Input Lag
Posted: 31 Mar 2016, 16:10
http://www.displaylag.com/video-game-in ... -database/
Finally, here's proof of something I've been telling fighting game players for decades. (No one ever disagreed with me, just that it was hard to confirm). All computers and video game consoles have inherent input lag. According to the link, it varies from a minimum of 4 frames for the best games, 5 frames for many games, down to 8 frames in some games. The link also contains their testing methods and further explanation. Depending on how you view their testing methods, and multiple other theoretical considerations, you might have a slightly different interpretation of these results, by a +1 frame difference. (I've given the games the benefit of the doubt here, and subtracted 1 frame from their tested results).
Previously, I always justified my claim by theoretical arguments (which changed slightly over the years, as hardware technology changed). Assume that the monitor displays its image all at once, at the very instant that image has been fully received, instead of scanning like in the CRT days. (Plasma is said to display synchronously. LCD monitors supposedly still scan to display, however many scan the whole image much quicker than one frame, in roughly 2 ms, which can be taken as instant). If you press a button the exact instant the monitor displays frame 0, the monitor is currently being sent the signal for frame 1. The console must then be readying frame 2 for output. This consists of overhead tasks that are effectively outside the game engine, such as copying an already-rendered game image to the proper display memory, rescaling the image to the output resolution, then converting the image to an HDMI or analog signal. All these tasks don't need to take up 1 whole frame of time, but the console could be hard-coded to allocate 1 frame to this step. Meanwhile, the game must simultaneously be rendering frame 3. It has exactly 1/60th of a second to complete this task, otherwise the game slows down. Your button press cannot affect this frame, because it has already started to be drawn. Finally, frame 4 is the earliest possible frame that can show the result of your button press.
The overhead step doesn't have to exist, so it's possible to have a console with 3 frames of input lag. In the CRT days, on a CRT with no digital processing, or only line-by-line digital processing, it was possible to have a console with 2.5 frames of input lag, assuming you react to an image at the center of the screen.
http://www.displaylag.com/display-database/
Lately, third parties have started to properly measure the input lag of many monitors and TVs as well. It appears that most computer monitors have a display lag of 10 ms. ASUS isn't the fastest like everyone kept claiming all these years. Their monitors are the same as the every other brand. Bad monitors, and good TVs in game/PC modes have display lags of 16 ms to 33 ms, so 1~2 frames. Most TVs are at least capable of keeping the display lag under 48 ms, or 3 frames. Bad TVs, or most TVs with too many processing features turned on, have display lags of up to 100~150 ms, or 6~9 frames.
The dangerous thing with TV input lag is that it varies wildly with the particular model, with no officially published results. Studying all the data carefully, there is no correlation with manufacturer, year, type of display (LCD, plasma, etc), cost, resolution, refresh rate, response time, or anything else. It's a total crapshoot. The only pattern is that very similar models, from the same manufacturer, from the same year, may have a similar input lag to each other. Even that is not guaranteed, as I recently found out Samsung TVs have a secret sub-model number associated with them. Usually there are several sub-models per TV model, and you cannot guarantee which you will get unless you buy in person and look on the actual item's box. The sub-models are made in different countries, and may not even be the same type of display! (LCD and plasma won't mix, but you may get an LCD panel with fundamentally different pixel shape and performance).
http://www.rtings.com/tv/tests/video-games/input-lag
The Samsung UN40JU6500 bedroom television I just bought has a 1.5 frame lag in game mode, but a 3 frame lag in PC mode (which is unfortunately the one I'm forced to use because of other quirks of this model). I noticed the difference before I read the data regarding it. I play my Xbox 360 online in the living room on a Sony KDL-46W5100 though. I can't find lag data on it but comparing to my Samsung it feels better, so I'm guessing it might be 1 frame lag.
Finally, here's proof of something I've been telling fighting game players for decades. (No one ever disagreed with me, just that it was hard to confirm). All computers and video game consoles have inherent input lag. According to the link, it varies from a minimum of 4 frames for the best games, 5 frames for many games, down to 8 frames in some games. The link also contains their testing methods and further explanation. Depending on how you view their testing methods, and multiple other theoretical considerations, you might have a slightly different interpretation of these results, by a +1 frame difference. (I've given the games the benefit of the doubt here, and subtracted 1 frame from their tested results).
Previously, I always justified my claim by theoretical arguments (which changed slightly over the years, as hardware technology changed). Assume that the monitor displays its image all at once, at the very instant that image has been fully received, instead of scanning like in the CRT days. (Plasma is said to display synchronously. LCD monitors supposedly still scan to display, however many scan the whole image much quicker than one frame, in roughly 2 ms, which can be taken as instant). If you press a button the exact instant the monitor displays frame 0, the monitor is currently being sent the signal for frame 1. The console must then be readying frame 2 for output. This consists of overhead tasks that are effectively outside the game engine, such as copying an already-rendered game image to the proper display memory, rescaling the image to the output resolution, then converting the image to an HDMI or analog signal. All these tasks don't need to take up 1 whole frame of time, but the console could be hard-coded to allocate 1 frame to this step. Meanwhile, the game must simultaneously be rendering frame 3. It has exactly 1/60th of a second to complete this task, otherwise the game slows down. Your button press cannot affect this frame, because it has already started to be drawn. Finally, frame 4 is the earliest possible frame that can show the result of your button press.
The overhead step doesn't have to exist, so it's possible to have a console with 3 frames of input lag. In the CRT days, on a CRT with no digital processing, or only line-by-line digital processing, it was possible to have a console with 2.5 frames of input lag, assuming you react to an image at the center of the screen.
http://www.displaylag.com/display-database/
Lately, third parties have started to properly measure the input lag of many monitors and TVs as well. It appears that most computer monitors have a display lag of 10 ms. ASUS isn't the fastest like everyone kept claiming all these years. Their monitors are the same as the every other brand. Bad monitors, and good TVs in game/PC modes have display lags of 16 ms to 33 ms, so 1~2 frames. Most TVs are at least capable of keeping the display lag under 48 ms, or 3 frames. Bad TVs, or most TVs with too many processing features turned on, have display lags of up to 100~150 ms, or 6~9 frames.
The dangerous thing with TV input lag is that it varies wildly with the particular model, with no officially published results. Studying all the data carefully, there is no correlation with manufacturer, year, type of display (LCD, plasma, etc), cost, resolution, refresh rate, response time, or anything else. It's a total crapshoot. The only pattern is that very similar models, from the same manufacturer, from the same year, may have a similar input lag to each other. Even that is not guaranteed, as I recently found out Samsung TVs have a secret sub-model number associated with them. Usually there are several sub-models per TV model, and you cannot guarantee which you will get unless you buy in person and look on the actual item's box. The sub-models are made in different countries, and may not even be the same type of display! (LCD and plasma won't mix, but you may get an LCD panel with fundamentally different pixel shape and performance).
http://www.rtings.com/tv/tests/video-games/input-lag
The Samsung UN40JU6500 bedroom television I just bought has a 1.5 frame lag in game mode, but a 3 frame lag in PC mode (which is unfortunately the one I'm forced to use because of other quirks of this model). I noticed the difference before I read the data regarding it. I play my Xbox 360 online in the living room on a Sony KDL-46W5100 though. I can't find lag data on it but comparing to my Samsung it feels better, so I'm guessing it might be 1 frame lag.