[wdmaudiodev] Re: newbie questions

  • From: niaren 9 <niaren9@xxxxxxxxx>
  • To: Tim Roberts <timr@xxxxxxxxx>
  • Date: Mon, 11 Oct 2010 23:40:57 +0200

Thanks Tim,
Point taken! What I meant was the most used OS versions today. I believe XP
is one of them.

If I understand you correctly then if I want to support OS versions from XP
and beyond then there is no obvious (best practice) way to do it because XP
requires an avstream filter driver implementation and for Vista and win7
this is not recommended. That is not what I had hoped fore. Then two
different implementations are required, one for XP and one for the
I'm not familiar with the new audio philosophy but in the scenario I have in
mind the user actively starts a control application for the AVStream driver.
In this view a given media player does not directly request extra audio
features in the audio stream but the user requests it by starting the
control application and by enabling the features in the GUI control
What I want is to process the audio stream before it is going to the
speaker(s). In this way I don't have to implement a movie player myself in
order to demonstrate the audio features for movies. Any player would do.

Windows XP was released in 2001.  It's not really accurate to call it
> "newer".
> > and with any media player available (not just windows media
> > player).The audio processing must be controlable for the user and the
> > audio processing is intended for music and movie playback
> > primarily.How can I do that? From what I have read, it seems I could
> > achieve the above by inserting a filter into the audio driver stack. I
> > believe this should be possible by implementing an AVStream driver.
> > My first question: Is this correct?
> In XP, that's really the only option.  In Vista and beyond, you have the
> option of implementing a System Effects Audio Processing Object (SysFx
> APO), although the philosophy is that such an object is directly
> associated with a specific piece of hardware.  The new audio philosophy
> simply does not allow your model.   There should not be anything in the
> audio stream that the application did not specifically request.  Thus,
> you are fighting the system.
> > Follow up question? Is there is an easier way to achieve what I want?
> > Can it for instance be done without any driver development?
> That depends.  If you just want to grab a copy of the final speaker
> output, do something with it, and send it somewhere else, you can do
> that by using a rendering endpoint in loopback mode.  That won't let you
> modify the output stream, but you can monitor it.
> --
> 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
> http://www.wdmaudiodev.com/

Other related posts: