Re: Grab a pixmap / screenshot thing

[zentara <zentara1 sbcglobal net>]

On Tue, 7 Nov 2006 15:41:52 -0500 (EST)
"muppet" <scott asofyet org> wrote:

> A. Pagaltzis wrote:
> > * zentara <zentara1 sbcglobal net> [2006-11-07 21:00]:
> > > I wonder if it can be used in a thread, to take a series of
> > > screenshots thru a timer, which can then be assembled into an
> > > mpg movie of the screen action. ?
> >
> > Theoretically yes. Too much CPU load in practice for any useful
> > framerate. To do this well would require speaking XDamage to the
> > server to pick up only parts that have changed from frame to
> > frame.
>
> Really, it's more the fact that the image is sent back to the client from the
> server with XGetImage().  That means marshalling from device pixels to 24-bit
> RGB and sending that over the wire to the client (possibly shm on the same
> machine, but still, IPC).  The performance suckiness of such a scheme is why
> things like XDamage and XVnc exist.  ;-)

> muppet <scott at asofyet dot org>

Yes, I finally discover Gstreamer, and it's ximagesrc plugin,
I read it uses XDamage if available.

This pipeline does a rudimentary job of capturing, without using
too much cpu. 

gst-launch -v ximagesrc ! video/x-raw-rgb,framerate=5/1 ! ffmpegcolorspace !
mux. avimux name=mux ! filesink location=ztest.avi 
#
#mencoder ztest.avi  -ovc lavc  -o ztest.mpg   







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