Film-Tech Forum ARCHIVE: Note from distributor to run at another speed

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Posted by Rob van Ede (Member # 1457) on 11-21-2003, 02:47 AM:

We got a note from the distributor of the film Pipo (that's not a typo but the name of a dutch movie that will arrive next week) that this film should be run at 25 FPS instead of the 24 FPS that we normally use over here. The note stated that when run at 24 FPS, the film would not run smoothly through the projector.

Personally, i cannot think of any reason for problems when running a film at another speed other than the film being slightly longer at 24 FPS (our Ennemann 15s have no speed adjustment control that i know of). Am i missing something or is this warning pure nonsense?

Posted by Carl Martin (Member # 1146) on 11-21-2003, 03:41 AM:

sounds like pure nonsense to me. i'm guessing this will only have an analog soundtrack. imdb lists "Pipo en de p-parelridder (2003)" but has few details on it.

probably this was intended to be seen mostly on tv and somebody had a cow over frame rates when they shouldn't have.

carl

Posted by Frank Angel (Member # 248) on 11-21-2003, 03:57 AM:

Ron, I agree with Carl. That's just a crock. It is just a distrib who never handles film making a big deal about 24 vs. 25, which even if you had perfect pitch, you couldn't tell the difference in the sound. As for not running correctly in the projector....well, that just tells you how little distribution knows about what goes on in the booth. Seems this particular bunch are technical dunces. You should put a note back in the cans -- "On the contrary, this print runs fine at either speed."

Frank

Posted by Howard Johnson (Member # 62) on 11-21-2003, 04:04 AM:

It's just rubbish. Many projectors in UK are from preview theatres and run at 25 fps , I know of a triple where one of the projectors runs faster than the others although they are identical machines. I doubt if many projectors run at exactly 24fps. This film was probably shot at 25fps and somebody at the distributor has got mixed up.

Posted by Ian Price (Member # 14) on 11-21-2003, 11:46 AM:

If it was shot on video in PAL then its native speed is 25 fpm. I had a guy who had shot a short called The Piano at the Telluride Film Festival who insisted that I run his film at 25 fpm. I thought about it for a minute, said "sure, no problem." And ran the film. He was happy.

Posted by Steve Guttag (Member # 268) on 11-21-2003, 12:14 PM:

On the contrary...if you have perfect pitch...you'd easily notice the difference between 24 and 25 fps. In fact, we recently modified an ELMO LX-1100 for variable speed. We used a Reliance motor controller and did the math for a 60Hz frequency equalling 24 fps.

Upon playing several films, my boss claimed...it is running too fast that the voices did not sound natural. He adjusted the speed until he thought the voices sounded correct.

So here you have a motor controller displaying that it is putting out 60Hz but someone claiming that it is too fast. Who do you believe?

I took out a strobe and confirmed that the machine was indeed running too fast! Furthermore, when he set the speed by ear...he was DEAD ON...to within fractions of a percent!

So what gives?...wanting to get to the bottom of it...I put a digital OScope on the output of the converter and sure enough...it was putting a higher frequency that what it was displaying! Measuring the frequency when my boss set the speed by ear...came to exactly 60Hz.

So back to the topic...25fps is NOT the same as 24fps...can you get away with it? Sure but even without perfect pitch you can see and hear the change in speed. You would be running 4% too slow at 24fps...4% is quite perceivable to even the lay person.

Many European machines with frequency converter drives (e.g. Kinoton D or E series projectors) have a 24/25 fps switch so selecting the proper speed is easy. The note in the can would greatly assist those theatres in choosing the proper speed. If, on the other hand, you have an async motor or no means to affect a speed change...you are probably just going to live the incorrect speed for the one film. If it became a habit, then you might consider investing in the proper equipment...kinda like 1.66 or 1.37 lenses...for a one-shot...you'll make due with the materials you have...if you run them all the time...get the proper lenses.

