[MPlayer-dev-eng] mga_vid and brightness/contrast control.

[D Richard Felker III]

On Sat, Feb 02, 2002 at 10:20:19PM +0100, Dariusz Pietrzak wrote:
> Hello,
>  i've just commited changes that enable mga_vid to control brightness
> in the same style that radeon_vid does
> (echo "brightness=120" > /dev/mga_vid ).
>  There should also be contrast control implemented, but all I know about
> contrast is that neutral value is 0x80, and that this is '1.7 value
> ranging from 0 to 1.99'.
> 
> What is '1.7 value'?
> 
> I am assuming that it means that first bit is 0 or 1, and the rest would
> be integer from 0 to 99 ?
>  This would look like BCD format, i thought BCD is long extinct?

I imagine it means the scale is nonlinear, i.e. 0x80 represents
1.7/2 contrast on a linear scale, i.e. about 85%, 0xff represents
100%, and 0x00 0%. I seriously doubt it has anything to do with bcd.

Rich