I’m logging this here so I can find it in the future. Here is how to export a movie from After Effects with transparency:
1. There is a dedicated icon to toggle transparency on and off in the viewer:
This is where you find it:
2. When exporting, make sure
RGB + Alpha is selected:
Regarding straight and premultiplied alpha, I didn’t find any noticable difference. Here is a good rundown on the two. From what I can understand the straight is a better option.
(I don’t understand why there is a dedicated button for transparency in After Effects. Photoshop solves this problem nicely, eg. every layer you’re working with is transparent and if there is nothing left you see the void, aka checkerboard pattern. Here you see “black”, or the setting for your composition – there is no way to set “transparency” for your comp background, it has to be a color. I guess this used to be like this since from ages or the pro editors might make a case for this. Point being: in After Effects you need to research and learn a lot, otherwise nothing will work as expected, ie. my expectation is when I submit transparent assets, my exported video will be transparent as well.)