is it possible to mask videos with GEM ? I tried pix_mask, but it doesn't work with videos (at least, with .MOV videos in linux).
bye, andrei
Zitiere "Andrei R. Thomaz" andreithomaz@bol.com.br:
is it possible to mask videos with GEM ? I tried pix_mask, but it doesn't work with videos (at least, with .MOV videos in linux).
movies or live-videoINs are just sequences of still-images in Gem, so masking is possible and should work, with any supported video-format.
mfg.a.dsr IOhannes
Hi, What I've found when exporting from Final Cut Pro, is that the only codec that keeps the alpha channel is "Animation" when using Millions of colors+. Anyone found another one? If you want to mask according to a color of the image (like chroma keying), you can use either [pix_coloralpha] or [pix_ chroma_key], depending on what you need. Don't forget to put [alpha] somewhere in the chain to enable alpha blending, and be careful of the rendering order (gemhead number), because objects drawn earlier, even if in front will not blend correctly.
Cheers, Andrés
Andrei R. Thomaz wrote:
is it possible to mask videos with GEM ? I tried pix_mask, but it doesn't work with videos (at least, with .MOV videos in linux).
bye, andrei
On Dec 17, 2004, at 6:43 AM, Andres Cabrera wrote:
Hi, What I've found when exporting from Final Cut Pro, is that the only codec that keeps the alpha channel is "Animation" when using Millions of colors+. Anyone found another one?
The 'None' codec should do this as well, but the data rate is really
high. All of the usual codecs and project settings in FCP are the
video color-space, YUV/YCbCr , which does not have an alpha channel.
The default color-space in GEM on OSX is YUV.
If you want to mask according to a color of the image (like chroma keying), you can use either [pix_coloralpha] or [pix_ chroma_key], depending on what you need.
Two things about [pix_coloralpha]: One, it does nothing on YUV data.
Two, it just averages the R,G,B values, which really doesn't correspond
to anything useful. In other words, drastically different colors will
give the same mask, and the only really useful values are full white or
black (the only unique ones when averaging).
Don't forget to put [alpha] somewhere in the chain to enable alpha blending, and be careful of the rendering order (gemhead number), because objects drawn earlier, even if in front will not blend correctly.
Good suggestions.
cgc
chris clepper wrote:
Two things about [pix_coloralpha]: One, it does nothing on YUV data.
Two, it just averages the R,G,B values, which really doesn't correspond to anything useful. In other words, drastically different colors will give the same mask, and the only really useful values are full white or black (the only unique ones when averaging).
That's right, [pix_coloralpha] is mostly useful to create a mask with a black and white (greyscale) image.
Andrés
-
Andrei R. Thomaz -
Andres Cabrera -
chris clepper -
zmoelnig＠iem.at