[wdmaudiodev] Re: Vista 5.1 speaker mode question

  • From: Mike Preston <mike@xxxxxxxxxxxxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Wed, 14 Mar 2007 16:11:53 -0700

Thanks for the valuable information. I just wanted to make sure we're talking about the same thing. I'm talking about a Speaker endpoint on an HD audio codec that supports 7.1, but is configured for 5.1 mode. Does the pin configuration you're talking about come from the verb tables in the BIOS? Is there an API for getting the codec's pin configuration that is available above the driver level? The only thing in the Core Audio API that is remotely related is the IAudioChannelConfig, but that only allows you to get the current configuration. It also seems to be unrelated to the jack information for the endpoint. Any suggestions?

Mike Preston

Hakon Strande wrote:
If it is the Windows Vista HD Audio class driver you are running we
use the HD Audio codec's pin configuration default values to
determine the channel mask of the multi-channel device through pin
config sequence numbers in the logical device association. If a
system vendor has set the pin config values of the integrated HD
Audio device to indicate that the 5.1 device uses side speakers then
we expose that to the OS when it asks the driver through the channel
config property request but if the system vendor uses the pin config
sequence values in the multi-channel device association to indicate
that the 5.1 system has rear speakers the HD Audio class driver will
expose that to the OS as the channel mask for that device instead.

See the chapter "Speaker Configurations" in the HD Audio pin
configuration programming guidelines document here for the background
on how we interpret pin config values into speaker configurations in
the HD Audio class driver:


If your repro is not with the class driver and/or not with HD Audio
solutions then I think you'll have to ask the driver developers who
created the drivers you are using why they expose different 5.1
configurations because Windows Vista uses the channel mask
information provided by the driver to decide what type of
multi-channel device we are dealing with.


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

-----Original Message----- From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Mike Preston Sent: Tuesday, March 13, 2007 7:44 PM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Vista 5.1 speaker mode question

I have a question regarding side vs. rear speakers in 5.1 mode in the
 Speaker Setup wizard on Vista.  I've noticed that on different
systems that support 7.1 (i.e. both side and rear speakers are
present), on some systems, 5.1 mode uses the side speakers, while on
other systems, 5.1 mode uses the rear speakers.  How does Vista
determine which to use?  If anyone has any info on this, it would be
greatly appreciated.

Thanks, Mike Preston

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