[PD] gemwin frame rate limit?

[William Brent]

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.

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.  I
haven't looked at triple buffering, is there some documentation you could
point me to on that?  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?


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 <william.brent at gmail.com<mailto:
>> william.brent at gmail.com>> 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>
>>
>>    “Great minds flock together”
>>    Conflations: conversational idiom for the 21st century
>>
>>    www.conflations.com <http://www.conflations.com>
>>
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>

-- 
William Brent
www.williambrent.com

“Great minds flock together”
Conflations: conversational idiom for the 21st century

www.conflations.com
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