Definitive list of Quicktime codecs that support alpha.

Question

Definitive list of Quicktime codecs that support alpha.

I've been spending quite a bit of time trying to find a list of which codecs that are supported in Quicktime that allow you to embed an Alpha Channel.

Apple Animation codec is the most frequently used, but is this the only one?

Thanks!

G5 (dual 2.3Ghz), Mac OS X (10.4.8)

Posted on Dec 14, 2006 10:17 AM

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Answer 1

Dec 14, 2006 3:19 PM in response to Stephen Barrante

Could you elaborate on your requirements? Are you talking about compositing?
Any video track using any codec (except JPEG) can have "transparency":
Highlight the video track in Movie Properties and click the Visual Settings tab. Setting a color can only be done by version 6 (Color Wheel). You can choose from premultiplied black or white, straight alpha (or blend) and composition.
Animation codec is used because of its fast speed (rendering) and its nearly loss-less compression.
I'm not a video "pro" and I don't own any high end apps so my level of skill is only QuickTime Pro. Some of the high end tools include a Motion-PNG codec. Since you know it supports alpha channels, combined with the right software and hardware, it seems like a logical choice. This is not the same as "blue" screen video.

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Answer 2

Dec 14, 2006 3:27 PM in response to QuickTimeKirk

If you exporting a video (from what ever program) that has a alpha channel and you wish to keep the alpha channel so you can bring it into an editing program like Final Cut Pro. Most people use the Animation codec.

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Answer 3

Dec 14, 2006 3:27 PM in response to QuickTimeKirk

Well, I can't tell you if transparency and alpha are considered the same when a movie is compressed. But, in my recent experience, I have only discovered that the Animation codec and No Compression will result in videos that contain Alpha channels. I guess I was just looking to see if any of the other 20 or so codecs in the list support Alphas, without doing a test on each one.

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Answer 4

Dec 14, 2006 3:40 PM in response to Stephen Barrante

Again, Animation codec is used to preserve quality (and do it pretty fast).
If your source contains an alpha channel exporting 5 seconds to various codecs would be enough of a test.
Since the codec is only chosen based on the "delivery" method (Web, CD, etc.) those simple tests could prove/disprove the alpha channel mystery. You wouldn't use an file with the Animation video codec on the Web (file size way too large).
The QuickTime .mov container can have up to 99 tracks and each track could have different "transparency". Each track can also have a "mask" (simple 1 bit color) that can also be applied.

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