September 5, 2012
adobe premiere & animation frame rates
by sven at 1:12 am
Earlier this year I finally broke down and purchased Adobe Creative Suite 5.5 - Production Bundle. ...Only a week or so before CS6 was released — sigh. Happily, though, I did a lot of shopping around and managed to get a very good deal from SoftwareMedia.com.
The critical application for me was Adobe Encore, which seems to be the only good option for authoring Blu-ray discs from a Mac. Going into this, I didn't know that Adobe Premiere is the hub of the production experience in CS5.5. It's been interesting getting familiar with the software.
The only film editing software I'd worked with previously was iMovie — and I kind of hated it. Premiere, on the other hand, is a pleasure. I particularly enjoy editing to music: looking for the best moments in my library of film clips, and finding ways for the visual beats to coincide with audio dynamics.
I've spent a lot of time watching instructional videos in order to get up to speed. (Google "Adobe TV" for the best starting place.) But now that I've begun to get my legs under me, I really appreciate some of the professional magic tricks I can work. The most crucial of these is converting frame rates.
Converting framerates for the NW Animation Festival
I'm going to oversimplify: video in Europe is 25fps, film in the USA is 24fps, and TV/DVD video in the USA is 30fps. If you tell a computer to convert one frame rate to another, it's just going to insert or delete frames — which creates a very noticeable stutter. (Unless you interlace — which is a whole 'nother nightmare.) ...What to do?
Well, first off, I've got a big advantage because I'm dealing with animation. Live action filmmakers often shoot footage in 30fps. Only a very tiny minority of animators originate films in 30fps. We work and think in 24fps. When our films get transferred to 30fps for TV/DVD use, they get degraded in the process. In the world of animation, we want to avoid 30fps if at possible.
Happily, we've finally entered an age where we can avoid 30fps. Blu-rays and broadcast HDTV can accommodate 24fps. 30fps is still in usage — but there's real movement toward 24fps becoming a universal standard for film and TV.
So, based on what's native to animators, and in hopes of a universal standard, I've settled on 24fps as the master frame rate for the NW Animation Festival. In the upcoming year, I'll be encouraging animators to send me their original source files — which are most likely 24fps — and strongly discouraging them from burning playable DVDs.
This still leaves the issue of how to work with 25fps. (Q: Where did that number 25 come from? A: It's an artifact of European electrical current being 50hz, whereas ours is 60hz.) After a lot of research and a good tip from the Steve Herring at Proludio, I've settled on this strategy: slow the films down by approx. 4%, and pitch shift the audio up by +.75dB. The change in speed is imperceptible, and no frames are lost.
In the context of Adobe Premiere, one uses the "interpret footage" menu to play back individual frames at a different rate. Audio needs to be adjusted in Adobe Audition. Once you find the settings and grasp the underpinnings, the conversion is fast and easy. Getting to the point of understanding why this is the right solution, and how to accomplish it — that was decidedly not easy.
Impressive mental calisthenics, par excellance, Sven.
Any point in an animator shooting at 30fps?
Posted by: Shelley Noble at September 5, 2012 7:08 AM
you make this sound so easy and reasonable, but i know it obscures a whole lot of THINKING and hours of BLEEDING through your eyes. thank you for doing that for us! :)
Posted by: gl. at September 5, 2012 10:01 AM
If you were making animation specifically for Standard Definition broadcast television in the US, it would theoretically look better if your film was 30fps.
However, I wouldn't recommend it. You'd have to shoot more frames, which makes a big project even bigger. Also, as you're animating, it helps to be able to divide a second into equal increments... Easy enough with 24 — but you can't divide 30 into 4th or 8th. Only computer animators might not blink at these issues.
I say animation for TV would "theoretically" look better at 30fps, because SDTV is going to tear up your film no matter what. It takes 30fps and divides the ~480 vertical lines of visual data into two fields of ~240 lines that get interspersed with each other. When you convert 24 to 30 for TV, you're not simply repeating frames — you're "interlacing" repeated fields.
There's an uneven rhythm to the repetitions that's called 3:2 pull-down... I don't have much experience with it, but stuttering should be less noticeable because you're now essentially working with 60fps (albeit with half the visual info in each frame).
Posted by: sven at September 5, 2012 10:24 AM
ah, yes; this looks much more like the frame rate tarpit I knew was lurking in there somewhere. :)
Posted by: gl. at September 5, 2012 10:52 PM