Re: Picture wobbling

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Rémi Arnaud (remi++at++remi)
Thu, 11 Dec 1997 00:57:37 -0800 (PST)

Performer Mailing List wrote:
>
> I have been having the pictuyre wobble problem for a while on my Onyx2
> 2-pipe IR using a VR4 HMD. The video format required by the VR4 is
> 640x486_30i. It seems to work well using a Sync on Green.
>
> I have tried several different methods of locking the frames but have
> been unable to get rid of the wobble. When I genlock the two pipes
> (using Pipe 0 as master with Internal Sync and Pipe 1 as slave with
> external sync and both set to Horizontal sync only), the gfxinfo tells
> me that pipe 0 is set to internal sync and is not genlocked while pipe 1
> is genlocked.

 Yes. set both format with Hsync, and also composite sync in green
 if you need to. Check that the Sync format in the Edit globals is set
 to 640x486_30i as well.

> However, whenever I get pipe 1 genlocked, the video
> format seems to cause problems for the VR4. I have tried setting the
> VR4 to sync on green and also to separate sync sending the horizontal
> sync from each pipe to the two screens of the VR4.
>
> Any suggestions?
>
> Is anyone out there with a VR4 HMD and a two pipe IR that has a
> successful implementation????
>
> Thanks in advance
>
> Jay
>
>
>
> Angus Dorbie wrote:
> >
> > On Dec 8, 3:48pm, Rémi Arnaud wrote:
> > > Subject: Re: Picture wobbling
> > > Angus Dorbie wrote:
> > > >
> > > > On Dec 8, 1:32pm, Gerard R. Tyra wrote:
> > > > > Subject: Re: Picture wobbling
> > > >
> > > > > Okay, correct me if I am wrong
> > > >
> > > > OK, here's the correction.
> > > >
> > > > You call swapbuffers and it simply isn't going to happen until
> > > > everything is drawn so blocking in SW is little difefrent from
> > > > blocking in HW provided the transport delay of a swap call is
> > > > small which it is. The key question is "can I do usefull
> > > > gfx work after my call to swap but before HW swap", the answer
> > > > is no, the pipe blocks almost immediately, hence swapready isn't
> > > > essential.
> > >
> > > Swap Ready becomes mandatory when all the video do not come from the
> > > same box. It is now working fine, included in the very-soon-to-be-released
> > > Performer2.2 and does not have the latency that a software lock has that
> > > can in extreme cases make your software missing frames. It has
> > > the cost of a cable connecting every pipe SwapReady to each other, but
> > > will work in any pfPhase modes.
> > > Note that SwapReady is useless if you do not genlock the videos.
> > >
> >
> > Yes, ofcourse swapready is usefull with multi host based rendering,
> > this is a different class of problem. With multi host based rendering
> > the sync can actually be achieved using ethernet assuming you are
> > aiming for a steady frame rate, and have few overload conditions, but
> > that's an exercise left to the reader, it is not without it's flaws.
> >
> > Cheers,Angus.
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