Input Lag, Or Why Faster Isn't Always Better

mr_sifter writes "LCD monitor manufacturers have constantly pushed panel response times down with a technique called 'overdrive,' which increases the voltage to force the liquid crystals to change color states faster. Sadly, there are some side effects such as input lag and inverse ghosting associated with this — although the manufacturers themselves are very quiet about the subject. This feature (with video) looks at the problem in detail. The upshot is, you may want to test drive very carefully any display boasting low integer millisecond pixel response times."

Comments

Another thing to look out for

[Hyppy]

First, we have to look for monitors with 6bit or 7bit color instead of 8 per channel, now we have to start testing for overdrive voltages? Buying an LCD is becoming a real pain in the arse.

Re:Another thing to look out for

[Elledan]

6-bit TN panels don't seem like such a good idea to me, as the interpolation (rapid cycling of pixels to get the desired colour) used to compensate for the lack of full 16.7 million colours other screens have is (together with the flickering of CCFL backlights) responsible for most of the complaints about LCD screens giving people a headache.

As for the article topic, any screen with an input lag of >1 ms will never be 'good' at displaying rapidly changing images, and will be nearly worthless for rapidly-paced games. Plasma, CRT, SED, FED, OLED... all technologies with sub-1 ms latency. Getting that 15" OLED screen LG will be releasing this year as a monitor may not be such a bad idea. Sure, it's not as big as your 24" LCD, but it will have perfect colours and blacks, extremely low-latency, low power-usage, weigh even less than an LCD, and so on.

Let's admit it, LCDs were just an intermediate technology for displays as margins in the CRT market got lower and lower, while new display technologies which could match or beat CRTs in IQ and other factors were still a while off.

Re:Another thing to look out for

[hairyfeet]

That is why if you care about such things, and don't have a teeny tiny desk, you should go talk to the local PC shop about a CRT. I picked my CRT for $45, has a great picture and plays my FPS games with a nice clean screen. I have him keeping an eye out for a couple of 19-21 inchers so I can sock a few back. Hell he gets them cheap enough I don't even bother keeping monitors in my shop anymore for anything but displays and instead just send them to him if they need a monitor. I have found in just about every town there is a little mom & pop shop that can score you great deals on monitors.

So why go through all the hassle if you game when you can just pick up a monitor from the local shop and keep the cash flowing locally? I know that he is happy for the extra business I send him and I am happy with my nice CRT. And if you are playing games on a PC I doubt it is going to be a low power "green" PC anyway so why risk spending the cash on something that'll give you problems? I don't get as much time to play as I'd like so when I do get a chance I want everything to be nice and pretty. And my old faithful CRT does perfectly, whether blowing up the splicers in Bioshock or slaughtering the good guys in BFME 1&2. So if you are having problems with your LCD like in TFA, why not go to the local shop and see what they got in stock? Sure as hell beats having one of those heavy bastards shipped across country that's for sure.

Re:Another thing to look out for

[slyn]

No, I'm not claiming that I'm perfect, I never even claimed I could do what your saying.

What the article is about is various forms of lag inherent to certain types of monitors. Someone claimed that any lag at around 10 ms or less will have no effect on gameplay. That is false. When playing a game like Rock Band the timing window in which a note is open to be hit is probably around 40 ms, maybe a little less, maybe a little more. If your Video Lag as calibrated by Rock Band to offset the inherent lag of the TV is off my 2 ms, then you effectively handicap yourself out of 2 ms. Now 2 ms is not much in the grand scheme of things, but relative to the 40 ms window that I can hit the note in the first place, it is a loss of 5% of the perceived available time to hit the note.

BECAUSE I'M NOT PERFECT AND ALL MY STRIKES VARY IN ACCURACY, that 5% loss could mean the difference between an 100% full combo or a -1 note 99%. The difference will become especially striking when I'm playing a 2k+ note song or if I'm playing a song that is extremely fast paced like the one I used in the example.

The reality is not that I'm actually consciously noticing the video lag, but that through the interaction with the game I can tell if there is a lag of >10 ms. I threw out the 2 ms example because I recently changed the video lag and it made a big difference on a song that I have been struggling with.

And I'm not claiming I'm the only one who will notice an improvement from this. I have a friend who used to play only on hard and had a notable improvement in how well he played after I helped calibrate his TV for him. It took a couple tries to get the right delay, but once it was configured he began to ace songs relative to how he was playing them before, and his video lag was only changed from 0 to 6 ms IIRC.

Reason for input lag

[Rotaluclac]

The reason for input lag is that manufacturers want the on-screen image to quickly change without ghosting. Here, quickly means "in as few ms as possible", not "without delay". So if you see a change only two seconds later, but the change is instantaneous, that's considered good.

To achieve this, the display electronics must know what the next frames look like. So they buffer two or three frames, then adapt the overdrive on a per-pixel basis to the contents of the next few frames.

Pro: smoother video playing
Con: a delay of two or three frames

Rotaluclac