| Author | Message | ||
     Antonio Scuri Rating: N/A |
I would like to share an experience we had. We tested the InFocus LP340 at 800x600x120Hz for HW page flipping using OpenGL. And surprisingly it works. Since then we spend some time testing other DLP projectors but everyone failed. We contact the InFocus support and they told us that this projector line in particular does not have internal frame buffering, so it can operate in the same frequency of the input data. Some DLP projectors accept high frequency at the VGA port, but internally they work at 60Hz (remembering something already posted to this list). The problem is that this same line is out of production. For now we will keep using our LP340. Hope this information is useful for someone. Best, Antonio Scuri | ||
| Giorgio Bogoni Rating: N/A |
Antonio, let me understand, please. Do you mean you get a 120 Hz page-flipping with a DLP projector? A perfect active-stereo image without a CRT? Or maybe you meant in worked @ 60 Hz even if supplied with a 120 Hz signal? What graphic board have you used? THX for info. Giorgio. Are you from Italy working in Brazil? | ||
| Anonymous Rating: N/A |
LP340, LP340B and LP350 ... all of them have been successfully tested???? | ||
| Christoph Bungert (Admin) Rating: N/A |
###they told us that this projector line in particular does not have internal frame buffering, so it can operate in the same frequency of the input data.### What happens at 85, 100 or 140 Hz? If this would be true it should work, but I doubt it. Which 3D-driver did you use? I don't think a DLP-device can work without any kind of buffering. The DLP-chip certainly has restrictions regarding input frequency and actual displayed frame rates. It's suspicious it worked at 120 Hz which is just native DLP 60 Hz x 2. Thank you Christoph | ||
| admin Rating: N/A |
More questions. Was there any visible flicker? Does it really display a 120Hz image? Does it work at 60Hz? Maybe this projector just has a native frequency of 120Hz? Thank you. This would be a solution to the 3D problem, if we can fin projectors which have a native frequency of 100 Hz or higher. We would always have to use this frequency, but I can live with that. Christoph | ||
| AntonioScuri Rating: N/A |
All the answers at Once... Do you mean you get a 120 Hz page-flipping with a DLP projector? A perfect active-stereo image without a CRT? YES!!!! Or maybe you meant in worked @ 60 Hz even if supplied with a 120 Hz signal? It does not seems to be... What graphic board have you used? Which 3D-driver did you use? GeForce 3 with RivaTuner Tweaked driver + StereoGraphics Stereo Enabler (since this board does not have the MiniDin 3PIN) There is also an old ASUS adapter that works fine. It is installed in the case and uses an internal power source connector. LP340, LP340B and LP350 ... all of them have been successfully tested???? NO. Only the LP340. The InFocus support reported that all the 3 work the same way. What happens at 85, 100 or 140 Hz? If this would be true it should work, but I doubt it. While the VGA input accept it we push it higher, but sometime after 120Hz stops working. It's suspicious it worked at 120 Hz which is just native DLP 60 Hz x 2. Yes, but they say "they are direct pass through". Whatever this means. More questions. Was there any visible flicker? Does it really display a 120Hz image? Does it work at 60Hz? I may be being deluded by the projected image and the situation, and the output could be at 60Hz. But the flicker would be high, and that´s not happening. I will do another test to compare the stereo at 60Hz, with the one at 120Hz, and check again if they are the same. This will be place on Wednesday. scuri | ||
| M.H. Rating: N/A |
None of the projectors work at 120 Hz. I know that InFocus LP340 and LP 650 work in stereo at 60 Hz. I use LP 650 for this purpose. At higer freq. it does not work in stereo. DLP always use buffering. In 60 Hz the time delay produced by buffering is exactly 1/60 sec (visible as eye swith in comparion to calibrated VESA DIN-3 sync out on graphic card) ... | ||
| Anonymous Rating: N/A |
Waiting for Wednesday ....! | ||
| Antonio Scuri Rating: N/A |
About the tests. We did 2 separate tests. One with the LP340 and another with a LP340B. Both presented the same performance. We turn the ambient lights off to avoid interference. Between each change of configuration we delay some time. We tested at 800x600x60Hz and 800x600x120Hz. The Status item in the projector menu displays 60Hz and 85Hz for these configurations (!). The flicker is more noticeable in the 60Hz configuration. The LP340B displayed a better image than the LP340. It is clear that the projector is not at 120Hz, but something between 60Hz and 100Hz. But my impression is that we have a more acceptable image at 800x600x???Hz (greatter than 60Hz). For me is a good alternative low cost for active stereo. I can make demos and explain concepts. I don´t think is for a daily basis usage. That´s it. Sorry if I made too much noise about the projector. But it was an experience... Best, Antonio Scuri | ||
| M.H. Rating: N/A |
Maybe you should try to set 85 Hz input. I doubt that 120Hz -> 85 Hz downsamplig made in the projector electronic does not destroy stereo. I do not beleve very much you are working in better than 60 Hz mode. I had tested several InFocus projecotrs - none of them work in stereo correctly in higer than 60 Hz frequence ... | ||
| Giorgio Bogoni Rating: N/A |
"The LP340B displayed a better image than the LP340" Do you mean a better STEREO-image? As it can work @ an higher refresh rate? Are you sure that the flicker is more noticeable when you set you PC @ 120 Hz (apparently downsampled to 85)? For downsampling is needed an internal frame buffer, or am I wrong? Does anybody know what's going on? Giorgio. | ||
| AntonioScuri Rating: N/A |
"The LP340B displayed a better image than the LP340" I mean less flicker. I really don´t know what´s going on. I´m going to use the LP340 again on monday, with more people around. So I´m going to test it again using 85Hz and other frequencies. I will try to find another LP340B, the previus one is hard to get it. What´s the best image to test flicker? In the previous test I look for gradients in a static image. scuri | ||
| Giorgio Bogoni Rating: N/A |
Try a stereo image with a lot of contrast like black objects on a withe background ... and let us know. | ||
| Antonio Scuri Rating: N/A |
White background is a killer machine... Again I tested in many configurations the LP340. This time above 75Hz, the Status menu displays 75Hz always. But flicker is much better than 60Hz, even with white background... I demo the system to several people in the lab and the opinion is the same. We don´t know what´s going on, but the projector has an unsual operation mode. The stereo is not lost at "75Hz" and above for the input data at the VGA port. Just for the records we use wireless NuVision Glasses (300:1). The screen is a Rosco Gray, but used with normal front projection. I guess that´s it. Thanks for the interest. Feel free to contact me by e-mail. Best Regards, Antonio Scuri |
