[wdmaudiodev] WaveRT event driven Capture
- From: "Markus Bollinger" <bollinger@xxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Tue, 17 Mar 2009 09:16:01 +0100
Ok, I try it again with a shorter question:
In WaveRT event driven mode, what value does the Audio Engine expect when
reading the PositionRegister after the drivers KeSetEvent(NotificationEvent) ??
Any Microsoft advice ??
Regards,
Markus.
> -----Message d'origine-----
> De : wdmaudiodev-bounce@xxxxxxxxxxxxx
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] De la part de
> Markus Bollinger
> Envoyé : vendredi 13 mars 2009 18:28
> À : wdmaudiodev@xxxxxxxxxxxxx
> Objet : [wdmaudiodev] WaveRT event driven Capture in exclusive mode
>
> Hello,
>
> I try to implement the Event driven mode in my WaveRT driver for a
> Playback and Capture device.
>
> Playback works as expected, but with capture I found some strange
> behaviour :
>
> When my driver notifies the first time the capture event after Start
> (the DMA has passed the middle of the circular buffer),
>
> A Wasapi application then gets out of its WaitFor***Object
> and tries to
> do : pCaptureClient->GetBuffer(&pDataIn, &packetLength, &flags,
> &position, NULL); and gets as result AUDCLNT_S_BUFFER_EMPTY
> which is NOT
> as expected !!!
>
> On the following notifications, GetBuffer() works, but the application
> is getting back the wrong half of the circular (pin-pong) buffer !!!
> On the second notification it gets the first buffer back that
> is at this
> moment newly getting filled by the DMA !!!
>
> To avoid this Error, I tried following:
>
> - returning error in CMiniportWaveRTStream::GetPositionRegister()
> - adding offset to Position->PlayOffset=Position->WriteOffset in the
> CMiniportWaveRTStream::GetPosition() method
>
> Result : When the position returned by GetPosition() is 512 bytes (64
> stereo samples offset) or more behind the middle of the
> circular buffer,
> everything gets working : the app is getting back the first
> half of the
> circular buffer after the first notification.
>
> YES, I know there is a function called
> CMiniportWaveRTStream::GetHWLatency(), where the hwLatency->FifoSize
> should indicate some offset,
> But all values that I put there don't change anything.
>
> In http://msdn.microsoft.com/en-us/library/ms678736.aspx I found that
> exclusive-mode event-driven capture is broken on Vista RTM, but it
> should be fixed in SP1, not ?
>
> Who knows what goes wrong ???
>
>
> Markus.
>
> P.S. my adapter can be configured with DMA size = 8,16 or 32
> samples, so
> it would not be nice to abandon the GetPositionRegister()
> method and add
> some offset that increases the latency !!!
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