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Keying with Keylight Question - quicktime alpha playabck

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Terry HahinKeying with Keylight Question - quicktime alpha playabck
by on Oct 14, 2009 at 3:36:29 pm

Hello,
I do a good amount of keying with Keylight (1.2)2, the one that comes directly with AE CS4.

My editor works on an AVID, which in previous experience could not unpremultiply an alpha channel. Therefore I submit a Quicktime (animation codec) with a straight alpha channel.

Problem is I get weird playback results in quicktime. I know it's a strange playback, but I'm talking real strange. The Quicktime siplays information that is not there, or is at least so small that I cannot even see it on a subpixel level.

Attached are 2 jpegs, one the showing the playback in quicktime, and one showing playback in AE.

So my question is, has anyone else experienced this? My client's get very nervous when they open my file in quicktime and get a bunch of wierd gabblydygook that I "promise will not be there after the final composite." Which is true, but I would like to stop worrying about it?

Any thoughts?





Terry Hahin

Designer and Editor
terryhahin.com


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Todd KoprivaRe: Keying with Keylight Question - quicktime alpha playabck
by on Oct 14, 2009 at 4:24:07 pm

When you have a movie with a straight alpha channel, the RGB data in areas of total transparency is totally irrelevant. It's undefined, actually. If you play such a movie in a player that is not interpreting the alpha information as transparency, it'll try to interpret these undefined RGB values as image data. Hence the gobbledeygook.


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Todd Kopriva, Adobe Systems Incorporated
putting the 'T' back in 'RTFM' : After Effects Help on the Web
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If a page of After Effects Help answers your question, please consider rating it. If you have a tip, technique, or link to share---or if there is something that you'd like to see added or improved---please leave a comment.


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Dave LaRondeRe: Keying with Keylight Question - quicktime alpha playabck
by on Oct 14, 2009 at 5:19:03 pm

Todd is absolutely correct as you would expect.

However, I have a more fundamental question: why are you simply pulling a key and not doing the entire shot? When you include the background and render the completed shot, AE gives you tools to color correct so the key matches the background, and to add light wrap and fake shadows to make the shot far more convincing. You may even spot tiny errors in the key, and you can correct them.

If you just pull a key, the editor slaps it over a background and it looks like the local weatherman giving the forecast. An editing application just can't do what AE can do.

The editors I work with reply, "Well, I have more creative flexibility if I have just a piece of alpha-channeled footage."

My response is this: "Baloney! You just can't make up your mind, that's all! You're talking about effects work, and if you don't know what you want to do beforehand, you're already in trouble. So quit waffling, make some decisions, and let's get the whole shot DONE!"

It's probably a good thing I don't work much with clients.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Terry HahinRe: Keying with Keylight Question - quicktime alpha playabck
by on Oct 14, 2009 at 6:51:34 pm

Thanks for your quick responses on this.

Trust me, if I could take over the whole process and be involved for each step, I would be. I am simply part of a chain, as is often the case with After Effects Artists.

That being said, I will take it as a wake up call to try and take more control of future projects.

Unfortunately, the reality is that my job is to send straight alpha channels to people who may not know what's up. On a technical level the gobbledygook is "irrelevant." But on a practical level it's not irrelevant when the client is looking at it.

What would you do in my situation?

Terry Hahin

Designer and Editor
terryhahin.com


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Todd KoprivaRe: Keying with Keylight Question - quicktime alpha playabck
by on Oct 14, 2009 at 6:57:32 pm

> What would you do in my situation?

I've been in your situation. And I've said something like this: "That's just extra, irrelevant image data in the areas that are transparent. Don't worry; it won't show up in the composite. Straight channels aren't meant to be viewed by humans---they're meant to be consumed by computers."

---------------------------------------------------------------------------------------------------------
Todd Kopriva, Adobe Systems Incorporated
putting the 'T' back in 'RTFM' : After Effects Help on the Web
---------------------------------------------------------------------------------------------------------
If a page of After Effects Help answers your question, please consider rating it. If you have a tip, technique, or link to share---or if there is something that you'd like to see added or improved---please leave a comment.


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Dave LaRondeRe: Keying with Keylight Question - quicktime alpha playabck
by on Oct 14, 2009 at 7:00:46 pm

What do you do? Screw the boss' workflow, and start an amiable insurrection.

Take the editor out for a beer; I recommend Goose Island at 1800 North Clybourn -- great beer, great food, better than the one in Wrigleyville. Have a heart-to-heart chat about the situation. Describe how much better the shots could look if you were to do more than simply pull a stinkin' key. The two of you then take it from there.

Not everything will get settled in that one session, but you will make an extremely good start.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Terry HahinRe: Keying with Keylight Question - quicktime alpha playabck
by on Oct 14, 2009 at 8:13:27 pm

That's good advice. I think I will join him for a beer.

Haven't been to the Goose Island on Clyborne in a while, and I've never heard of a better excuse!

Cheers boys! thanks for all you help,

Terry Hahin

Designer and Editor
terryhahin.com


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Dave LaRondeRe: Keying with Keylight Question - quicktime alpha playabck
by on Oct 14, 2009 at 8:18:06 pm

Say.... ever do any work for WTTW? I have a old buddy there who's a director: he does Chicago Tonight, and also directs weekend evening newscasts at WMAQ.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Terry HahinRe: Keying with Keylight Question - quicktime alpha playabck
by on Oct 15, 2009 at 3:48:45 am

Can't say that I have Dave, but would love to. I do a lot of work in corporate video, some independant doc and narrative, and a good amount of video advertisements that end up on the web. Haven't broken out into much motion Design work for TV, but would love to.

If you friend is ever in need of some motion graphics work I'd love to contact him.

Cheers, and thanks again for your suggestions today,

Terry Hahin

Designer and Editor
terryhahin.com


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