Control the speed

[Steve Bentley]

I’m not sure what you are trying to do. The loop out expression just repeats the motion set by the keyframes in the position parameter once the last keyframe has been handled.
If you attach the motion of the lens flare to the output of soundkeys (I assume that’s what you are after) that flare is going bounce all over the place like crazy.
Are you trying to have the flare travel along a path so that the soundkey data controls its position along that path?

[Moira Elefson]

The sound keys must control the speed of executing the path. When the music is with more bass the flare is moving faster according to the path.

[Steve Bentley]

The problem is that a bass hit is instantaeous. So the flare will jump to the end of the path then retract to the beginning. Is that what you are after?

[Moira Elefson]

Do not worry about the bass. We must find out a way to control the speed of comp with an integer or variable

[Moira Elefson]

So initially the speed of comp is 1 .
I must control that somehow to be 1.3 , 1.5 or what else

[Steve Bentley]

I’m not sure what you mean by “Speed of comp”.
If you have an expression going you can always add a slider (expression controls/slider) and then tie that value to your expression. Then you can keyframe that value and change it over time.

[Moira Elefson]

Can I set the amount of frames played from that animation in a second ?

[Steve Bentley]

You can set the frame rate in the comp settings (cntrl K). But you can’t change that interactively. You can change the fps after you start working on the comp but be warned that it may mess with where footage ends and how animations happen. After effects for the most part doesn’t care about frames per second – it just sees a frame as a frame and renders out every frame in the time line. The FPS setting just tells AE how fast to ripple through those frames.
But it also tells AE how to consider footage that isn’t at the same fps rate as the comp. A 15fps movie put into a 30fps comp can appear to be half as long as the length it ran in say something like QT movie player. Because AE is looking at say 10 seconds of footage (at 15fps that’s 150 frames) and you are putting that into a 30 fps comp where AE expects 10 seconds to be 300 frames, so AE can take every frame of that 150 and put it in every frame “slot” of the 30fps comp, and the footage would end at the half way mark.
But you can alter this behavior. You can tell AE to “interpret footage” and assume that its at 15fps or 30 fps or whatever. Tell it to assume the footage is at 15fps and the 10 second clip will last 300 frames in your 30fps time line, but with every frame doubled to stretch the time out. Or you can say interpret at 30 fps and you will get what happens in the first example above. (AE tends to import footage and “interpret as” based on what you did last time it was open)
You can also do the opposite and tell AE to imagine the clip is running at 60 fps and then AE will make the clip only last 1/4 of the 10 second 30fps comp length.

Think about it as “how do you want every single frame of your source footage (no matter the frame rate) to placed in each frame “slot” in your project.
I find it also helpful to not work in Minutes and seconds in the AE comp and work in frames instead. This also helps with the dreaded Zero frame problem and with a number of the time warping effects that rely on frame information and with expressions that often work better with frame information instead of 0.033 of second.
Music files are a little different in that they respect the fps rate of the comp – music files don’t really have frames or frames per second in the movie sense. So a 1 minute music file will last 1 minute in your comp’s timeline no matter what fps the comp is set to.

[Moira Elefson]

Why it’s so difficult to explain that ????

ok i will send a link to a video

https://youtu.be/U2e8ZayOEVs

so that flare must move faster to that trajectory, but without moving the keyframes

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[Steve Bentley]

The keyframes are what cause the motion – the loop expression just makes it happen again and again.
So you can do a few things – squeeze the keyframes together (select them all and alt-drag them from the end toward the beginning, they will all scale in time correctly.
Or you can precomp that layer (move all attributes to the new comp) and then time warp the precomp shorter (or enable time remapping and shrink the keyframes on that, or use the time warp effect etc)