[wdmaudiodev] Re: Enumeration of Nodes on Instantiated Pins
- From: Art Edwards <snowdog0@xxxxxxxxxxxx>
- To: wdmaudiodev@xxxxxxxxxxxxx
- Date: Wed, 25 Sep 2002 14:28:18 -0400
You assume correctly. I am referring to the mixer API.
OK. But don't laugh.
I'm interested in implementing an el-cheapo audio generator/analyzer. I've
been using Directsound for the generator. I'd like to have some ability to
predict what the output level (in volts or something similar) will be.
For calibrating the system, I was hoping to take the approach of adjusting
the wave volume while reading the volume node until I get it somewhere near
0dB. Then I figured I'd capture the mixer API setting & use that. I told
you it was el-cheapo.
I suppose a better approach would be to go Kernel Streaming the whole
way. Then, I'd have a handle to the pin I created. But, I'm not sure how
to accomplish that. Any news on that white-paper BTW ?...
At 01:48 PM 9/25/2002 , you wrote:
>By mixer, I assume you mean the mixer API and not Kmixer (Kmixer doesn't
>need to know anything about the topology of downstream filters).
>
>The mixer API gets the topology of the whole graph through Sysaudio.
>Sysaudio exposes the audio graph as a few unconnected "virtual" filters.
>E.g. The "wave" render graph is virtualized as a single filter with all
>the nodes of all the real filters in the graph. The inter-filter
>pin-to-pin connections are hidden in this view, which simplifies things
>for the clients (e.g. Windows APIs). So if the mixer API needs to set a
>volume control, it does so through a "virtualized" pin handle on the
>Sysaudio filter. Sysaudio routes the call appropriately.
>
>Out of curiosity, what are you trying to accomplish (big-picture-wise)?
>Thanks.
>
>Mitch Rundle
>Microsoft Corporation
>
>This posting confers no rights and contains no guarantees.
>
>
>-----Original Message-----
>From: Art Edwards [mailto:snowdog0@xxxxxxxxxxxx]=20
>Sent: Wednesday, September 25, 2002 10:00 AM
>To: wdmaudiodev@xxxxxxxxxxxxx
>Subject: [wdmaudiodev] Re: Enumeration of Nodes on Instantiated Pins
>
>
>
>Yes, I forgot to mention that I can get the count of pin instances from
>the filter.
>
>Hmmm, as I suspected...
>
>So, how does the mixer send property requests to the volume control=20
>pin-nodes on a wave out filter ?
>
>At 12:43 PM 9/25/2002 , you wrote:
>
> >It depends on what you mean by "enumerate". You can infer the count of
>
> >pin instances, but you cannot get handles to them (which is what you=20
> >need for sending property IOCTLs) unless you instantiated them yourself
>
> >(e.g. via KsCreatePin).
> >
> >Mitch Rundle
> >Microsoft Corporation
> >
> >This posting confers no rights and contains no guarantees.
> >
> >-----Original Message-----
> >From: Art Edwards [mailto:snowdog0@xxxxxxxxxxxx]=3D20
> >Sent: Wednesday, September 25, 2002 5:45 AM
> >To: wdmaudiodev@xxxxxxxxxxxxx
> >Subject: [wdmaudiodev] Enumeration of Nodes on Instantiated Pins
> >
> >
> >
> >Does anyone know if an application can
> >enumerate pin instances on a filter ?
> >
> >If so, did I miss it when I searched the
> >DDK help and the WDMAudioDev archives ?
> >Or, is it top-secret ?
> >
> >I am trying to send IOCTL_KS_PROPERTY
> >requests to volume nodes associated with
> >a pin instance (i.e. so called
> >pin-nodes) on a filter. I have been
> >successful sending such requests to
> >nodes that are global to the filter.
> >(i.e. so called filter-nodes).
Art Edwards
Art's <http://members.localnet.com/~snowdog0/Resume>resume.
Art's <http://www.soniqboom.net>band (a.k.a. Soniq Boom).
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