[Mplayer-cvslog] CVS: main/DOCS/tech colorspaces.txt,1.4,1.5

Arpi of Ize arpi at mplayer.dev.hu
Sat Apr 13 04:17:45 CEST 2002


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.
+




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