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Old June 14th, 2004, 01:22 AM   #1
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Mixing frame rates

Hi all,

I am putting together an action scene with slower stuff, and was wondering if I am able to mix all the frame rates (24, 30 and maybe 60i) in Premiere? There are slow-mo stuff, then speed up again, like in the Matrix style of cine.

The reason I am asking, is because I've noticed in movies like the matrix, there is a disctinct lack of strobing, which leads me to believe that they did not film the movie at 24, but a higher frame rate, then changed it later.
Anyone know what frame rate did they typically used?
I know they did some high frame rate filming for alot of fights (120p), but how did they mix it all together, and can I do the same with Premiere?
Thanks!
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Old June 14th, 2004, 03:46 AM   #2
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Yes, if they want to do slowmotion with film they just shoot it at
a higher framerate (48 fps or higher for example). In the case
of The Matrix they also used high speed still camera's to capture
the bullet-time going around effect.

So you can only shoot at one framerate there is no mixing of
framerates in Premiere. If you had movies with different frame
rates then, sure, you could mix these. It will probably not look
that great, though.

It is very hard to do convincing slow-motion with our 24/30 fps
acquired footage. Whether or not Premiere can do a good job
of that, I don't know. Most people here seem to stay away from
real slow-motion (sometimes a slight slow motion effect will work
more easily) and effects such as you describe.

Is there a real reason you want to do this? Keep in mind that
all of the Matrix effects have been copied and imitated to death
already and a lot of people dislike them for that reason.

If possible it might be far easier to do the scene in another
fashion or come up with some other cool idea you can more
easily do with the limited tools we have.
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Old June 14th, 2004, 12:37 PM   #3
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Hi Rob, thank you for the reply :)
So Premiere can only work with one framerate on the timeline per video? Hmmm...
How about after effects? Or Vegas?

Yes, there is a very real reason why I need to jump from a 24p "look", but still be able to slow it down periodically and have it look good.

In order to acheive a very realistic "film look" with DV, I really need to film 24p with my dvx100, and not 30p. However,
for a fight scene with fast action, and some slow effects, I hope there is no reason why I should have to be stuck with 24p for those segments, because hollywood movies (and some television M.F.T.V movies) mix frame rates often enough to avoid the motion blur which articulates the movements better. That's what I'm hoping to do..

Actually, the matrix comment was just an example...I am not imitating the matrix at all :) (no bullet-time) it was an example of how they jump from a 24p "look", to a high clarity/high frame rate "look" all bunched together in the same movie but is transparent to the viewer.
There must be a way to do this because hollywood does it all the time, and I am essentially trying to figure out how I can do this in Premiere with my dvx. Or even Vegas or After Effects. Unless that is a limitation of Premiere possibly or off the shelf NLE's in general?
So in summary, any idea how to jump from 24p "normal" scene, to a high-action "30p" scene in Premiere?
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Old June 14th, 2004, 01:09 PM   #4
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I did not say that Premier will not support multiple framerates.
It will support video's with different framerates (I assume), but
it will convert them all to one framerate (the framerate set in
your project or the setting used when exporting).

But that should not be a problem since you seem to want to
slow down the faster footage.

If you edit in 24p I would start a new project and load up the
30p footage and convert that to 24p (thus slowing it down) and
then load the converted footage in your main 24p project.

This will allow you to more easily work on the effect and do not
have to worry about messing up settings lateron.
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Old June 14th, 2004, 01:52 PM   #5
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Vance,

Much of what is possible for a Hollywood production house is possible because of VAST ammounts of money, time , talent, rendering speed and MONEY. (Yeah, I said money twice.)

I am not real clear on what you are trying to achieve. By different frame rates in the timeline... do you mean you want the final product to playback a varying speeds??? I don't know of any deck that would do that "automatically".

Remember. Hollywood movies (U.S.) ALWAYS play at 24 fps. That's what they are projected at in the theatre. (In the US). So, even if they shoot something at say, 120 frames per second... when they edit and print it, they are still working with it in 24 frames per second... five times faster shooting results in 1/5 the speed in playback.

The DVX100 will shoot in 24 or 30. As far as I know, there are no consumer or even "prosumer" cams that shoot at "high speed" to render slow motion. Some of the big HiDef cams do... but still not as high as film cams.

When you ask an NLE to create a slow motion effect, it simply duplicates extra frames/fields (Depending on the NLE and the options offered) to make up the difference and stretch out the time.

