Intro to WDM/KS audio filtering

NTDEV
10

To your question #1. No, it is not possible.
While there are ways to inject a component in an abitrary graph, nothing prevents an app from
building graphs in totally manual fashion using direct pin connection.
In that case interscepting graph rendering is impossible unless you resort to hooking.

This leaves you with only one real alternative and that is filtering KS stack, which is completely
undocumented.
This is about as bad as hooking and subject to breaking at any moment.

Check out archieves. This has been discussed numerous times.
– Max.

-----Original Message-----
From: xxxxx@lists.osr.com [mailto:bounce-229460-
xxxxx@lists.osr.com] On Behalf Of David Lavo
Sent: Tuesday, December 13, 2005 6:01 AM
To: Windows System Software Devs Interest List
Subject: Re:[ntdev] Intro to WDM/KS audio filtering

Hi Maxim,

I’m still investigating this issue, and have not yet found the best
answer. Specifically, I would much appreciate it if you (or anybody
else) has information on the following two questions:

  1. Can I insert a DirectShow filter (or DMO) into the default audio
    capture path so that audio received by third-party (or legacy) apps will
    go through my filter and get the signal processing?

  2. I have read in several other posts (including many by you, Maxim)
    about using a user-mode driver associated with winmm.dll. Is this still
    a viable approach, and if so is the only documentation on this available
    in the NT/Win95 DDKs?

Thanks a lot for any help on this,

David

Maxim S. Shatskih wrote:
>>seem more complex than what I need. I assume that I need to be able to
>>be the default sound recording and voice recording device, so I think
>>this rules out a user-mode/DirectShow filter.
>
>
> Why? With DirectShow, you go to user mode/KS only if there is some
hardware.
> Otherwise, stay in user mode.
>
> Maxim Shatskih, Windows DDK MVP
> StorageCraft Corporation
> xxxxx@storagecraft.com
> http://www.storagecraft.com
>
>
>

Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

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