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Question for user – sam.mltn
Hi,
I used the expression you posted regarding a 24p title roll. What I started out with was an imported illustrator file that I just animated position on. The length of the roll was supposed to be 2:15. So the speed was determined by that. The expression I applied worked in that the edges of the text were the same from frame to frame. I noticed that the expression changed the pixel speed on the first keyframe to a multiple of 24 which is probably what accomplished this. I’m just looking for some insight on how this expression worked. So here are my questions if you can answer them,
First, why did this expression change the value of pixel speed only when I’m parked on the first Position keyframe?
Second, does this actually change the speed of the roll? Because I’m still ending on the same keyframe position. I don’t see a speed change visually.
Third, does the length of my animation have any bearing on the speed that the expression sets? And should the length of my animation be a multiple of 24 as well? Cuz the expression set pixel speed to 3072. Should I set my animation length to the same amount of frames or if I want it longer, to something like 3600 (150 x 24)?
Finally, would this expression work as is, with 30fps footage? Or are there variable in the expression I would want to change.
Any breakdown of the expression would be awesome. Thanks in advance.
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1 Reply
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I’m sorry to say I don’t know much about that expression except that I found it here at the cow while searching for solutions to add to the chart I keep in my how to do stuff binder. as far as I can tell the expression just rounds off the position value to a whole number. you can still get the jitters if the speed is wrong if the speed makes the title move 2 frames most of the time then 1 or 3 other times.
maybe someone understands this better than I do and can give you an answer, maybe if you modified the expression so that it rounded to the nearest half pixel there would be more speeds where the type doesn’t jitter.
wish I could be of more help
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