New iMac with Hitfilm 12.3 thru 13 stuttering video playback

suaveimagery Posts: 11 Just Starting Out
edited September 2019 in Post-production techniques

Hello all,

I have:

1. iMac 5K, 27 in

2. 3Ghz i5 processor

3. 8GB 2667Mhz RAM

4. Radeon Pro 570X, 4GB video card

Question: Why does Hitfilm stutter with video playback, even with no effects applied to a composite or transitions in the editor window.  When looking at the Activity window on Mac, it shows the video card maxed out on memory and the processor running almost 90 percent!!  I also own Final Cut, and when playing clips back, there is no lag and the performance of the video card is 1/2 of the usage it gets when I'm running Hitfilm.

I know Hitfilm is pretty much processing the rendering, playback, and encode/decode at the same time, but I believe my computer is more than adequate to support those things. I've even backtracked to previous versions of Hitfilm to see if there was a difference in playback, but it stutters on all versions back to 12.1

My clips are on external drives also, so I tried to place them on my desktop and run them from there, but still, same results.

Any help would be appreciated.


  • TheBenNorris
    TheBenNorris Posts: 2,042 Staff

    Hi @suaveimagery, can you provide more details on your cpu, specifically the generation of the i5, as this is the only thing i can see that would be an obvious sign for the issues you're having, especially if you have issues with 12.1 too.

  • DibsMcCallum
    DibsMcCallum QA Tester Posts: 164 Staff

    @suaveimagery did you manage to find the rest of the machine's specs so we can help you out?

    Also, it may be worth looking into where the media was sourced from as there could be an issue with it being a variable FPS  amongst many other things. But we are here to help if you need it.

  • Triem23
    Triem23 Posts: 20,574 Ambassador

    Mods aren't Staff (so listen to Dibs and Ben over me), but check your GPU drivers. Old GPU drivers can cause issues, and Apple tends to only use whatever driver was out when Apple does a Mac OS update. 

    The team have a FAQ on updating drivers here:

    @DibsMcCallum asks where your media is from, and mentions "Variable Frame Rate" (VFR). If your footage is from a phone, tablet or screen recorder, it's probably VFR.

    This video is more PC specific, but will explain what VFR is, why it's problematic, how to use MediaInfo to check, and options to convert to Constant Frame Rate (CFR). The description text has timecodes for reference. 

  • suaveimagery
    suaveimagery Posts: 11 Just Starting Out

    @DibsMcCallum @TheBenNorris sorry for the delay. My CPU is as follows:

      Model Name: iMac

      Model Identifier: iMac19,1

      Processor Name: Intel Core i5

      Processor Speed: 3 GHz

      Number of Processors: 1

      Total Number of Cores: 6

      L2 Cache (per Core): 256 KB

      L3 Cache: 9 MB

      Memory: 32 GB

    I did just find info that Hitfilm does not like MP4 at all and I have since encoded some of my video files to Apples Pro Res. No need to buy fancy converter apps for a Mac either. Just right click the MP4 needing encoding, choose Pro Res from the drop down menu..Done! The results have been totally opposite. I created a new project importing those encoded files. Playback was fine and not taxing my CPU or GPU like the MP4s did. Thats something that needs to be put on the "front of the box"'ve been using Hitfilm the entire year thinking I needed to go get the fastest computer on Apples roster...Sheeessshhh!! 

    Since I'm here, could either of you tell me why ALOT of the keyboard shortcuts don't work with the "Magic Keyboard" that comes with the iMacs? And yes, I have been on a google tangent trying to find the answer for found somewhere that the shortcuts won't work while the view window of the editor or a composition is open. If that is the case, they will never work. My viewer is always open to see what I'm trying to edit. Please help....I'm weird.

  • TheBenNorris
    TheBenNorris Posts: 2,042 Staff

    @suaveimagery the keyboard shortcut issue sounds like a different problem altogether. Could you contact support with more information about this if possible, as I'm familiar with one or two shortcuts not working but not all of them.

  • suaveimagery
    suaveimagery Posts: 11 Just Starting Out

    Ok. Thanks for the response!!! 

  • suaveimagery
    suaveimagery Posts: 11 Just Starting Out

    Hello again. I've since updated my Hitfilm to the latest and greatest. The keyboard shortcuts are functioning properly with my "Magic Keyboard"...Thanks again all for the help!!