GPU encoding uses CPU (?)

Discussion in 'MSI AfterBurner Overclock Application Discussion' started by Eastrider, Dec 26, 2014.

  1. Eastrider

    Eastrider New Member

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    Hello. I've ditched Shadowplay and I'm trying to learn to use the MSI Afterburner recording module.

    Thing is, both Quicksync (3570k) and NVENC (GTX 660) work perfectly, full quality, audio is great, yey.

    The problem is here. I try in RaceDriver GRID, Dishonored, or Crysis 3. No FPS drop using Quicksync, slight FPS drop using NVENC (logically, since NVENC uses a bit of the GPU to encode, and Quicksync is a different GPU). Everything cool so far.

    The problem is when I start Guild Wars 2, FSX, or GTA IV. In the moment I hit "record", i get a massive (about 15-20 FPS) drop. The GPU % usage goes down a lot, no matter if using NVENC or Quicksync, and the CPU usage seems to go up a bit, as seen if I enable the external encoding server (it uses around 7-8% of the CPU).

    Since the CPU is already clogged with the game, the extra effort makes it start dropping FPS like no tomorrow, *and this also happens while using NVENC, something that shouldn't happen, given it's something completely external to the CPU, and Shadowplay (which uses NVENC as well) has almost 0% CPU tax (0.5 to 1%)*

    Why is that in Afterburner, no matter if using the Intel or the NVidia GPU, do I get a huge FPS drop, *only in CPU intensive games*? Am I missing something? Is there something mis-configured on my side?

    My config: i.imgur.com/M57S10b.png (C: is an SSD drive)

    What can I do?
     
  2. Unwinder

    Unwinder Moderator Staff Member

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  3. Eastrider

    Eastrider New Member

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    Ohh, thanks so much for such a detailed expalantion. I would've never thought of it!

    So the "bottleneck itself" would be the "lack of efficiency" of the frame capture method? I might have understood it wrong... why does, then, become noticeable only on CPU-intensive games? And why does it happen regardless of selecting NVidia or Intel GPU's? Since they don't break a sweat while encoding at all, would the "frame capture" tax the CPU itself, making it noticeable on those games?

    Sorry if I don't have the understandment or the knowledge of a developer, I'm just trying to learn and see if I can do something to improve my recordings.
     
  4. Eastrider

    Eastrider New Member

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    Giving it a second read, (I'm trying to understand it and learn the most of it, if you don't mind me asking), it says that you've gone for a slightly less efficient method, but that allows for windowed-mode recording. (That would explain why Shadowplay On vs Off is around 5 fps loss, and in Afterburner is around 10, but only the second can record in windowed mode, right?)

    But then, why is the Intel Quicksync method in Afterburner giving "only" 10 FPS penalty, just like the NVidia method? Shouldn't NVIFR, as implemented on Rivatuner, work only on NVENC method, or it will work to capture the frames either way, regardless if you use NVENC or Quicksync?

    I hope you're not uncomfortable with replying to some curiosity, but I understand if you prefer to keep how AB works as a secret.
     

  5. Unwinder

    Unwinder Moderator Staff Member

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    In new drivers NVIFR and NVFBC are now completely locked by NVIDIA for their internal tools only. Some green(dy) vendor want to artificially limit performance difference between Shadowplay and traditional video capture tools.
     
  6. Eastrider

    Eastrider New Member

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    Uuuuh... i understand. So, if they were open, AB would technically be on par with Shadow... understandable that they locked it, but that doesn't make it any less of a shame.

    Im not sure if you would know the answer but, then, how come that Steam In-Home-Streaming makes use of NVIFR and NVFBC when using hardware encoding? Is it used "via shadowplay" instead of directly, or Steam simply gets an special treatment from that green-dy vendor?

    Thanks, by the way, for Afterburner and for taking the time to answer my questions. :)
     
  7. kaloc

    kaloc New Member

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    I've also tested that feature in Steam's IHS and am equally curious as to how they can do it when no one else can. I'm hoping there is a way anyone can use it, but you're probably right about the exclusive deal.
     
  8. Darkness Knight

    Darkness Knight Member

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    The implementation/optimization is different in each recording software, for example with Action Mirillis (Quicksync/1080p@60fps) 0-2 fps drops only, with MSI AB varies between 0-15fps, but maybe the quality....

    Salu2 - Darkness Knight
     
    Last edited: Dec 26, 2014

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