Slow preview - Blender problem?

NoExitNoExit Website User Posts: 4


I've just begun using Hitfilm and followed Hitfilm's tutorial on how to import an AT-AT 3d model from Blender.


I then created a composite shot with the AT-AT and an mp4 movie clip (circa 4MB).  All the AT-AT related files, including material pngs, take up circa 114MB.

Unfortunately, there is considerable lagging previewing, causing  jerky movements.

Here's what I tried to fix it. I've made a proxy for the composite shot and the movie clip but that did not help. I tried lowering the Viewer quality to a quarter but it is still lagging. I also maximized the RAM preview to 24 GB - no change.

For reference, creating a new project and importing  and previewing a 312MB large mp4 movie clip causes no lagging what so ever.

How do I fix this?

Intel Core i7-4800MQ [email protected] GHz
Intel HD Graphics 4600 
Windows 10 Enterprise





  • YeremyahYeremyah Website User Posts: 1,000 Enthusiast
    edited April 2017

    This seems like a problem?

    Intel HD Graphics 4600 

    Get a more powerful dedicated card?

  • NoExitNoExit Website User Posts: 4

    Thanks, Yeremyah. I googled the graphics card earlier but it does fulfill the Hitfilm basic requirements.

    Maybe you are right, but I d like to know for sure. And also if there is something else I can do except switch cards?

  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 17,779 Ambassador
    edited April 2017

    Yeremyah hasn't phrased it elegantly, but, FYI, in Hitfilm the GPU is going to be the most important element in a computer, overall. 

    The CPU (and an i7 4800mq is a good one--it actually outperforms my i7 6700) is used by Hitfilm for file I/O, video file decodes and encodes, and calculating particle sim physics. 

    The GPU handles all render/drawing tasks. 

    The Intel 4600 is a low-end graphics card, so that is going to be your bottleneck. 

    Besides turning down viewer resolution, have you turned off lights, shadows, DoF, motion blur in the preview? That will speed things up a lot if you haven't. 

    Another thing to try is going into the Options menu and (temporarily) turning down max texture size for 3D models. This will downsample the textures, speeding up previews. Just remember to turn that back up when you're ready to render. 

    RAM preview allocation doesn't directly speed up previews. The RAM preview is a manually-built scratch-render to quickly check a shot without committing to a full disc-render. Increasing that allocation just allows creating long previews. That said, 24GB of 32 might be a bit high because you've set that aside for a specific function leaving only 8GB RAM for all OS and Hitfilm functions. Turning your RAM preview allocation DOWN might help a little bit. Try taking RAM preview down to 12 or 16 GB and see if that helps. 

    You've already adjusted RAM preview allocation, so you've certainly found the Options Menu, but, just in case you haven't found everything yet, or don't know where the "build RAM preview" controls are, or where the toggles are for lights/shadows etc, this tutorial covers the interface in depth. 

    With all that said, there's a high possibility you'll still encounter some lag. 

    Oh, the last thing to try is optimization of your video assets. Hitfilm isn't the fastest NLE for just basic video decode and scrolling, and transcoding video to an optimized format before import can also help. There's "Norman AVC"  if you want to keep your file sizes down, or the big three of edit codecs--ProRes, DNxHD and Cineform--if you want blazing fast performance but much larger file sizes. 

    More information on that here. 

    Or these threads.

  • NoExitNoExit Website User Posts: 4


    Great! Thank you so much for your in-depth answer and recommendations!

  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 17,779 Ambassador

    You're welcome. Hope you can get performance up to a smoother level! 

  • YeremyahYeremyah Website User Posts: 1,000 Enthusiast
    edited April 2017

    @HitFilmer205776 You're welcome ;)

    The reality is, no matter what you do, you can fiddle around with everything all day long, but at the end of the day, that Intel HD Graphics 4600 will hold you back.

    I have a NVIDIA GTX 960 and that is still struggling on my PC to do complex stuff.

    When someone says "basic requirements" that doesn't mean it will run at peak performance.

    All the best :)

  • NoExitNoExit Website User Posts: 4


    Yeah, I got it. Yours and Triem23's answers were precisely what I wanted. :)


  • YeremyahYeremyah Website User Posts: 1,000 Enthusiast

    @NoExit Awesome :)

    All the best with the upgrades.

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