Variable Frame Rates Versus High Frame Rates.

A

androbot2084

Carbonite Member
The real revolution in film making was not 4K but it was the invention of the Panasonic Varicam which for the first time in history allowed the recording of on the fly variable speed frame rate ramping as well as variable speed playback. The result was that a skilful cinematographer could preserve the film look by using a lower frame rate yet preserve the high motion fidelity by ramping up the frame rate for the fast action sequences.

The secret to all this is everything is recorded in a 60 frames per second stream. Lower frame rates are simulated simply by repeating frames. Playback is at 60 frames per second and lower frame rates are simulated by repeating frames. Thus there is no over cranking or under cranking unless the footage is converted.

The result is that the film look is totally preserved and there is no soap opera effect. Yet fast action sequences have better motion fidelity because higher frame rate such as 30fps or 60 fps can be used.

Unfortunately I know of no major motion picture that ever took advantage of this revolutionary technology.
 
Actually it is basically how the tape Varicam worked; it always recorded 60fps no matter what frame rate you set it at, and it used frame duplication to pad out the sequence to fill 60fps. So when set to 30p, it would record each frame twice. When set to 20fps, it recorded each frame 3 times. When set to 24fps, it recorded each even frame twice, and each odd frame three times.

The potential could have existed therefore to do high-action stuff at 48 or 60fps, and the dramatic sections in 24fps, yet deliver it all from one 60p master tape.

The reason it was never done "for films" is because the projection technology didn't allow for 60fps playback, we were still working with film projectors that ran solely at 24fps.

Could you do it today? Certainly. You can use today's 1080/60p cameras and film action stuff in 60p, and drama stuff in 24, and output it all in a 1080/60p sequence and gain basically the effect of switching timebases in one program. But you'd still have to find a way to deliver 1080/60p -- or convert it to 720/60p or 1080/60i for broadcast or blu-ray or to SD for DVD delivery...
 
Perhaps I'm getting a little intent-confused here...

I took the original post to mean in one shot, you could have 24p cadence for dialogue then some action happens and you ramp to 60p for clearer motion (live football) and then back to 24p for that calm moment before it all happens again. Everything playing in realtime.

I came into the industry right when the Varicam was a hit but only used it in a 23.976fps timebase sense... Forgive me if I've spoken wrongly. Would like to know the answer though.
 
You could actually do that, yes, it did have frame ramping, and it's all recorded in 60p... Offhand I don't remember if you could frame-ramp back down to 24fps when you were done?
 
Sorry, I don't think the 3:2 pull down conversion of 24f to 60f looks "cinematic" at all. It is a broken cadence. I'd rather see higher frame rates or true 24.
 
Razz16mm said:
Sorry, I don't think the 3:2 pull down conversion of 24f to 60f looks "cinematic" at all. It is a broken cadence. I'd rather see higher frame rates or true 24.
Click to expand...

So, every movie you've ever watched on television/VHS/DVD (until quite recently) had a "broken cadence" and didn't look "cinematic" at all?
 
I might seem delusional here, but I get the feeling that the OP androbot2084 just posts this stuff to get a reaction and sits back to watch the DVXuser community bicker back and forth over his posts.
 
David Jimerson said:
So, every movie you've ever watched on television/VHS/DVD (until quite recently) had a "broken cadence" and didn't look "cinematic" at all?
Click to expand...

Not necessarily. 3:2 pulldown conversion is just particularly annoying. 24f has enough issues with motion stutter and flicker without giving it a limp too. :cool:
I consider cinematic qualities to be a more a product of what you do in with and in front of the camera: Exposure, Lighting controls, production design, composition, movement, than anything specifically connected with a frame rate. I used to shoot industrial videos on 16mm film at 30fps to get a frame for frame transfer. I'd rather watch 30fps anyday than 24fps 3:2.
 
Razz16mm said:
Not necessarily. 3:2 pulldown conversion is just particularly annoying. 24f has enough issues with motion stutter and flicker without giving it a limp too. :cool:
I consider cinematic qualities to be a more a product of what you do in with and in front of the camera: Exposure, Lighting controls, production design, composition, movement, than anything specifically connected with a frame rate. I used to shoot industrial videos on 16mm film at 30fps to get a frame for frame transfer. I'd rather watch 30fps anyday than 24fps 3:2.
Click to expand...

Every 24 fps movie (or TV show) you've ever watched on a 60 Hz screen -- interlaced OR progressive, whether from the air, from VHS, from DVD, even from Blu-ray (heck, even 24p video on a computer screen with a refresh rate of 60 Hz) -- has had a 3:2 pulldown in it.
 
David Jimerson said:
Every 24 fps movie (or TV show) you've ever watched on a 60 Hz screen -- interlaced OR progressive, whether from the air, from VHS, from DVD, even from Blu-ray (heck, even 24p video on a computer screen with a refresh rate of 60 Hz) -- has had a 3:2 pulldown in it.
Click to expand...

