[winswitch] NVENC and xpra

[...]

Antoine,

Great information.  Thank you!

So, VirtualGL would theoretically work for multiple users per card
(multiple applications on multiple displays)?

My intention is to be serving modern video games, like Minecraft, League of
Legends, etc.  I guess I would have to look into if openGL acceleration is
all that is needed.

I look forward to trying out the virtualGL with my simple setup, and
working towards getting having a need for NVENC.

-Elliot




On Tue, Dec 10, 2013 at 10:33 PM, Antoine Martin <antoine at nagafix.co.uk>wrote:

> On 11/12/13 06:18, ... wrote:
> > Hello,
> >
> > I had some questions about NVENC.  Sorry if this information is somewhere
> > already and I didn't find it.
> I assume you've already read:
> http://xpra.org/trac/wiki/Encodings/nvenc
> > Can xpra use a kepler enabled nvidia card to both render graphics
> (hardware
> > accelerated) and h264 encode them before shipping them off to another
> > display across the network?
> According to Nvidia:
>
> https://developer.nvidia.com/sites/default/files/akamai/cuda/files/CUDADownloads/NVENC_AppNote.pdf
> "NVIDIA's latest generation of GPUs based on the Kepler architecture,
> contain a
> hardware-based H.264 video encoder (henceforth referred to as NVENC). "
> So, assuming that this is a pro card or that you found a license key
> (...), yes you can use NVENC with such cards.
> This answers the second half your question.
>
>
> As for the "render graphics hardware accelerated", it is a little bit
> more complicated. Based on your description, I assume that the card is
> not connected to a monitor or that this monitor will not be used for
> viewing. If that's not the case, the answers below are going to be
> inadequate.
>
> First, you need to define "accelerated":
> * if you mean OpenGL acceleration - which is often enough, then this
> will do what you want and is supported:
> http://www.virtualgl.org/
> * if you want to use the regular "nvidia" X11 driver for acceleration
> directly, there are ways to use a regular X11 server (usually running as
> root) to replace xpra's Xvfb, you may need to use the "
> ConnectedMonitor" option if no monitor is attached to the card. This
> will only work for a single user per card and your mileage may vary: it
> "should" work.
> Using "xpra shadow" to copy an existing display is not a good solution
> at present as it uses polling and will use far too much CPU time -
> though that could be fixed.
>
> The main downside of the current xpra 0.11 code is that it is not really
> tailored for this Nvidia specific use-case: during screen updates the
> pixel data will be downloaded from the GPU to the CPU and then uploaded
> again to the GPU for compression... which is a complete waste of
> valuable memory bandwidth. It shouldn't be too hard to bypass this
> unnecessary copying, and if there is enough demand for it then we can
> certainly look at it.
> > If not, is this something that some other VNC like program can do?
> Not as far as I know: xpra is the first, and at present the only
> open-source software to have NVENC support.
> >   If so,
> > are there any other hardware requirements or issues that I should know
> > about?  Would any kepler/NVENC enabled nvidia card be able to do this?
> As per above, with consumer cards (GeForce) you will need to find a
> license key...
>
> I do wonder if some consumer protection law could force Nvidia to
> provide the keys required to take advantage of the features they
> advertised when the cards were sold (and earlier SDKs did not require
> license keys either).
> As can be seen here in the GTX680 whitepaper:
>
> http://www.geforce.com/Active/en_US/en_US/pdf/GeForce-GTX-680-Whitepaper-FINAL.pdf
> "All Kepler GPUs also incorporate a new hardware-based H.264 video
> encoder, NVENC.  "
> > Does anyone have any experience with this?
>
> Cheers
> Antoine
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