[wdmaudiodev] Re: AVStream for audio - change of direction?

  • From: BlazeAudio Developer <developer@xxxxxxxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Thu, 29 Jun 2006 17:05:21 +0530

Matt,

Thank you for the response. It's good to know that it is "possible" to do those things.

We ended up using portcls for our solution - mainly because of the availability of samples. One of the things we wanted to make sure we provided was a pin that could provide AC3 over SPDIF with an interface supporting both standard and looped streaming(so that DirectSound apps. can use it).

And we could not find any indication (positive or negative) about whether this is possible with AVStream.

We know for sure that this is not possible with the stream class mini drivers!

Thanks.
Devendra.

At 11:18 AM 6/28/2006, Matt Gonzalez wrote:

It is possible to create audio subdevices dynamically with AVStream - in addition to KsCreateFilterFactor, you may also need to call KsFilterFactorySetDeviceClassesState for things to work properly.   You may also need to create the appropriate WDM interface.

AVStream is the Microsoft recommened way to go for external devices.  
The driver I've been developing for our FireWire boxes uses AVStream for MIDI and audio.  AVStream will (supposedly) continue to work under Vista.

It is a fair amount of pain because there aren't any samples.  At the end of the day, you end up creating a filter that looks the same as it would with PortCls.  You also have to add support for things like KSPROPERTY_AUDIO_POSITION yourself, instead of PortCls doing it for you.

Sorry to take so long to get back to you-

Matt

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