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Jeff Wexler

24fps: where does it come from?

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-from Facebook post -Nate Clapp

 

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Pictured is one of movie's first sound men checking the Vitaphone recording with a microscope while recording. Sort of a human playback head

 

Back in the day (turn of the last century) there was no such thing as camera batteries or sound men. Men were men and cameras were hand cranked. As they had evolved from still cameras they were sort of still camera Gatling guns, capturing still frames as fast as you cared to crank. Somewhere past 14fps something magical happened and persistence of vision started to fuse the images so rather than a fast slide show it started to look like motion. So cameras were built to move one linear foot of film per two cranks, which meant if you cranked at "coffee grinder" speed you hit 60 feet per minute, which comes out to 16fps, just north of that 14fps effect. Cranking faster improved the persistence of vision thing, but producers didn't like you blowing through all that expensive film, and besides there was really only one stock available and it was slow, about 24asa. Cranking faster meant less light per frame. Sometimes you cranked even less than 14fps to squeeze a bit more exposure out of it.

 
This is where it gets a little weird. Projectionists, who were also often hand cranking their projectors had a habit of cranking faster. Faster meant faster turnaround in seating, which meant more $ and even better persistence of vision without annoying flicker. Sure, action was sped up, but the whole thing was new, no one seemed to complain. In fact, by 1925 The Society Of Cinema Engineers (now known as SMPTE) had codified it recommending 60 feet per minute (16fps) for camera speeds and projecting at 80 feet per minute (21.3fps) seems weird now to pick a different speed for display from capture, but to review, faster cameras cost more money, and faster projectors made money, and after all, producers are paying for everything. 
 
Anyway, someone decided it would be a great idea to add sound. How hard could it be? In fact, several companies tried to be the first to bring sound to the movies, hoping to capture the market. Funny thing is they all insisted on capturing at the same frame rate they displayed at. If you didn't, the pitch would be all wrong and everybody would sound silly. And forget about music. Some picked 80 feet per minute (the already established speed for projection), some picked 85 feet per minute, and some picked 90 feet per minute. First one to get a working system was Warner Brothers Vitaphone. It was used in the 1927 "The Jazz Singer" which was the first feature length film with sync dialog and is considered the official start of the "Talkies."
 
The Vitaphone engineers had picked 90 feet per minute, or 24fps as their capture and projection speed. If one of the others had been first, we easily could be shooting 21.33fps or 22.66fp as a standard today. So sometimes you get lucky. 
 
Except the Vitaphone system was terrible. It sounded good but that's all that could be said about it. The sound was recorded on 16" disk records separate from the film. They could only be played 20-30 times before they were no good, and they could break, so you had to send lots of duplicate disks with each roll of film to the projectionist. A disk only covered one reel so every reel change you at to cue up another record. And synchronizing the needle with the head of the roll was a pain in the ass. And if you broke the film for some reason and spliced it back, everything past that point was out of sync. During recording, the camera had to be motor powered from the mains, and the disks had to be made in recording booth adjacent to the set. In fact it was such a bad system that it was abandoned 5 years after it was implemented. And it only lasted that long because all the theaters that wanted to have sound had bought into that technology and had these crazy phonograph contraptions connected to their projectors and weren't eager in throwing them away just after having bought them. Movietone, which used technology that put the audio as an optical track on the film had many advantages, but it was a little late out of the gate. Because Vitaphone was first, the engineers of Movietone decided to stick to the same frame rate. Soon enough Movietone lost ground as well, as technology changed but all subsequent sound systems stuck with the now established 24fps. 
 
So blame a sound man. Or thank him. Your choice. 
 

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My understanding was that 24 fps in picture was just above the threshold of when most humans start seeing flicker. Using the fewest frames with out seeing flicker was the objective more or less.

 

I love reading about how this all came to be and what roads got traveled down for better or worse.

 

Scott harber

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24 fps in picture was just above the threshold

 

Persistence of vision is about 30 pictures-per-second. It will vary slightly from person to person and with image contrast and speed of the motion but that's the rough standard.