As to projectors running at speed...Most projectors made today run just about perfectly at speed since most now use Sync. motors and the line frequency is pretty tightly regulated.

Those with async motors are certainly more wild since loading affects the speed greatly. Even those however will not be off by a full frame per second..in fact they are often within a percent of proper speed. There are exceptions to the rule, however.

Steve

Posted by Pete Naples (Member # 761) on 11-21-2003, 12:24 PM:

Yup, anyone who knows what they are listening for, especially a musician will detect that 1fps error. Ages ago we were screening a film, follow the moonstone I think it was called, anyroad it had music by Ally Bain, the fiddler in it, he was at the premier during the Edinburgh Film Festival, and didn't complain, just commented about the pitch. On some investigation with a tachometer the old Westar was running way down at 22 fps. On the Westrex machine that is usually due to the 'V' pulleys wearing, one timing belt conversion kit later and proper speed was restored.

Steve, with invertor controlled machines I don't trust the indicated output, I measure with a tachometer and adjust until the sprockets are turning at x fps. The indicated frequency is often well off from the calculated.

Posted by Rob van Ede (Member # 1457) on 11-21-2003, 05:03 PM:

Thanks for your thoughts, it shouldn't be a problem then. I'll listen very carefully when the film arrives next week.

Rob

Posted by Steve Guttag (Member # 268) on 11-21-2003, 07:10 PM:

Pete,

I think it depends on the inverter as to how accurate they are...if they are crystal controlled...then they should be dead on...the Reliance controller is the first I've stumbled upon that said one thing and did another...not it wasn't wildly off...the projector was still within 1 fps of accurate but I think we had to have something like .7Hz compensation factor.

One thing most inverters allow is to program in an RPM speed based on frequency...I normally put this mulitplier in such that 60Hz equalls 2400 RPM...then put a "dot" on the display so it reads 24.00. On this controller...life was not that easy...after the correction factor...I had to loose the last significant digit so it read 24.0...still good to within a 1/10 of a frame per second. Checking with a strobe we had less than a percent error.

Steve

Posted by Andy Muirhead (Member # 712) on 11-21-2003, 07:17 PM:

Not sure if I remember correctly, but I think the difference in audio between 24fps and 25fps translates to a semitone. Which would change the key of a piece from major to minor, and vice versa.

Ally Bain Rocks!

Posted by Carl Martin (Member # 1146) on 11-21-2003, 07:58 PM:

quote:
Which would change the key of a piece from major to minor

if selected notes were changed, but not if they all are.

Posted by Gordon McLeod (Member # 33) on 11-21-2003, 10:21 PM:

Carl films projected at the wrong speed are "film done wrong"
I have many times had to provide speed control to accomodate 25FPS on some films

Posted by Carl Martin (Member # 1146) on 11-22-2003, 02:28 AM:

agreed. my assumption was that 25fps was the "wrong" speed, though, since 24fps is a pretty universal standard for sound film and i can't think of any reason for it to be 25 (except pal). but if it was shot at 25fps, then there you are.

projecting it at 24fps would hardly be as gross an error as using the wrong ratio, though. after all, silent films were and are shown at a much greater range of speeds.

carl

Posted by Michael Schaffer (Member # 1204) on 11-22-2003, 03:18 AM:

25 vs 24 fps result in a pitch difference of about a quarter tone. As already stated, this is just a shift in tuning, not a change of the key or the major/minor mode.
The truth is, even most trained musicians would not really mind that too much. There is no absolute defined pitch for any note. A` is defined as a frequency of 440Hz, but in reality a lot of orchestras tune to 444Hz, while some tune as low as 435Hz.

