Framerates!

February 14, 2012 2:30 PM

Why are old, black&white films (seemingly) always presented sped up to a modern framerate, making them jerky and fast? The explanation I have of that is that they were recorded with a slower frame rate, so if you want to play it on a modern TV, you have to speed it up. But can't we do better than that now?

At least in the computer world, we should have the technology to have variable frame rates, right?

Or use twixtor to interpolate to whatever the native rate is. Obviously the native frame rate might not be pre-given, or even constant, but I imagine you should be able to make a fair approximation. Is there any reason this hasn't been done?

posted by BungaDunga to media & arts (19 answers total)

Yes, that's called telecine. Its how all filmed movies are converted to the faster "video" frame rate. The fast motion sequences you're describing are intended to be fast motion and were shown that way during their time. "Nosferatu" for example, is from the silent era but does not employ this technique and thus is not shown that way today.
posted by modernserf at 2:41 PM on February 14, 2012 [1 favorite]

I'm guessing that when archival footage is used in documentaries, they deliberately leave it like that to evoke "oldness", just as the LP era can be conjured up by adding the sound of vinyl pops and crackles. Have you noticed this on DVDs of actual feature films from that era? I'd be surprised if they didn't adjust those for modern viewing conditions.
posted by Crane Shot at 2:42 PM on February 14, 2012 [2 favorites]

Extremely oversimplified answer follows:

Film is shot at 24 frames per second. NTSC, the US TV standard, and PAL, the EU etc. TV standard, are 60 fields per second and 50 fields per second respectively for reasons arising from the oscillation frequency of AC power transmitted by the electric grid. Thus, to show film content on devices that operate at these frequencies:

24 fps content is telecined (cut into sections with an obvious 3:2 frames/fields pattern) to 60 fields per second, which caused characteristic "judder" in viewing; or

24 fps content is sped up to 25 frames per second, which neatly divides into 2 fields per frame for a total of 50 fields per second.

Undoing the process used in NTSC content is often referred to as "inverse telecine" or "IVTC", and you will hear references too to "PAL speedup" or "PAL to film slowdown".

With modern displays, we enjoy much more flexibility: content on Blu-ray, for example, can be presented at 24 or 23.976fps depending on the real speed of the original film (or digital video recording set up to have a "film" look). This type of presentation is used for various types of content, including "old" films that in the past would have been telecined or sped up for a DVD release.
posted by Inspector.Gadget at 2:42 PM on February 14, 2012 [1 favorite]

Where are you seeing this? If it's an old BW film played within another modern movie or TV show, then it's just a convention (partly deliberate) to portray in a very obvious way that "an old movie is being played", similar to how a lack of a TV signal will be portrayed as "snow on screen" instead of a black screen with NO SIGNAL as all modern TVs actually behave.
posted by wutangclan at 2:43 PM on February 14, 2012 [2 favorites]

Also, if you mean later black and white films, people just talk way faster in those, no camera trickery involved.
posted by modernserf at 2:44 PM on February 14, 2012 [2 favorites]

At least in the computer world, we should have the technology to have variable frame rates, right?

And to answer this, yes! VFR is mostly used in the anime fansub "scene" to allow for high perceptual quality in encoding mixed film-rate and video-rate content (e.g., traditional animation shot at a film framerate and credits produced for broadcast at 60 fields per second). Most other commercial film content is shot on one medium or compatible mediums and thus can be presented at a constant frame rate with no headaches.
posted by Inspector.Gadget at 2:45 PM on February 14, 2012

I think the main reason is that, as you alluded to, most of that footage was hand-cranked and the frame rate varies quite a bit moment to moment. It would totally be possible to use a retiming plug-in to fix it (or at least improve it) manually, but the issue then becomes one of labor. Your standard History Channel filler programming is produced with relatively tiny budgets, and under tight time constraints. Unless you can automate the process, you're going to be spending $30-50/hour for a compositor to use her best judgement, and she's going to be spending quite a bit of time on each piece of footage.

Another hang-up is that, until you've retimed the footage, you have no idea of its duration, which makes it tough to put together an edit using placeholders. You end up having to re-time things first, and then if you end up not using part of that footage, you've wasted money.
posted by balistic at 2:47 PM on February 14, 2012 [1 favorite]

Where are you seeing this? If it's an old BW film played within another modern movie or TV show, then it's just a convention (partly deliberate) to portray in a very obvious way that "an old movie is being played", similar to how a lack of a TV signal will be portrayed as "snow on screen" instead of a black screen with NO SIGNAL as all modern TVs actually behave.

Yeah, this is the sort of thing. I guess I can understand the "oldey timey" aesthetic, but for me the whole appeal of really old film footage is to make things feel less old, not moreso. The question came to mind most recently when I saw this video which pulls footage from a Ken Burns docu.

