EDID decoding in libXrandr?

[Kai-Uwe Behrmann]

> Date: Fri, 16 Nov 2007 15:24:58 -0800
> From: Keith Packard <keithp at keithp.com>
> On Thu, 2007-11-15 at 18:59 +0100, Soeren Sandmann wrote:
> 
> > The monitor name displayed to the user should be computed based on
> > both the display descriptor strings, and on the vendor ID, depending
> > on what information is available. 

Oyranos parses EDID 1 information for monitor identification. It uses the 
18 byte blocks starting from 54 for a monitor manufacturer, model and 
serial ID string. In case the manufacturer was omitted, it switches back 
to scan the 2 byte ID's starting at position 8. The later could be 
extended to model(10) and serial(12).
 
> All I was suggesting was that the server should probably provide much of
> what you want in a EDID-indepenent fashion, so that the same tools will
> work with non-EDID monitors.

Yes, this is a good point.

> If you've got a list of identifying information that you'll be pulling
> out of EDID, we can see which make sense to have as output properties.
 
> > I also need the ability to compute an identifier that will allow the
> > client to recognize whether a monitor we have seen before, or a
> > sufficiently similar one, is plugged in so that the mode can be set
> > with no user interaction required at all.

A md5 or the like of a broken EDID block can possibly be used as a 
substitution for a serial number? The parser may not be able 
to identify manufacturer or model in such case.

> RandR 1.3 will have a fairly long list of 'standard' properties to try
> and make user interfaces more consistent across different video drivers
> and monitors; if you've got information you're interested in, having us
> standardize the content and format will help not only your application,
> but video driver developers as well.
 
Not shure if the colorimetry information will make sense for some people.
I mean the RGB primaries and the witepoint from position 25 till 34 and 
gamma in 23.
As I see, this information is dangerous for broken monitor EDID's and of 
not much value for most of the others. Still it is there.

Hope this email provides some helpful information.

thanks,
Kai-Uwe Behrmann
--
developing for colour management 
www.behrmann.name + www.oyranos.org