Le 31/05/2012 14:36, William Brent a écrit :
Thanks Chris & Cyrille. I don't have an nvidia GPU, so I'll see what I can
find in the Xorg.conf. For totally digital displays, how does the refresh rate
come into play? I'm seeing out there that VBL doesn't apply to digital.
If you don't sync to VBlank, the screen can display the top of an image, then a
new image is rendered so the bottom of a screen display the new image.
I tried single buffer mode with each metro tick banging the gemhead and then
clearing the gemwin, but got jittery results with the video stream.
certainly the same kind of what you'll get without VBlank sync.
I haven't looked at triple buffering, is there some documentation you could
point me to on that?
i did not find lot's of documentation around this. it's just a flag for nvidia
card, i don't know if other allow it too.
internet is your friend.
The reason I want faster than screen rendering is that I'm doing video
tracking. If the control streams from the tracking algorithm can be updated
faster than the refresh rate, that would be ideal. Or is it not possible to
run an algorithm on frames that fall between the cracks of the refresh rate and
aren't fully displayed on the screen?
best is to stay with 60Fps, sync to VBlank, for the rendering part. (you can't
go faster than the screen anyway).
for video tracking, if you got a fast camera, you can use a gemhead at other
speed than the rendered one :
stop the gemhead sending it a 0, then use a metro to bang the gemhead at the
desired frequency.
cheers
c
On Thursday, May 31, 2012, Cyrille Henry wrote:
hello,
on Linux, you can change vertical syncro that using nvidia-settings tools
if you use a nvidia GPU. Otherwise, i don't know, certainly tweking the
Xorg.conf.
(look for"sync to Vblank")
Using triple buffer may provide solution for faster than screen rendering,
but i don't see the point in that.
If you have a shader or somthing else that sould be faster than sreen
rendering, you still can bang gemhead with a metro...
cheers
cyrille
Le 30/05/2012 21:22, chris clepper a écrit :
GEM is set to VBL sync based on your monitor's refresh rate. I vaguely
recall putting some sort of message about turning this on and off in the
gemwin. With it off you will often see horrible tearing artifacts on the
display, which is why it defaults to 'on' on OSX (and apparently Linux too).
On Wed, May 30, 2012 at 3:15 PM, William Brent <[email protected]
<mailto:[email protected]>> wrote:
Hi list,
I'm trying to get the fastest possible frame rate from GEM, and seem
to be hitting a limit of 60fps. Is this a known limit? I searched
the documentation and pd-list archives, but maybe I'm missing
something. The final application I'm working on is video tracking,
but here's a test patch with nothing more than a gemwin and a
counter
incremented by the gemhead. With a frame rate of 90 for the gemwin,
it takes exactly 3 seconds to get the counter up to 180, when it
should only take 2 seconds. At a frame rate of 60, it takes the
expected 2 seconds to get the counter to 120.
I'm running this with Pd-0.43-2 and GEM 0.93.3 on Ubuntu 12.04 using
the -noaudio flag. I get the same results on Mac OS 10.6.8.
--
William Brent
www.williambrent.com <http://www.williambrent.com>
<http://www.williambrent.com>
“Great minds flock together”
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