Exported Video very choppy

OmarJallouq Posts: 1 Just Starting Out*


I am trying to film a documentary-style video, with the use of my iPhone 11 as a camera. On my phone, I have the settings set to 1080p at 30fps. When uploading the videos (converting them to mp4 so that Hitfilm accepts them), I edit them and all is good. My project settings are the same as before, 1080p at 30fps. When I did the editing, I export my contents but all the time my exported video is VERY laggy/frame ratey. This was not the case literally a week ago, and I haven't change any settings. I have even tried to change my project settings to 720p at 30fps in case I got my phone properties wrong, with no prevail.

One theory I have is that when I'm putting my recorded videos onto the timeline, I'm getting that message that the project and the video are not in the same resolution (even if they are supposed to?) and I'm clicking ignore as they should be the same. Please help I've got a deadline due soon!


  • spyresca
    spyresca Posts: 288 Enthusiast
    edited March 2021

    If your phone footage is variable frame rate (probably!) you really should transcode it to constant frame rate before editing it in HF. Otherwise, you're asking for issues.

  • Triem23
    Triem23 Posts: 20,396 Power User

    Your iPhone footage is Variable Frame Rate (VFR), which can cause issues with audio synch, playback smoothness, and speed effects. Basically, instead of recording a true "30" fps (easier to type than 29.97), your phone is recording "30, 30, 31, 24, 23, 30, 18, 30, 26, etc.." (I've seen "29.97 fps" VFR footage that varied between 31 fps and 0.5 fps).

    You'll need to use third party software to transcode from VFR to Constant Frame Rate (CFR).

    This video covers several methods to do so, starting at about 23 min in.

    Now, for your existing project, save as a new project. In the new project try right clicking your media clips in the Media Bin, right clicking and selecting Relink. Select the transcoded file. This will swap the original footage out and will preserve most of your edit.

    I say most because the VFR variance will probably cause some of the corrected footage to have drifted a few frames. Easy enough to fix. That's what the Slip tool is for. 😊