How to use Multiple film rates (60 and 24)

dbretz Posts: 1

Here is a quick run down of whats happening. When i play through my timeline and get to the 24 fps it gets choppy then back to the 60fps it goes smooth again.

One other issue i have sometimes is running two different clips at one time like a PIP and one of them will surely be choppy.


Intel Core I7-9700 [email protected] 3.0ghz 15.8 ram 64 bit x64bit Based Processor.

Thanks for any help!


  • Triem23
    Triem23 Posts: 20,072 Ambassador

    The system specs shown - do you have a GPU you didn't mention? If not, the UHD 630 built into your i7 is fairly near minimum specs. Without a dedicated GPU your system is very low-end for Hitfilm use.

    What is your project frame rate? I'm assuming 60 (59.94)?

    Media is "conformed" in real-time when added to a Timeline. If you are adding 24p media to a 60p Timeline Hitfilm is having to duplicate frames on-the-fly to make your 24p footage conform.

    24fps is 40% of the frame rate of 60fps. Hitfilm can't simply double the frames and be done with it. Some of those 24p frames are going to be duplicated three times, not twice. This will affect the playback cadence (perceived smoothness). Hitfilm does not interpolate frames (@NormanPCN sanity check, please?), only duplicate or drop.

    Duplicate or drop is important. If you were putting 60p media on a 24p Timeline HF can't just drop every other frame - sometimes it will have to play two of the 60p frames back to back then drop one. Again, this affects cadence.

    Now, because it's the 24p clips being "jerky" I know you're using a 60p Timeline. The 60p clips go from streaming "1 (frame), 1, 1, 1, 1, etc" to "2, 3, 3, 2, 3, 3, 2, etc" (or "2, 3, 2, 3, 2, 3, etc) with Hitfilm parsing the frames in real time.

    Using an external transcoder, like Handbrake, to convert your 24p to 60p (or vice versa) before import to Hitfilm might give better results. If nothing else the transcode will" burn in" the duplicated frames so Hitfilm doesn't have to think about things in real-time. This will improve editor performance.

    Otherwise, when running multiple clips and PIP effects - Hitfilm processes and renders all frames displayed through the GPU. The UHD 630 is designed to stream a single 4k 60fps stream. Once you start layering clips together - especially with different frame rates (spacing frames) and PIP (scale and overlay)... Any GPU will hit a point where things start to lag. With a UHD 630 this is sooner rather than later.

    The UHD 630 benchmarks* at about 70% faster than the min-spec HD 5000. An Nvidia 3080 benchmarks over 3600% faster than the UHD 630. The UHD 630 is slow... If you have a desktop I highly recommend saving up for a GPU. An Nvidia 1650 Super runs about $150 and is about 800% faster than the UHD 630.

    *Benchmarks ain't perfect since they related to standardized tests, not per-program comparisons, but, fuzziness of benchmarks aside, the bottom line is a dedicated GPU is almost a must for Hitfilm. I run Hitfilm Pro on three machines. One merely has an Intel UHD 620, one an Nvidia 1080 (mobile), one an Nvidia 2060 (mobile). My UHD 620 machine can barely play back a 4k 60p smoothly, and pretty much any effects work brings lag. My 2060 can handle multiple 4k 60p streams with light color correction in real time.

  • NormanPCN
    NormanPCN Posts: 4,082 Enthusiast

    Hitfilm does not interpolate frames (@NormanPCN sanity check, please?), only duplicate or drop.

    Correct. Only the Speed effect has frame blending. Everything else timeline conform and the rate stretch tool are simply drop/duplicate.