Where to start? BenQ MP776ST

[alejandro]

Hi,

I have a BenQ Projector (MP776ST) and in the specifications it says it's DLP 3D Ready, so I was wondering, how can I see the content in 3D?

Thanks for you answers!

[Dom]

Hi all those new dlp 3d ready projectors are to use dlp-link shutter glasses, either from x-pand or bit cauldron. I just seen a post of a member that wants to take orders from folks who want these glasses because first he found a store that sells them and second they can get them for like 133 or something similar.

So anyways with these new dlp-link glasses they are the best of the best better than anything else because they are 2.4ghz wireless and they have no delay or syncronization issues. Most places if you search are not selling them now I think too so look to this post http://www.mtbs3d.com/phpBB/viewtopic.php?f=3&t=8634" onclick="window.open(this.href);return false;

[DmitryKo]

new dlp-link glasses they are the best of the best better than anything else because they are 2.4ghz wireless

DLP Link glasses are optical, they sync to a series of bright flashes emitted by DLP displays and projectors when they are in stereo mode.

I have a BenQ Projector (MP776ST) and in the specifications it says it's DLP 3D Ready, so I was wondering, how can I see the content in 3D?

Good question. WIth BenQ 772/776/777, stereo 3D is available through 1024x768 @120 Hz page flipping on the VGA input, so it needs shutter glasses; I'd guess the sync is only possible with the computer, but the exact technology is not really clear. Overall, this looks very similar to Nvidia 3D Vision projectors, however these models are not "certified" for 3D Vision.

I don't quite understand how an analog VGA projector would sync using DLP Link glasses, snce page flipping doesn't really provide any information on which frame is Left and which is Right, and the projector does not use self-synching formats such as DLP checkerboard or HDMI 3D. It probably uses some kind of analog VGA Sync like "Blue line" signalling with standard VGA cable... I just don't know, the user manual does not mention any 3D capabilities at all.

http://www.benq.us/products/Projector/? ... ds&dtype=M" onclick="window.open(this.href);return false;


PS. The user manual for a similar ViewSonic PJD6531w says it supports several sync modes:

http://www.viewsonic.com/products/pjd65 ... _downloads" onclick="window.open(this.href);return false;

• 3D Sync
• Off: Disable 3D function
• 3D-Vision: For NVIDIA 3D Vision application
• DLP-LINK: For TI 3D DLP-LINK application

• 3D Sync Invert (for TI 3D DLP-LINK only)
• On: Invert left and right frame contents.
• Off: Default frame contents.

I guess we need to figure out what does that "TI 3D DLP-LINK" really mean in regard to analog VGA connection. TI's pages are not very informative on this.

www.dlp.com/projector/dlp-innovations/3d-ready.aspx
www.dlp.com/projector/dlp-innovations/dlp-link.aspx

[alejandro]

So imagine I get the glasses and now I need to sync it with the projector, it's supposed to be wireless sync so I Imagine that it is always sending information to all receivers (glasses) so there's no need to do anything for the sync between projector and glasses, but how can I send the content to the projector, it doesn't supports HDMI so I guess it would be through the VGA cable, but what drivers do I need in order to send 120hz?

How can I generate content?

Thank you!

[DmitryKo]

I guess it would be through the VGA cable, but what drivers do I need in order to send 120hz?

The product literature on DLP.COM mentions that you need "a graphics card with quad buffer support"; I guess it's a vague way to reference the new capability in Catalyst 10.3, since BenQ projectors are not really certified for Nvidia 3D Vision.

The brochure also mention the Stereoscopic Player http://www.3dtv.at/" onclick="window.open(this.href);return false; and 3rd party providers of educational 3D videos.

As for gaming, if this "DLP Link" is indeed a blue line sync, iZ3D drivers v1.10 offer experimental support, and beta v1.11 should appear very soon.

