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High Speed Footage
Hi there, I am doing a project using green screen footage shot at 500 fps. I want to get a variable speed effect, ie. footage at normal speed then slowing right down for certain pieces of action then returning to normal speed again. I thought I’d use time remapping in Afx and wondered if anyone had any tips or rules of thumb to bear in mind when doing this as I haven’t done it before. Cheers!
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8 Replies
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500 fps takes special gear. are u sure it wasn’t shot at 1/500 second?
If it’s really 500 fps then time remapping is easy because 1 second in real time will have 500 frames so you should have no frame blending problems or extra frames
just set keyframes where you want to speed up and slow down then drag them around by selecting all keyframes right of the point you want to change and work from left to right.
did that make sense? after you get the timing the way you want you may want to ease in and out.
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(Note: time remapping is a toggle. The same command enables it, then disables it. Beware: disabling it deletes all time remapping keyframes, so re-enabling means you start over. )
If you apply Time Remapping (TR) to a layer in a comp, you’ll see a number for the TR in the timeline. This value of the TR at any given frame is the number of the footage frame being shown at this point in time.
So if you just apply TR then leave it alone, the value of TR will match the comp time. No surprise: at frame 0035 in the timeline, the TR value is 0035. This means we’re seeing frame 35 of the footage at that point in the comp.
But if we then drag the second TR keyframe to the left or right, we see that the value at comp time 0035 changes. This means we are now displaying a different footage frame at that point in the comp.
How is this useful? Well, TR can be confusing, and one way to tame it is to:
1) write down key points in the footage, say, if something enters frame at frame 0075 of the footage.
2) mark key points in the comp or layer (music hits, for example) where you want those key footage frames to be seen.
3) make TR keyframes (apply TR first, if you haven’t already) at those points in the comp.
4) move the current-time indicator to a keyframe, then in the TR value graph (in the timeline), drag the keyframe up or down until the value matches the frame that you want to show at that specific time.
5) repeat for the rest of the points that you marked in the comp and tweak.That’s one way. It really depends on what you want to do, what you know you want to happen, and what you want to make match something else.
But if you think of time remapping as controlling the frame that you see at a specific point in the comp, you may be on your way to taming TR.
Does that help?
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[Steve Roberts] “But if you think of time remapping as controlling the frame that you see at a specific point in the comp, you may be on your way to taming TR.”
Yeah, think of each frame having a number assigned to it, and that by typing in a number into the Time Remap property, you are calling up the frame with that number. So if you were working with footage at 30 FPS in a 30 FPS comp – and you have a Keyframe for Frame # 1, and then 10 frames later you have a keyframe for frame # 100, then your footage will play 10 times faster than normal – to fit 100 frames of video in 10 frames of time.
Man, I would love to see how this turns out. I did a tutorial on my DVD on creating High-Speed FX that can be slowed down and time remapped in AE for variable speed FX, but I’ve barely had the opportunity to work with footage shot at such a high speed.
Sounds really cool. Good luck.
Aharon
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Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
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Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com -
[Aharon Rabinowitz] “… by typing in a number into the Time Remap property, you are calling up the frame with that number.”
Ah, of course. That’s more efficient than dragging the value graph.
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yes, but dragging is much better if you don’t know what frame you want, becasue you can watch the frames pass by until you find the right one. I use both methods A LOT.
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Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
—————————————-
Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com -
I had a problem when time remapping two greenscreen shots (keying with Keylight).
On both shots during the time when the footage was playing back, at a rate other that the normal rate, the key was showing some small level of the greenscreen (light gray as the color suppression was on). This went away at the keyframe of the time remap that begain the portion of the shot that played at 29.97 fps.This did not show if I removed the time remapping. My solution was to time remap the shots, render, reimport and then key.
I never figured out what was going on and as I was junking up the shots with lots of other effects downstream of the key the pre-rendering wasn’t an issue.
TonyTony
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Indeed. 🙂
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Ok Thanks alot for your feedback everybody, much appreciated. I’ll post a link to the finished piece when it’s done. Cheers!
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