Frame Rate Ramping?

[Jeff Kilgroe]

I thought it was mentioned before, but I can't seem to find it now....

I'm assuming that frame rates can be ramped up or down while shooting and I just wanted to clarify that this is the case. Also, how do the controls for this work and is there a way to program a ramp or jump in FPS so it can be easily repeated? I just haven't seen any controls like a dial on the RED One camera renders and I would assume it's all done by pre-defined settings in the user menus and then pressing one of the function buttons to ramp up/down.

..Or am I just dreaming and this isn't a feature we're getting with the RED One???

[CVB]

Jeff, I'm fairly certain that that will be supported. I recall someone from RED saying that it is possible.

[Jeff Kilgroe]

I recall someone from RED mentioning it as well... I just can't seem to remember when or where it was mentioned, so I was hoping for some clarification on the matter. :)

Even if it's a capability that relies on external control or interface via a RED SDK or set of API functions, that would be fine. This is just something that I would like to be able to do with RED and this has been my main reason for renting a Varicam for a few projects -- rampable frame rate.

[Alex Boothby]

I seem to recall that Stuart confirmed this at one point - and RED also mentioned a couple of trigger buttons on the camera smart side (bottom right) to trigger more complex camera operations (I think...)

Unfortunately it now occurs to me that the likely exposure compensation method for a digital intervelometer will be shutter speed, and not aperture. That means that when we switch from slow motion to fast motion, the motion blur will reduce, resulting in a narrow shutter look. Shutter speed compensation seems to be the only realistic method, without an external mechanism to rack aperture on the lens in synch with fps (or an intelligent ND system :) ).

If this is true I think I will probably be doing my ramping in post.

[Corrado Silveri]

I think the best way is to shoot all the sequence at the maximum frame rate that you need.
And do the ramp in post.
It's a lot better (you can choose the in/out point of the ramp, speed, curve, etc...)
More secure (you don't make any mistake during the shooting).
More... confortable.

just my two cents.

[Jaime Vallés]

I think the best way is to shoot all the sequence at the maximum frame rate that you need.
And do the ramp in post.
It's a lot better (you can choose the in/out point of the ramp, speed, curve, etc...)
More secure (you don't make any mistake during the shooting).
More... confortable.

just my two cents.

Definitely. Shoot at the highest rate (60p), and then you can speed up whichever parts you need faster ad nauseum.

[Nikolai Vavilov]

Crazy idea -)
If we have an option to precisely and smoothly manage sensor sensitivity (like on digital photo cameras, but with more short step), combined with frame rate ramping some kind-of-magic tricks will be possible to do.
For example: You're start shooting night road filled with traffic on 2fps with iso rating 10, with nice tail lights and blured cars, and when the desired car is approaching you made a smooth ramp up to 60fps, and the ISO rating increased due to exposure time of each frame, to ISO 320. Real time-stretching, absolutely impossible to do with film... but with RED - who knows)

[Jeff Kilgroe]

Definitely. Shoot at the highest rate (60p), and then you can speed up whichever parts you need faster ad nauseum.

...But that wouldn't nedessarily produce the desired effect. I'm hoping to be able to set the shutter speed/angle relative to a given frame rate, sensitivity, etc.. As the frame rate is altered, so are those other settings to keep motion looking smooth and the frame rate change becomes imperceptable to the viewer, the motion on screen just appears to slow down or speed up at the intended rate. Simply shooting at 60p and slowing it down in post wouldn't create the proper temporal blur or motion properties. This is why the Varicam allows for ramping up or down while shooting. ...Sorry it's late and I'm having a bit of trouble getting this explaination to flow the way I want.

Also, shooting at 60p isn't necessrily the direction I'd want to go... Perhaps I'd want to ramp from 30fps with a 180 shutter / 50% blur to 6fps with the same exposure time over a period of 3 seconds. This shot played back at 24fps would start with a subtle slow motion and increase to 4X normal speed all while keeping the same temporal motion and blur properties... Simply shooting at 30p or 60p and changing the fps rate in post would just look like someone changed the frame rate in post. Not what I'm after...

I think Nikolai understands....

[J. Bernard Vallon]

i definitely think that ramping the frame rate is going to be something that happens in post in the future. In the same way that no one would "fade to black" in camera anymore, frame ramps will go the way of FCP.

However, if your going all the way from time lapse, 5fps to slow, 60fps, you might actually be better suited to shoot twice, once at 5 and once at 60, and see if you could fake it. (slow fade between the shots or something. i'm thinking it would be pretty smooth) Thats only if RED doesnt support frame ramping.