[Dom]

More about the dlp-link shutter glasses is that I think they come with a usb dongle to plug into your computer, from there they sync with the vga dlp 3d ready projector wirelessly from the computers motherboard. There are variations of dlp-link dongles some for tv's and projectors too. I think they are to be used with iz3d drivers. Some may just be for lcd\plasma televisions

But really you will need a personal computer to hook to your projector for content like video games and movies. If you dig deep and actually get these glasses to work on a dlp projector through vga I might choose this path too except my projector is not 3d ready. You can also limit your computer hardware to old school glasses that are cheaper right now and work but have slowdowns a bit. It would be this configuration in spec:

winxp: 91.31FW, 91.31Stereo for gaming and movies with a Nvidia 7600gt or similar to 7900gt, or this spec
winxp,winvista,win7: Anyvideo card agp and up using iz3d driver interlaced or edimensional,x-force glasses and ed.exe edimensional utility ONLY for 3d Movies and interlaced gaming.
I know its not worth the risk to buy incompatable hardware glasess and configurations but some of these options should be a wise decision either dlp-link glasses or older dollar cheaper sets. One more note is that it is still decent to view 3d content in 85hz too if that helps.

[DmitryKo]

Khm. Looks like you can get the projector to work with 3D Vision glasses in "Generic CRT" mode, even though it's not certified as per 3D Vision Hardware Requirements page...

projectorcentral.com/3D_gaming_nvidia_3d_vision_benq_mp776st.htm

More about the dlp-link shutter glasses is that I think they come with a usb dongle to plug into your computer

No, they don't. DLP-Link glasses only sync to white light on the screen.

[alejandro]

Thank you very much for all your answers, I think I'll go for the NVidia 3D Vision solution, though I'm not so sure how I'm going to hook all together I'll come with news the next time

[DmitryKo]

I just want to stress that the next version of iZ3D drivers will work as well (somehow); you'll need DLP-Link glasses such as XpanD X102 to sync with the projector.

[asdfqwer]

My guess is that the DLP LINK option simply inserts white(?) flashes between frames. This should be trivial for any DLP device.

The 3D vision option is more interesting: the projector does not have the VESA minidin3 for the IR emitter, so what is the purpose of that option? Output the sync through RS232?

[DmitryKo]

the projector does not have the VESA minidin3 for the IR emitter, so what is the purpose of that option?

Well, DLP-Link option enables DLP-Link glasses and sync to white flashes, and 3D Vision option just disables DLP-Link white flashes, since you have 3D Vision glasses that sync to their own emitter. Yes this is a bit confusing, since for older DLP TVs you were supposed to connect the 3D Vision emitter to the VESA Stereo port on the back of the TV, however 3D Vision-compatible DLP projectors do not seem to require this.

The question is, how the L and R frames should be marked in the analog VGA signal for DLP Link mode to sync properly. Anyone with extra $5000 to spare for a DLP developer kit?

[asdfqwer]

Maybe they are not marked at all, hence the 3D Sync Invert option.

[DmitryKo]

From the technical standpoint, that would be a totally retarded way to do sync; I don't think Texas Instruments were so unable to come up with a better solution.

I guess they somehow mark the initial L and R frames with some kind of predefined pattern in order to turn the DLP-Link on, then continue with pure frame sequential signal with no marking. I've read reports on the iZ3D forum that some projectors lose sync with time, but so far no-one said they had to manually invert the sync each time they start the 3D mode.

[asdfqwer]

It is a retarded way to do sync. What I meant was that DLP Link was probably designed with HDMI/DVI in mind, not VGA. Are there any indications that it is synchronized over VGA at all?

I guess they somehow mark the initial L and R frames with some kind of predefined pattern in order to turn the DLP-Link on, then continue with pure frame sequential signal with no marking. I've read reports on the iZ3D forum that some projectors lose sync with time, but so far no-one said they had to manually invert the sync each time they start the 3D mode.

It should be possible to test that without the dev kit. From what I heard, the picture gets considerably brighter when DLP Link kicks in. A quick test can be done:

1. Set up the screen settings on the PC (ie 1024x768, 120Hz), using the generic CRT trick with EDID pins removed
2. Power up the projector with the VGA cable unplugged, enable the DLP link on the projector.
3. Plug in the VGA cable, see if there is any change in brightness.
4. Start 3D content, see if there is any change in brightness
5. Turn off DLP link on the projector
6. Turn on the DLP link on the projector

Do the following steps without wearing the 3D glasses. If there is a noticeable change in brightness after doing step 4, the first frames are marked. If there is a noticeable change in brightness after doing step 6, every frame is marked.

