Classical Science: why the movie 24 fps on the line, but the game 60 fps?

We play the game for so many years, perhaps a few clouds dream questions: why 2D pixelated antique Super card playing up in Mali, but 3D game card? Why film at 24 frames per second unconsciously card? Hardly 30 fps but the game he had card to Wang Xing-man? Although there are a variety of answers, but many are not scientific enough to, so I’d better overall about science.

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Physiological basis

Classical Science: why the movie 24 fps on the line, but the game 60 fps?

Film frame-by-frame information record

All stories from the human eye “persistence of vision” and “fill” phenomenon, which refers to the human retina light signal disappears, afterimage will retain a certain time which make up the middle frame of the screen is the brain’s own “brain up” function. They mix, let us think of 24 frames per second playback photo is “continuous”.

And why put the number at 24, there is more conventional and the occult, movie size itself has undergone a change of 16 to 24 frames, this number also will continue to grow. PAL/NTSC/SECAM three television signal specification, set at 25 frames per second and the frames 30 frames of reason, just because the power supply in different parts of different frequencies (50Hz and 60Hz) … … In order to simplify the calculation, using NTSC system of the United States and Japan, in the game naturally follows the habits of 30 frames per second (NTSC NTSC is 29.97 frames).

But why no endearingly 24 frames of film, but 30 fps or 60 frames will also appear in the game card? Here said the conclusion, the game to fluency, 4: motion blur effect, action response uniformity, frame rate and frame rate, including motion blur is most important.

Dynamic fuzzy

Dynamic fuzzy refers to the camera shutter is slower than motion ghosting caused by motion. Important differences of 3D games and movies: the movie was realistic light and shadow records, and 3D games are real-time rendering of 3D shape/position, the former will have motion blur, while the latter does not.

Films is a constant frequency of film/digital photos, it can record light information over time. Generally 24 frames-per-second video will select 1 time times higher 1/50-second shutter, you can record information half a second light. These “extra” the rich image information will be stacked together like ghosting caused by motion blur/smear, the principle and the “light painting”, the shutter is not for a few seconds, 1/50 seconds.

Classical Science: why the movie 24 fps on the line, but the game 60 fps?

Set of high shutter speed

Classical Science: why the movie 24 fps on the line, but the game 60 fps?

Set of low shutter speed

In the human brain, motion blur is one of the most important visual information, even if the actual number of frames is not enough, adding motion blur the image of an interval is enough for us to use for brain repair in order to achieve “flow”. In addition, run it, if the same 24 frames per second, if there is a shutter speed to 1/96 seconds, the microfilm record light only 1/4 seconds (24*1/96), loss of light information will blur effect weakens, this movie looks will be felt too.

Classical Science: why the movie 24 fps on the line, but the game 60 fps?

A record amount of light different shutter speed on the left (slower shutter, recorded the more light), right for footage

While the game is the “shutter speed” to the Acme products, 30 fps in the game, is the game engine generated 30 infinitely short moment scene, and these moments no matter how fast, the object itself is clear, Cliff does not blur. If played at 24 frames per second, the brain protests, this move so fast, why do I see so clearly, not science, “and brain fill smooth screen” process cannot take place, we really are watching broadcast slide show.

To resolve this issue, or increasing the sampling rate, or artificially increase the blur effect. Former is the following when it comes to programmes of high frame rate, which is to increase the blur cheat brain, it believed they were seeing a high amount of images (blur effect is very resource intensive, however).


Frame rate

Objects in the game if you move 1 pixel per second, we may be able to feel smooth, but if an object moves 10 pixels per second, it is obviously feeling. Need to increase the sampling rate, fill out missing picture in the Middle, and if the number of frames up to 10 frames per second, we can see closer to just 1 second 1 pixel fluency.

Picture by at 24 frames per second, up to 48 or 60 frames per second, eyes receives a large amount of information to a certain extent, just long enough to “brain up” a smooth effect. Although the perfect game should be in the frame as much as possible, that is the real simulation of reality, but for games, rendering more frames, you need higher performance, the cost of the programme is too big. And now everyone is recognized, can achieve 30 frames of brain repair process.


Frame rate uniformity Moschino cases

However, in the actual game, 30 frames will still be there when Caton, even up to 60 fps is still stuck. We usually roll phone testing time, often two different GPU cell phone, even if the displayed FPS (frames per second), so will smooth differences, why is that?

Classical Science: why the movie 24 fps on the line, but the game 60 fps?

Two frames to video card comparison Moschino iPhone 6 cases

Classical Science: why the movie 24 fps on the line, but the game 60 fps?

Two graphics cards frame render time comparison

Problem here in a “frame” on the accuracy of. Even before the time of more than 30 frames rendering, but as long as there are so few moments below 30 fps, it still is. Ideally at 30 frames per second, 30 frames evenly, but in fact there are probably half a second before rendering frame 29, last exactly half a second to render 1 frame.

As computing power and the complexity of the screen limits (for example, suddenly there was a huge explosion from the plain picture), half a second before rendering the pressure is small, full frames run. But when the explosion scenes, the operation of the surge, no time to render, followed by number of frames dropped. Although the absolute value of the number of frames is not sensitive to the naked eye, but obviously change the number of frames can easily detect.

Obviously we usually see the FPS (frames per second) accuracy is not enough, we need to get the accuracy, how many frames per second, up to how many frames to accurately measure every millisecond frame rate stability.


Response time with hands

The biggest difference between games and movies are, game is to require the user to make action and the action is real-time feedback. In addition to the Visual flow, we also need to operate smoothly. We pursue high frame rate of 60 frame important reasons is to reduce response time. We perceive an action completed, is to machine received operational information, and ultimately reflected in the next frame is finished. In practice, most game engines after receiving instructions, to 3 frame interval is reflected on the screen.

Frame number the higher the refresh rate, we can perceive the operation faster. 30 fps game, even ignoring the operating instructions transmission speed, each scene for 33 milliseconds (1s/30=0.033s), an operation requires a 100-millisecond (33 milliseconds * 3 frames) can be reflected on the screen, and 60 fps game, you only need 50 milliseconds to respond here. 50 milliseconds and is likely to decide that you are in the game blast someone else’s head, also was shot in the head.

In addition, if a picture appears too much pressure, too late to render the machine, the picture appears frames even Caton, our instructions will be postponed to the next input. Effect is the operation we do a few seconds ago, appear on the screen one by one after a few seconds, this is the legendary cards chengxiang … …

Classical Science: why the movie 24 fps on the line, but the game 60 fps?



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