Update of /cvsroot/mplayer/main/DOCS/tech In directory mplayer:/var/tmp.root/cvs-serv13202 Modified Files: colorspaces.txt Log Message: RGBvsBGR added Index: colorspaces.txt =================================================================== RCS file: /cvsroot/mplayer/main/DOCS/tech/colorspaces.txt,v retrieving revision 1.4 retrieving revision 1.5 diff -u -r1.4 -r1.5 --- colorspaces.txt 13 Apr 2002 02:09:18 -0000 1.4 +++ colorspaces.txt 13 Apr 2002 02:17:43 -0000 1.5 @@ -79,3 +79,26 @@ IYUV: the same as I420 YVU9: 9 bpp, full sized Y plane followed by 4x4 subsampled V and U planes +Huh 2. RGB vs. BGR ? +==================== + +The 2nd most missunderstood thingie... + +You know, there are Intel and Motorola, and they use different byteorder. +There are also others, like MIPS or Alpha, they all follow either Intel +or Motorola byteorder. +Unfortunatelly, the packed colorspaces depend on CPU byteorder. So, RGB +on Intel and Motorola means different order of bytes. + +In MPlayer, we have constants IMGFMT_RGBxx and IMGFMT_BGRxx. +Unfortunatelly, some codecs and vo drivers follow Intel, some follow Motorola +byteorder, so they are incompatible. We had to find a stable base, so long +time ago I've choose OpenGL, as it's a wide-spreaded standard, and it well +defines what is RGB and what is BGR. So, MPlayer's RGB is compatible with +OpenGL's GL_RGB on all platforms, and the same stay for BGR - GL_BGR. +Unfortunatelly, most of the x86 codecs call our BGR to RGB, so it sometimes +confuse developers. + +If you are unsure, try the OpenGL driver (-vo gl). There is at least software +OpenGL implementation for all major platforms and OSes. +