[Jeff Kilgroe]

OK, I remembered where I read it originally. HDforindies.com, the interview with Graeme and Stuart back in November. Well, Here is the link. (http://www.hdforindies.com/2006/11/hd4nds-exclusive-big-red-update-part-2.html)

So, what does the RED team have to say? is this still the plan?

[Jochen Schmidt-Hambrock]

i definitely think that ramping the frame rate is going to be something that happens in post in the future.

But then you´d have to motion blur each moving object in each frame separately (and differently), right?

Jochen

[Corrado Silveri]

Sorry guys.
Tell me if I'm wrong:

Higher frame rate = higher shutter speed = less motion blur

I think that during the speed ramp usually you don't want to change focus, aperture, zoom.

So, if you ramp up the speed in post you have to add an extra motion blur when the speed is up.

The "extra" motion blur must be added with the same curve of your speed ramp.

And that's it.

I remain at the same point.
Add the ramp in post is more secure, confortable, bla bla...

[Nikolai Vavilov]

Elcurado, can you show me example of timelapse shoot on 60 (or even 24)fps with speed-up and motion blur applied in post? Are you shure it looks same like true 2 fps shoot with 1/2 sec. exposure?

We don't want to change focus, aperture, zoom during the ramp - we want to change shutter speed and sensitivity (iso rating).

[ColinSmith]

You could shoot at 60p with a 360 degree shutter and then blend frames in post to get any effective exposure time / shutter angle / frame rate below those (limited only by how the numbers divide)

[Corrado Silveri]

Elcurado, can you show me example of timelapse shoot on 60 (or even 24)fps with speed-up and motion blur applied in post? Are you shure it looks same like true 2 fps shoot with 1/2 sec. exposure?

We don't want to change focus, aperture, zoom during the ramp - we want to change shutter speed and sensitivity (iso rating).

Give me the time to find those shots.
And I will be happy to show you the work done.

[Dominic Jones]

I much prefer doing speed alterations in camera than in post. In post you get the extra "safety" factor, but it is not possible to do smooth ramps in the same manner as a live frame ramp can achieve, unless you're shooting at horrific framerates or interpolating frames (one is not possible with this camera, and the other is never desirable, imo).

The problem is that the intervals between frames will not fall at the same place when shooting say 38fps vs 60fps, so pulling 38fps from a 60fps file in post you will always have to settle for either a non-linear motion cadence or interpolated frames.

You can only do quality time-remaps when the destination framerate is a factor of the originating framerate - e.g. pulling 20fps from 60fps is fine, as is 30 fps from 60fps. 38, 42, 23, or any other non-factorial of the base-rate (a max of 60 in this instance) is not. As ramps necessarily go through a wide range of narrowly separated framerates, it's not great to do in post, unless you've got an immensely high (and very well selected) base framerate, as mentioned before.

This is on top of, and independent to, any motion blur issues...

That's why people are so exited about getting variable framerate digital cinema cameras - a flat 60fps doesn't help all that much.

[Antoine Baumann]

Hi guys, I have a shot @25 fps, playing @25 fps and I like to speed it, to approximately 2/3, so probably 18 fps (playing @25 fps) how would be the best to do that.

Thanks,
antoine.

[Stuart English]

Re "Higher frame rate = higher shutter speed = less motion blur" Generally true with a mechanical shutter (film) camera, but not with RED.

Why? In a film camera the exposure time is set by a spinning shutter blade. As it rotates faster, the exposure time will be reduced - unless you can also change the angle of the shutter blade during the speed ramp.

With RED, the exposure time adjustment is electronic. It can be adjusted on a frame by frame basis if desired. But in a speed ramping case we ideally want the per-frame exposure time to remain constant as the frame rate changes up or down.

There is no conflict at all until such time as 1 sec / frame rate < exposure time. At that point the frame rate is forcing the exposure time to be less than desired.....

[Dominic Jones]

Stuart,

Good to hear that the exposure will be compensated as much as possible - just one quick question:

Will this feature be disable-able (now that's great English, isn't it!)? I'm just thinking that if you wanted to get beyond the in-camera compensation barrier (and therefore needed to pull aperture with the ramp), you might well decide (I probably would, for instance, if I were AC'ing the shot and the DP didn't mind) that you'd prefer to pull aperture the whole way, rather than trying to catch and match speed with the cut-off point, which might be tricky to do smoothly.

Just a thought...

[Nikolai Vavilov]

Dominic, manually pulling aperture during ramp is very tricky, I think even impossible to match. My idea was to match _sensor sensitivity_, not aperture with increasing/decreasing shutter exposure values during the ramp. Purpose of trick is to get "motion-freeze" effect, smoothly going from strong motion blur to sharp and clear slow-mo.

