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Linear speed in graph editor

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Toni Martin DobrzanskiLinear speed in graph editor
by on Jan 11, 2012 at 8:46:40 am

Hi all...

I've been Googling for a long time but this thing really keeps bugging me...

I've just made a roll credit for a documentary in AEF CS5 by adding a keyframe on the start and end of a composition with a PSD-textfile of the credits. I set the start position on the first keyframe and the last so the text moves upwards through the screen.

In the graph editor I can see that my speed is a constant of 174.85 px/sec. Now, since I don't want the text to filcker on the TV I would like to adjust the speed manually. But each time I try to move the keyframes up/down in the graph I get ease in/out on my keyframes and I really don't know how to remove those (they are automatically added on the speed graph). I tried selecting both keyframes and moving the graph but that will only let me move it horizontaly. I need to move it verticaly.

So how do I change the speed of a movement between two keyframes and keeping it at a constant px/sec (for example 200 px/sec)?

Thanks in advance!

Toni

Toni Martin Dobrzanski
Film Composer / Video editor/photographer
SoundComposer - Denmark


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Tudor "Ted" JelescuRe: Linear speed in graph editor
by on Jan 11, 2012 at 10:00:09 am

Changing the speed on your animation will not necessarily reduce flicker. Here are a few things that usually do the trick:
AE motion blur (give by the layer's movement, with adjustments to the motion blur settings)
A .3 to .7 blur applied to the animated layer
OR CC Force Motion Blur (again, play with the settings)

Tudor "Ted" Jelescu
Senior VFX Artist


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Toni Martin DobrzanskiRe: Linear speed in graph editor
by on Jan 11, 2012 at 10:26:52 am

Hi Tudor

Thanks for your answer. I already put "Reduce Interlace Flicker" filter on (0.5) and Fast Blur (0.3). I just need to be able to control the speed of my motion since the movement has to be a whole amount of pixels per frame.

Do you know how to do this? Control the speed so it's constant? I can't make it work in the graph.

Thanks!

Toni Martin Dobrzanski
Film Composer / Video editor/photographer
SoundComposer - Denmark


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Tudor "Ted" JelescuRe: Linear speed in graph editor
by on Jan 11, 2012 at 2:31:27 pm

By definition, if you have 2 linear keyframes only you will get constant speed. If you need to change the speed you will adjust the time in which the animation happens - you can change the position of the keyframe in the timeline for that, no need for the graph editor.
If you get bezier handles in the graph editor when you move a keyframe, you can always select that keyframe and use the check boxes at the bottom of the graph editor interface to convert back to linear.

Tudor "Ted" Jelescu
Senior VFX Artist


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Dave LaRondeRe: Linear speed in graph editor
by on Jan 11, 2012 at 5:55:18 pm

The problem of top & bottom edges of characters "frying" during a credit roll has ALWAYS been a problem, even in Hollywood. As evidence, look at the credits in newest Star Trek movie, the one directed by JJ Abrams. Those credits are just God-awful!

There are many threads on this problem in this forum on the COW You can search for "scroll" or "credit roll" to find an expression that eliminates it.

For perfection, there will be a tradeoff to be made: your credits will either move too fast or too slow, or they will run too short or too long. You'll have to take your pick.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Esky ChingRe: Linear speed in graph editor
by on Jan 11, 2012 at 2:30:19 pm

In "Preference" you can set spacial interpolation to "linear"


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Walter SoykaRe: Linear speed in graph editor
by on Jan 12, 2012 at 1:43:32 am

[Toni Martin Dobrzanski] "So how do I change the speed of a movement between two keyframes and keeping it at a constant px/sec (for example 200 px/sec)?"

For a smooth credit roll, we don't care moving at a round number of pixels per second -- we care about moving a round number of pixels per frame (and if you're using interlaced video, an even number).

You can use the following expression to get a smooth scroll. Alt-click the position property stopwatch, and enter the following expression:
speedPxPerFrame = 2;
currentFrame = (time - inPoint)/thisComp.frameDuration;

value - [0, currentFrame*speedPxPerFrame]


Expressions are evaluated every time a frame is rendered. This expression gets the x and y positions as defined by the layer's position property, then subtracts 2 pixels from the y position for every frame that's happened since the layer's in point. You can change the speed of the roll by changing the value assigned to speedPxPerFrame.

You can also manually adjust the layer's position point to change where it will begin (just don't add keyframes to the position property -- you'll get unexpected results).

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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Toni Martin DobrzanskiRe: Linear speed in graph editor
by on Jan 26, 2012 at 11:27:46 pm

Thank you all! Your posts have been very valuable :-)

Toni Martin Dobrzanski
Film Composer / Video editor/photographer
SoundComposer - Denmark


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