Jittery playback with proxy

Brain132Brain132 Website User Posts: 34
edited February 2016 in HitFilm

Here are my specs: 

AMD 8 core processor 4ghz

16 gb ram

I don't have any problem with playback until I put a composite shot of a masked image with a motion blur effect above one of my videos. Then it got jittery. So I made both the video and the image proxies. This only helped a little. So I turned down the quality to quarter. Still jittery. 

The image is a bag of chips and I'm trying to make the chips fall from top of frame to bottom frame of the video. But I can't make an accurate judgement of how fast the bag is falling with the jitter. I'm using a computer worth more than 1 grand. I don't know why I can't do something as simple as this. 


  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 18,292 Ambassador

    You've not listed your GPU or whether your storage media is SSD or HDD. So, I guess I am asking. 

    Hitfilm uses the GPU for most rendering, so that is more important than your CPU.


    Motion Blur is NOT a simple effect. Motion Blur breaks the movement down into subframes determined by the sample value, which defaults to 20,calculates those positions, then blends these subframes together with different transparencies Simply put, you just increased Hitfilm's workload by more than 2000% with that one effect. 

    Proxies are a lossless compression scheme at about a 3:1 ratio--so a 1920x1080 proxy, 32-bits (8 bit color channel, 8-bit alpha transparency) at 30 fps is going to be  over 600 megabits per second of data flow from storage. 

    Now the machine is decompressing the proxy for playback to it's full 1800 megabits per second, per stream. 

    From your description you also layered the two composites on the Editor Timeline, so now you have two proxies and a two layer composite happening. Still a pretty heavy workflow. 

    The money spent on the computer isn't important. For sake of argument, if your thousand dollar machine is two years old, then it's this week's Newegg special for $150. 

    So, what are your GPU and storage? Let's see if that's your bottleneck. 

    Also, if you're comping these on the Editor Timeline, create a new Composite Shot, embed your source Composites in it and take advantage of RAM previews. (RAM previews would be nice to have on the Editor Timeline.)

  • Brain132Brain132 Website User Posts: 34

    My storage media is HDD.  As for GPU, AMD Radeon (TM) R9 380 series.

    I'm guessing that's my gpu anyhow. Let me know if what I just listed is something else entirely.

  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 18,292 Ambassador

    Ok, by February 2016 standards the R9 380 is a fairly low-to-mid level card--it's equivalent to an Nvidia 680 GTX, which was Nvidia's top card three years ago. 

    The HDD you probably don't have the speed of the drive at hand--5400rpm or 7200rpm--but a 7200rpm HDD would have been recommended for video work in SD, 15 years ago. 

    So, the realtime slowdown is understandable. As stated above, turning on motion blur means Hitfilm is calculating each frame 20 times, then blending. Even a top GPU is going to slow down. 

    The HDD is probably bottlenecking the proxies. I just got a new system a couple months ago--my previous system was all HDD, and could still stutter with multiple proxies. The new system is SSD and much faster. 

    So, to avoid the obvious--do you have upgrade funds?-- Let's discuss workflow. Above I suggested the final assembly be done in a comp shot, but lets do something else. Turn off Motion Blur! Just removing that effect will really reduce the workload on your PC, so animate the chips without blur. Get your timing correct, THEN turn blur back on, and do a RAM preview to check it out. Next proxy this final Composite Shot and move it to the Editor Timeline. You'll speed up your animation phase, and reduce two proxies on the Edit Timeline to one, which will speed up your editing phase! 

    It's advisable in Hitfilm to do as much layering and Compositing in Composite shots as possible and keep your editing timeline as minimal as possible. Think of it like this--Composite Shots are where you create your clips, and the Editor Timeline is just where you put them in order, add final transitions and cut audio. 

    General hardware note for Hitfilm. Computer components from most to least importance are GPU, RAM, storage, CPU.  The GPU does all the rendering. RAM allows Hitfilm to hold more media/data "in mind." Storage determines total data available and how fast Hitfilm can get it into memory. CPU is mostly driving the UI. For frame, it's really only doing particle calculations and some of the subframe calculating, but it's passing that to the GPU for render. On export the CPU is doing frame compression and disc write, but only after GPU passes it a rendered frame. 

    Hopefully,  this information helps. 

  • Brain132Brain132 Website User Posts: 34

    Yes, that information is exactly what I needed. Thanks alot Triem :)

  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 18,292 Ambassador
  • chibichibi Website User Posts: 257 Just Starting Out

    HF should add ram previews in the Editor.
    Proxies are not as smooth as ram previews in the compositor.
    Wonder if they removed the ram limit on the compositor as well.

  • NormanPCNNormanPCN Website User Posts: 3,947 Enthusiast

    "HF should add ram previews in the Editor."


    The lack of this is baffling given the comp timeline has it.

  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 18,292 Ambassador

    It's even more incomprehensible than lack of scopes!


  • PalaconoPalacono Website User, HitFilm Beta Tester Posts: 3,442 Enthusiast
    edited February 2016

    <hijack + complain>/on
    My problem with RAM preview is that you can't display markers over it, so if you select a bunch of points to see them move with a camera, say, then if you make a RAM preview, they become invisible.

    So, what this means is: if you highlight some markers, RAM Preview  a small section of a clip (or that's all it can do in the available RAM) then as you play from before the RAM preview section to after it, the markers will be visible, invisible (during RAM section) then visible again.

    Drove me bonkers when it first did it as they were invisible for the whole of the section I was interested in tracking them for.

    Also reminds me: It's also not possible to select an already selected point from one of the many on screen you highlighted so you could see them in the first place. So you have to play eeny-meeny-miny-moe with them on the timeline until the one you want appears on the screen. Even having their name appear somewhere would be useful.

    Oh, and RAM preview doesn't give you the same results as the edit viewer window, or the 'normal' proxy. See here: hfp4-ram-preview-quality

    <hijack + complain>/off

  • SimonKJonesSimonKJones Moderator Website User, HitFilm Beta Tester Posts: 4,450 Enthusiast

    Further to @triem23's notes about importance of hardware components, I should also add that the CPU is used extensively for particle simulation (before they're handed off to the GPU for actual rendering), so if you're regularly working with particles the CPU becomes more important.

    RAM preview on the editor would indeed be useful. I'll make sure it's on the internal list, if it isn't already.

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