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Compressing Video With an Alpha Channel for PowerPoint

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Jenny Collier
Compressing Video With an Alpha Channel for PowerPoint
on Dec 15, 2010 at 6:28:10 pm

Hi All! I hope I'm not "double posting" or anything... I had this in the AE forum and they suggested I might get more help here:

I need to make some alpha AVI video clips even smaller than they are.
What I’m doing is inserting video clips with an alpha channel into PowerPoint2010. So far, I’ve found only ONE way to do it. If anyone can suggest viable, specific alternatives to any part of this workflow, I would be ecstatic. Here’s what I’m doing:

1) Creating animation in After Effects

2) Rendering full quality AVI clips with alpha channel and no compression --(avg size: 686.6 MB)

3) Re-importing uncompressed clips into new After Effects composition

4) Rendering clips again using Techsmith Screen Capture Codec compression (the only codec on my After Effects list that supports an alpha channel…RIGHT???) --(avg size: 19.9 MB)

5) This is pretty great, but still not nearly small enough. SO,

6) For even smaller files I’ve skipped the last step and rendered instead using TSSCC with Best quality at HALF resolution. (Aesthetics are much less critical than file size here, and half res is plenty good looking for my purposes). --(avg size: about 9.0 MB)

7) Importing clips into PPT2010, where they play with no prob.

This pipeline WORKS, but I’ve GOT to get these files even smaller. I’m talking down around 3 MB or less.

I understand After Effects is a poor program choice for video compression, and that a dedicated compression program is best, but I haven’t been able to find one that would produce viable files. The only Sorenson Squeeze codec that supports an alpha channel produces SWF files, and I need AVI. It doesn’t look as though Microsoft’s encoder is going to work either.

My specific questions are these:

Is there a way to render an alpha channel with the current AE codecs that I’m not aware of? The only way to get an alpha channel to my knowledge is to select RGB+ Alpha in the CHANNELs dropdown (choosing “lossless with alpha” does nothing without that channel setting), and TSSCC is the only codec on my list for which that’s an option. What is this “key frame” stuff I’ve been hearing about, and how does it relate to the creation of an alpha channel?

Would it help, or would I have more options if I rendered my animations from Premier/some other program as opposed to AE??

Is there any dedicated video compression program available (FOR LOVE OR MONEY) that will squish my AVIs and preserve the alpha channel? One with a RANGE of codecs would be best, bc PPT is really choosy.

Thank you so much for the help,

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Michael Kammes
Re: Compressing Video With an Alpha Channel for PowerPoint
on Dec 18, 2010 at 4:33:47 pm

Codecs with Alpha Channel are few and far between. Namely because they are specific, and not used as commonly as others...needing an Alpha Channel is uslaly reserved for higher end garphic work. Codecs with Alpha are NOT Long GOP, and thus will take up tons more space than non long GOP.

2 popular ones are the Animation Codec, and ProRes 4:4:4:4 (Mac). Both of these are NOT light on compression and take up a large amount of space.

Why do you need an alpha channel? Aren't you just flattening the movie and placing it in PPNT?


.: michael kammes mpse
.: senior applications editor . post workflow consultant
.: audio specialist . act fcp . acsr

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Craig Seeman
Re: Compressing Video With an Alpha Channel for PowerPoint
on Dec 18, 2010 at 4:54:03 pm

Flash On2VP6 is one of the few codecs that supports Alpha channels. I'm not sure if PowerPoint can handle the files or the alpha channel though.

One possibility would be to build an interactive Flash presentation as that can handle VP6 alpha channel.

Animation codec can also use Alpha channels but you'd have a very large file and again I'm not sure if PowerPoint can handle it.

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