Originally Posted by xhonzi
If not, perhpaps you have a PC or a laptop you can use to do a different, slightly less objective test: Run this timer http://www.flatpanelshd.com/focus.ph...&id=1229335064
on both displays at the same time and take a high speed photo of both. Your projector will show an earlier (older) time than the other display. The difference between them will tell you how much slower the PJ is than your PC display, which doesn't tell us everything if we don't know how fast or slow the PC display is... but it will give us a ballpark idea.
I haven't run the test listed above, but after reading the site explaining it, frankly I think the method might be flawed and generate inaccurate results (someone correct my logic if you see an error).
The method mentioned using a video card with two outputs in clone mode. While i imagine it depends slightly in the way each video card (and their respective drivers) do the "cloning", my understanding is that typically this does involve some level of video memory copying... ie: each screen has two separate buffers in memory of the video card (if a single card) - which is what allows the screens to be able to have two separate images if you have them that way. In clone mode, I understand the driver actually copies memory from one buffer into the other.
My understanding as well, is that typically one buffer is written FIRST, before that data is copied to the other. Thus, the video card itself may very well induce lag when cloning is setup.
Again, please correct me if this is not the way this is done nowadays. But if this is the case, then I'd imagine that depending on which port you plugged the projector and monitor into, you'll either increase or decrease the amount of lag seen with the projector, but the amount of lag that the cloning adds. (BTW using two separate video cards for this would DEFINITELY introduce lag here since copying will DEFINITELY take place. My only question is if the drivers might be smart enough to write to both memory locations at the same time when using two ports off the SAME video card (or if perhaps they map each display to the same memory buffer - definitely not though if the output resolution or refresh rate is different) - my guess is no - typical use cases for cloning probably aren't to ensure screens synced between two cloned screens in a gaming environment - not to mention that this WOULD create lag for BOTH screens if this were done (but make them somewhat consistent)).
Of course I'm willing to admit I'm wrong with how the cards and drivers do cloning if someone can point me to a reference. I also admit that this may not be 100ms of lag due to cloning, but it probably adds up.
Another possible difference would be if the screen resolution of each port (ie: for the monitor and projector) were set to different resolutions (due to scaling) or refresh rates.
Assuming I'm correct, the best way to test this would be instead to NOT use cloning, but instead to use a splitter (which would be much easier to do with analog VGA on each). That would eliminate any lag due to "cloning".
That said, even with that, another factor would be that even if the output resolution and refresh rate were the same, if either the monitor or projector weren't cable of natively displaying that resolution, the circuitry in the CRT or projector itself would scale. So in order words, if they're not both 1920x1080 NO interlaced (progressive) displays, there would be additional lag to convert this. This would invalidate the test to some degree since my guess is that you typically wouldn't be running the games, etc, in a mode that you'd want it to scale by default (yes in many cases perhaps, but remember the idea here is to measure lag of the projector on an equal footing).
Ok, so if you don't have a way to split the signal and have to use the cloning technique, I'd suggest hooking the PJ and monitor up to each port and running a few tests (let's say 3) and averaging the numbers you get. Then REVERSE which one is hooked up where (without changing anything on the computer) and run 3 more tests and average that. Subtract the two results from one another and divide by 2, and you should have a more accurate lag figure. If they're both relatively the same, then perhaps there is no cloning lag in your setup, but I still think trying this makes a MUCH more accurate test.
One additional thing to mention... Most projectors (and some monitors) also have default settings that do image processing BEFORE displaying the image on the screen. This creates additional lag as well. Projectors generally have much more advanced image processing capabilities than a monitor (as typically a monitor doesn't need it - software in the PC or the video card typically is used to change this). As a result, my guess is to get the best picture, projector manufactures have many of these settings on by default.
I'd say that the only accurate test would be to turn off ALL of this that is possible on both monitor and PJ. ie: thinks like enhanced sharpness (especially when related to parts of the image versus just the whole), enhancing certain colors over others, automatic iris, etc. I think its only "fair" to turn off all of this possible.
Now once that is done and you have your numbers, you'd have the theoretical best lag for the PJ. Then you need to decide if the display is something you'd actually good enough (without the enhancements turned on) for playing the games you'd like. So I'd suggest starting with all of these off and slowly tweaking settings until you get a more palatable screen on the PJ for playing games, and then run the tests again. My guess is (if you're conservative about turning on the enhancements and first try those that require the least amount of image processing (ie: whole screen color adjustments, etc)), that your lag when you run the tests again will be slightly if not MUCH better.
Just an educated guess, haven't tried that, but I think this would help.
SO in summary, deficencies I see in the lag test mentioned by the link include:
1. Cloning of displays between the ports on the card typically involves memory copies by the driver (with one memory buffer typically getting written first), thus this could introduce lag. Suggestion: either don't use cloning and try a video (most likely VGA) splitter, or else run two sets of tests swapping cables between tests.
2. If resolution of each screen is not set the same, then the video card may do scaling to match the monitor resolution, thus introducing lag.
3. If refresh rates are different for monitor and PJ, then this could account for some level of lag.
4. If output resolution of the video card (and refresh) are the same but not the native resolution of both the monitor and PJ, then the electronics on board will need to scale the image before it goes to the screen, resulting in additional lag. NOTE: THis may not apply to CRTs since they just change the sweep rates of the electron beam for different resolutions typically - no need to scale pixels like an LCD monitor or projector (LCD or DLP) would need to do.
5. Any advanced image processing done by the monitor or PJ will certainly add some level of lag. Especially things that are done to regions of the screen versus the whole screen (in most cases). Such as "thin" or "thick" line sharpening, color scaling for some colors, dynamic iris (I would imagine, though technically not a digital image enhancement), etc. Note that the 3010 has a ton of these options, and projectors typically have more than monitors since PJ manufacturers can't rely upon assumptions to assume that other input devices would handle this (ie: different BR/DVD players, game systems, may provide limited or no image enhancment - not to mention that this is how PJ manufacturers differentiate themselves when using the same panels as other vendors, etc).
So not saying that once you take this into consideration that the 3010 will come out showing little lag, perhaps it will still be bad. No idea. Just stating that IMHO the methodology here could use some tweaking.
Even if all of these items above only provide minimal effect to the lag measurements (ie: tens of ms or less), when you add them all up, that can be significant.
Also note that even comparing a CRT with an LCD monitor you will note that the LCD will typically have more lag anyway (which is why they recommended CRT).
Of course, please feel to disagree with me... I'm learning here too.