And when they announced the restoration of a long-lost film of northern Canada, I could swear the timing seemed a bit... off (especially in the bits where they're rowing ungodly fast). Also, deshake the darned stuff. I don't care if the original film is slightly misaligned, if I can deshake my awful handheld shakeycam then you can deshake the judder out of an otherwise static shot.
posted by BungaDunga at 2:55 PM on February 14, 2012

In the time of Edison's kinetoscope (late 1800s), things were really unstandardized. 30, 40, 48, 6 frames a second, you could find it all. In the early 1900s, things got standardized in the U.S. due to vicious patent battles at roughly 16 frames per second. Take those images, play them back at 24 frames per second, and you'll get the noticeable speedup you see in old black and white film.

So yes, it would be possible to make them look normal speed, but that's not what the producers do. In the filmmakers' defense, 16 fps is pretty jerky if played back at speed. Playing it back at 24 at least makes the movement smooth, even if it's fast.
posted by wnissen at 3:14 PM on February 14, 2012 [1 favorite]

Slightly off-topic, but this advice for hand-cranking projectionists of 1914 is interesting:

The picture may be improved by reducing flicker when possible by reducing the illumination....

Flicker may be reduced by speeding up the rate of turning, also. In the case of a picture having the upper part of the screen white sky and the lower part dark foreground, the illumination must be retained to make the foreground visible, and the only means for reducing the flicker is speed.

The sentiment of the picture may be watched and speed may be used accordingly, the operator turning more rapidly where he deems the action of the picture could be improved thereby. The manufacturer should have timed his action when making the picture, but sometimes this is neglected.

This suggests that speeding up the film was a necessary and expected part of the presentation.
posted by Knappster at 3:17 PM on February 14, 2012

Film is shot at 24 frames per second.

That's only been the standard since c.1930, when the ability to maintain an accurate framerate became necessary for synchronizing sound.

The older stuff the OP is referring to was often hand-cranked at around 16 fps, but inexplicably telecined as if it were shot at 24fps. That's why it looks sped up; it is sped up to nearly double its intended speed.
posted by Sys Rq at 3:17 PM on February 14, 2012 [1 favorite]

The "standard" frame rate of old hand cranked film cameras was somewhere around 16 fps. So yes, projecting them on a modern projector at 24 fps causes the "fast motion" effect we associate with "old timey" footage.

On a computer, yes, you could play them back at 16 fps. The motion would then be at the correct speed, but there would be a noticeable stutter effect from each frame being on screen longer than we are used to.

For TV and modern projection you're stuck with 24, 25 or 30 fps for all intents and purposes.

So... on to Twixtor.

Twixtor is great for slowing down already slow footage even further. I just cut something shot on Phantom at 2000 FPS and we were able to slow it down a further 400% because there was so little perceivable difference between each frame that Twixtor was able to interpolate the extra frames it needed to create. You pretty much couldn't even tell. If something is shot at 16 FPS however they difference in data from frame to frame is going to be really extreme and it's going to bug Twixtor out, even with weighted frame blending and the like you start to get all kinds of weird artifacts. And if something approaches the edge of the screen and then goes off you get even weirder artifacts because Twixtor doesn't know how to reconcile that in one frame there was a guy and in the next it was half a head, an arm and a leg.
posted by nathancaswell at 3:19 PM on February 14, 2012 [1 favorite]

(I think I wrote too much, but what the heck:)

Up to around 15 years ago, telecines (film projector specially intended for TV use to avoid flicker) owned by TV stations and libraries and processing houses worked only at 24 frames per second, specially designed to avoid flicker at TV's 30fps (in US).

The telecine machine would blend the frames to stretch 24fps over 30fps. So most video frames include a varying percentage of two film frames. You can see this easily if you go frame by frame on a DVD or VHS transfer which was done cheaply. It looks almost like ghost frames, on most video frames, but not all video frames! Twixtor etc would blur things horribly. (There was also the "Rank-Cintel" video transfer processor which precisely doubled frames and split fields as necessary for video. Using this cost 10x as much and took time at the relatively few facilities that had one. This machine created the "3:2 pulldown" you may see noted on high end DVD players and TVs even now, as they can undo this system precisely, or should.)

Old 16mm or 35mm silent films were usually shot at 12 to 16 fps, but they simply played them at 24fps on the telecine for video transfer. Back in the days of hand cranked cameras and hand cranked projectors in theaters, they were shown at the proper 12 to 16 fps. Or speeded up to move people in and out faster.

The 24fps film (US) standard was settled on for a variety of reasons but mainly because of US 60hz current and the gearing which could be used from 60hz motors. (It is somewhat similar that "78" records are actually 78.26, an industry standard agreed when electrical recording became the standard. Before that, acoustically recorded records might be anything from 60 to 80 rpm.) (The film standard is 25fps UK for similar reasons.) (And the US NTSC TV standard of 30fps or 60 fields per second similarly, or actually 29.97 for color....this can get all tangled up explaining)

There were ways around it to make a proper speed video transfer, but they cost far too much back then. So, much old film that was transferred to video back then is of that 24fps TV type telecine on a 30fps video master. Most TV stations and small libraries don't even have normal projectors or telecines now. Higher end archives do. Much old original film that was transferred to video years ago may not even still exist. There have been many fires in such lower budget archives, even if they thought everything was then safe on video.

