Compositing Via After Effects

JMRoe · Post by **JMRoe** » Thu Oct 28, 2004 4:56 pm

I have just made an animation with Moho and need to composite it onto another image with after effects. So far the only way I've had any success is setting the project background to a blue and keying out the blue in AE, but it doesn't look that good. I'm using a Macintosh and exporting with quicktime. Anyone have any suggestions? Any help would be greatly appreciated!

spasmodic_cheese · Post by **spasmodic_cheese** » Thu Oct 28, 2004 5:11 pm

you could use the Huffyuv AVI codec, it exports transparency, its lossless compression too

http://neuron2.net/www.math.berkeley.ed ... ffyuv.html

Post by **Lost Marble** » Thu Oct 28, 2004 5:17 pm

The Huffyuv codec is Windows-only. If you're on Mac, or using QuickTime on Windows, you don't need it.

Moho always generates an alpha channel when rendering out a movie, which works great for compositing within After Effects. The only issue is making sure you choose an output format that supports alpha. When exporting to QuickTime, pick a codec that offers "Millions of Colors+". The "+" is QuickTime's notation for an alpha channel. Some codecs that suppprty this are Animation, PNG, and TGA.

Once you've exported a movie with an alpha channel, just tell After Effects to use the alpha channel for compositing.

You might want to consider turning on the "Don't premultiply alpha" option in the Export Animation dialog. This will make the movie look strange if you play it back on its own, but will make it composite more nicely in After Effects, espceially if you have varying levels of semi-transparent objects, such as smoke or fire effects.

7feet · Post by **7feet** » Thu Oct 28, 2004 5:20 pm

The trick when exporting with Quicktime is to set the "Depth" to "Millions of Colors+". The "+" tells the codec to also export the Alpha channel for transparency. Not all of the codecs support it. Also, I would suggest that you do try to export in as lossless a format as you can. Animation can get mighty ugly at compression settings that would be fine for regular video, and multiple compressions are a killer.

--Brian

spasmodic_cheese · Post by **spasmodic_cheese** » Thu Oct 28, 2004 5:26 pm

wow i didnt know there were codecs that were platform specific.. *goes back into his hole and strokes his flash*

Post by **Lost Marble** » Thu Oct 28, 2004 6:36 pm

Speaking of the Animation codec: if you choose Best quality, it is lossless. Otherwise, yes, it can be pretty ugly when set to lower quality settings.

kdiddy13 · Post by **kdiddy13** » Thu Oct 28, 2004 7:41 pm

The Quicktime Animation codec is definitely the way to go before compositing or compressing anything. You won't wan to use it to share with friends, but it will get you the best image quality without being as big as Uncompressed.

Also, if you actually nudge it back a hair from "Best", you probably won't notice the quality difference and you'll save a significant amount of disk space.

If you do happen to export a premultiplied alpha channel, all is not lost, After Effects give you the option to select the premulitplied color in the clip's settings import dialogue (you can also change this by pressing command F or control F with the clip selected). It defaults to black but you may want to change it (depending on what you have your background set to in Moho).
________
230

mooncaine · Post by **mooncaine** » Tue Aug 28, 2007 1:18 am

I'm so happy to be getting alpha channels out of ASP right now, to QuickTime.