Motion effect... can I make the speed constant?
- Thread starter jchenier
- Start date
overnighttolondon
Well-known member
For experiment's sake, try applying one motion at a time to a clip (only scale, and then only moving across it). I suspect that you'll notice your problem only with the zooming. Here's the deal:
Premiere is going to create a steady transition between your keyframes. This is going to give you a constant speed for your clip that only moves across the image (which is what you expect and what you want in the first place). However, when we're talking about changing scale percentages in a constant way, things are a little different.
Let's say you've got scale keyframes at 0sec and 2sec. At 0 sec, you're at 150% scale. At 2sec, you've got 50% scale. Obviously, Premiere is going to do an inbetween so that at 1sec, your scale is going to be 100%. Sounds good. But let's think about how that's going to look for us.
0sec ----- 1sec ------ 2sec---
150% --- 100% ----- 50%---
<Key> ---------------- <Key>---
In the first second (between 0sec and 1sec), the image goes from 150 to 100. This means it loses 1/3 of its size (it drops by 50, which is a third of 150).
But in the second second, it drops from 100 to 50. In this second, it loses 1/2 of its size -- this will make it seem to be shrinking faster.
Scale is a bit weird. In order to get linear-looking motion, you need your values to be changing logarithmically (not linearly). If you have access to something like After Effects, this is easy to do - you can play with the Bezier handles on your keyframes. In Premiere, it's not so simple. I don't think there's any way to change the method Premiere uses to interpolate between keyframes (I'll check on this though, there might be).
You best bet might just be to fake it up manually. Start with the kind of thing we have above - a keyframe on each end. Then, move to the middle of the clip and make another keyframe (don't change the value - leave it at, in our case, 100). Then, since we found that the second part of our motion happened too fast, drag that keyframe to the left a bit to give the right side more time. Repeat this until you've got better motion (i.e. now make a keyfram halway between the middle and the end).
Sorry if this was overly mathy - hope it helps. I'll look into that advanced keyframing thing too... if you come across anything called "interpolation" or "easing" you're on the right track.
Premiere is going to create a steady transition between your keyframes. This is going to give you a constant speed for your clip that only moves across the image (which is what you expect and what you want in the first place). However, when we're talking about changing scale percentages in a constant way, things are a little different.
Let's say you've got scale keyframes at 0sec and 2sec. At 0 sec, you're at 150% scale. At 2sec, you've got 50% scale. Obviously, Premiere is going to do an inbetween so that at 1sec, your scale is going to be 100%. Sounds good. But let's think about how that's going to look for us.
0sec ----- 1sec ------ 2sec---
150% --- 100% ----- 50%---
<Key> ---------------- <Key>---
In the first second (between 0sec and 1sec), the image goes from 150 to 100. This means it loses 1/3 of its size (it drops by 50, which is a third of 150).
But in the second second, it drops from 100 to 50. In this second, it loses 1/2 of its size -- this will make it seem to be shrinking faster.
Scale is a bit weird. In order to get linear-looking motion, you need your values to be changing logarithmically (not linearly). If you have access to something like After Effects, this is easy to do - you can play with the Bezier handles on your keyframes. In Premiere, it's not so simple. I don't think there's any way to change the method Premiere uses to interpolate between keyframes (I'll check on this though, there might be).
You best bet might just be to fake it up manually. Start with the kind of thing we have above - a keyframe on each end. Then, move to the middle of the clip and make another keyframe (don't change the value - leave it at, in our case, 100). Then, since we found that the second part of our motion happened too fast, drag that keyframe to the left a bit to give the right side more time. Repeat this until you've got better motion (i.e. now make a keyfram halway between the middle and the end).
Sorry if this was overly mathy - hope it helps. I'll look into that advanced keyframing thing too... if you come across anything called "interpolation" or "easing" you're on the right track.
Jezz, that's bloody detailed, but I completely follow you! After I posted my message, I started to think that the scale and zoom combined to create the appearance of increased speed.
You've given me a great detailed explaination... thanks a million!
Justin
www.beyondtimemedia.com
You've given me a great detailed explaination... thanks a million!
Justin
www.beyondtimemedia.com