Problem w/ sync on Viewsonic PJD5112 + DLP-Link glasses

[cybereality]

I'm testing out this Viewsonic PJD5112 that they have at work, and its problematic getting the DLP-Link glasses (or the content) to sync using the Stereoscopic Player. I'm running this off my Lenovo Y570 laptop w/ a VGA cable. I have the PJ as the primary display, running at 800x600 @ 120Hz (the native res).

Whats weird is that I was able to use the IZ3D driver in "120Hz display" mode and played about 10 minutes of L4D with perfect sync and no inversions. Afterwards I played the Stereoscopic Player and watched about 5 minutes of a video, no prob. Then a few minutes later I tried the Stereoscopic Player again (in software page-flipping mode) and it was flickering like mad and constantly swapping eyes. Why did it work once and then not again? I did not change the settings at all.

Is there any trick to getting 3D videos to work on DLP 3D projectors that I am missing? Please help, thanks.

[Fredz]

Software page flipping is not reliable, you need to have hardware page flipping for guaranteed synchronization.

[cybereality]

Yes I know that. But it did work one time for 5 minutes straight. So there must be some way for it to work.

How is everyone else with DLP projectors watching videos?

[Fredz]

Hmm, I'll say it more clearly. You can possibly have a good synchronization with software page flipping for quite long moments, but that duration is not guaranteed.

It depends on the kernel scheduling which you don't have any control over. Most of the time you can have good results when there is low CPU charge, but if the periodic timeslices given to your app by the scheduler don't happen exactly during a vertical retrace, the synchronization won't work. And even at 0% CPU charge there are still other applications requiring CPU time, like services for examples.

That's why hardware page flipping is reliable, it doesn't depend on the timeslices given by the scheduler since the code to execute it's directly connected to the IRQ signal of the GPU.

For DLP-Link users, I guess they use hardware page flipping in one way or another (3D Vision, AMD HD3D) or they just can stand the occasional eye inversions. Considering DLP-Link doesn't even guarantee a correct eye order each time a movie is launched, I guess they don't really mind for occasional inversions.

In your case, if you really can't get any synchronization at all after several attempts, it may be a problem with Stereoscopic Player or a change in your GPU driver settings concerning the vertical retrace.

[cybereality]

Well that kinda sucks. Pretty much what I had thought before, but I was just hoping there was something I missed. I need this to do some presentations in 3D, and I wish to run a video on loop for maybe an hour at a time (unattended). So I cannot have random eye inversions, especially not with a handful for people wearing glasses. So this is a big problem.

What is the best solution for this? I could maybe get an HDMI 1.4a projector, which would solve the issue of page-flipping but then maybe there would still be no guarantee that DLP-Link would sync to the correct eye. A 3D Vision certified projector would be the cheapest thing (starting at $300) but I am not sure my laptop can support 3D Vision (it has only VGA and HDMI out). Plus I need to buy around 5 or 10 pairs of glasses, and the DLP-Link ones seemed the cheapest ($40 each, maybe less in bulk). Any ideas?

[Gae43]

Well i don't know if this can help you at all but here are my experiences with stereoscopic player and page-flip mode.

1) If the resolution of the movie is too high then my CPU can't cope and the sides will reverse or not sync up at all (shaky picture syndrome).
2) Version 1.1 of Stereoscopic player worked fine with page-flip but when I upgraded to Version 1.7 the page-flipping didn't work. I still don't know why.
3) Page-flipping doesn't work while using dual-monitor mode.
4) Sometimes when coming out of fullscreen mode, the graphic card can change its resolution and refresh rate and lose synchronisation with page flip.

Doubt if there's anything there to help you, but you never know.

Gae43

[Fredz]

Are you sure it's really a Viewsonic PJD5112 that you have at work ? Because it's compatible with 3D Vision according to the NVIDIA system requirements page, the 3D compatible projectors list and the ViewSonic website.

NVIDIA sysreqs : http://www.nvidia.com/object/3d-vision- ... ments.html" onclick="window.open(this.href);return false;
3D Compatible Projectors list : http://www.3dmovielist.com/projectors.html" onclick="window.open(this.href);return false;
ViewSonic : http://www.viewsonic.com/products/archive/pjd5112.htm" onclick="window.open(this.href);return false;

So you shouldn't have any problem with hardware page flipping using the 3D Vision driver. In the manual it's even said that you have a 3D Sync Invert option when using ther DLP-Link mode if the eyes are inversed.

ViewSonic PJD5112 manual : http://www.viewsonic.com/assets/052/13083.pdf" onclick="window.open(this.href);return false;

[cybereality]

Actually maybe I am mistaken on the model number. I do believe the native res is 800x600, so maybe its the PJD5111, which is still Nvidia supported. I will double-check on Monday. If it is supported by Nvidia, that would be great. Hopefully that is the case, as I'd rather not have to buy my own projector if I don't have to.

Another question: will multiple DLP-Link glasses keep the same sync together? For example, if I start and video/game and get one pair of DLP-Link glasses to sync properly, will this mean all other pairs of (identical) glasses will have the same sync? Or is this also just the "luck of the draw"?

[Fredz]

There shouldn't be any problem using several DLP-Link glasses, the protocol has different timings for left and right eye so they will all be synchronized in the same way. Some glasses have their own button to invert the eyes though (like the ViewSonic PGD-150), but you should tell spectators to not use it if the eyes are inverted. This should be done on the projector itself so everyone is synchronized again.

[cybereality]

Awesome, thanks.