Haven't tried it myself, but everyone lately is recommending the AVID DNxHD codec - http://www.avid.com/US/industries/workflow/DNxHD-Codec
Don't know that it does alpha channel though.
As a long time Matrox user, I'm used to working with their MPEG-2 I-Frame HD 4:2:2 codec (100-300Mbps user selectable), which does offer an alpha channel version, but I don't know how the quality measures up to ProRes or DNxHD, which are both newer codecs.
There's also the Lagarith codec, but again don't know if it does alpha.
Hope this is helpful
I've used DNxHD in QuickTime containers with Premiere Pro, and it's pretty similar to ProRes. DNxHD also commonly exists in MXF containers in Avid workflows. DNxHD supports alpha channels.
UT and Lagarith are both lossless codecs that you can use in AVI containers. I don't find either of them very pleasant to work with in real time, but they are excellent intermediate formats.
What's the purpose of the export?
The purpose of the export: intermediate codecs and occasional delovery for further editing.
Some clips would transcoded to editing codecs for a couple of different editing applications. Others would be used as animated lower thirds; hence the need for an alpha channel. Still others would go to a delivery codec for editing. I figure it would be 1/3 - 1/3 - 1/3 split over the course of time.
Since I don't yet know delivery codec specs for the editing applications, I figure I can create lossless files and transcode as necessary.
Thanks for the suggestions thus far.
I've heard of Lagarith, but never UT. I also presume that the Avid and Matrox codecs mentioned above are for AVI media containers. Like I mentioned earlier -- I'm clueless.
I have used UT a lot because of the recommendation here on the forum, and I lige it very much.
Lagarith and UT usually come in AVI containers. The Matrox codecs I have on one of my machines go in an AVI container. The Avid DNxHD codec typically goes in a QuickTime or MXF container. All the workflows I've participated in and read about for DNxHD used QuickTime containers, and that's because I'm using Premiere. Avid NLE workflows use DNxHD in MXF containers, but as far as I can tell, Premiere still doesn't support DNxHD in an MXF container. Premiere does support several codecs in MXFs - I use XDCAM HD in an MXF container almost every day - but for DNxHD, you need to use QuickTime.
Thanks, everybody! I appreciate all the useful advice.