[wdmaudiodev] Re: External clock synchronization and sample rate issue
- From: "Philip Lukidis" <plukidis@xxxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Tue, 16 Jan 2007 16:00:17 -0500
Hello, I hope you don't mind if I ask a question again on this topic. After a
delay of a few days I managed to get back on this and I got it to work- but
only after a few somewhat painful measures.
First I tried registering using the same HardwareID for my device and
registering the appropriate subdevice based on the selected sample rate, but
this did not work, despite the fact that I gave the subdevice a different name
(the name passed to PcRegisterSubdevice, and KSStudio confirmed that the name
was different). My single HardwareID in the INF would register all interfaces
(one for each sample rate). While it worked for first sample rate during
installation, it never worked for any other sample rate; the system kept on
remembering the first sample rate. For now, I would switch sample rate by
using a registry value. So a "switch" is provoked by an unplug of the device,
changing the registry value, and replugging. Also, this only worked with a
DataRangeIntersection handler- if I implemented a
KSPROPERTY_PIN_PROPOSEDATAFORMAT handler, it did NOT like an absence of 44100.
I was only able to get it to work by moving to a different device altogether,
by having my virtual bus driver announce a different HardwareID based on the
sample rate (so we are no longer talking of subdevices on a device object; the
device object is now different). Of course, the first switch to a new rate
provokes an installation, which is not the end of the world, but not ideal
either.
My question is: can I get this scheme to work with just registering the
appropriate subdevice on the same device object based on the sample rate (Frank
Yerrace's text suggests- at least to me- that it can)? If so, any clues on
what I may have overlooked? I have not even yet touched dynamic subdevice
unregistration and dynamic physical disconnection.
thanks,
Philip Lukidis
> -----Original Message-----
> From: wdmaudiodev-bounce@xxxxxxxxxxxxx
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx]On Behalf Of Jeff Pages
> Sent: Wednesday, January 10, 2007 5:55 PM
> To: wdmaudiodev@xxxxxxxxxxxxx
> Subject: [wdmaudiodev] Re: External clock synchronization and sample
> rate issue
>
>
> I had a similar problem, where I wanted the audio engine
> sampling rate of
> each endpoint to match the hardware clock on my card which
> was set globally
> in a driver property page.
>
> One of the Microsoft people suggested I have several different wave
> miniports (each with a different name) defined in my inf file
> and driver,
> with each supporting only one sampling rate in its pin
> datarange structure,
> and only instantiating the one corresponding to the hardware
> clock. Since my
> driver was unloaded and reloaded if the hardware clock was
> changed in my
> Device Manager property page, this was pretty easy to
> implement and worked
> well.
>
> In your case, where the external clock can change while the driver's
> running, you might be able to use the
> IUnregisterPhysicalConnection and
> IUnregisterSubdevice interfaces to remove the current
> subdevice and then
> activate and register the one corresponding to the new rate
> (see the stuff
> on Dynamic Audio Subdevices in the WDK).
>
> Jeff Pages
> Innes Corporation Pty Ltd
>
> ----- Original Message -----
> From: "Philip Lukidis" <plukidis@xxxxxxxxxxxxx>
> To: <wdmaudiodev@xxxxxxxxxxxxx>
> Sent: Thursday, January 11, 2007 9:20 AM
> Subject: [wdmaudiodev] External clock synchronization and
> sample rate issue
>
>
> > Hello. I'm wondering if anyone else has any clue about
> solving this
> > issue. My audio device can be clocked from an external
> source. For
> > example, the audio format of the device can be set to 16
> bits 44100 in the
> > advanced tab in the MS audio cpl, and thereafter using our
> own control
> > panel be clocked off an external source which is at the
> same rate of
> > 44100.
> >
> > Now say that the external source's clock changes from 44100
> to 48000.
> > Under XP, my datarange intersection handler would merely
> constrain the
> > format's sample rate to match the new external sample rate.
> Under Vista,
> > the system will never try to send at any other rate other
> than what is the
> > selected rate in the advanced tab of the audio device.
> >
> > Does anyone have a suggestion as to how to cope with this?
> Is there a way
> > to programmatically change the selected format of the
> device? Or is there
> > another approach?
> >
> > thank you,
> >
> > Philip Lukidis
> > ******************
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