you would no longer have a consistent motion experience on multiple screens. Stay under 30 fps as a final delivery rate unless you are specifically producing for a 720p TV station, like the ±41 in the US I listed in this article or for a private showing where you know you can play at higher than 30 fps, aka a corporate presentation with an HDTV or projector that you know can support it.

If editing on a traditional computer

If you are going to edit the iOS shot footage on a traditional computer, be sure to use a video editing app that definitely supports VFR source material (or transcode first). For example, the latest versions of  Final Cut Pro X indeed supports VFR, but Adobe Premiere CS6 does not. Several NABs ago, an Adobe product manager told me that VFR support had been added to Premiere Pro CC, but would never be added to Premiere Pro CS6.  I am not sure whether DaVinci Resolve 14 can support VFR. If you have problems with your editor, either change to one that does support it, or transcode to a CFR (constant frame rate) using a program like Handbrake.

Set the project (timeline) in your software video editor manually for the desired target framerate. Do not let the project set itself automatically based upon the first clip.

If editing on iOS, set the approximate target framerate when creating a project in an app like LumaFusion:

  • If you want a final product of 23.976p, create a ±24 project in LumaFusion. (You’ll be selecting 23.976 in a later step.) This gives you a filmic cadence while maintaining compatibility with broadcast television in NTSC or ex-NTSC regions and is also compatible with the web, DVD and Blu-ray.
  • If you want a final product of 24.000p (presumably for film-out/DCP or web, not for TV broadcast or DVD), create a ±24 project in LumaFusion.
  • If you want a final product of 25p, create a ±25 project in LumaFusion. This is a similar cadence as 23.976 or 24, but matches the television framerate in PAL and ex-PAL regions and also works for DVD and Blu-ray.
  • If you want a final product of 29.97p, create a ±30 project in LumaFusion. (You’ll be selecting 29.97 in a later step.) This matches the television rate in NTSC and ex-NTSC regions and also works for DVD and Blu-ray.

Choose the more exact framerate in the sharing step in LumaFusion

  • If you want a final product of 23.976p, select 23.976 when sharing.
  • If you want a final product of 24.000p, select 24 when sharing.
  • If you want a final product of 25p, select 25 when sharing.
  • If you want a final product of 29.97p, select 29.97 when sharing.

See the related article

See the related article LumaFusion 1.4 for iOS adds pro audio functions and raw support for grading, illustrated above.

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No manufacturer is specifically paying Allan Tépper or TecnoTur LLC to write this article or the mentioned books. Some of the other manufacturers listed above have contracted Tépper and/or TecnoTur LLC to carry out consulting and/or translations/localizations/transcreations. Many of the manufacturers listed above have sent Allan Tépper review units. So far, none of the manufacturers listed above is/are sponsors of the TecnoTur programs, although they are welcome to do so, and some are, may be (or may have been) sponsors of ProVideo Coalition magazine. Some links to third parties listed in this article and/or on this web page may indirectly benefit TecnoTur LLC via affiliate programs. Allan Tépper’s opinions are his own.

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Born in Connecticut, United States, Allan Tépper is an award-winning broadcaster & podcaster, bilingual consultant, multi-title author, tech journalist, translator, and language activist who has been working with professional video since the eighties. Since 1994,…

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When did Premiere Pro CC start supporting variable frame rate? I’ve been waiting for this for a long time and didn’t think that day had come yet.