Apha channel in videos ;-( help ideas?


im trying to build something that needs several video layers.
ive read that this is kinda hard, since windows has a hardtime with video codecs that support alpha

ive also tried the key module by kalle, witch works, but does not allow gradiants and smooth edges …

then i decided to build something that just changes the alpha png texture file every 0.08 second.
its working great, but its also sucking lots of performance

any suggestions?


hola hairness,

it could help going into details here. try to explain what your actual goal is. don’t tell us how you are thinking to realize it, but tell us what you’re actually trying to achieve. that may help us shifting you in the right direction.

Once I did a little shader for this.
Its working like this: You double the height of your video. Upper half is a greyscale image where black is for transparent and white for opaque and grey is inbetween. Lower half is you orignal video.
So, this shader just takes incoming video and let content of the bottom part/video passing, after adding alpha values of upper grey image half.
There are two values to set one for overall height of video and one for the border where upper one stops. So, you can adjust a little there.
But you have to make some video editor work first - putting the grey mask onto it. If you go in trouble with video codecs (most only accept 4:3 scale) I recommend HUFFYUV.

alphamovie.zip (3.0 kB)