[wdmaudiodev] Re: AVStream Audio Frustration
- From: Tim Roberts <timr@xxxxxxxxx>
- To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Fri, 2 Nov 2012 15:14:11 -0700
Matthew van Eerde wrote:
>
> It's good that you're suppressing formats you don't support from your
> advertised data ranges, and from your data intersection handler. I
> don't know why Windows is trying formats you don't advertise. Are you
> also returning failing status codes for pin creations when the format
> is one you don't support?
>
There's a critical piece of information that is relevant here that I
just now noticed. When I created my driver originally, I only had the
one output pin. That filter shows up in graphedt as a "WDM Capture
Device". It works properly. The pin shows up with exactly the one
format in my pin descriptor. However, in that state, sysaudio will not
talk to me, so I don't appear as a waveIn device. I can only be used by
apps specifically looking for WDM devices. My client is using a Flash
webcam app, and that needs a waveIn device.
Yesterday, I finally added a microphone bridge pin and a fake internal
node, which was sufficient to get sysaudio to acknowledge me. I now
appear as a waveIn device, and in the "Audio Capture Devices" list in
graphedt. THAT'S the scenario that fails.
To answer your question, I never get the opportunity to fail pin creation.
When my driver restarts, I see a series of create/delete sequences for
my filter. I presume this is coming from the Audio Engine. I can bring
up graphedt, instantiate my filter, look at the pin properties, and
render the pin, and ALL OF THAT happens without any communication with
my driver. No pins are ever created. The data intersection handler is
not called, even though graphedt now shows that the two filters have
agreed on a format (44100-S-16, which I do not support).
The pin doesn't get created until I start the graph. At that point, I
get a SetFormat request for whatever the "Default Format" is in control
panel (NOT the format shown in graphedt!), and streaming starts. The
data intersection handler is never called. In this case, the SetFormat
I got was for 22050-S-16, which is different from the pin format in
graphedt, but the audio worked, so someone is doing a sample rate
conversion on my behalf.
So, this is evidently a manifestation of my interaction with sysaudio
and the Audio Engine, but I still need to know how to fix it.
Basically, I need to tell the Audio Engine what my "default audio type"
is during initialization.
--
Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.
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