Slashdot Mirror
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."
No, plasmas have near instantaneous response times that are pretty much identical to what you get on a CRT. The issues you get with a plasma is called "phosphor lag" which has to do with the three colors not quite lining up perfectly and it gives you a trailing image of the colors. It's especially noticeable on high contrast edges or if things are moving really quickly. It can be especially noticeable in gaming, but at least IMO it's much less annoying an artifact than the ghosting, smearing, and horrible motion resolution you get with LCDs (and yes they are present even on 120hz LCDs before someone brings that up).
I knew somebody would make some gross misstatement like "The human eye only sees at 25 fps anyway"
And for that, here is the obligatory link to 100fps.com
In short, the shortest flash a human eye can see depends on a lot of things. These factors are explained thoroughly on that web site. The tl;dr version is this: The human eye can discern A LOT MORE than 25 fps.
The refresh rate needed to avoid flicker with an impulse light characteristic display is unrelated to the frame rate needed for perfectly realistic motion quality. Note however that non-flicking sample and hold displays such as LCDs will produce lower motion quality than impulse response displays of the same refresh rate because of the temporal smearing. (see http://www.microsoft.com/whdc/archive/TempRate.mspx for explanation).
CD-ROMs don't. They use "Zone CAV". It's much cheaper and easier to make a drive spin at a constant angular velocity. Unfortunately that results in higher data rates at the outer edges of the disc, so what drives do is they split the disc up into zones. The disc is spun faster for a zone closer to the center of the disc.
Older CD-ROM drives used straight constant-angular-velocity, and would advertise the fastest data rate (which was at the outer edge of the disc).
The only time a modern CD drive will spin with constant linear velocity is when it's playing back audio in real-time. And even then, many players buffer now, so they use the Zone CAV method anyway.
Actually, the issue here is probably more due to the fact that movies are shot at 24 frames per second. 24 doesn't fit into 60 properly, so there will be times where the scene repeats more in one set of refreshes than another. See wiki entry on Telecine, notably telecine judder: http://en.wikipedia.org/wiki/Telecine
With a 120hz refresh, 24 can go into 120 evenly, so you won't see any choppiness.
Karnal