[FFmpeg-user] RES: A question on the Quadro P6000 and maximum simultaneous NVENC encodes in FFmpeg

[Dennis Mungai]

Actually, specifying -hwaccel nvdec just works.

See the debug log. Tested on the current git master.

It's more of a case of missing documentation.

On Fri, 24 Aug 2018 at 01:32, Yang Zhang <yzfedora at gmail.com> wrote:

> for some reason, the developer called it cuvid, but nvidia called it
> nvdec. so there is -hwaccel nvdec is a wrong option.
>
> On 8/24/18, Dennis Mungai <dmngaie at gmail.com> wrote:
> > For full GPU transcoding, shouldn't -hwaccel be nvdec?
> >
> > FFmpeg's documentation on this is missing, but for NVENC, the decoder
> > should be set to nvdec.
> >
> > On Fri, 24 Aug 2018 at 01:24, Yang Zhang <yzfedora at gmail.com> wrote:
> >
> >> If you didn't specify -hwaccel option, then the full gpu transcoding
> >> is disabled. for example:
> >>
> >> 1. full gpu transcoding.
> >> $ ffmpeg -hwaccel cuvid -c:v h264_cuvid -i test.ts -c:v h264_nvenc ...
> >>
> >> 2. gpu transcoding via memory copy.
> >> $ ffmpeg -c:v h264_cuvid -i test.ts -c:v h264_nvenc ...
> >>
> >> 3. cpu decoding and gpu encoding.
> >> $ ffmpeg -i test.ts -c:v h264_nvenc ...
> >>
> >>
> >>
> >> On 8/24/18, Dennis Mungai <dmngaie at gmail.com> wrote:
> >> > Is it possible to disable hwaccel decode explicitly in an FFmpeg
> >> instance?
> >> >
> >> > Say, -hwaccel none such that no hardware-accelerated decoder instance
> is
> >> > initialized on launch?
> >> >
> >> >
> >> >
> >> > On Fri, 24 Aug 2018 at 01:14, Yang Zhang <yzfedora at gmail.com> wrote:
> >> >
> >> >> Yes, 25 hd1080p channels use -hwaccel cuvid options to do full
> hardware
> >> >> acceleration transcoding. other channels use the GPU encoding only.
> >> >> this
> >> >> should can let you transcoding more channels. and fix the stutter
> >> problem.
> >> >>
> >> >> You can use "nvidia-smi dmon" to check the usage of NVDEC/ENC chips.
> >> >>
> >> >> On Fri, Aug 24, 2018 at 6:02 AM Dennis Mungai <dmngaie at gmail.com>
> >> wrote:
> >> >>
> >> >> > So, to clarify:
> >> >> >
> >> >> > If you were to disable hwaccel decode (and rely solely on
> >> software-based
> >> >> > decoding) BUT utilize NVENC on a system with a beefy processor and
> >> >> adequate
> >> >> > RAM, you should be able to eliminate the bottleneck, correct?
> >> >> >
> >> >> > Because what you're implying (by the bottleneck at decode side)
> would
> >> be
> >> >> a
> >> >> > limitation in how FFmpeg handles filter performance (hwupload, to
> be
> >> >> > exact), an issue that can be circumvented by eliminating hwaccel in
> >> >> decode.
> >> >> >
> >> >> >
> >> >> >
> >> >> > On Fri, 24 Aug 2018 at 00:57, Yang Zhang <yzfedora at gmail.com>
> wrote:
> >> >> >
> >> >> > > The problem is even you using the Tesla P100, and you can see it
> >> has 3
> >> >> > > NVENC chips inside it. but it has only 1 NVDEC chip, this is very
> >> very
> >> >> > > important. the bottleneck is at decoding side. this is why you
> got
> >> >> > freezing
> >> >> > > or stutter problem. basically, perhaps you can use Tesla P100
> >> encoding
> >> >> 75
> >> >> > > hd1080p channels, but you can not decoding more than 25 hd1080p
> >> >> channels
> >> >> > on
> >> >> > > it.
> >> >> > >
> >> >> > > On Fri, Aug 24, 2018 at 5:51 AM Dennis Mungai <dmngaie at gmail.com
> >
> >> >> wrote:
> >> >> > >
> >> >> > > > No.
> >> >> > > >
> >> >> > > > This is as tested on the Tesla P100.
> >> >> > > >
> >> >> > > > On Fri, 24 Aug 2018 at 00:26, Pedro Daniel Costa <
> >> >> > > > portalnet2 at outlook.com.br>
> >> >> > > > wrote:
> >> >> > > >
> >> >> > > > > Ok
> >> >> > > > >
