Philip Lamb schrieb:
Hi all,
For one of our projects which we are connecting to OSG, we use YCbCr
pixels where possible, via the GL_APPLE_ycbcr_422 OpenGL extension on
Mac OS X and/or the GL_MESA_ycbcr_texture OpenGL extension on Linux.
I see no support for these extensions in OSG, and I wonder if anyone has
considered it / put it into the too hard / don't care basket?
I did some tests with GL_APPLE_ycbcr_422 and the Quicktime-movie-plugin.
It was a bit wonky (but twice as fast), and I had not enough time to
investigate the problems.
What I did: the quicktime-plugin uses a subclass from ImageStream. I set
up the image with:
image->setImage(_textureWidth,
_textureHeight,
1,
(GLint) GL_RGBA,
(GLenum)GL_YCBCR_422_APPLE,
computeInternalFormat(),
(unsigned char*)buffer,
osg::Image::NO_DELETE,
2);
and computeInternalFormat looks like this:
GLenum MovieData::computeInternalFormat() {
GLenum format;
#ifdef GL_YCBR_422_APPLE
if (getYUVPlaybackUsed()) {
#if defined(__APPLE__) && defined(__BIG_ENDIAN__)
format = (GLenum)GL_UNSIGNED_SHORT_8_8_REV_APPLE;
#else
format = (GLenum)GL_UNSIGNED_SHORT_8_8_APPLE;
#endif
}
else
#endif
{
#if defined(__APPLE__) && defined(__BIG_ENDIAN__)
format = (GLenum)GL_UNSIGNED_INT_8_8_8_8_REV;
#else
format = (GLenum)GL_UNSIGNED_INT_8_8_8_8;
#endif
}
return format;
}
As far as adding support for these formats, AFAICT some additions would
be needed in osg::Image and osg::Texture2D and osg::TextureRectangle.
For me there was no need to modify the core-osg. Set up the image with
the right parameters and it should work out of the box.
Which is the preferred base for making a proposal in the form of a
patch? Latest release, or a specific cvs branch / revision?
see
<http://www.openscenegraph.org/osgwiki/pmwiki.php/Support/SubmissionsProtocol>
HTH,
Stephan
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