Go Back   nV News Forums > Linux Support Forums > NVIDIA Linux

Newegg Daily Deals

Reply
 
Thread Tools
Old 07-22-10, 01:02 PM   #1
mrnick
Registered User
 
Join Date: Jul 2010
Posts: 11
Default Syncing Quadro card's 2 outputs for dual flat panel 3D display

Hello,

After the success with you guys solving my last query, I have another on syncing display outputs from a Quadro card...

We have a Quadro 3800 driving a True3Di stereoscopic display:
http://www.true3di.com/monitor.html

The display uses two 1920x1200 flat panels at 90 degrees to each other, with a bit of semi transparent glass in between to reflect a true 1920x1200 3D image. (The viewer wears passive polarised glasses.) One panel is connected to the DVI out on the Quadro, the other to the Display Port out (via a Displayport to DVI adapter).

We are using RV player to send 2 streams of 1920x1200 video to the two displays - one for left eye and one for right eye.

This setup uses Twinview Cloned displays and the 'passive' stereo mode in the nVidia Linux driver (Stereo mode 4). The driver version 195.36.24.

However we are getting sync issues where it looks like the 2 outputs from the Quadro aren't sync'd. I.e. the left eye frame sometimes advances before the right eye, or vice versa, meaning we don't always see matching left eye, right eye frames on the display.

Does anyone know how I would sync the 2 outputs? Both panels are the same res and refresh rate. Do we need extra hardware to achieve this?

Any advice greatly appreciated,

Nick
mrnick is offline   Reply With Quote
Old 07-22-10, 04:51 PM   #2
bwheaton
Registered User
 
Join Date: Nov 2008
Location: California
Posts: 59
Send a message via AIM to bwheaton
Default Re: Syncing Quadro card's 2 outputs for dual flat panel 3D display

Oh, that's bad. It sounds like you have everything right. I assume the app is using a Quad Buffered Stereo GL context? Does the app work properly on other systems?

Then I'd have to guess that the DisplayPort and DVI out are not timed together, which is a bit crazy. One workaround would be to use a Matrox DualHead2Go - that should make the two outputs you need from one connector. Or try with an older Quadro card that has two DVI outputs - a 5600, say.

The other guess would be that the two flat panels are buffering and off time, but that sounds odd too - it's a 3D product, after all.

Bruce
bwheaton is offline   Reply With Quote
Old 07-23-10, 08:27 AM   #3
mrnick
Registered User
 
Join Date: Jul 2010
Posts: 11
Default Re: Syncing Quadro card's 2 outputs for dual flat panel 3D display

Hi Bruce,

Thanks for your thoughts. As far as the app goes, I contacted them and they said it should be possible. The app's documentatipn says:

"RV can render into left and right bu ffers if your graphics card supports hardware stereo. You can tell if this is the case by seeing if the menu item View->Stereo->Hardware can be selected. If so, RV should be able to create left and right bu ffers."

It then refers to a page out the nVidia driver manual listing the 4 stereo modes.

I guess I could try another card but it seems strange like you say if the nVidia docs offer "TwinView clone mode stereo" as feature.

Nick
mrnick is offline   Reply With Quote
Old 07-23-10, 10:44 AM   #4
AaronP
NVIDIA Corporation
 
AaronP's Avatar
 
Join Date: Mar 2005
Posts: 2,487
Default Re: Syncing Quadro card's 2 outputs for dual flat panel 3D display

The driver automatically locks the two outputs together if their mode timings are identical. Are you using a single-link passive DP-to-DVI adapter, or an active dual-link one? I would recommend starting X with "startx -- -logverbose 6" and the comparing the mode timings for the two heads. If they're different at all, that might explain why they're not locked.
AaronP is offline   Reply With Quote
Old 07-23-10, 12:11 PM   #5
mrnick
Registered User
 
Join Date: Jul 2010
Posts: 11
Default Re: Syncing Quadro card's 2 outputs for dual flat panel 3D display

Hi Aaron.

Thanks for helping. I am using the single link adapter that came with the card:

http://www.costcentral.com/proddetai...3000/10540516/

What would the advantage of an active dual link adapter be?

The evaluation display has gone back for the moment, but I will run it up with verbose logging when we get it back in a week or so and check the timings are matched.

