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render transparent video - How?

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Gilles Gagnon
render transparent video - How?
on Sep 4, 2014 at 6:02:45 pm

Hi folks,
Trying to create a short video clip with a transparent bg to be added to other videos as an overlay.
When I render to mp4, the bg is always black.
I read in some other posts that I must render an AVI file with transparency turned on in the custom template setting.
I tried this... still black. And... it generated a huge file for this few second clip.

What is the correct way of doing this?

MOOOOOOOOooooooooooooooooo!
G

Gilles


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Norman Black
Re: render transparent video - How?
on Sep 4, 2014 at 6:25:56 pm

You have to right click the media, and tell Vegas what you want it to do with the Alpha channel. It defaults to None. There are many options, Straight should work.

Almost no codecs support Alpha channel. In Vegas AVI Video for Windows, only uncompressed supports this.

Some Quicktime codecs can support Alpha. The PNG codec can, maybe others. It should be smaller than uncompressed. I don't know what all the PNG options mean.

Cineform can support Alpha, but not the free version of the codec. If you are really into Alpha channel rendering and want smaller files, then the Premium version might be the ticket.

The free Quicktime DNxHD codec can support Alpha but from what I have read, it get the Alpha channel backwards. Going from Vegas and back into Vegas you might still be okay.


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Gilles Gagnon
Re: render transparent video - How?
on Sep 4, 2014 at 6:31:07 pm

Thanks Norman!

Since the track I'm trying to output is a sony text event, I didn't think I'd have to fiddle with the alpha of the media.

Isn't this correct? since the clip itself has transparency?

Gilles


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Norman Black
Re: render transparent video - How?
on Sep 4, 2014 at 6:38:09 pm

Vegas by default ignores the Alpha channel in a media file and you have to tell Vegas what to do with the Alpha channel via the media properties.

For text type renders with Alpha, the Quicktime PNG codec should compress very well, keeping the file size WAY down versus AVI uncompressed.


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Gilles Gagnon
Re: render transparent video - How?
on Sep 4, 2014 at 6:41:52 pm

I said "text" for simplicity's sake for this post but there are also images included.
Sorry.
Still use QT Png codec?
will others have the ability to include this video into their own video editors?

Gilles


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Norman Black
Re: render transparent video - How?
on Sep 4, 2014 at 7:24:44 pm

PNG uses lossless compression so it is as good as uncompressed quality wise. It uses the same compression algorithm as ZIP files. PNG will always be smaller than uncompressed. Pictures and video will not compress nearly as well as text. Some of the PNG filter options might increase the compression amount depending on your source material.

By using the QT PNG codec, then anyone you give the file will need Quicktime installed for their NLE.


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Gilles Gagnon
Re: render transparent video - How?
on Sep 4, 2014 at 7:35:36 pm

Thanks Norman,
In this case I'll try again with avi. The end user is not an adept NLE user.
Cheers,
G

Gilles


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Norman Black
Re: render transparent video - How?
on Sep 4, 2014 at 7:38:30 pm

If you try PNG, then remember to set the pixel to 32bpp from 24bpp.

24bpp is RGB which has no alpha, 32bpp is RGBA.


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Gilles Gagnon
Re: render transparent video - How?
on Sep 4, 2014 at 7:39:20 pm

Thanks for the heads up.

Gilles


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