[Nikolai Vavilov]

Give me the time to find those shots.
And I will be happy to show you the work done.

Thanx, Elcurado.
I'll be happy if you find one

[Mike Devlin]

I have to agree with Elcurado that ramping in post is the only way to go, although some of that may be the type of shooting we do.

When you are shooting whales breaching, sharks taking prey, bears tussling over spots to catch salmon, etc there is no way you can be messing with "in camera" ramping and such while everything is happening unscripted in realtime. We usually shoot 60P with a 24P timecode (Sony HDC1500 with SRW1 HDCAM SR deck with cache board, great combo). We have found that we often have to experiment with the right shutter speed for different kinds of subjects by shooting some footage and doing a quick edit (with effects) in the field to see how it looks. That is why we usually have an Avid Media Composer setup with us in the field.

In post there are infinitely more options to choose what and when you ramp. Plus you can use the same shot for freeze frame (requires fairly fast shutter depending on subject and light and how crystal you want the shot to be), slow motion, realtime, etc. With modern post tools (Avid for sure) you can add whatever motion blur or other effects you want. You can produce great looking shots that people love.

Purist can argue about whether it looks filmic, I want a shot that looks great and captures both the action and the emotion I am trying to communicate (better than filmic!). That is why it is encouraging that the RED team is focused on both a great camera and a great workflow so we can produce the images we want with the full power of digital technology.

[Stuart English]

I guess that my point is that with an electronic shutter, there isn't any exposure "compensation" to perform. Exposure just IS. You set the value and forget about it until such time as the frame rate forces the frame time to be less than the desired exposure time...

If you wanted to also adjust aperture, then I'd suggest driving the camera and a high precision lens motor from an external P.C based controller.

If, on the other hand the purpose of the ramp is to achieve a motion blur change, then two alternative modes could be entered into - a) constant shutter "angle" or "%" - this makes the exposure time track the frame rate, which mimics a mechancial shuttered film camera, - or b) exposure ramp - drive the exposure time from an external P.C based controller and also have that controller drive a motor on your lens so that exposure stays constant.

As for adjusting sensor sensitivity, the nett effect is exactly the same as applying a frame-by-frame variable "push" on the RAW footage in post, so its probably best done there ... RED's noise floor is so low its got lots of headroom to be exploited.

[Dominic Jones]

Dominic, manually pulling aperture during ramp is very tricky, I think even impossible to match. My idea was to match _sensor sensitivity_, not aperture with increasing/decreasing shutter exposure values during the ramp. Purpose of trick is to get "motion-freeze" effect, smoothly going from strong motion blur to sharp and clear slow-mo.
Sorry, I was not really discussing the same issues as you, simply putting a question to Stuart - although I agree adding sensor sensitivity into the auto-adjust equation is a good idea...

Matching ramps with aperture pulls certainly is very tricky, but certainly not impossible. Indeed, on a fair few 16mm and 35mm cameras it is the *only* way to keep a constant exposure whilst ramping speed, and bear in mind that cine lens apertures are geared for attaching to a follow focus mechanism (as opposed to SLR lenses) with a smooth, moderately long throw for exactly this kind of thing - my point was that I think it *will* be damn near impossible to smoothly transition from an auto-adjusted ramp to an aperture pull, if one needed to - hence the ability to turn off the feature in the (albeit rather rare) circumstances that you wanted to - no disagreements with your points though, just a bit of a separate issue!

[Dominic Jones]

When you are shooting whales breaching, sharks taking prey, bears tussling over spots to catch salmon, etc there is no way you can be messing with "in camera" ramping and such while everything is happening unscripted in realtime.
Ah yes, well now *that* is a different situation!! I'm thinking in drama terms, but I quite agree with you that in your situation ramping in post is most certainly the only way to go. :)

Bear in mind though, that that's probably a minority application for Red shooters (or maybe it's not??)...

[Jeff Kilgroe]

For shooting wildlife or other live, unscripted type stuff, I agree with Mike and Elcurado that ramping in post is the only way. But it's nice to have the option of a controlled, repeatable ramping ability in-camera. Lots of situations where that can be handy and produce the filmic effect not always possible with a ramp in post.

[Dominic Jones]

Here here - great to have both options finally, and the choice of which to use in the situation you find yourself in.

[Corrado Silveri]

Thanx, Elcurado.
I'll be happy if you find one

Nikolai,
just a test:
Please notice (apart from the quality of the speed ramp / and of the shot himself) the amount variation of motion blur.

Varicam 720p60 - Speed variation with Shake.

http://idisk.mac.com/elcuradin-Public/Test_out_2_H264.mov.zip