In that sense, they all handle "different frame rates".
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Old June 15th, 2004, 11:56 PM   #6
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Hmmm... okay, let me approach this from a new angle, because I think I'm not explaining myself correctly, which I apologize if that's the case.

This is all about mixing frames shot at different times on the same timeline without looking wacky.
Could be 24p with 30p, then 120p with 24p.. just diffent footage at different frame rates, all working properly on the same timeline.
I've never done it yet, so that's why I am asking this.
To help clarify what I am up to in a different way: Let's say I am filming two people talking. 24p will suffice since there is not alot of movement. So, here I am filming that sequence at 24p...this is the first footage I would import into premiere.
Now let's say there is an explosion, or a fight breaks out with fists flying..basically very fast motion is occuring.
Let's say I want to film the fast motion with a higher frame rate so there is less motion blur; thus, 30p is my next option on my dvx100 (if I had a faster cam, then let's say 120p).
I find "stills"and "slow-mo" to be much more acceptable at 30p than at 24p for fast action.

Here's my problem: How do I transist filming two people talking at 24p, to suddenly jumping to 30p for the explosion or a fist flying, and making it look seamless?
Is there a technique for it to make it flow properly on the same timeline?

Richard: Just curious, but what is the method for fitting in 120fps into 24p?
Doesn't it have to drop frames to fit? Not sure how that's done..

On the same token, I had once mixed 60i (from a sony) with 24p footage from my dvx.. and the 60i had a very choppy look to it compared to the 24p shots. The 60i had an almost like a "black hawk down" fast shutter frame look to it. Why is that?


Thanks guys :)
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Old June 16th, 2004, 03:54 AM   #7
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That is because the application is doing framerate conversion
(which I'm not sure off how well Premiere will do this). I've
explained all your questions already, but let me break it down
for you:

1) Any (most?) NLE I know off supports one framerate at the
timeline. This usually follows your project settings. So if you
setup a 24p project the NLE will convert your 30p footage to
24p removing 6 frames every second.

2) With this in mind you should NOT mix different framerate
movies on the same timeline because it will get you into
trouble as you already experienced.

3) The solution is working with in one framerate and convert
everything to the other framerate.

I'm assuming that 50 - 75% of your movie will just be plain
24p speed footage. So this is what your main project wants
to use etc.

How to convert the rest of the footage to 24p is a question I
don't have a correct answer off. It will also depend highly on the
software you have available and whether a 20% slowdown is
enough or not (playing back 30p as 24p).

In some NLE's you may be able to change at what rate the file
is played back (so you can have a 30p file playing back at 24p
which is a 20% slowdown) instead of it being converted to 24p
in which 20% of the frames are dropped and the playback speed
remains normal instead of slowing down.

So what you are looking for is a way to slowdown that footage
20% or more and render that out to 24p. Then integrate that into
the rest of your project.

In this way you can also solely work and focus on the slow-motion
until it looks good. Then you can simply cut it as usual with the
rest of the footage.
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Old June 16th, 2004, 03:08 PM   #8
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Ah, okay, that makes sense!

Last question; on an actual dvd, can you have one title (video clip) be 24p, and all the other titles 30p with no problem?
Ever tried that by any chance?
They aren't on any "timeline", but are separate clips rendered out at two different framerates, for two different looks...can that work?
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Old June 16th, 2004, 04:21 PM   #9
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I haven't ever tried that, so I don't know. I would suspect this
will work. Whether or not it is legal within the DVD specs, I don't
know. You can always try it out.
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Old June 16th, 2004, 07:19 PM   #10
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Okay, thanks Rob :)
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Old June 16th, 2004, 08:03 PM   #11
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Vance,
The 120 fps doesn't "fit" into 24fps... that's why it's in slow motion. IN order for your explosion to look "Normal" when you project it, the projector would have to project at 120 frames a second.

Slow motion is manufactured by increasing the number of frames exposed WHILE FILMING a scene, and then playing the footage back at the normal rate. THus to get slow motion, you shoot more frames per second than you project/play. The converse is true for fast motion... you slow down the frame rate while shooting, and then play it back at the normal rate.

In the US film is "normally" shot and projected at 24frames per second. (25 in Europe).

In the US, NTSC video is (nominally) 30 fps... or 60i. Hence the need for pulldown/pullup conversions going between the mediums.

Clear as mud now, I reckon.
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