How To Generate Alpha Channel Clip

[poisondeathray]

It it possible to generate a base clip using blankclip or some other avisynth function but using no color ? (RGB32, but alpha channel only instead of "black" for the background color) ? or what "color" do I specify for no color ?
http://avisynth.org/mediawiki/Colors

e.g.
blankclip(pixel_type="RGB32", color=?)
subtitle("test")


I want to generate a "transparent" video with some overlayed material for usage in other programs

[Gavino]

I'm not sure I understand the question.
BlankClip(pixel_type="RGB32") does give a transparent clip, ie it has alpha=0.
If you want a specific alpha value, you can use color=$aarrggbb.
You can also use Mask (http://avisynth.org/mediawiki/Mask)() to set the alpha channel directly.

Perhaps your problem is how to overlay the later material so that it gets the right alpha?
For that, you need to use ShowAlpha() and Mask(), eg
BlankClip(pixel_type="RGB32")
Subtitle("test")
Mask(ShowAlpha().Subtitle("test", text_color=color_white, halo_color=color_white))

[poisondeathray]

Thanks Gavino