[GEM-dev] 0.90 and pix_video under Linux
IOhannes m zmoelnig
zmoelnig at iem.at
Mon Jun 21 12:15:08 CEST 2004
Mirko Petrovich wrote:
>
>
>> probably your [color]/[colorRGB] is set to black ? (or the
>> alpha-channel is 0 ??)
>> thinking of this, it might be, that the video4linux-driver is able to
>> produce RGBA-images but unfortunately sets the alpha-channel of each
>> pixel to 0. in this case, you will have to raise it manually.
>
>
> I checked this, and it's not the problem , the strange thing is that
> alpha works in pix_gray and even in pix_yuv (I get a distorted image, I
> guess this is right).
this isn't strange as [pix_grey] and [pix_yuv] use colour-spaces that do
not have an alpha-channels (so it is automatically set to 1)
i still believe that the problem is, that [pix_video] returns
RGBA-images with alpha=0 (you could watch this with [pix_histo]
furthermore, you can send a [colorspace YUV( or [colorspace GREY(
message to [pix_video], which might be faster (depending on the
video-capture-device)
>
> I was calling pix-mixers (I forgot there was a pix_mix object) as a
> generic name, actually I'm using compose,add,subtract,diff,compare,
> chroma_key,mask, etc... and my idea was to fade the resulting image
> textured in a lot of geos (with openGL-alpha blending).
i was just asking; could have been possible that you were only
interested in simple mixing...
mfg.a.sdr
IOhannes
More information about the GEM-dev
mailing list