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Old December 26th, 2008, 08:21 AM   #1
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Uploading to web at 25fps?

.
  • Here in the UK, and in much of the world - http://upload.wikimedia.org/wikipedi...-SECAM.svg.png - we shoot everything at 25fps. However most people's computers display at around 60Hz.

    Maybe I should do some tests on this (yawn...) but it seems to me that if a web page is running at 60Hz then embedding a video encoded at 25fps may well cause some loss of quality.

    Or do the likes of Vimeo and YouTube re-encode to a different frame rate? That can't be good...

    Anyone know anything about this...?

    p.s. for a comparison, there's plenty of videos on this page originally encoded at 25fps: Video Embedding Comparison Tests
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Old December 26th, 2008, 03:45 PM   #2
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True, this is the unlucky part of living in PAL land. If the Web is your target, consider shooting 50i (not 25p), deinterlace down to 30p then check motion restitution on your computer before uploading. The new YouTube HD is significantly better than Vimeo which is plagued by frame rate throttling and image freezes.
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Old December 26th, 2008, 04:14 PM   #3
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Thanks Stephan.

I've been told that Vimeo supports a maximum of 24fps for HD videos. Seems odd to me. Uploading 30fps video at HD resolutions apparently results in choppy motion, as would 25fps.

I must now own up. I've posted this question elsewhere, and gotten a brilliant reply, which I should share:
Uploading 25fps to the web..? - Cinematography.com Community of Film and Video Production Professionals

Man, I love the web!
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Old December 27th, 2008, 06:03 AM   #4
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That response over there is great, maybe a bit overly complicated though. Before you run into clock skew problems and hand-code your own player (better than that of the PS3?) you will need to manage the frame rate conversion and will also run into the codec issues which weren't mentioned (like bandwidth starvation). Or said differently, don't worry about phase-lock loops, you should be reasonably fine with YouTube.
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Old December 27th, 2008, 07:16 AM   #5
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Can you translate that into English please...?

No really, I don't expect you to.

Have a good festive season!
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Old December 27th, 2008, 12:19 PM   #6
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Quote:
Originally Posted by Karel Bata View Post
I've been told that Vimeo supports a maximum of 24fps for HD videos.
That used to be true. If one uploaded 30p their transcode would just dump the last six frames of video each second and it ended up looking like the dog's dinner. But sometime this past March or so they added support for 30p. I've been doing 30p since then without any unusual issues. I don't know if they have ever supported 25p.
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Old December 27th, 2008, 12:32 PM   #7
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Originally Posted by Karel Bata View Post
...most people's computers display at around 60Hz.
...if a web page is running at 60Hz then embedding a video encoded at 25fps may well cause some loss of quality.
I think you may be comparing apples and ostriches here. Screens can refresh at 60Hz, but they don't have to. It depends on what the display supports. I just checked my laptop and desktop and TV LCD screens and they only support 60Hz. It would seem odd for manufacturers to settle on a refresh standard that would not give optimum quality to the majority of the world that lives on 50Hz power. Then again, I've seen companies I have worked for make some awfully stupid decisions regarding the technologies in their products.

It's completely possible that there is some truth to your statement. However I don't know if there are many of us on the planet with eyes good enough to notice the difference.
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Old December 27th, 2008, 01:40 PM   #8
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Cheers!

I could devise a shot that would show up any irregularities of that sort to the eagle eyed, but in the real world it's not going to show.
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Old December 27th, 2008, 04:32 PM   #9
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Originally Posted by Tripp Woelfel View Post
I think you may be comparing apples and ostriches here. Screens can refresh at 60Hz, but they don't have to. It depends on what the display supports. I just checked my laptop and desktop and TV LCD screens and they only support 60Hz. It would seem odd for manufacturers to settle on a refresh standard that would not give optimum quality to the majority of the world that lives on 50Hz power. Then again, I've seen companies I have worked for make some awfully stupid decisions regarding the technologies in their products.

It's completely possible that there is some truth to your statement. However I don't know if there are many of us on the planet with eyes good enough to notice the difference.
Karel's point really is correct... but how bad that feels to people's eyes is 100% culturally dependent. Tripp, I understand you're in the US? 25fps playback on 60Hz displays is very similar to 24p movies on NTSC broadcast TV: many people like it, many others hate it, some work long hours to achieve the intense judder (esp. in pans).

As for Vimeo I also heard about the 24fps limitation being lifted, but never was able to find the right settings or codec combination. Always had the horrid 1Hz frame jump.
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Old December 28th, 2008, 06:40 AM   #10
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Not just cultural - Americans might be interested to note that we in PAL countries will often observe flicker on a 30fps tube TV until we get used to it - but also age. I used to see fluorescent lights flickering out of the corner of my eye until I was about 16, and right up to my mid-twenties a big colour TV set would drive me out of the room because of the high pitched whistle.

Presumably a very small child sees virtually our whole world flickering around it: TVs, lights, clock displays, LEDs. Gawd knows what a cat or dog sees...

Try turning a CRT upside down (or stand on your head). You may be surprised that you can see the flicker. Out of the corner of your eye (which is more sensitive to change so you're not caught out by any predators creeping up on you) you most likely will.

p.s. Vimeo say they're about to introduce 25p HD.
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