Cheers
Nick
mrnick is offline   Reply With Quote
Old 07-23-10, 02:08 PM   #6
snash
Registered User
 
Join Date: Nov 2003
Posts: 5
Default Re: Syncing Quadro card's 2 outputs for dual flat panel 3D display

Mixing DVI and Display Port is not recommended. There can be mode and timing differences
between the two.

Can you use both the Display Ports instead?
snash is offline   Reply With Quote
Old 07-23-10, 03:44 PM   #7
mrnick
Registered User
 
Join Date: Jul 2010
Posts: 11
Default Re: Syncing Quadro card's 2 outputs for dual flat panel 3D display

Hi Snash,

I haven't tried that but it's a good point. I will test using just the 2 display ports.

Nick
mrnick is offline   Reply With Quote
Old 08-04-10, 06:36 AM   #8
mrnick
Registered User
 
Join Date: Jul 2010
Posts: 11
Default Re: Syncing Quadro card's 2 outputs for dual flat panel 3D display

Hello Chaps,

So we have a 3di monitor again. We are still getting the sync issue. I am currently running the monitor with 2 display port outputs on the Quadro 3800.

I am using Driver 256.44, mode timings look to be the same for each panel - 1920x1200 at 60Hz . (This is from looking at the xorg log and setting the nvidia driver to debug mode)

Nick

Last edited by mrnick; 08-04-10 at 07:05 AM. Reason: more info
mrnick is offline   Reply With Quote

Old 08-04-10, 11:13 AM   #9
AaronP
NVIDIA Corporation
 
AaronP's Avatar
 
Join Date: Mar 2005
Posts: 2,487
Default Re: Syncing Quadro card's 2 outputs for dual flat panel 3D display

I asked because the single-link DP-to-DVI adapters are usually passive pass-through cables, while the dual-link ones show up as active DisplayPort devices and may subtly perturb the timings.

As for locking two native DP displays, if it's not working for you then please generate an nvidia-bug-report.log.gz after starting X with the verbose logging option and then attach it here.
AaronP is offline   Reply With Quote
Old 08-13-10, 06:47 AM   #10
mrnick
Registered User
 
Join Date: Jul 2010
Posts: 11
Default Re: Syncing Quadro card's 2 outputs for dual flat panel 3D display

Hello Aaron,

Thanks for all your help on this. I have done some more investigation and it makes me think this probably isn't a driver problem. We tested as follows...

Using different 3D playback software that also uses the hardware stereo (Framecycler as opposed to RV) we still got the issue.

We then tried with a different workstation with a different mainboard and a Quadro FX1800 as opposed to FX3800 and still saw the issue.

Finally we tried with a Windows XP64 machine with Quadro FX1800 and RV as playback, and still saw the issue.

So, at this stage I guess it is either something with the monitor, or maybe the Nvidia Card / monitor combo. (I have a support ticket in with the monitor manufacturer.)

One thing that makes me suspicious of the monitor is that it reports a native resolution of 1920x1080 in the EDID for both displays. However the panels are actually 1920 x 1200 (as stated in the monitor manual).We tried running the tests at this res and lower and still saw the problems.

To give more information on the sync problem, it seems to glitch regularly. Every second or so the left eye right eye frames will be out of sync. The frequency of the glitching doesn't change if we change the playback speed. Even the marker on the timeline seems to glitch, so it's not just the frames we are playing back. When we step through frames one by one on the timeline, all looks well and everything is matched up. I thought it may be an internal timer issue of some sort, but the linux machines are using the HPET as reported by dmesg.

I realize this may be the wrong forum for this now, but I thought I'd post to see if anyone may have any ideas.

I'm attaching the bug report and installer log just in case they are of use.

Thanks again for your help.
Nick
Attached Files
File Type: log nvidia-installer.log (24.8 KB, 73 views)
File Type: gz nvidia-bug-report.log.gz (83.3 KB, 76 views)

Last edited by mrnick; 08-13-10 at 06:50 AM. Reason: tweak
mrnick is offline   Reply With Quote
Reply


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 11:22 PM.


Powered by vBulletin® Version 3.7.1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 1998 - 2014, nV News.