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I think it's safe to say that the results are inconclusive at best...Even if it does sugest there's slighly more lag with Vsync on...But I think it cannot be use to do objective testing.
Can't you at least *try* it and report back what you got? You could test it on other NES emulators and see if it's a Nestopia-only thing or if others give you similiar lag. I'd really like to fix this (provided this is in fact a bug in Nestopia) but you gotta give me something to work with. I asked those questions because they're relevant to the issue and they'll help me a great deal by letting me concentrate on certain parts in the source code that may affect this behaviour.
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I'm curious what is the exact fps of the Nes?
NTSC: 21477272.72 / ((262*341*2-1)*2) = ~60.0988 fps
PAL: 26601712.5 / (312*341*5) = ~50.007 fps

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NTSC: 21477272.72 / ((262*341*2-1)*2) = ~60.0988 fps
Thus, a NES emulator which ran at 60 frames per second in order to synchronize with the monitor's refresh would be off by a factor of only 0.0016.

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Jagasian, I searched for the USB polling rate driver hack you mentionned but the only info I found on it concerns USB mouse polling rates...

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Can't you at least *try* it and report back what you got? You could test it on other NES emulators and see if it's a Nestopia-only thing or if others give you similiar lag
Ok I did some test and here are the results:

Nestopia Fullscreen VsyncON 60hz - = 243
246,246,246,213,246,213,246,279,246,279,213,246

Nestopia Fullscreen VsyncOFF 60hz - = 197
197,213,197,181,197,181,181,213,197,197,197,213

I also tested with VirtuaNes 092e (60hz with both vsync on and off) the average was about 213. I also did my own blind test and haven't notice any difference with vsync on or off.

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Here are my results using my Saitek P880 with Nestopia 1.28:

Full Screen 60hz with VSync Off= 213.33
197,230,230,197,230,197,213,213,230,197,213,213

Full Screen 60hz with VSync On= 217.33
197,213,213,213,230,213,230,213,230,230,213,213

Like I said before, I never experience any lag.

-Trebor

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I just tested with the latest MESS and found no lag whatsoever with or without triple buffering. I did the usual blindtest.

Incidently vsync doesn't prevent screen tearing in MESS while TB does..Exact opposite of Nestopia.

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Ok don't flamme me or anything but I just got another idea...and this one doesn't suck (I think).

If Blargg doesn't mind coding another test rom (this will probably be even more simple than his reflex_test rom)

The basic idea would be to program a rom that simply make a noise at the exact same time it change the display.
So basically you start the test by pressing A, one second later the screen turns white and at the exact same time you hear a noise.


This is resting on the assumption that,while the display may be lagging, the audio will not (or not as much at least)

So the person can evaluate if there is lag between audio and video (if any) in various setups,emulators,hardware etc...Like a desync avi movie or something.


So how does this sound? (btw I realise there's allready a poping noise with the current reflexetest rom, but I don't think it has been programmed with the intention of comparing video and audio in mind, the pop clearly comes afterward)

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The basic idea would be to program a rom that simply make a noise at the exact same time it change the display.
Nifty idea. This of course relies on the user to do the timing, but it might provide further useful data. The current test should allow this somewhat, since it makes a click at the same moment it changes the screen.

Hmmm, I could write one which only relied on the user to adjust the timing until the image and sound occurred at the same time. You could use left and right to adjust the relative timing until you perceived them to be in synchronous, then press a button to get the relative delay the test is having to introduce. Run this test with two different configurations and compare the two values to find the relative difference in latency.

That gives me another idea for the original test. It could display a steady tempo of flashing/sound and have you press the button at the same regular rhythm. Presumably this would remove reaction time, since you could anticipate the regular rhythm. You'd unconsciously adjust your timing so that you were pressing it just as the image appeared (unless you absolutely suck at music and rhythm, in which case it's time to hit Parappa for some practice first).

I guess I'll have to do some writeups on these tests eventually, to help people write them for other platforms, since they're so useful for measuring responsiveness.

