Dropping frames from iPhone footage even after transcoding for CFR

As the title says- I have footage that was shot on an iPhone 6s at "29.97fps" VFR (h.264, not HEVC), which upon import is rendering with up to 7 frames per second missing sporadically (i.e. every nth frame repeats itself x times), depending on what's happening in the footage. I have transcoded the footage into constant frame rate using several different settings combinations in Handbrake (including those recommended by Triem23), yet HitFilm is not only still erratically dropping/duplicating frames, it's dropping so many more with the transcoded files that the resulting imported CFR footage varies from 13-15fps in the render (which is significantly worse than the original non-transcoded VFR  .MOV's at 23-30fps, as mentioned; there's even one frame in the transcoded footage that repeats itself 5x in a row.)

More specifically, I've tried transcoding via Handbrake to CFR at 29.97, 30, and "same as source". I used MediaInfo to confirm that the footage was indeed transcoded to the correct frame rate with a Constant status. I have confirmed several times that the HF media timeline settings frame rate is matching up precisely with the frame rate of the media (that includes imported media transcoded to 30fps into a 30fps timeline to avoid the possibility of an inaccurately approximated/oscillating "29.97fps" being exported from HandBrake), and even tried mixing and matching 29.97/30 just to try it, yet the issue persists.

The problem is also not with only with the pre-rendered preview in HF either: I've both rendered within HF and exported the footage, and the problem persists.

I have already watched the video from Triem23 on transcoding, and seen most of CleverTagline's responses on this sort of problem saying that simply transcoding into a constant frame rate will fix this issue. The original .MOV footage and all transcoding combinations I've tried can all be scrubbed frame by frame perfectly within QuickTime, which at least tells me that this footage is all there as MediaInfo and QuickTime Inspector are reporting. I'm under a huge time crunch for this project so is there any way around this or do I just need to bite the bullet, buy Premiere Pro, and ditch HitFilm?

Any help that anyone can provide will be IMMENSELY appreciated!


  • Stargazer54
    Stargazer54 Posts: 3,967 Ambassador

    @sage36 Sorry to hear you are having trouble.  I would certainly recommend using VirtualDub and transcode to Cineform as a better option.   That said, my question is do you see skipping with scrubbing on the timeline or merely playing footage on the timeline?  If so, it is not uncommon for HF to exhibit that behavior in the editor.  However, if you render the footage and playback the rendered file on a different player than HF does it still skip?  (e.g. how does VLC handle it?)  I assume you're using QT player?

    Which version of HF Expresss?   And please supply system specs?

  • sage36
    sage36 Posts: 4
    edited January 2019

    Thanks so much for the quick response, @Stargazer54!

    As far as timeline preview vs scrubbing/rendering, the frame dropping/duplication is indeed visible in timeline frame by frame scrubbing, and as mentioned I've both rendered within HF and exported the footage (and played in QuickTime), yet the problem persists :(

    I'm running HitFilm Express version 11.1.0002. I could be wrong, but don't think I can use VirtualDub though, since I'm on a Mac... (the specs of which are below)

    iMac (Retina 4K, 21.5-inch, Late 2015)

    3.1 GHz Intel Core i5

    8 GB 1867 MHz DDR3

    Macintosh HD

    Intel Iris Pro Graphics 6200 1536 MB

  • CleverTagline
    CleverTagline Posts: 3,345 Ambassador

    Wow! That's definitely bizarre behavior. How big are the source files before transcoding? Would it be possible to post one somewhere for a few of us to download and test? I'm on a Mac as well, so it might be a good apples-to-apples comparison (pun not intended, but gladly used).

    By the way, what version of the Mac OS are you running? I hope it's not Mojave, as that's not officially supported by HitFilm yet. The devs have found an issue with buggy video drivers under Mojave that cause odd problems, and have said that a fix is forthcoming, but obviously haven't given a timeframe for this fix to be released.

  • CleverTagline
    CleverTagline Posts: 3,345 Ambassador

    Just noticed a comment from @JavertValbarr in this thread, announcing the release of the bug fix that affects Mojave. Even though the primary fix is for kernel panic issues, it might be worth updating just in case.

  • sage36
    sage36 Posts: 4

    Thanks for the response, @CleverTagline!

    I am running Mojave actually, and I have indeed been having the kernel panic crashing issue at random intervals ever since the next-to-latest update... So I updated HitFilm Express with the update that Javert mentioned, and while that has so far eliminated the kernel crashing, the h.264-codec/mp4-container/29.97ConstantFPS files I transcoded via HandBrake (as well as the original variable frame rate MOV's straight from the iPhone 6s) were still dropping/duplicating frames all over the place.

    However, somehow I then randomly happened to click on and scrub through the MPEG-4 codec version of the footage that I had transcoded, and THAT one wasn't dropping any frames, for whatever reason.

    So as far as I can tell, if you are running Mojave and have variable frame rate footage to work with (as all iPhone users will), the HandBrake settings I will enumerate below are currently the only ones that will allow you to work with HitFilm smoothly- all other variable rate footage and even transcoded (h.264) constant rate footage will have dropped/duplicated frames. (<- paging @JavertValbarr, @DannyDev, and @CedricBonnier as an FYI because this was extremely frustrating until I figured it out,  and I'm worried other iPhone users may start ditching HitFilm because of this like I very nearly did before stumbling upon a solution.)


    The specific HandBrake settings that are currently allowing me to work in HitFilm Express 11.2.0003, running Mojave 10.14.2, with iPhone 6s footage, and have no dropped frames are as follows:

    Summary tab: default ( [Format]: "MP4 File", select "Align A/V Start" )

    Filters tab: change [Deinterlace] from "Decomb" to "Off"

    Video tab: set [Video Encoder] to "MPEG-4", under [Framerate (FPS)] select the target frame rate, then underneath select "Constant Framerate", then under [Quality] select "Constant Quality" and slide the slider all the way to the right ("QP 1")

  • CleverTagline
    CleverTagline Posts: 3,345 Ambassador

    Glad to know that you got it working! Interesting that switching to MP4 solved it. On that note, you might want to read through this thread for a related transcoding option:


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