[wdmaudiodev] Re: Discovery of Analog Audio Device

  • From: Marc Lindahl <marc@xxxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Tue, 6 Nov 2007 16:25:13 -0500

Very interesting paper.
I really hope this goes quietly away... IMO a very misguided effort.
Main reason - no proposal given to actually measure these impedances in a real device. Personally I can't think of any circuit that wouldn't compromise the audio quality and increase the cost. For the benefit of? 
Second reason - methodology is pseudo-scientific at best.
But - it is a valid and interesting question ... perhaps worthy of some real research. 
Anyone have change for my $0.02?
Marc

On Nov 6, 2007, at 2:53 PM, Hakon Strande wrote:


I found it

http://www.microsoft.com/whdc/device/audio/analog_impedance.mspx

Sincerely,

Hakon Strande | Windows Sound Team PM | (p) 425.705.0637


-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Ernest_Burghardt@xxxxxxxxxxxx 
Sent: Tuesday, November 06, 2007 10:10 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: Discovery of Analog Audio Device

Thanks Hakon, I would love to read that whitepaper.

Ernest L. Burghardt
Software Engineer
Logitech
360-256-3239 (office)
Hakon Strande To 
             <hakons@xxxxxxxxx         <wdmaudiodev@xxxxxxxxxxxxx>
icrosoft.com> cc
Sent by: Subject 
             wdmaudiodev-bounc         [wdmaudiodev] Re: Discovery of
             e@xxxxxxxxxxxxx           Analog Audio Device


             11/06/2007 09:57
             AM


             Please respond to
             wdmaudiodev@freel
                 ists.org






Some vendors use Impedance Sensing to guess the nature of the analog
peripheral connected as impedances are different from Microphones to
headphones to speakers to line level devices. It is hardly an exact science 
but the results are surprisingly accurate when those who implemented it
knew what they were doing...
There was an MS white paper published on the subject but now I can't find 
it on our web site. I'll keep looking.

Sincerely,

Hakon Strande | Windows Sound Team PM | (p) 425.705.0637

-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of
Ernest_Burghardt@xxxxxxxxxxxx
Sent: Tuesday, November 06, 2007 9:35 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Discovery of Analog Audio Device


Hi All,
Is there a way to know what the analog audio device (i.e. speaker) that is 
plugged into the jack?

Thanks in advance,
Ernie

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