Black screen delete expression?

[Dan Ebberts]

You could probably hack something together using time rempapping and sampleImage(), but I think it would be really slow. Did you want it to skip black frames (which would speed up the movie) or hold the previous non-black frame (which would be easier and faster)?

Dan

[Cedric Bogaert]

Uuh, I’m not really used to all the after effects expressions, so I just need a expression that I need to add to the movie layer. I think it would be better when it just skips the black images, But I would be happy to see when it just reshowed the previous image! Thanks for your reaction already! Ow, yeah, couldn’t it maybe be done with a luma key on that layer, so that that layer becomes transparant when it is black. And then, when you precompose it you maybe could add an expression like IF frame=transparant, then skip that frame
Or something like that xP
Of course I’m just suggesting, but I’m sure that more advanced people in expressions will be able to help me out! Thanks!

When it HURTS to look back, and you’re SCARED to look ahead,you can look beside you and Bogstar will be there

[Dan Ebberts]

Well, here’s the simple version that just holds the most recent non-black frame. You have to enable time remapping and then add this time remapping expression:


for (f = timeToFrames(); f >= timeToFrames(inPoint); f--){
L = rgbToHsl(sampleImage([width,height]/2,[10,10],true,framesToTime(f)))[2];
if (L > .01) break;
}
framesToTime(f);


You might have to adjust the .01 value in the third line to get the sensitivity you need.

Dan

[Gorm Horger]

Hi Dan,

i tried to copy/paste your code to an After Effects CC – Project i’m working on. The result is either a “timeout while waiting for the engine” on values for L larger than .2 or a replication of the first frame over the whole timeline (like a frozen image) on values smaller than .2

It is the first time for me working with expressions why it could be an operationg error too. To eleminate this, i’ll try a step by step description on how i applied the expression:
1. going to first frame of video in composition
2. rightclick on video in composition
3. select time / time remapping
4. alt+click on the clock of time remapping in composition
5. copy/paste your code

result:

link to image

I would be glad if you could help me with some advice how to hold the most recent non-black frame until the next non-black frame comes…

[Dan Ebberts]

Try making this correction to the first line:

for (f = timeToFrames(time); f >= timeToFrames(inPoint); f–){

If that doesn’t help–what are your comp dimensions?

Dan

[Gorm Horger]

working great. thanks!!!

for (f = timeToFrames(time); f >= timeToFrames(inPoint); f--){
L = rgbToHsl(sampleImage([width,height]/2,[10,10],true,framesToTime(f)))[2];
if (L > .01) break;
}
framesToTime(f);