[Edwin Street] “Does ProRes4444 only have one extra layer (Alpha Channel)?
And how can I see this extra channel? Do I need to use Motion or After Effects?”
The 4’s are sampling channels. 4444 can carry four streams of image information — RGBA or Y’CbCrA.
Your green bar might mean that you are carrying RGB in the 4:4:4 tables, which might give FCP some issues. Unfortunately there are no flags in the ProRes4444 codec to explicitly state what it is, exactly, that is being transported. RED usually exports into PR4444 as RGB.
There are ways to examine the alpha channel, if it exists. In FCP’s Viewer, you will notice three buttons imbedded in the center along the top frame. The one on the right has a “cornerframe” icon. Clicking on it will reveal some options — Overlays, wireframes, and “RGB”, “Alpha” and “RGB&Alpha”. RGB, of course, shows you your color picture. Alpha will show you your key-holdback, and RGB&Alpha will give you a sense of how the alpha will interact with the foreground picture elements to punch-through a background. Its a red/monochrome representation.
Most compositing software has to be able to show you the alpha channel, extract it, modify it, and re-embed it.
jPo
“I always pass on free advice — its never of any use to me” Oscar Wilde.