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(btw I realise there's allready a poping noise with the current reflexetest rom, but I don't think it has been programmed with the intention of comparing video and audio in mind, the pop clearly comes afterward)
Heh, it actually occurs a few milliseconds before the image changes (at least on a NES). This thread is bringing to light some interesting physiological facts (like the average 200 msec reaction time).

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Thanks for the idea, Redx; the new tests are great and much more accurate (well, assuming I've written them correctly).

Time_Latency.nes times overall latency from joypad input to audio output. When run, it clicks at a regular interval and your task is to press a button in sync with the sound (any button on the joypad will work). After you establish a good rhythm and maintain if for the last four presses, you can stop pressing the button and read the result on screen, which is the average of the last four presses. It's best to close your eyes to avoid visual distraction (especially trying to read the time on screen, which could influence you adjust your timing to get a particular value). I noticed that I normally pressed the button early, so I had to consciously delay a bit until the sound of the button pressing was in synchronous with the click. When that occurred, there was a clear audible difference in my head that I was in sync; it was as if the click and my button press became one (experiment and you'll hear what I mean).

Audio_Latency.nes times the relative latency of audio as compared to video. When run, it clicks and flashes a box at a regular interval. Use the joypad to adjust the delay until the sound and image seem synchronized. Up and down make coarse adjustments, and left and right make fine adjustments. Hold the direction to adjust the delay value shown, as it changes fairly slowly. Adjust the value past what seems correct, so you get a feel for how much of a difference there is between synchronized and unsynchronized.

Both tests display the value in milliseconds relative to a NES. Time_Latency gives an emulator's input+audio latency, and the difference of Time_Latency - Audio_Latency gives the emulator's input+video latency.

On my NES emulator with vsync disabled on a 76 Hz CRT monitor, Time_Latency gave 58 msec and Audio_Latency gave 20 msec. This means that joypad input to audio output latency is 58 msec greater than a NES, and joypad input to video output latency is 58 - 20 = 38 msec greater than a NES. For reference, a video frame is 16.7 msec long.

NESASM-format assembly source code available on request.

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Quote:
but it might provide further useful data. The current test should allow this somewhat, since it makes a click at the same moment it changes the screen.
Now I'm not a Nes/Famicom guru but currently the small "p-pop" sound like some kind of audio device being initialized. Maybe the sound should be longer. (For example, the first triangle note of the third world music in SMB3)

Also I see no reason to fill in the whole screen. Just a small portion should be enough.Probably preferable for this kind of test imo. The reason for this is I get the impression the whole screen "filled up" progressively (barely noticable though). The smaller the portion of the screen, the more "instantaneous" it appear. And it's just less distracting to focus on a small visual area. Anyway, not really important I guess.


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Hmmm, I could write one which only relied on the user to adjust the timing until the image and sound occurred at the same time. You could use left and right to adjust the relative timing until you perceived them to be in synchronous, then press a button to get the relative delay the test is having to introduce. Run this test with two different configurations and compare the two values to find the relative difference in latency.
Could be useful, as long as there is an option to have them come up at the exact same time (independently of any user perceptions)

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That gives me another idea for the original test. It could display a steady tempo of flashing/sound and have you press the button at the same regular rhythm. Presumably this would remove reaction time, since you could anticipate the regular rhythm. You'd unconsciously adjust your timing so that you were pressing it just as the image appeared (unless you absolutely suck at music and rhythm, in which case it's time to hit Parappa for some practice first).
Excellent idea. Imo I can see this could give more consistent result (overall) than the reflex test (the reflex test can still be useful in some cases of course).


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I guess I'll have to do some writeups on these tests eventually, to help people write them for other platforms, since they're so useful for measuring responsiveness.

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(btw I realise there's allready a poping noise with the current reflexetest rom, but I don't think it has been programmed with the intention of comparing video and audio in mind, the pop clearly comes afterward)
Heh, it actually occurs a few milliseconds before the image changes (at least on a NES). This thread is bringing to light some interesting physiological facts (like the average 200 msec reaction time).

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Oh shoot, you posted the test while I was replying! Oh well :p I'll check the new test now.

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