Film speed up.

[colly0410]

Been reading about Taylor Swifts Opalite video being shot on film, I presume at 24 frames a second. When shown on 50Hz TV/video would it still be sped up by 4%? Or do they use some frame store gubbins to keep the speed & tone correct? Do they still use 3/2 pulldown for 60Hz systems?

[ppppenguin]

Hard to say what's done these days as all options are possible.

Shooting options:
* 24fps or 23.98fps
* 25fps
* 30fps or 29.97fps
* 50fps
* 60fps or 59.94fps

The non-integer frequencies are a legacy of the NTSC system where the H and V scan rates were lowered by 1000/1001 so that the sound subcarrier could stay put while minimising sound/chroma beat patterns. This change later caused merry hell with timecode.

The 50 and 60 options are unlikely for actual film.

Any of these can be converted to any other for transmission, more or less transparently, using framestore based converters with motion compensation. There's an advantage if your input isn't interlaced (always true with film) as it's relatively hard to de-interlace without losing something.

Traditionally 24fps film was speeded up to 25fps for 50Hz countries. The audio pitch can be compensated but it's only 2/3 of a semitone. Similarly 3:2 pulldown was used in 60Hz countries. This is a horrible process which I hope has died the death. There are frame rate converters that can detect the 3:2 cadence and undo the damage.

[colly0410]

I was reading a book by an American bloke with perfect pitch who was watching a film on Australian TV & the second thing he noticed was the 4% pitch shift. The first thing he noticed was the 50Hz flicker. I never noticed the pitch change as I don't have perfect pitch, most musical thing I ever did was play little donkey on the piano in front of the school...

[ppppenguin]

Yanks often used to notice 50Hz flicker. Now that most sets are LCD which inherently has no flicker the field rate isn't so important.

At the Broadcast Engineering Museum we have a demo with three unlabelled monitors side by side. PAL, SECAM and NTSC. All fed with the same digital component source via high quality standards converters. We ask people which is which. For those who know, NTSC is easy. Just look at them in peripheral vision and the one that doesn't flicker so much is NTSC. PAL and SECAM can be remarkably hard to tell apart. With test card F displayed you can see the missing high frequency gratings in SECAM as compared to some cross colour in PAL.

[colly0410]

My late wife (who died in Feb) had epilepsy & could not go near 625 CRT TV's as she could feel it affecting her. When we were in America in 1989 it didn't affect her so much, of course the lcd sets never bothered her at all. When I came back from America I'd notice the 50Hz flicker till I got used to it...

[ppppenguin]

I have a friend (who didn't have epilepsy) who was badly troubled by 60Hz computer displays. 75Hz was just about OK for her but she really wanted 85Hz.