Rendering .avi with alpha?

I started working in Blender a while back and I know how to render and export videos, but what I would like to know is how to export videos with alpha. I am making some transitions fr my school’s “The Falcon Report” and the videos are going to be used like overlays. Does anyone have any experience with exporting videos with the alpha channel? Who knows of any good .AVI Codecs for this purpose (if they exist)?

You need to use a video codec that can have an alpha channel such as Quicktime Animation codec. I believe the latest versions of blender for windows drooped quicktime support. Ideally though, use an image sequence such as .png which can have an alpha. Decent video editing applications should be able to use an image sequence.

The free Lagarith Codec makes lossless AVIs with an alpha.

But remember, if you transfer your video to another computer you will have to install the codec on that computer as well which requires Admin rights. Not very school friendly.

An alternate approach is to make two videos. One with RGB and one that is just the alpha as Black&White. Then you can use the B&W video as a matte for the diffuse RGB version. This should require no special codec.

Sorry for the late response, I had to go for a while and I completely forgot about this post. I’m looking into the code you suggested right now.