Posted by John Anastasio (Member # 607) on 11-22-2003, 07:23 AM:

Michael's right. Changing pitch doesn't change mode. You can easily hear the difference in pitch when a 25fps film is projected at 24fps, but you'd probably only notice it if you had something to reference it to. If you know what someone is supposed to sound like, or if you have perfect pitch, the change in frequency can make you uneasy...and tuning a machine by ear isn't all that difficult. I can easily detect a pitch difference of a 1/8 of a tone. In the western world, our music uses a half tone as its smallest pitch change, but some Indian modes, for instance, use quarter tone pitch changes. That's equivalent to playing in the cracks on a piano keyboard. I was the director of a symphony orchestra for a couple of years (I have a degree in music, in addition to other things) and we tuned to A440. Our colleagues up in Boston, however, were famous for tunning to A444, not a large difference, but nevertheless enough of a change to give the orchestra a very bright sound. All that aside, though....I don't think I'd get all upset over the difference in sound if I had produced the film. It's all very subjective.

Posted by Danny Hart (Member # 659) on 11-22-2003, 08:49 AM:

I agree with Steve above - playing at 24fps would be 4% too slow (if the soundtrack was recorded at 25fps). I have a variable speed CD player, and have just listened to a couple of things 4% too slow. The difference is VERY noticeable, and I'm not pitch perfect. I'd be able to tell that difference a mile off.

Just as an aside, with an analogue soundtrack, it's agreed that this would make a difference in pitch AND tempo. But, how would this difference in speed affect a digital soundtrack, being data?

By the way, off topic, some radio stations (particularly commercial/pop) play alot of their music slightly faster than it should be played (only by about 2 or 3%). The idea is the music sounds "brighter" on their station than their competitors.

And yes, Phil Cunningham and Aly Bain are FAB!!! Aly bain could do with a wee smile from time to time, though. They haven't performed here for a while.

Posted by Randy Stankey (Member # 64) on 11-22-2003, 10:55 AM:

quote:

Danny Hart: The idea is the music sounds "brighter" on their station than their competitors.

Do they play the ADVERTISEMENTS 3% faster than normal?

At 3% faster you get 1.8 more minutes per hour to play ads. Enough time for three or four more 30 second spots per hour! It sounds more like greed to me! [Wink]

Posted by Per Hauberg (Member # 529) on 11-22-2003, 08:24 PM:

Several danish low-budget films lately have been marked: "Will run correct only at 25 fps". -Isn't this just a sign, that the films has been shot on video (they all look so, at least - dark and grainy).
Wish, the producers would make up their mind: "Is this film worth the expence of real film, or should we just drop it..?"
And btw: itsn't it just what happens, every time a film is transferred to video or television - from 24 to 25 ? -Wide audience never get an idea of it...
Newer Kinoton projectors has a 24/25 shift button - and some very fine, old projectors has the possibility of 30. -But serious: Those producers know to little about the cinemas, they are making films for, don't they ? As standard, I do not know of other projectors than the Kinotons being able to chance speed without further alterations.

Per

Posted by Manny Knowles (Member # 1171) on 11-23-2003, 07:47 AM:

quote:
Randy wrote:
At 3% faster you get 1.8 more minutes per hour to play ads. Enough time for three or four more 30 second spots per hour! It sounds more like greed to me!

That's *exactly* what I was thinking when I read that!

Posted by Dominic Case (Member # 1830) on 11-23-2003, 10:55 PM:

quote:
The note stated that when run at 24 FPS, the film would not run smoothly through the projector.

They could be thinking of what happens on PAL telecine. When a film is transferred at 24fps, the telecine doubles up and repeats one field (1/2 a frame) every half second, giving a just-perceptible stuttering action. That's one reason why films are transferred for TV/video at 25fps to match the PAL frame rate. Faster, higher pitch (25 for 24 is a 4% increase in frequency, whereas a semitone is 6%) but smooth action, no jitters.

But there's no such jittering problem if a film projector runs fast.

Posted by Leo Enticknap (Member # 534) on 11-24-2003, 01:50 AM:

How would the slight speed change affect a digital track? I seem to remember that Dolby digital will 'tolerate' a 2fps speed variation from 24 in either direction. But if the projector is running a bit slow or fast how does it sync the sound playback? I suppose that in theory, you could increase or decrease the speed of the sound at the digital to analogue conversion stage without adjusting the pitch of the original (unlike with analogue, where you can't vary one without varying the other), but will it actually do this?

