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

[Yang Zhang]

yes, I saw that there are some commits in the current git head. for
rename the cuvid codec to nvdec.

On 8/24/18, Dennis Mungai <dmngaie at gmail.com> wrote:
> 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".
>> >> >> > > > > _______________________________________________
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>> >> >> > > > >
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>> >> >> > > > _______________________________________________
>> >> >> > > > ffmpeg-user mailing list
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>> >> >> > > >
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>> >> >> > > _______________________________________________
>> >> >> > > ffmpeg-user mailing list
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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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>> >> > _______________________________________________
>> >> > ffmpeg-user mailing list
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>> >> >
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>> >> _______________________________________________
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