The client wants to have the matte pulled so they can comp a person walking on to a webpage. They'd like me to pull the matte/key the subject and so they just have composite it.
I am having a bit of trouble with Alpha Channels. In Motion 5 I pulled the matte using the key filter. When I exported using share I made sure under Render that the Color+Alpha was enable and premultiply checked. Then I made sure it was ProRes 422 since I heard .H264 does not carry Alpha channels. I brought the .mov into FCPX and when I looked at the Alpha it was a solid color and most frustrating i could not comp the FG element over a BG by layering or connect to primary storyline.
Bringing the same video into Motion 5 did not work and seemed to not have a Alpha Channel which was really odd....I thought.
When you export Titles from Motion 5 it works great. I found a work around which was export Alpha only from Motion 5 then layer that over the FG in FCPX then choose in Composting Stencil Luma and connect the clips and bingo I'm rocking a BG behind the FG element.
Am I not finding the magic setting for export out of Motion 5 or is FCPX not reading an Alpha that does exist in the file. Compositing gurus please help.
As Kyle already said, you'll have to make a Prores 4444 movie OR in Animation Codec.
Could be that in FCPX, you also have to go to the Info Tab in the Inspector of the Prores 4444 Files and see if there is (maybe in Extended View) a checkbox with Alpha turned on. Don't know the specifics anymore, but I remember that there was something like that.