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RGBvsBGR added 

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@5588 b3059339-0415-0410-9bf9-f77b7e298cf2
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arpi 2002-04-13 02:17:43 +00:00
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commit 96da430d08
1 changed files with 23 additions and 0 deletions
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DOCS/tech/colorspaces.txt
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@ -79,3 +79,26 @@ I420: 12 bpp, full sized Y plane followed by 2x2 subsampled U and V planes
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.