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Old 30th April 2019, 15:57   #1  |  Link
kabelbrand
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NVidia GPU encode performance differences

Hi,

as I understand the encode engine is separate from the CUDA engine so the CUDA core count does not seem to be a (huge) factor.
I suspect there is no big performance difference within a GPU generation and only depends on the number of NVENC, see here.
So in theory a Quadro P5000 would be twice as fast as a P4000 and a P2000 would still be as fast as a P4000!?

I am wondering how GPU generations differ in encoding speed, e.g. K2000 vs. M2000 vs. P2000 or P4000 vs. RTX4000.
Does the number of streams per NVENC roughly translate into fractions of real time for a single stream?

Any thoughts are appreciated.

Thank you.

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Old 30th April 2019, 19:10   #2  |  Link
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Don't own any card which multiple encoder (NVENC) chips, but I thought that 'the number of encoders' * 'the number of parallel encodings' would be the number of streams you can encode in parallel with that card,....
(Total # of NVENC) * (Max # of concurrent sessions) = 'number of streams that can be encoded in parallel'

Never thought that multiple chips could be used to speed up the encoding of a single stream,...
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Old 30th April 2019, 19:13   #3  |  Link
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I would be surprised if single-stream encoding performance increases on those cards with multiple NVENC engines, but since they are rather expensive, I can't really confirm or deny it officially. Single Stream encoding is already quite fast even on consumer GeForce cards though.

The generation of the card certainly matters however - even more so in quality then speed however. Turing for example made pretty big leaps in quality.
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Old 1st May 2019, 05:04   #4  |  Link
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@kabelbrand... don't bother, I have an NVIDIA Quadro M4000 but I don't use it to encode 'cause the quality of the resulting encode is not suitable for production as it falls way behind CPU encoding on SSIM/PSNR tests. I use it to scroll the timeline of my NLE smoothly and sometimes with OpenCl when I have to encode in x264, that's all.
For everything else, there's CPU only encoding.
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Old 2nd May 2019, 11:05   #5  |  Link
kabelbrand
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Thank you guys.

Yes, it would not make sense if encoding a single stream uses more than one NVENC. When testing with large Quicktime and MXF files I noticed the limiting factor was not the GPU but I/O and audio encoding so a single NVENC will be sufficient.

In terms of quality I guess using the latest generation is the way to go. And even if I don't aim for quality in my current scenario it doesn't hurt if it's the best possible quality at a given bitrate.

A few years back I did some tests with a Kepler card and wasn't very impressed with the encode quality but the Pascal card I recently used performed much better in terms of quality.

So the Quadro P2000 seems to be the obvious budget choice here and the RTX4000 the encode quality pick. I guess NVidia will also introduce entry level Turing Quadro cards later on.
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Old 2nd May 2019, 20:54   #6  |  Link
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Unfortunately a recently released low end Turing, the 1650, has the older Volta generation NVENC with quality more similar to Pascal's. You have to be pretty careful when buying a GPU for its NVENC generation.

Edit: Why do you only discuss Quadros for encoding? Wouldn't a 1660 Ti be the budget choice? Do you need lots of concurrent sessions? That seems to be the only difference for single NVENC chip Quadros, with Geforce limited to 2 sessions while Quadros can run as many at once as you want. Curiously none of the RTX cards have multiple NVENC chips.
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Old 2nd May 2019, 22:49   #7  |  Link
nevcairiel
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Quote:
Originally Posted by Asmodian View Post
Unfortunately a recently released low end Turing, the 1650, has the older Volta generation NVENC with quality more similar to Pascal's. You have to be pretty careful when buying a GPU for its NVENC generation.
Wow, wonder what sort of recycling is going on there. Good that I was impatient and got a 1660 a few weeks ago instead of waiting for the 1650.

Regarding concurrent sessions, that is purely a driver limitation. The implication being that if one is crafty enough, it can be lifted....
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Old 3rd May 2019, 10:42   #8  |  Link
kabelbrand
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Quote:
Originally Posted by Asmodian View Post
Why do you only discuss Quadros for encoding? Wouldn't a 1660 Ti be the budget choice?
The GTX 1660 is a good choice indeed but my interest in single session performance is more out of curiousity and a 2 session limit would heavily restrict use cases.
Messing around with drivers or firmware is not an option either. Also I'd prefer a single slot card since this is supposed to go into a 1U 19" enclosure.
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