Render?

Dan Sherman wrote on 6/28/2010, 4:04 PM
Need to render to .MOV for client to support alpha channel.
Green screen shoot.
But rendering out using PNG setting results in a huge file (13GB)
Seems way too huge!.
Any suggestion on how to achieve a much smaller file without losing alpha channel?
Thought I knew something about compression, but can see there is much more to learn.

Comments

Former user wrote on 6/28/2010, 6:49 PM
AVI only supports an alpha channel in uncompressed.

You can use the Animation Codec in QT which retains the alpha channel, or I believe the DNxcHD also retains the alpha. And Pro Res might as well.

Dave T2
Grazie wrote on 6/28/2010, 7:47 PM
AVI only supports an alpha channel in uncompressed.

Isn't this what Lagarith does? It creates compressed lossless AVI material and supports an Alpha channel?

http://lags.leetcode.net/codec.html

Grazie
LReavis wrote on 6/28/2010, 7:53 PM
"Need to render to .MOV for client to support alpha channel.
Green screen shoot."

It sounds like you're planning to render out the chromakeyed (transparent) color to the alpha channel. That can be done in Vegas, but not well - regardless of which codec or uncompressed format you use. I and others have found that Vegas, even when the chromakey video looks clean when placed over another track below, will NOT look good when rendered with alpha and the clip then is imported over another clip below it.

The problem is a dark halo around the keyed-out areas. Better put the clip with alpha back into Vegas or another NLE with it placed over a light-colored clip and look for the dark halo (you won't see it if you place it over a dark-colored clip or generated media, but it'll be a nuisance over brighter scenes). Experiment a bit with the chromakey settings to see if you can tolerate the halo before you spend too much time on proceeding into this project . . .

I do a lot of green-screen work in Vegas, and I sure wish someone could tell me a fix for the dark halos in the alphas (I don't see them when I create alphas in, say, Particle Illusion).
Dan Sherman wrote on 6/29/2010, 3:58 AM
New Blue does a clean job of keying.
It's the render that has me stymied.
Another recipe in the oven as I write this.
Thanks y'all.
Former user wrote on 6/29/2010, 6:29 AM
Grazie,

You might be right. I don't use Lagarith so am not familiar with all of its features.

Dave T2
Former user wrote on 6/29/2010, 7:35 AM
You could output a mask track that could be TC locked to the original video track to effect a key. But then again, if your client requires an MOV with transparency then I assume they are wanting to use the resulting keyable footage in a non editing application like Flash?
MacVista wrote on 6/29/2010, 7:54 AM
I think the dark halo you are seeing is because Vegas is rendering the Quicktime as premultiplied with black.
If you go into the clip properties and change the Alpha channel to "Premultiplied" the halo should go away (and the key should look better)