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Thread: 25fps good, 30fps better?

  1. #1

    Default 25fps good, 30fps better?

    I currently create my videos (animated) at 30fps. I understand 25fps had been common frame rate in the past. And nowadays we might all prefer to use 60fps or higher.
    I have done some tests, and am currently unsure whether I can tell the difference beween 25 and 30. I have done it with and without any 'frame blending'. Although the blended tests are smoother; they are, of course, less sharp.
    My question is, albeit rather obvious; but is there really a much of a difference between 25 and 30fps? And does anyone use 25fps for any particular purpose?
    Whilst it makes the resulting video file a little smaller, more importantly it reduces the number of frames I need to render from the animation program I use.

  2. #2
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    25 fps was the frame rate used on film for UK television. Series still shot on film (in Europe) are 25fps for telecine to 50 fields per second for broadcast. This was because European electricity is 50hz and it was easier to sync the telly to the electricity supply. Most European broadcasters will still insist on a 25fps or 50interlaced frame rate.

    I've never managed to see any difference between 30fps and 25fps when projected, or when viewed on a computer but have heard from numpties who claim that they can see a difference. Then I worked on "Bad Science" and a doctor told me that it's physically impossible to spot a difference between the two. You can spot a difference between 25fps and 40 or 50 fps but anything less than a 50% increase is not noticeable. So it's a good "bullshit detector".

    Nowadays with computers, plasma telly screens and suchlike it's not such an issue.... Except for broadcast.

    Edit: In the USA (and some countries like Japan who are NTSC biased) 30fps or 60i is their broadcast "standard". As a result, the Yanks, and a lot of independents, shoot on 24fps, which is the "standard" film projection speed. This is because it's easier to convert 24fps to 30 fps (for yankee telly) and for 25fps, they simply slow down the projection and nobody notices.
    Last edited by Rembrandt Rob; 10-24-2013 at 12:28 PM.

  3. #3

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    I use 25 fps as it was the recommended settings for Youtube videos in my video editing software
    Furthermore do I not recognize the difference to 30 fps.

  4. #4
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    There seem to be even those who prefer 24fps over 25, as if it could possibly make a difference. When it comes to 25 vs 30, I actually ended up doing things in reverse. Years ago, the camera my parents had shot 30fps for some reason (29,97, I believe) and only few years ago moved to 25fps with new(...er) cameras. Haven't really spotted any difference. When shooting with real camera, it hardly matters whether it is 25 or 30 as far as human eye is considered, but in 3d animation I think it's much easier to spot the difference.

    I remember toying around with Adobe Flash for a school project (horrible, still having flashbacks...) and there you could set fps for your animations. I first tried 24fps, remembering it is what most films are shown in, but was able to tell it was a bit choppy. Setting it to 30 or higher seemed to make a difference there.

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    What's important to realise is that there is a difference between "persistence of vision" and "flicker'. Many people (especially teachers) confuse the two.

    When you see an image it is "retained" for about a 15th of a second. This is why early films were shot at 16 frames per second. Nowadays the "minimum" is 18 fps, to allow a bit of leeway.

    However, you can see "flicker" at anything less than 30 flashes a second. So how can you watch a film at 24 frames per second, or TV at 25? The answer is that each picture is shown twice! In cinemas each frame is shown twice, so you get 24 frames per second but 48 "flashes". This is where a lot of people mix up the two. On a computer animation the picture is only refreshed when something changes, so a 25 fps animation will "flash" 25 times a second, slow enough for your brain to pick up on it. When you convert it to video, and show it on a TV, this "stutter" will appear to have gone as the conversion automatically converts it to 50i.

    Even better... You are very sensitive to movement at the edge of your vision (needed to spot the sabre-toothed tiger a few thousand generations ago) and in low-light conditions. Which is why you sometimes get the impression out of the corner of your eye that a neon or fluorescent is flickering but when you look directly at it... It's not.

  6. #6

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    In cinemas each frame is shown twice, so you get 24 frames per second but 48 "flashes".
    That's interesting, It makes me wonder about how the Hobbit really looks, I understand it was shot at 48fps so in the cinema would they show it at 48fps with a single frame flash, 24fps with the double frame flash or what ? AND for anyone who has seen it does it look ok, horrible, too video like etc. ?

  7. #7

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    I have seen it in 48 fps and the action scenes looked much smoother (and sharper) than in LoTR.

  8. #8
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    Midnight, The Hobbit was very interesting. I do understand when people say it was even "too fluid/fast", as it might get some getting used to earlier on in the film. For most parts, there is not too much difference, but in action scenes you can notice the definite lack of motion blur and the smoothness of movements. Some compare it to videogames, as they usually lack motion blur but have similarly smooth animation. Then there are those who say it looked speede up, as speeded up film usually does not have motion blur either. Only time will tell whether it was bad move or not, but I for one am going to see the next ones in 3d/48fps too. It is noteworthy to say that I'm not even that big fan of 3d, in very large portion of movies it is simply unnecessary.

    The biggest gripes I had with Hobbit had nothing to do with the 3d or 48fps technology.

  9. #9

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    Having digested these helpful responses, I ran more tests at 25 & 30, with and without various degrees of 3d motion blur.
    I am now resolved to continue using 30fps. Very fast moving objects are noticeably smoother, and the additional frames are more flexibility if I want to change the clip's speed in post.

    Once again I grateful for your useful replies. And next time I see a flicker in the corner or my eye, I shall know it is only a tiger.

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