Since DCP is 24fps, why not shoot at 24fps?

[Daniel Stilling]

It just means that in the course of 1 second, you would have 23 frames and a fraction of the last, so you would have 24 frames in a second and a few milliseconds.

 

[Sabovic Adis]

Slightly off topic I'm sorry, but can someone help me understand how in progressive capture, where 1 frame is 1 frame, you could have a 23.98FPS?

If 1 frame is 1 frame how do you get .98ths of a frame?

I'm sure there's something simple I'm missing, but any help would be appreciated!

Thanks!

EDIT: P.S. And how is that effected by a rolling shutter vs global shutter?

What .98ths of a frame? :smile5:

24 FPS means a frame every 0.0416666666666667 s (1 : 24 = 0.0416666666666667).
23.976 FPS - a frame every 0.0417083750417084 s (1 : 23.976 = 0.0417083750417084).
That's all.

 

[Marc Wielage]

So if we are making film then we should always be 24p? Unless perhaps it might be broadcast on TV, then it becomes trickier and we need to decide between 24p and 23.976?!

I would ask the distributor or broadcast channel what standard they want, and do what they ask. Get it in writing, and make sure all departments are aware of what that decision is.

If you don't have a distributor, then my advice (wearing my post sup hat) would be to shoot 23.976 because it's a very well-known workflow that everybody understands. The normal delivery standards for Discovery, HBO, Showtime, Amazon, Netflix, and all the major networks are out there. Pick one and stick with it.

If you shoot at 24.00fps, sound can be at either 24.00F or 30.00NDF TC. As long as it's an integer framerate, you can always apply the .1% pulldown to sync it up for TV if you had to. If the edit system is running at 24.00fps, there won't be a problem. I would be concerned about sound stock footage at 23.98 or B-roll footage or second-unit crews that may go off and shoot at their normal framerates. I have been part of shows where other crews have shot material "wrong" (at least, wrong framing, wrong framerate, wrong timecode), which led to problems once that material was incorporated into the main show.

 

[Marcus Friedlander]

It just means that in the course of 1 second, you would have 23 frames and a fraction of the last, so you would have 24 frames in a second and a few milliseconds.

So the 24th frame will incorporate a tiny piece of second number 2? And so on, and so on?

That makes more sense.

So hypothetically, if you shot for long enough, the difference between 23.98 and 24 could lead you to recording a full "second" later?

 

[Marcus Friedlander]

What .98ths of a frame? :smile5:

24 FPS means a frame every 0.0416666666666667 s (1 : 24 = 0.0416666666666667).
23.976 FPS - a frame every 0.0417083750417084 s (1 : 23.976 = 0.0417083750417084).
That's all.

This actually helped a ton!!!!

By phrasing it that way, it makes a lot more sense! Thanks!

 

[Marcus Friedlander]

Wait a sec, hold on, if it takes 0.0417083750417084 seconds to capture a full frame, then what happens when you cut in the middle of the progressive capture? So you've only done .02 seconds instead of .04 seconds? What happens to that last frame? Where does the data come from for the last half of pixels? Or does the camera always finish the frame it's on no matter when you press cut?

 

[David Battistella]

A frame is a frame. It's the timebase that varies. 24 frames is 24 frames. The timebase determines how they are played back. You can play 24 frames in a 29.97 timebase or a 24 frame time base (with pulldown) or in a 23.98 timebase. The camera still captures every frame.

Film is 24 unique frames per second, the RED works exactly the same way as film.

 

[Sabovic Adis]

Wait a sec, hold on, if it takes 0.0417083750417084 seconds to capture a full frame, then what happens when you cut in the middle of the progressive capture? So you've only done .02 seconds instead of .04 seconds? What happens to that last frame? Where does the data come from for the last half of pixels? Or does the camera always finish the frame it's on no matter when you press cut?

:rofl:


.02 sec means 48 FPS. :biggrin:


E:
Plus, what David said. :thumbsup:

 

[David Battistella]

No. That is the short answer. See the other post.

