keying

xjerx wrote on 9/7/2004, 10:04 AM
How can I render a file with a transparent background. For example..what I want to do is to make a 30 sec video clip with an animated lower thrid and text..i want to render the video and use the rendered file on another computer and use it to key over a live video show. Can I do this in vegas? and does that make sense? I know i can just have a black background...but if my animation has any black in it..won't that be keyed out as well?

Thanks
Jeremiah

Comments

jetdv wrote on 9/7/2004, 11:07 AM
Render to uncompressed AVI making sure you turn ON the Alpha Channel.
xjerx wrote on 9/7/2004, 1:12 PM
i'm transfering these video clips from computer to computer via DVD....will the alpha channels still work after burning them in DVDA2...or do i need to set some more options?

Jeremiah
Chienworks wrote on 9/7/2004, 1:32 PM
If you burn a Data DVD with .avi files on it you'll be fine. You can store files up to 2GB on the disc and that's enough for about 51 seconds of uncompressed 32 bit avi without sound. Split the files up appropriately and you can fit about 2 minutes' worth total.

Alternatively you could render them as Quicktime .mov files with alpha channel. Use a bitrate of at least 6Mbps for decent quality and you can fit 100 minutes on a data DVD or 15 minutes on a CD.
xjerx wrote on 9/7/2004, 4:06 PM
I now have another question....as far as I know....this video clip will be keyed over the live video feed by keying out the black....that doesn't really sound like the best way to me...since it will not just key out the part I want gone..but will also key out any other black areas. Any suggestions on how to do this right?

Jeremiah
Chienworks wrote on 9/7/2004, 4:36 PM
That's why you use the alpha channel. It specifies the areas to make transparent no matter what color they or whether those colors also appear in the image. If you had a solid background that didn't appear in the image then you could simply key rather than using the alpha channel.
xjerx wrote on 9/7/2004, 5:40 PM
The video will be run through a program called mediashout and will be layed over a live video feed coming from a video truck...my problem is that i'm not to sure that mediashout can work with alpha channels, I think it just does chroma keying. So instead of chroma keying out blue or green, mediashout will chromakey black, (which i'm doing on vegas to see what it looks like..and it doesn't look as great as opposed to setting the properties of the clip to straight unmatted) But I think I'm terribly confused on both these topics. Sorry for my inability to understand...and thanks for your help :o)

Jeremiah
[r]Evolution wrote on 9/9/2004, 10:22 AM
If you're only option is to KEY out the background color:

Make your Lower Third Video with a Background color that is NOT included in your Lower Third Graphic. Then when you select the Background color to be KEYED out your Lower Third will not be affected.

ie- if your lower third is BLUE - make your background RED
if your lower third is GREEN - make your background ORANGE
--- You don't have to use these colors they are just to show you to use a color that is NOT in your Lower Thirds Graphic.
bStro wrote on 9/9/2004, 11:00 AM
I've not used MediaShout, but this page seems to suggest that it can key out colors other than black.

Rob
[r]Evolution wrote on 11/30/2004, 1:49 PM
You can KEY OUT any color!

It's not just MediaShout that has this function. KEYing is just selecting a color, any color, and telling it to make it transparent.
Grazie wrote on 11/30/2004, 11:25 PM
Well said Lamont! . . I've stopped thrusting my knuckles in my mouth. . . ..

"In Space no one can hear you scream!" and this by Edvard Munch


Grazie

PeterWright wrote on 11/30/2004, 11:42 PM
If you're going to use Chroma key, make it a colour that does not occur except for the transparent region, e.g. a bright purple. (Unless of course your subject is wearing a bright purple suit.)
Grazie wrote on 11/30/2004, 11:45 PM
.. knuckles gone back into mouth .. thanks Pete! :)