From: O.Riedel++at++CENIT.DE
Date: 03/20/2000 22:00:13
Hi Allan,
Can you please explain the SMOC a little bit in deepth? We have genlock
problems (may be caused by SMOC) with a 3 pipe (an up) machine and do not
have very good explantion right now about all the influences from:
* cabeling
* ircombine
* and vfc
The PFCHAN_SWAPBUFFERS is activated.
Cheeers
Oliver
------------------------------------------
Dr.-Ing. Oliver H. Riedel
Director Virtual Reality
CENIT AG Systemhaus
o.riedel++at++cenit.de
phone +49 (0)711 780 73 349
fax +49 (0)711 780 73 649
Schulze-Delitzsch-Strasse 50
D-70565 Stuttgart/Germany
-----Ursprüngliche Nachricht-----
Von: allan++at++sgi.com [mailto:allan++at++sgi.com]
Gesendet am: Montag, 20. März 2000 23:10
An: Devrim Erdem; info-performer++at++sgi.com
Betreff: Re: 3 Pipe Onyx Genlock
On Mar 20, 10:43am, Devrim Erdem wrote:
>
> I will be using a 3 pipe onyx soon and having no experience on the 3
> pipe config , I will build a question :
>
> In what circumstances, a 3 pipe onyx config will need genlocking for
> a 3 pipe performer app ?
For most multi-pipe Performer applications the answer is "always".
The definition of genlock is the synchronization of two (or more)
video outputs, such that the horizontal and vertical sync signals are
aligned. Users of multi-pipe vis-sim programs typically require the
pipes' video outputs be genlocked so that monitor refreshes occur
simultaneously on all pipes.
When multiple pipes are being used to view a single out-the-window
scene you want the video timing to be in lock-step so that new frames
appear simultaneously on all three screens. If you didn't synchronize
them (didn't genlock them) then you might see a disparity at the edges.
Activating genlock is just a SMOC (Simple Matter of Cabling) and some
fiddling with ircombine to activate it.
Another multipipe synchronization issue to think about is the timing
of the framebuffer swap on each pipe. Imagine if the pipes were
unbalanced -- one pipe running at a 60Hz frame rate (perhaps a side
view) and the other at 30Hz. if there were NO synchronization you'd
see disparity at the edges again as the 60Hz pipe moved along before
the 30Hz pipe caught up. This would be quite disconcerting :-). Use
the pfChannel share-flag PFCHAN_SWAPBUFFERS so that Performer can
synchronize all the channels' framebuffer swaps for you.
Allan
--
Allan Schaffer allan++at++sgi.com
Silicon Graphics http://reality.sgi.com/allan
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