I am well aware of that. My current TV has a 120Hz refresh and true 24p mode for Blu-Rays. You still get pulldown on broadcasts though. The visual discontinuity for me is more evident with current film styles that have a lot of camera movement, quick cuts and fast action. But then the whole love affair with 24f is about discontinuity IMO.

The industrials I shot at 30f on film for TV were mostly marketing films for production line bottling and packing machinery with lots of fast rhythmic mechanical motion cut to jazz soundtracks. 24f was too discontinuous to work well for that. Telecines were projectors so for 24f, pulldown was a mechanical cadence of the projector mechanism, not like modern digital tools at all. You get one frame for two interlace fields, then one frame for 3 fields so the 3rd video frame was made up of fields from two sequential film frames. Progressive video did not exist.
 
Last edited:
Razz16mm said:
I am well aware of that. My current TV has a 120Hz refresh and true 24p mode for Blu-Rays. You still get pulldown on broadcasts though. The visual discontinuity for me is more evident with current film styles that have a lot of camera movement, quick cuts and fast action. But then the whole love affair with 24f is about discontinuity IMO.

The industrials I shot at 30f on film for TV were mostly marketing films for production line bottling and packing machinery with lots of fast rhythmic mechanical motion cut to jazz soundtracks. 24f was too discontinuous to work well for that. Telecines were projectors so for 24f, pulldown was a mechanical cadence of the projector mechanism, not like modern digital tools at all. You get one frame for two interlace fields, then one frame for 3 fields so the 3rd video frame was made up of fields from two sequential film frames. Progressive video did not exist.
Click to expand...

I was never impressed with 24f, but that's a problem with 24f, not with 3:2 pulldown. I don't think Canon ever quite revealed how exactly 24f worked, but it was creating a simulated "24p" out of interlaced CCDs, so it was something in ITS processing which caused the problem.

As for "the visual discontinuity for me is more evident with current film styles that have a lot of camera movement," well, that's probably a matter of poor 24 fps camera movement. It doesn't have anything to do with the 3:2 cadence. If it did, you'd always see it, in every movie, in every (dramatic, at least) TV show. Heck, in almost every commercial.
 
androbot2084 said:
With variable frame rate ramping if one wishes to avoid pulldowm 20 fps, 30 fps or 60 fps can be chosen.
Click to expand...

20 fps and 30 fps will both have pulldown. Pulldown isn't just a 24p thing. It's what you need to do any time you want to display any slower frame rate within a faster frame rate. The pulldown is the repeated frames.

If you want to show 30 fps over-60, then it's a 2:2 pulldown. If you wanted, for some reason, 20 fps to be played back in real-time over-60, then it would be a 3:3 pulldown. (Though I can't imagine why you'd want 20 fps; if you think 24 fps is stuttery, that would be noticeably worse.)
 
20 frames per second would give you more of the traditional film look because before sound was invented movies were filmed at a slower frame rate than 24 fps. 30 frames per second will give you higher motion fidelity while still preserving the film look. 60 frames per second is good choice for the action shots and still preserves the film look because the film look is always relative to the amount of motion between each frame.

The result of using variable frame rates is that the film look is preserved without destroying motion fidelity.

Of course half of the spatial resolution will be lost because the movie will have to be delivered in the Blu-Ray 720p format. However the increased motion fidelity will add sharpness which will help make up the loss of spatial resolution
 
Why would the spatial resolution be lost? That would depend on what you shoot; the original Varicam was 720p.

It's when you have more motion that you notice more of a difference between frame rates. A lot of motion at 60 fps will look distinctly live; the "film look" will be lost.

30p is fine if it's what you like, but it's not 24p and doesn't look like 24p.

20 fps will not have the "traditional" film look; it'll have more of a "Keystone Kops" look.

Look, if you don't like 24p, that's up to you. But most film enthusiasts do.
 
But what is the betting mans choice for the future? Today most film makers choose 24p with the exception of Doug Trumbull, George Lucas, James Cameron and Peter Jackson who want to revolutionize the film industry with higher film rates. So far their revolution has not been successful because of the soap opera effect.

As far as the future is concerned it does not matter which format is popular today but which format will preserve the film look while at the same time preserving a reasonable amount of motion fidelity?

And it could very well be true that even with fast action 60 frames per second could generate an undesirable live look. The solution to this problem is to choose a slower frame rate . What it boils down to is that frame rate becomes a creative choice.

I suppose a cameraman could just follow orders and shoot everything at 48p because that is what the director Peter Jackson wanted. But this does not really do him any service if the movie ends up getting panned.
 
You must log in or register to reply here.
Back
Top