What about for video? would i do the same procedure?

i ask because...i tried rendering a clip that has a blackbackground and i want to use it in othe movies...but i cant get rid of the background properly..i tried chroma key and it makes my picture look stupid...i tried rendering it uncompressed with alpha channel and it was still there..when i would make the clip smaller..the black would still be there..how do i get rid of it?

to render apha channel video, must render AVI uncompress, check the template options , choose video, check APHA channel option.

This seems to have been asked (and answered) quite a lot recently. You'll find one of the best answers in the following thread (which highlights my own misunderstandings - and eventual realization of what this is all about).

Look here Creating animated AVI's in Vegas with Transparency

The critical steps are as follows;
1. Render to AVI (default template - uncompressed) - make sure the "RENDER ALPHA" is set to yes.
2. Load this into other projects and right click the media and select properties/Alpha straight (this is CRITICAL - without doing this your AVI will appear as if the backround is solid black - and not transparent)

Hope that helps.

Groan, I hate to get in over my head on these things but to my knowledge you can't just make what you consider the background into an alph channel. You need to have a mask to separate the foreground from the background.

i.e. you have to mask the arrows and then render with the background as alpha. The arrows are then a matte which separates them from the background. Otherwise Vegas doesn't know what is foreground and what is background.

Nickle.

It sounds like you are saying what you think is the case - rather than saying this from experience? Which must be the case - otherwise you would know that what you are saying is not correct.

I don't think anyone is implying you can do this without somehow making the appropriate parts of the original "arrows" transparent first. That can either be done using a mask (bezier) over the arrows - or by doing a chroma key FX).

The question (that I read anyway) was about how to render that original Veg in a way that the resulting AVI could be re-used in other Vegs - in which case the method of preserving the transparency/alpha channel becomes the critical piece in the puzzle.

You seem to have the same misunderstanding that I had - that when you render with that black background (uncompressed AVI even with the preserve alpha channle setting) - how does Vegas know the black area is indeed "transparent"? If it <really> were black then I can see how Vegas would have a hard time figuring it out. The thing is it only shows as black because there is no other video track to display it as anything else. When you render this in the right way - the <real> alpha channel/transparency is preserved.

There is no further need to use masks on this AVI file when you load that into another veg (and specify the properties to be alpha/straight as I suggested). The alpha channel information IS in the AVI - you just need to tell Vegas that is is there.

This works this way - I know it - because I have done it.

Well maybe I'll learn something here. I had a clip with a black backround which I chromakeyed out and tried to render it as an alpha channel and it didn't work.

The black area was transparent after the chromakey, but not after the render. Unless I missed something.

In this initial post, everything apples IF blacksheep does in fact already have an alpha channel in his clip...but I don't think he does from the way he described it. I thought he was trying to make one.

BUT - the crtitical step is that when you load that AVI back into a new project YOU MUST set the properties of the clip to be alpha/straight. Otherwise the alpha channel information will be ignored. Note - this is NOT the same as setting the properties of the track header. This is the properties of the actual clip itself in the media pool. Try it.

I did try it again, exactly the way I did before (chromakey then render) and this time it worked.

In the last series of posts we did, the only way it worked for me at first was the parent child thing, But when you said you didn't use it, I tried again and it did work without it.

Maybe I am missing steps here and there, but it seems that things don't necessarily work the first time.

I don't have a whole lot of experience at Vegas though but rotoscoping and alha channels I have been experimenting with quite a bit and in other programs as well.

I am looking for an alternative to a green screen but without all the work of rotoscoping so many frames.

Liam

I guess I did learn something. I never use the media pool, I always just kept everything in separate folders and used explorer. But in the media pool there is the one I chromakeyed sitting there with a checkerboard background (an obvious alpha channel).

Although the first one I rendered is sitting there with a black background. Properties shows alphachannel - premultiplied (dirty) because I try them all.

Thanks for the tip about the media pool. I'll start using it.