Realtime capture and streaming of a 4K HTML5 Session under Linux?

[Stirling Westrup]

On Thu, Oct 31, 2013 at 7:22 AM, Sebastian Dröge
<sebastian at centricular.com>wrote:

> On Mi, 2013-10-30 at 16:40 -0400, Stirling Westrup wrote:
> > I have a Linux application where we want to capture a live HTML5 browser
> > session and stream the results through gstreamer to a 4K projector.
> Because
> > of the size the final results will be shown at, we would like to do the
> > capture at 4K resolution, rather than upscale it for projection.
> >
> > We have the back-end working fine: if we feed in a canned capture of a 4K
> > session, we can stream and project it fine. However, we can't seem to do
> a
> > capture in realtime. I'm hoping its just because we took the naive
> approach
> > of setting up a dummy Xorg session (we don't have any 4K video cards),
> and
> > launched Mozilla on it. We then used ximagesrc to capture from the Xorg
> > session into gstreamer. The results were FAR too slow to be usable.
> >
> > I was hoping someone here would have some suggestions as to things we
> could
> > do to capture and stream more efficiently.
>
> You could also run a browser in some kind of offscreen window and
> capture from that,


I'm not sure I see how that would be any faster than what we've been doing,
especially if the offscreen window if 4K wide. Many graphic cards simply
refuse to let you create a window that big.


> or run something like a webkit web view in your
> application and have it render directly to a GStreamer buffer (Qt and
> GTK both have ways to render to memory instead of a X11 window). That
> should provide you with better performance as ximagesrc.
>

Yes, that occurred to me not long after I posted the above. I've been
looking into gecko- and chrome-based webkits, but I must admit that's an
area where I don't really know much, so I'm having trouble figuring out
which would be better for our purposes. Mating such a webkit to a gstreamer
source element might also prove an interesting challenge.


> Otherwise it would be best to check where exactly ximagesrc is too slow
> and try to get around that.
>

I have an outstanding bugzilla error on that point, and there is some
interesting discussion on how to fix it, but it appears to be a fair amount
of work.


-- 
Stirling Westrup
Programmer, Entrepreneur.
https://www.linkedin.com/e/fpf/77228
http://www.linkedin.com/in/swestrup
http://technaut.livejournal.com
http://sourceforge.net/users/stirlingwestrup
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