[60fps] Framerates do matter | Hacker News Reader

[60fps] Framerates do matter

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36 pointspeterwwillis18 comments

The reason TV produce smooth motion is not because of the blurring effect but because they really work at 60 frames per seconds (NTSC) or 50 fps (PAL). But the effect is achieved only with interlaced TV (CRT).

The motion on films is not smooth at all, shaky at best. That’s why cameramen make sure not to move their camera too much and use a lot of tricks to avoid "motion sickness". In one hand they do use full frames (aka progressive frames) but only at 24 fps.

That’s not exactly what you call "Motion blur" to be "the biggest reason TV and film get away with smaller framerates".

However, yes, to have a good motion you need to have a good framerate.

You can read a very good interview of James Cameron about it: http://www.variety.com/article/VR1117983864.html?categoryid=...

It basically says: Perceived resolution = pixels x replacement rate. and the magic number is known: it’s 48 fps.

The main problem is not only having the game/software logic to send the frames to the display fast enough but also having the display being able to display them!

CRT were able to do it through interlaced frames, but mainstream flat panel technologies (plasma/LCD) basically can't. OLED should do better on the near future.

That said when there is no motion, 1 fps is just fine :-)

1 fps, 1 dpi. This is too low even for a game like "Simon."

As a musician, I consider 1/100 of a second just a bit beyond human perception. 1/48th of a second is something like "magician sleight of hand time" to me.

If you were sitting in a dark room, you would notice a flash of bright light a lot shorter than 1/100 of a second. You might find this interesting:

http://www.100fps.com/how_many_frames_can_humans_see.htm

Of course, for audio, the brain is very sensitive to the lag between left ear and right ear hearing the same sound, as that's part of how sound direction is determined.

You can notice a single frame of light at faster than 200FPS, but it's a lot harder to notice a frame of darkness at 100FPS. That has more to do with signal response and nerves taking longer to drop down after a lot of stimulus than vice-versa. Appearance of fluidity has to do with a succession of similar frames, not the interjection of a vastly dissimilar one.

>If you were sitting in a dark room, you would notice a flash of bright light a lot shorter than 1/100 of a second.

You can see cosmic rays that last a lot shorter than even that. The real test isn't a single flash of light, but how quickly we can distinguish two separate flashes covering more or less the same spot on the retina. i.e. how high do you have to turn up a strobe light before it starts being perceived like an ordinary light? Since old school fluorescent lights (in good working order) had only slight visible flicker at the edges of peripheral vision, I'd say it is around 120hz.

But measuring the duration of a tone or a light coming on for an interval -- this is of interest to me as a musician. And 1/100th of a second is way too short to notice reliably.

doh, meant 60hz, mixed up the grid's voltage/freq.

Plasmas can produce 600fps.

Good LCDs can do 240fps. Many can do 120fps.

Only by repeating or interpolating input frames.

I'm not sure what you mean. The inputs (eg. HDMI) don't support the bandwidth necessary for 120 Hz, but if they did, the LCD could display them. Interpolating frames is similar to upscaling DVDs to an HDTV. You make a better picture out of the inputs available.

Since framerate choice is not usually a technical but an editorial decision in order to create a particular effect, then saying interpolated frames create a "better picture" is hugely debatable.

Not true. HDMI 1.4 has enough bandwidth to do 2048x1080 at 96fps (or 4096×2160 at 24fps).

Motion blur really is the reason film gets away with smaller framerates. A movie played on a computer's LCD screen (not interlaced) at 24fps simply doesn't look as choppy as a game at 24 fps on the same same screen. This is also the reason CG movies (e.g. Pixar) use motion blur.

Here is a good explanation of Persistence of vision which relates to how the Human Eye actually sees motion. In reality, your eye does not work in frames.

http://en.wikipedia.org/wiki/Persistence_of_vision

And here is a breakdown of Motion Perception:

http://en.wikipedia.org/wiki/Motion_perception

To the first point, "FPS" is a different unit than "Hz". A significant number of games run their physics, logic, rendering, networking, and other processes at different update rates. Forza 3, for example, renders at 60 frames per second, but updates physics at a much higher frequency (360 hertz, IIRC)

Yes, framerates do matter, but other things matter more.

There is a tradeoff of what you are going to use your computing power for - do you want pretty or smooth?

As explained in a linked article from Insomniac Games, majority of people prefer extra quality of graphics over extra smoothness of motion:

http://www.insomniacgames.com/blogcast/blog/mike_acton/15030...

It also depends on the type of game and how well sync'd it is with the monitor refresh. There's something undeniably buttery smooth about a solid vsync'd frame rate equivalent to your monitor's frame rate, which just isn't present at lower frame rates. Smooth inputs result in slick oily outputs. And there's less lag between input and output as the frame time is smaller, while game loops are normally sync'd to the frame rate, so a higher frame rate will result in less lag between input and display.

I would also make the point that this is (to me) most visible in PC games controlled with the mouse, especially twitch-sensitive FPSes. Your link relates to console games, which need only cope with the relatively blunt instrument of a controller, and output to what's likely to be a relatively slow display. Most purists would agree that first-person shooters work best with a mouse and keyboard, rather than an analogue controller. And by slow display, I don't mean the refresh rate, but rather the combination of response rate and frame lag.

The blogger is completely right. I think games should always, always favor frame rates over better graphics. A game isn't a picture, a game is something that's alive, something that moves.

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