 

In the beginning, film was cranked at nearly 30 frames to accomplish an effective motion picture but that was a nuisance for the operating cameraman and an expense in film. Some very clever fellow (don't know who) figured out that it wasn't essential that each image be a progression from the prior image. The same persistence of vision occurred when each image was projected twice. That was accomplished with the use of a butterfly shutter with the film held stationary for a moment as one blade of the shutter passed and then pulled down during the momentary black-out as the second blade passed.

 

The twice-per-image projection was an effective work-around and was widely adopted. The standard of 16 frames per second was just one notch above the minimally effective rate of 15 frames.

 

David

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In the beginning, film was cranked at nearly 30 frames to accomplish an effective motion picture but that was a nuisance for the operating cameraman and an expense in film. Some very clever fellow (don't know who) figured out that it wasn't essential that each image be a progression from the prior image. The same persistence of vision occurred when each image was projected twice. That was accomplished with the use of a butterfly shutter with the film held stationary for a moment as one blade of the shutter passed and then pulled down during the momentary black-out as the second blade passed.

 

I worked on a silent movie documentary project for Leonard Maltin in the 1980s, and one of the segments was on frame rates and persistence of vision. My memory is that 16fps was the standard silent frame rate throughout the 1900s and 1910s, and had slowly drifted up to about 18fps by the 1920s. Leonard had us transfer all the clips for the show (done at Trans-American Video, Merv Griffin's company) at 16fps except for comedies, where we went as high as 20fps. 24fps always looked too fast and jerky for most silents. 16-20fps was our recommendation for silent films at Technicolor as well, but we'd just have to eyeball it and make a judgement call with the producer, since the standards were very loose prior to about 1924 or so. From 1927 on, everything was generally 24fps with rare exceptions (like 26fps Cinerama and 30fps Todd-AO in the 1950s, and Peter Jackson's 48fps for The Hobbit and other films). This is also in agreement with the classic Thames TV 1980 Hollywood: A Celebration of the American Silent Film TV silent movie documentary, which is a fantastic series that has yet to be reissued on DVD.

 

By the time sound-on-film rolled in, what I recall reading is that they needed a 20-frame gap between the picture shutter and the optical sound pickup, so they created a series of rollers to buffer out the jitter introduced by the pulldown claw. I have some old articles in the files and a 1930 book on film sound that says that 24fps was determined to be the minimum speed necessary for "reasonable fidelity," so that's why this speed was established by SMPE (later SMPTE) back in the day.

 

There were 2-bladed and 3-bladed shutters used in projectors for many years in order to reduce flicker, and this same kind of technique is used today even with digital projectors. Routinely, the 24fps digital image is displayed four times to provide a simulated 96fps frame rate to reduce blurring and help eliminate flicker. This is different from the "motion-smoothing" effects in consumer monitors, most of which look pretty crappy.

 

http://en.wikipedia.org/wiki/Frame_rate

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This is a fascinating chapter of film history that I've been interested in for many years. Some tidbits to think about:

-During the hand crank days of silent film, skillfull camera operators were quite aware of their cranking speed as the cranking speed affected the exposure of the negative. They could hear the pitch of the camera's whir next to their head.

-Sound for picture had been lingering in the back ground for decades before the 1920s. Check out the SMPTE paper by Earl Sponable "The Historical Development of Sound Films." It's a fairly comprehensive chronology of the sound-film development going back to the 1857. There were numerous researchers, inventors and scientists applying for patents prior to the 1920's. Outside of Hollywood there was a steady interest in sound developments.

-as is well known, the movie studios in 20's were reluctant to convert from silent to sound. Silent films had reached an artistic peak, production was uncomplicated, and the studios were making steady money. In today's parlance, sound was a "disruptive technology."

-If you think about it, in a sound-on-disc system, the film speed does not affect the quality of the sound recording, rather the speed of the disc affects the quality of the recording- so in theory Vitaphone could have had a different film speed than 24 fps. The Bell labs engineers who developed Vitaphone chose a disc speed of 33 1/3 rpm and used a 16" disc that would run for 11 minutes- matching the running time of a 1000' roll of 35mm running at 90ft/min (90ft/min = 24 fps)

 

- The specs I have seen from the 1920's regarding film speeds show feet-per-minute and not frames-per-second. It makes me think that people didn't really think in terms of FPS at that time. I'd like to find a cinematographer's manual from the period and have a look. Anybody know about this?