It should also be possible to test for no sync at all:
Get everything setup, start 3D content. Use the 3D Sync invert setting if necessary. Turn everything off, then restart it again. If there is no sync over VGA, you should have to change the 3D sync invert setting roughly every other time (50/50 change of getting it right).

Another interesting question is how do the glasses differentiate between L and R frames. Simply having a white flash between EVERY frame will not work. Also, people are saying that DLP Link glasses are able to block out the white flashes (picture is not overly bright), so having the flash trigger closing of the shutter will not work.

[DmitryKo]

DLP Link was probably designed with HDMI/DVI in mind. Are there any indications that it is synchronized over VGA at all?

DLP Link and 3D Vision projectors do not generally support 120 Hz over HDMI/DVI, and it's the same with the MP776ST, check the user manual. More than that, some projectors only feature analog VGA ports.

It should be possible to test that without the dev kit. From what I heard, the picture gets considerably brighter when DLP Link kicks in

If they do, it's a clever workaround to compensate for light loss in the shutter glasses, since even a fully open shutter reduces brightness because of the built-in polarizer.

If there is a noticeable change in brightness after doing step 4, the first frames are marked. If there is a noticeable change in brightness after doing step 6, every frame is marked

That would be an interesting test to perform.

Another interesting question is how do the glasses differentiate between L and R frames. Simply having a white flash between EVERY frame will not work.

They say the white flash is "encoded", so it's probably a series of flashes.


On a second thought, I would suggest that the projector actually starts the DLP Link mode (if it is set to On) every time it receives 120 Hz signal. This way, regular 2D pictures can be viewed even through the shutter glasses, so no harm for regular mono mode, and the projector is always ready to start displaying 3D content.

They could also completely get away with frame marking by always assuming "left = first". So when you start receiving non-blank signal in 120 Hz mode (or maybe after receiving some predefined "sync start" pattern), the left view is always the odd frame.


AFAIK, all modern video cards in the last 20 years always use page flipping, so there is always at least double buffering. Thre is back buffer which actually contains the picture currently displayed, and the front buffer where the next picture is composed. So when the picture in the front buffer is ready, the application switches the front and back buffers, as in "page flip".

When you start the quad buffered mode, the driver implements a kind of "stereo page flipping", by creating two back buffers and two front buffers and linking each odd frame in the 120 Hz signal to the "left" back buffer, and each even frame to the "right" back buffer. The quad-buffered video driver would keep track of the order of frames in the 120 Hz signal, so to always present the left frame and right frame from correct back buffers when the application completes rendering the front buffers and swaps the buffers using the Direct3D swap chain.

In theory that allow automatic self-syncing frame sequential stereo which does not need any interaction from the user or the application. Still, blue line code or similar frame marking scheme and 3D mode start markes sound reasonable too. Hopefully in the near future, more light will be shed on the details of the DLP Link implementation.

[mickeyjaw]

Hopefully in the near future, more light will be shed on the details of the DLP Link implementation.

Yeah, who wants to volunteer ?

We need to get a photodiode, power supply, oscilloscope and DLP-Link projector together in one (dark) room. Then all that need be done is to send a black picture over VGA and measure the waveform of the light using the 'scope and photodiode. I have everything needed except the DLP-link projector - does anyone want to lend me / provide access to one?

[RAGEdemon]

DLP link is superior to nVidia's shutters in a few ways.

Firstly, it is compatible with any page flipped image on the screen from any driver or software, not just nVidia's, so you can use any graphics card and iZ3D 120Hz driver, soon to be released.

Second, the XpanD x102/Viewsonic/Samsung glasses (all made by XpanD) are meant to be superior to nVidia's


I have had great results. Too bad my projector is buggy as hell. (pjd6531w thread in this section).

-- Shahzad.