Posted by Ivo Noorlander (Member # 1315) on 11-24-2003, 09:08 AM:

Hello everybody this is my first post here.

In Holland quite a few films are shot 25fps. This is not necessarily because it is shot on PAL video, as Per suggests. Pipo has been shot on (crappy) HD, so it could easily have been shot 24fps if desired. Films shot on 35mm are also frequently shot at 25fps for home video puposes, which is unfortunate, because post production houses can speed 24fps up to 25fps with pitch correction. So I guess they're just wasting money in terms of film stock by the added 4% when shooting the feature at 25fps

Luckily our Vic 8 projectors can now also be changed with a switch, so for us it's no problem.

Posted by Christian Appelt (Member # 1067) on 11-24-2003, 10:27 AM:

I had to screen many 35mm sepmag films (foreign films that had been dubbed for German TV), and the dubbing was done for 25fps PAL TV rate. When we screened those at 24fps, there was a noticeable change in certain (well-known) actor`s/speaker`s voices, so I believe that the pitch change in music should be quite noticeable.

FWIW, I discussed this with two sound mixers, and they said that speeding up (like in PAL telecine) was never a source of complaint, but the 1 frame slowing down from 25fps TV films shown in cinemas at 24fps would always be noticed by composers and musicians.

Posted by Andy Muirhead (Member # 712) on 11-24-2003, 07:47 PM:

quote:
Faster, higher pitch (25 for 24 is a 4% increase in frequency, whereas a semitone is 6%) but smooth action, no jitters.

Thanks for that Dominic, I stand corrected - I was previously informed 4% translated to a semitone. That'll teach me to listen to such nonsense without thinking about it, me being a muso too! Honestly I did pass my music theory!

On the subject of 24-25fps, the BBFC do state that running times for videos are 4% shorter than theatrical releases due to differing numbers of fps.

Danny, New Year is coming up so Aly will be wheeled out.. how big will those bags under the eyes be this year!

Posted by David M. Dorn (Member # 2298) on 03-30-2004, 08:20 PM:

I will post this query here rather than start a new topic since it is directly related to 24 vs 25 fps.
I noted that the manuals pages contained the manual for the Meopta 35mm projectors. Having used Meopta optical equipment in the past with favorable results, I was curious about their projectors. I read the manual and then visited their website.
Both the manual and the website specs state that their projectors run a 25 frames per seconds. The acutual spec reads
"Picture Fequency 25 frames . s-1".
Anyone know if this is correct (and not a misprint) and if so why?
Since Xenon lamps are DC I can not see 50hz/60hz shutter synch problems like you can have with a camers when using HMI lighting.

Posted by Brian Michael Weidemann (Member # 2243) on 03-31-2004, 02:27 AM:

quote:
And btw: itsn't it just what happens, every time a film is transferred to video or television - from 24 to 25 ?

I was under the impression that 24fps film transferred to 30fps NTSC video included the duplication of every fourth frame, which is only really noticeable when you pause video and advance frame by frame. You can count it ... change, change, change, change, same frame, change, change, change, change, same frame, etc. And analog and digital sound isn't recorded at a "frame rate" that is locked to the film's original projection rate, so there will be no speeding up. Its original play time will stay consistent with the video.

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-31-2004, 02:35 AM:

I was under the impression that they used PAL in Denmark. [Smile]

Posted by Per Hauberg (Member # 529) on 03-31-2004, 07:12 PM:

Right: Denmark is PAL country Denmark is 25fps videofilm-shit-in-cinema country Denmark is home of crap-crap-crap Dogme.
While cinema owners spend their money every time dictated on doing things better, producers and distributors today only believe in cheaper is better. DVD will win soon !

[puke]