- Sponable, who worked on developing sound-on-film with Fox-Case Movietone, said they settled on 90ft/min for Movietone sound-on-film because that's what Vitaphone was doing. (somewhere I read this quote- can't find it now.)

-Vitaphone despite it's short life and technical drawbacks, launched Warner brothers into the stratosphere. Their intention was to present musical performances to the public but it very quickly grew into a vehicle for dialogue. Silent film production ceased abruptly as the others studios scrambled to get their own sound departments up and running.

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This is a fascinating chapter of film history that I've been interested in for many years. Some tidbits to think about:

-During the hand crank days of silent film, skillful camera operators were quite aware of their cranking speed as the cranking speed affected the exposure of the negative. They could hear the pitch of the camera's whir next to their head.

 

There was an interesting bit in the 1980 Thames TV silent-movie doco that the hand-crank silent movie cameramen would crank while humming "Volga Boatmen" in their heads to keep the pace. Eventually, they hand spring-wound motors which were a lot more constant. But there are still people out there who have used hand-crank films for certain projects; I remembered Tony Scott used one for Man on Fire for a few shots not too many years ago. 

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Apologies if items are oversized? 

Apparently, the "insert image from URL" function was not working? (when I went to post these.)

Not sure from my end? Or, jw site?

These YT(s) were posted using the HTML "source" function.

Has anyone else had trouble posting YT(s) / Vimeo(s) (or 'images')- specifically using the "insert image from URL" function? (Since the site update a few days ago?)

The "studio demo" in this first clip starts @ 9m50s

https://www.youtube.com/watch?v=4yWXhpY76rU

OR

https://www.youtube.com/watch?v=4yWXhpY76rU&t=09m50s

 

https://www.youtube.com/watch?v=z_GyYapvkcw

 

https://www.youtube.com/watch?v=Z_4ar2ffgTI

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Dick Lester shot a film of Alexander Dumas's story about the Three Musketeers in the early 1970s - I say 'a' film, but it was so long it was released as two films, The Three Musketeers and The Four Musketeers (does anyone else find it odd that the eponymous musketeers use only swords and not muskets?). I was chatting to the production mixer (Simon Kaye) not long afterwards and he told me that there was quite an issue with the speed. Memory is hazy now, but I think that the fight sequences were under cranked, but they wanted the recorded dialogue to be in synch, yet not altered in pitch. The answer, apparently, was to transfer from 1/4" via a scanning head recorder (it was referred to as the Tempelhof, which must have sounded a little like its real name) so that somehow pitch was preserved put speed was altered. All this at the expense of audio quality, so post-synching was being seriously considered at the time of our conversation. Don't know how it panned out in the end.

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For a lighter and weirder look at the history of cinema in a parallel universe (Terry Pratchett's Discworld), I can highly recommend his book Moving Pictures. Featuring Vincent Tugelbend (can't sing, can't dance, can handle a sword a little), Theda (Ginger) Withel (stage name Delores De Syn), Gaspode the sentient dog and CMOT Dibbler, hot-dog entrepreneur and aspiring producer.

Here's an extract on the approach to sound:

"Sound! That was the problem. Alchemists toiled in sheds all over Holy Wood, screaming at parrots, pleading with mynah birds, constructing intricate bottles to trap sound and bounce it around harmlessly until it was time for it to be let out. To the sporadic boom of octo-cellulose exploding was added the occasional sob of exhaustion or scream of agony as an enraged parrot mistook a careless thumb for a nut.

The parrots weren't the success they'd hoped for. It was true that they could remember what they heard and repeat it after a fashion, but there was no way to turn them off and they were in the habit of ad-libbing other sounds they'd heard or, Dibbler suspected, had been taught by mischievous handlemen. Thus, brief snatches of romantic dialogue would be punctuated with cries of 'Waaaarrrk! Showusyerknickers!' and Dibbler said he had no intention of making that kind of picture, at least at the moment."

All the best,

John

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Truth is almost as strange as fiction:

I found this in The Oxford Companion to British Railway History, edited by Jack Simmon and Gordon Biddle, Oxford University Press 2000 ISBN 0-19-211697-5 page 15. 

https://dl.dropboxusercontent.com/u/40718050/Parrots.pdf 

I am supposing that the parrots and starlings had Scottish accents.

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