So the 24th frame will incorporate a tiny piece of second number 2? And so on, and so on?

That makes more sense.

So hypothetically, if you shot for long enough, the difference between 23.98 and 24 could lead you to recording a full "second" later?

 

[Marcus Friedlander]

Thank you all for putting up with me because I feel like an idiot with how much trouble I'm having over this!

So I get that in progressive capture, a frame is a frame
And I get that 24 frames is 24 frames
And I get that 24 frames played at 24fps is one second.

But I guess the question I'm really asking is, in a progressive capture rolling shutter system, what happens when the sensor is half way through it's read cycle and you press cut?


P.S. Sabovic math is not my thing first thing in the morning... or at any time of the day now that I think about it hahahahaha

 

[M Most]

I would ask the distributor or broadcast channel what standard they want, and do what they ask. Get it in writing, and make sure all departments are aware of what that decision is.

If you don't have a distributor, then my advice (wearing my post sup hat) would be to shoot 23.976 because it's a very well-known workflow that everybody understands. The normal delivery standards for Discovery, HBO, Showtime, Amazon, Netflix, and all the major networks are out there. Pick one and stick with it..

This is true only if you happen to be in North America. In nearly every other part of the world (with a very few exceptions) the requirement would likely be 24fps for theatrical features and 25fps for broadcast. The point is this isn't a "personal choice." It's part of a delivery spec that is supplied by whatever entity you're working for.

 

[David Battistella]

Marcus.

It finishes the cycle and writes the frame. We are talking milliseconds here. It's finishes the cycle and writes the frame to disk. No half frame or partial frame gets written to the card.

David

 

[Björn Benckert]

You have always understood something that is incorrect. Drop frame has nothing to do with the frame rate. It is a numbering scheme that was devised to make time code accurate to real time, and was developed for 60 field systems. The fractional frame rate came into being when color was introduced, and it was necessary to multiplex color images and sound on one carrier. The combination of frequencies prevented this from being done at 60 fields per second, so because of various mathematical necessities, the rate was slowed down to approximately 59.94Hz. The 23.976 came about years later when 24 frame video recording was introduced in HD cameras. This was done by using the same fractional slowdown as 60 to 59.94, making it simple to fit the "24" frame material into a 60 field broadcast world. Today, it is a legacy that is maintained by the needs of broadcast, but also by the rather entrenched infrastructure that was created around it, for both picture and perhaps more significantly today, sound in North America and some other territories.

Now that the history lesson is out of the way, 24 fps recording is widely used in feature work today. There are a few studios that are now mandating it (Fox and Universal), and essentially all post production companies can handle it as long as all production personnel, the producing studio, post sound, and editorial are all on board. We and most other companies involved in feature post production deal with it every day. It's not really a problem at all. You will not, however, encounter it in broadcast production for all of the reasons I just outlined.

You are talking about the states. The rest of the world try to stick to even numbers 25p is used for most drama both cinema and TV even though some films are shot in 24p

Question that you might have the answer to: What flickers first. 24p or 23.968p when being on 120V60Hz lights? Possibly none but if increased frame rates, for example if over cranking does 48fps or 2x23.976p start to flicker one before the other? As I run into quite a few problems trying to shoot 25p in the states I assume 24p will be more likely to flicker than 23.97p, no? As of interference with the phase in the electricity especially if you go down in extremely short shutter?

Edit did not see your post about 25p above until after writing the above.

 

[Marc Wielage]

This is true only if you happen to be in North America. In nearly every other part of the world (with a very few exceptions) the requirement would likely be 24fps for theatrical features and 25fps for broadcast. The point is this isn't a "personal choice." It's part of a delivery spec that is supplied by whatever entity you're working for.

Well, I did start off by saying "I would ask the distributor or broadcast channel what standard they want, and do what they ask. Get it in writing, and make sure all departments are aware of what that decision is."