[wdmaudiodev] Re: AW: Re: Loop back AGC in renderer audio path?

  • From: "Matthew van Eerde" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "Matthew.van.Eerde" for DMARC)
  • To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Tue, 26 Feb 2019 11:15:16 +0000

I’m not aware of any official documentation for the audio limiter. It doesn’t 
seem to be mentioned here
https://docs.microsoft.com/en-us/windows-hardware/drivers/audio/audio-processing-object-architecture

The limiter is not configurable. Can you elaborate on what kind of 
configuration you would want, and what scenario this would enable?

You may find these blog posts of interest
https://blogs.msdn.microsoft.com/matthew_van_eerde/2011/05/11/linearity-of-windows-volume-apis-iaudiometerinformation-and-full-scale-signals/

https://blogs.msdn.microsoft.com/matthew_van_eerde/2010/06/03/how-to-enumerate-wasapi-audio-processing-objects-apos-on-your-system/


From: Jacob Martin Riiser (JMRI)<mailto:jmri@xxxxxxxxxxx>
Sent: Tuesday, February 26, 2019 3:06 AM
To: wdmaudiodev@xxxxxxxxxxxxx<mailto:wdmaudiodev@xxxxxxxxxxxxx>
Subject: [wdmaudiodev] Re: AW: Re: Loop back AGC in renderer audio path?

Any info on the limiter in the audio path:

  *   Is it documented somewhere?
  *   Can it be configured (time constants etc.)?
  *   Other useful hints?

Thank,
Jacob

Best regards / Med venlig hilsen

Jacob Riiser (JMRI)
Sennheiser Communications A/S
Direct                  +45 5618 0004

From: wdmaudiodev-bounce@xxxxxxxxxxxxx <wdmaudiodev-bounce@xxxxxxxxxxxxx> On 
Behalf Of Matthew van Eerde
Sent: 22. februar 2019 16:52
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: AW: Re: Loop back AGC in renderer audio path?

There is indeed a limiter, but it is well after the SFX. The input to the SFX 
is not modified.


From: wdmaudiodev-bounce@xxxxxxxxxxxxx<mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx
<wdmaudiodev-bounce@xxxxxxxxxxxxx<mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx>> on 
behalf of Johannes Freyberger 
<jfreyberger@xxxxxxxxxxxxxxxxxxxx<mailto:jfreyberger@xxxxxxxxxxxxxxxxxxxx>>
Sent: Friday, February 22, 2019 3:55:13 AM
To: wdmaudiodev@xxxxxxxxxxxxx<mailto:wdmaudiodev@xxxxxxxxxxxxx>
Subject: [wdmaudiodev] AW: Re: Loop back AGC in renderer audio path?

Couldn’t it be he stumbled across the limiter inside the windows audio mixer?

Von: wdmaudiodev-bounce@xxxxxxxxxxxxx<mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx
<wdmaudiodev-bounce@xxxxxxxxxxxxx<mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx>> Im 
Auftrag von Matthew van Eerde (Redacted sender "Matthew.van.Eerde" for DMARC)
Gesendet: Donnerstag, 21. Februar 2019 23:14
An: wdmaudiodev@xxxxxxxxxxxxx<mailto:wdmaudiodev@xxxxxxxxxxxxx>
Betreff: [wdmaudiodev] Re: Loop back AGC in renderer audio path?

Windows does not do such a thing as you describe; what gave you that impression?


From: wdmaudiodev-bounce@xxxxxxxxxxxxx<mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx
<wdmaudiodev-bounce@xxxxxxxxxxxxx<mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx>> on 
behalf of Jacob Martin Riiser (JMRI) <jmri@xxxxxxxxxxx<mailto:jmri@xxxxxxxxxxx>>
Sent: Tuesday, February 19, 2019 7:51:35 AM
To: wdmaudiodev@xxxxxxxxxxxxx<mailto:wdmaudiodev@xxxxxxxxxxxxx>
Subject: [wdmaudiodev] Loop back AGC in renderer audio path?

Hi,

While developing an SFX APO (renderer), I have encountered some problems 
causing my output to exceed legal range – this is being addressed.
However, while looking into this, I got the impression that Windows (I presume) 
monitors the output level of the APO, and is able to apply AGC-like 
functionality by adjusting the input gain to the APO.

I would really like some info on this functionality, including:

  *   How does this work?
  *   Are time constants described somewhere?
  *   Can it be tuned or adjusted in any way?

Best regards / Med venlig hilsen

Jacob Riiser (JMRI)
DSP Engineer

Sennheiser Communications A/S
Industriparken 27
2750 Ballerup
Direct                  +45 5618 0004
Mail                     jmri@xxxxxxxxxxx<mailto:jmri@xxxxxxxxxxx>
Web                    
www.senncom.com<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.senncom.com&data=02%7C01%7CMatthew.van.Eerde%40microsoft.com%7C661c2993771b4fee4a8508d69bda75fd%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636867759956821527&sdata=hvwcqyhMuNp3b1Z%2FI1yKLO7bxyv5BAYKKNscs9zoBfs%3D&reserved=0>


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