Alpha Channels

[hawesm]

I've rendered some animated compositions (lower-third titles) in AfterEffects with an alpha channel but can't get them to key in TED. Since they have an alpha channel, I should be able to "enable overlay" but this doesn't work. I've tried rendering as uncompressed avi, and rtv. The book has plenty of info on chroma keys, but very little on alpha keys. Any suggestions?

[Rich Deustachio]

Import them into Aura then export as an rtv.

[mblade]

... or better still export from AE as an RTV with alpha.

If you do this make sure you don't select RTV as an avi codec, but instead use the RTV output module. That means when prompted to select the type of file, (video for windows, quicktime, etc) choose RTV. If you select video for windows and then select RTV as your VfW codec the alpha channel will not work (I don't think VfW supports it).

If you can't find the RTV option make sure you have rtvio.aex installed in the plug-ins/formats or plug-ins/standard/format directory of AE.

Finally, always always always render out with STRAIGHT colours not premultiplied. It looks really horrible when you look at without the alpha channel, but when you switch on the enable overlay status it will key so cleanly you will want to weep with joy.

Enjoy,

James

[hawesm]

The "import to Aura" didn't work well for me. I couldn't find the output settings and the default settings created an ugly file that wouldn't playback.

Using the correct render settings in AfterEffects solved the problem. I was outputting as "Video for Windows" with an RTV codec instead of "ToasterFile". Now it looks great. Thanks for the help. It has saved me from hours of turmoil.