[wdmaudiodev] Re: Audio input summing under Vista

  • From: "Hakon Strande" <hakons@xxxxxxxxxxxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Tue, 21 Feb 2006 13:29:15 -0800



With Vista and the UAA initiative we are taking big steps towards a more
transparent audio hardware ecosystem (I am referring to the consumer
market here - the 95% case) and through full discoverability of audio
device capabilities and the move towards independent devices we hope to
create a better user experience in our operating systems of the future
for the regular PC user. 


One important aspect of the usability and discoverability of logical
audio devices exposed by an audio adaptor is that they are independent
from each other. By this I mean the audio solution has enough
[converter] resources to treat each logical input and output
device/connector independently. In the cases where multiple audio
endpoints connect to a single DAC or ADC resource it is important that
the operating system is made aware of this through defined driver OS
interfaces so the user can be informed by the OS what device he can
expect to be active/operational. In the hardware realm, one of the UAA
technologies support the exposure of the system implementers intentions
for logical audio device support through a defined firmware method (read
about Pin Configuration registers in the HD Audio 1.0 spec or here
<http://www.microsoft.com/whdc/device/audio/PinConfig.mspx>  if you want
to learn more about that).


Ideally all inputs and outputs on a PC are wholly independent and the
capabilities of the audio device completely discoverable and that is the
direction we are driving for Vista and beyond. What we want to enable is
total transparency through simple audio path designs in hardware that
enable more powerful OS audio policy/troubleshooting features and more
flexibility with the use of the audio device for our future OS features
and for media applications running on Windows. 


This is equally true on the input side where when the ADC resources are
limited but the number of logical input devices exposed outnumbers the
available ADCs. While this in itself is not recommended, the muxed
behavior is preferable in the context of predictability and user
friendliness. It is hard for a normal user to understand why the
integrated microphones on the laptop still are recording after plugging
in the headset into the Line/Mic jack on the side for instance. In Vista
we discourage the use of mixed input devices sharing one ADC for
usability reasons and our operating system will treat these (when
exposed by the driver) as muxed devices sharing one ADC.


It seems you are missing the ability to expose a multi input mixed
device and my question would be, why? What common user scenario is
supported by mixing multiple inputs to one ADC?





Hakon Strande

PM Integrated, Internal, External, and Wireless Audio Devices

MediaTech/DMD/Windows Client/Microsoft


From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Jeff Pages
Sent: Sunday, February 19, 2006 4:41 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Audio input summing under Vista


With our multichannel sound cards, we have a summing node
(KSNODETYPE_SUM) in the input topology so that multiple physical inputs
can be summed into a single waveIn device. Under Vista, each input
bridge pin creates its own waveIn device, so it would appear that
summing multiple inputs to a single device is no longer possible. Is
this in fact the case, or is there something I'm missing?


Jeff Pages

Innes Corporation Pty Ltd

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