Why do video game framerates need to be so much higher than TV and cinema framerates?

It seems that video games need to have something like 60 frames per second in order to be smooth and realistic. But TV and films only have about 24 or 25. Why the difference?

Answer

Two reasons:

1. Responsiveness of input

There is a big difference in feel of the gameplay when input & response happen only 24 times per second vs. 60 times per second, especially for fast-paced games such as first person shooters.

Network buffers and input buffers are filled on separate threads, which means new state from the game server, or button presses from your gamepad, must wait until the next iteration in the game engine’s “update loop”. This wait can be as long as 42 ms for 24 updates per second, while only 16 ms for 60 updates per second. That’s a 26 ms difference or roughly 25% of the “lag” we experience on a 150 ms server connection vs. a 50 ms server connection.

2. Lack of physically accurate motion blur

Cameras in the real-world have what’s called a shutter, which is open for a continuous range of time, determined by the “shutter angle” or “shutter speed”. For instance a moving picture captured at 24 frames per second might have the shutter open for 0.02083 seconds per frame (1/48 of a second, or 180° shutter angle). This continuous interval of time captures and blends all motion happening therein, leading to what we see as motion blur.

Games on the other hand, render only an instantaneous moment of time. There is no equivalent interval where motion is recorded and blended, and instead you create what is essentially a crystal clear sample of the world at a particular instant — something that is not possible in the real world. Because no motion is recorded in the rendered frame, movement on-screen can look jerky unless the frame rate is increased to compensate (by capturing more inbetween motion). By increasing frame rate you essentially converge on real life “frame rates”, leaving us with the biological motion blur we get from our eyes (which are like shutters that are always open).

Though modern games feature “motion blur” now, this only captures motion blur under certain assumptions, and does not (yet) fully recreate the motion blur we see in film or in high-quality CGI renderings.

Demos

For 15fps vs. 30fps vs. 60fps see this demo or this video.

See also

Attribution
Source : Link , Question Author : callum , Answer Author : DuckMaestro

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