[wdmaudiodev] Re: APO, filter driver, virtual audio device and certification

  • From: Tim Roberts <timr@xxxxxxxxx>
  • To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Thu, 19 Nov 2015 11:47:23 -0800

Arthur Lepp wrote:

I'm trying to add effects to the captured data of a microphone before
the data reaches any user mode application, i.e. removing certain noise.
This shall work independently of the underlying hardware and drivers on
Windows 7 and above. If there is a microphone device enabled, then it
shall work for it.

Microsoft simply does not support this approach. This is not
particularly surprising, since you can't possibly know what noise
suppression is already being done.

You can certainly write an APO for a specific microphone, and have your
APO included as part of the driver package for that hardware. That's
the Microsoft model.

So my questions to this subject:
1. What do you consider the best approach? - Are there other approaches?

If you are unable to tie yourself to one manufacturer, then the Virtual
Audio Driver approach is the Microsoft model.

2. As of what I saw in the HCK and read about WHQL certification it is
not possible to certify a standalone APO and there aren't any audio
filter driver tests. Is this correct, or is it somehow possible to
certify one of these? - Probably by submitting them as a package with
the general Microsoft HD Audio driver class?

It is not possible to have a standalone APO at all. The HCK tests and
signs driver packages, and you can't install an APO with a standalone
driver package. It has to be installed as part of the primary driver
for an audio device.

In general, filter drivers cannot be WHQL-tested, because they cannot be
installed via INF. However, by the same token, WHQL certification
serves no purpose for a filter driver. You don't need the WHQL
signature, because you don't have an INF-based package to be checked.

What if I still release my APO to the public with a notice, that DRM
related content cannot be accessed while the APO is active. Am I somehow
defying any laws and can be accused or charged by Microsoft or is it the
responsibility of the user?

I would think your users would be pretty well pissed off if installing
your driver meant they couldn't watch the Hunger Games DVD any more.

Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.


WDMAUDIODEV addresses:
Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx
Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe
Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe
Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx


Other related posts: