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andersh80973950
Known Participant
February 22, 2019
Question

GPU and CPU encoding loads with effects

  • February 22, 2019
  • 1 reply
  • 993 views

Alright, so correct me if I'm wrong here, and if I'm wrong, would be nice with some explanation.

So I have this 20 minute timeline I'm currently rendring/encoding to h264 with Media Encoder and CUDA on.

The timeline consists of A LOT of 200fps .R3D clips time mapped so it's realtime in a 25fps timeline. The footage is a variation of 3-5K, downscaled to 2K (2048x858 due to 2.40:1 ratio).

I have the dust & scratches native premiere effect on almost all clips (dirty lens) and with an adjustment layer that consists of a simple grade/color correction on top of all clips.

So to the actual question:

When I rendered out a preview of the timeline, I get rendertimes down to around 11minutes, seeing my CPU load is between 70-95%, and my GPU load is around 30-60%.

Now when I'm rendring with the scratch & dust effect on the clips, (and yes, I know I'll get longer encoding/render times due to the effects), I see that my rendringtime is around 40minutes, CPU load is around 95-100%, but my GPU only uses around 10-15% ??

How come that adding a effect like scratch & dust makes an impact on how it's rendered between the GPU and CPU? In my head it should only "add more stuff cpu/gpu has to do" in other words, lets say that the GPU would need to work around 60-80% load?

I have a newly built Threadripper 1920x, 32gb DDR4 3600mhz, SSD's with an 2080ti, which is more than capable to render heavy stuff, I just don't understand why it's not that efficient when adding that effect..

Best regards

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    1 reply

    Ann Bens
    Community Expert
    Ann BensCommunity Expert
    Community Expert
    February 22, 2019

    Just to be clear: are you talking rendering timeline as in making preview files or export timeline?

    Your timeline might be using a different codec to render preview files opposite the codec used in the export.

    Different codec, different workload.

    A
    andersh80973950Author
    Known Participant
    February 22, 2019

    Sorry for the confusion..  I'm talking about the actual export of the final timeline. It's the exact same files getting exported from AME. So it's not really about the encoding time, because even I can understand that more effects equal longer export times.. It's more about the workload on the GPU/CPU with effects that confuses me.

    R Neil Haugen
    R Neil Haugen
    Legend
    February 22, 2019

    That I understand, but it still (no offence) doesn't answers why the GPU load drops when adding a simple effect, where it actually should rise imo.


    Look at the lego-blocks to the right for any effect in the Effects list. If you see one for GPU use, that effect uses the GPU. If there is no GPU Lego block there, it's only CPU processed.

    You keep talking about rendering a timeline then doing something else, so I think there is still miscomunication here. Export means you create a new file to a location on disc, which you could re-import or view elsewhere. Render meanscjustvto make previews of parts of a sequence for use in playback within Pr only, probably does not make even a complete file, and unless you've changed settings, uses a small low-quality codec.

    Neil

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