> >> >> > > > > But with the TESLA models, did you have any issues over 40
> >> >> > > > > streams?
> >> >> > > > >
> >> >> > > > > I am planning on budge project to run minimum 100channels
> >> >> > > > >
> >> >> > > > > -----Mensagem original-----
> >> >> > > > > De: ffmpeg-user [mailto:ffmpeg-user-bounces at ffmpeg.org] Em
> >> nome de
> >> >> > > > Dennis
> >> >> > > > > Mungai
> >> >> > > > > Enviada em: quinta-feira, 23 de agosto de 2018 13:54
> >> >> > > > > Para: FFmpeg user questions
> >> >> > > > > Assunto: [FFmpeg-user] A question on the Quadro P6000 and
> >> maximum
> >> >> > > > > simultaneous NVENC encodes in FFmpeg
> >> >> > > > >
> >> >> > > > > Hello there,
> >> >> > > > >
> >> >> > > > > For users with this specific card (and FFmpeg installed),
> >> >> > > > > kindly
> >> >> > > clarify
> >> >> > > > > on the following:
> >> >> > > > >
> >> >> > > > > (a). How many simultaneous encoder sessions can you run on
> this
> >> >> card?
> >> >> > > > >
> >> >> > > > > (b). Have you ran into any issues, such as stuttering and
> >> dropping
> >> >> > > > streams
> >> >> > > > > with multiple concurrent encodes?
> >> >> > > > >
> >> >> > > > > I ask because of a recent case where adding more than ~40
> >> >> concurrent
> >> >> > > > > encodes would make the output "drop" and stutter massively,
> as
> >> if
> >> >> > > FFmpeg
> >> >> > > > > itself was hanging, despite the GPU having more than enough
> >> >> > > > > VRAM
> >> >> > > (24GB?)
> >> >> > > > > and resources (under ~11% utilization according to
> nvidia-smi),
> >> >> > > implying
> >> >> > > > > some sort of artificial limitation in effect despite the GPU
> >> >> support
> >> >> > > > matrix
> >> >> > > > > specifying otherwise:
> >> >> > > > >
> >> >> https://developer.nvidia.com/video-encode-decode-gpu-support-matrix
> >> >> > > > >
> >> >> > > > > Your feedback on this is appreciated.
> >> >> > > > > _______________________________________________
> >> >> > > > > ffmpeg-user mailing list
> >> >> > > > > ffmpeg-user at ffmpeg.org
> >> >> > > > > http://ffmpeg.org/mailman/listinfo/ffmpeg-user
> >> >> > > > >
> >> >> > > > > To unsubscribe, visit link above, or email
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> >> >> > > > > with subject "unsubscribe".
> >> >> > > > > _______________________________________________
> >> >> > > > > ffmpeg-user mailing list
> >> >> > > > > ffmpeg-user at ffmpeg.org
> >> >> > > > > http://ffmpeg.org/mailman/listinfo/ffmpeg-user
> >> >> > > > >
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> >> >> > > > _______________________________________________
> >> >> > > > ffmpeg-user mailing list
> >> >> > > > ffmpeg-user at ffmpeg.org
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> >> >> > > >
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> >> >> > > _______________________________________________
> >> >> > > ffmpeg-user mailing list
> >> >> > > ffmpeg-user at ffmpeg.org
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> >> >> > >
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> >> >> > _______________________________________________
> >> >> > ffmpeg-user mailing list
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> >> >> >
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> >> >> _______________________________________________
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> >> >>
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> >> > _______________________________________________
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> >> >
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