For simple documentaries or research purposes, when an old piece of film is requested, it usually comes on an old 24fps-telecine-made 30fps video master. If that older 24fps video transfer is supplied, running that through twixtor or similar programs will only give a lot of blurring.

Working from the original film on a new digital transfer, which captures one frame of film to one frame of the digital file, the new transfer could be run through twixtor very well. But this is hardly done. Generally a new digital transfer from an older frame rate movie is just mastered at the film's original correct speed without twixtor interpolation.

I look forward to someone coming out with a program to regenerate original frame information from these old ghosty telecine video transfers. It could be done, but I don't think anyone has done it. (It is not but would be somewhat related to two existing processes which simulate 60/50 frame per second video from old 24fps/25fps telecine film shot from live TV in the 1950s and 1960s, but that is a whole different story)

There are a lot of ways to proceed for full film restorations, but I think your question is why those old films are still played too fast.

Summary: old video transfers were telecined at 24fps and look "too fast", and those old video transfers cannot be run through twixtor etc very well. A new digital transfer could go in many directions for quality. For lower budget uses, we are stuck with old SD video transfers for a long time to come. A lot of original film is lost or damaged now and can't be newly digitally transferred.
posted by caclwmr4 at 3:21 PM on February 14, 2012 [10 favorites]

David Shepard, for one, has spent a ridiculous amount of time in small editing rooms producing VHS and then DVD versions of historic films. Not sure if he is still around, but the re-tinted Lon Chaney Phantom of the Opera was released on Blu-Ray last year. It is stunning.
posted by Lesser Shrew at 3:30 PM on February 14, 2012

I can't speak to the video transfer or broadcast parts of this (on preview: I think caclwmr4 has that covered!), but I can tell you the facts of the film side of this question.

1: Except in rare cases (usually avant garde or otherwise experimental films), all sound films were shot at and were projected at 24 frames per second. In the silent era (anything before 1927 or so) some things were shot at 24 frames per second (especially later silents), some things were shot slower, and many things were shot, as balistic says, at varying speeds within a single film. Here is a nice essay from Kevin Brownlow on the subject of silent shooting and projection speeds. (FWIW, Brownlow says the 16fps thing is much less true than many sources would have you think - my experiences projecting silents back this up).

2: In modern day projection of silent films from film prints, theaters that are so equipped can physically vary the projector's speed to suit the film (even while the film is running through the projector, if necessary). However, not all film-equipped theaters are capable of this - so if your local art house is doing a Chaplin retro and doesn't have a variable speed motor installed, you'll see the same stereotypical jerky effect you're talking about simply because their projector is "stuck" at 24fps.

3: There are many excellent video and digital transfers of silent films at their "correct" speeds (David Shepard's work - yes, totally), but it is, as you note, common to see transfer speeds that look a little "off" (as in your Canadian example above - which, to my eyes, simply looks like it was transferred slightly faster than it ought to have been). The rigidity of playback speed in digital transfers of silent films is troubling to some of us who screen films for a living for exactly this reason. If it's a film print and we have the right equipment, we can change the projector speed to make it look right or to suit the pace of the musical accompaniment. If it's a digital file (as was the case for the theatrical release of the latest restoration of Lang's Metropolis), it's stuck - there's none of the flexibility of pacing that was originally inherent in the form. It would be cool if future digital video technologies - especially those used for theatrical projection - could retain some of that flexibility. I'm sure it's possible.

Further reading: here is a nice essay about the history of the projectionist's role as a creative actor in silent film, centered around the days when movie projectors were hand-cranked, giving considerable control over pacing to the poor ever-cranking projectionist!
posted by bubukaba at 3:46 PM on February 14, 2012 [3 favorites]

This isn't just about telecine. In Citizen Kane "older" footage in the newsreels was clearly shot at a lower framerate and then sped up to 24fps to give it an authentic look. I don't think you can blame the telecine process on that, since the movie was released in 1941 -- barely ten years from the advent of the sound era, this herky sped up motion was meant to signify "old".

I've read loooong articles by film restoration experts about finding the correct framerates for older movies. It's incredibly difficult as it changes from moment to moment. Many scenes were also intended to be played back at a higher speed for a comic effect.
posted by The Lamplighter at 3:49 PM on February 14, 2012

Hand-cranking and lack of standardization.
posted by Navelgazer at 5:39 PM on February 14, 2012

Kids these days now have such short attention spans that we have to speed up our old silent films to try to keep them from getting bored too quickly. (There is an element of truth to this).
posted by ovvl at 7:39 PM on February 14, 2012 [1 favorite]

As I understand it, the great silent comedians like Lloyd, Keaton, and Chaplin, were well aware of the framerate and deliberately undercranked many of their action sequences in order to have them move faster when projected. "Speed-correcting" these films can be a mistake: sure, it's what the action looked like as it was being filmed, but it's not necessarily what the director intended the audience to see.
posted by Devoidoid at 8:18 PM on February 14, 2012 [1 favorite]