If you use Media Player Classic, you'll no doubt be aware of its capability to apply pixel shaders to the video being played.

If you use x64 Windows XP, you'll have probably found out about faulty video files written by DOSBox that have the red and blue in the pallete swapped.

With a bit of guesswork I did some mucking around with the Media Player Classic shader editor and came up with this little fix. Just add this shader to your mplayerc.ini file and then turn it on when playing affected video files.

15=red-blue swap|ps_1_1|sampler s0 : register(s0);\nfloat4 main(float2 tex : TEXCOORD0) : COLOR\n{\n\tfloat4 c0 = tex2D(s0, tex);\n\treturn float4 (c0[2],c0[1],c0[0],0);\n}

By default, Media Player Classic seems to ship with 14 shaders, so this one ended up in slot 15. If you have more than that, just change the 15 at the start of the line to whatever is one more than your last shader number.

I imagine this shader will probably work with other media players that support whatever shader-writing language is used by Media Player Classic.