[wdmaudiodev] Re: Audio input summing under Vista

  • From: "Jeff Pages" <jeff@xxxxxxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Wed, 22 Feb 2006 09:53:12 +1100


Thanks for your detailed reply. Our cards are principally used in the 
professional audio environment, most notably sound broadcasting, and the input 
summing node was requested by a customer using our card with broadcast 
automation software, where audio coming from multiple sources (in their case 
multiple satellite channels I think) needed to be available at a single wave 
input device. Of course that could be done with an external mixer, but 
professional-quality mixers aren't exactly cheap and, for a low-budget station, 
having a sound card that included the mixer on its front end was a bonus for 
them (and a sale for us!).

It's not a major issue for us, and my main concern is that any of our existing 
customers who are using that feature may suddenly find it broken when they 
upgrade to Vista. Physically each of our inputs has its own A/D converter, so 
how they are presented is purely a firmware/driver issue. I have no problem 
presenting each physical input as a separate device, but it's just the 
backwards compatibility issue that's gnawing away at me.

By the way, will peakmeter nodes be supported under Vista? I've noticed under 
build 5270 that they're not being mapped into the mixer API. This really is a 
big issue for us, as one of our major customers relies heavily on having access 
to peak meters.


  ----- Original Message ----- 
  From: Hakon Strande 
  To: wdmaudiodev@xxxxxxxxxxxxx 
  Sent: Wednesday, February 22, 2006 8:29 AM
  Subject: [wdmaudiodev] Re: Audio input summing under Vista


  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 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

Other related posts: