Exporting alpha channel + keyed image layer
 

Did some digging on this one and haven't been able to locate an answer.

I've got several fairly long green screen projects on the table. My AE render times have improved since using 720p TGA image sequences, but they are still very long - about one hour per 1 minute of footage.

My question is if I can export the alpha channel/mask and the keyed image (with all Keylight effects applied - spill correction, etc) as separate sequences from After Effects, then import those into Premiere.

If I can get those into Premiere, I can work on the project much faster - with realtime previewing and not having to re-run the long AE render each time I make changes.

Bascially I only need After Effects for the keying phase of the work. Premiere is sufficient for most everything else I need to do to the projects (adding text, transitions, audio syncing, etc).

The problem is that now, if I want to change or adjust the background (or anything else), it means re-rendering the clip in AE each time. If I could do that in Premiere, my life would get much easier :)

Hi Dan. Yes you can render your keyed footage out of AE keeping the alpha channel and use it in Premiere. Just make sure that you use a codec that allows it - normally it is "millions of colours +' (the plus sign means that it will export the alpha). Render times can be long using Keylight, I presume you are using garbage matts which speed things up a little.

Dan, you can use Dynamic Link to import un-rendered sequences into Premiere if you have Production Premium. There won't be a realtime preview, but you'll save time and not have to re-render the timelines to make changes.

A speed(ier) tip: Before applying the Keylight filter, add a series of Color Key filters (up to 3, depending upon the range of green tones) above it to minimize the number of pixels Keylight has to render.

HTH,
Brian Brown
BrownCow Productions