hi,
i am having limited success
achieving color keying using 2 stream of video. Have tried using the
[pix_alpha] method and can achieve color keying using to picture
sources
or using video as the background and an image as the keyed foreground,
but replacing the foreground image with a movie does not work.
tried converting the foreground movie using
[pix_rgba] but no use, it just screws up the color. using
[pix_hsv2rgb] results in some sort of keying but not through the
pix_alpha method just as a result of shifting the color fields
around.
i was wondering if
a)
what i am trying to do is just wrong
b) some crucial step is missing
c) GEM implementation on OS X is lacking
which version of GEM are you using? there's not a final
release for OSX yet so you might be using a broken or outdated
version. try the one here:
http://taproot.dyndns.org/~cgc/downloads/index.html (make sure
you grab the appropriate one for either G3 or G4 cpu).
it has an object called pix_chroma_key that i wrote and it does
keying on both RGB and YUV sources. it's usage is quite simple
it takes a message for the key 'value' with three arguments for each
color channel, and a 'range' message which is the range of values +/-
the center value.
example for RGB:
value 150 100 50
range 20 10 10
would key using the red channel for a range of 130 to 170 the
green from 90 to 110 and blue 40 to 50. if this was for YUV it
would be the same ranges for Y (luma) Cb (chroma-blue) and Cr
(chroma-red) in that order.
there's also a 'direction' message that flips the keyed
areas.
cheers, tim