[wdmaudiodev] Re: MSVAD: synchronization of MSVAD and WMP with a real soundcard
- From: "Richard Fricks" <Richard.Fricks@xxxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Mon, 17 Oct 2005 10:41:30 -0700
In your scenerio, that master clock is the clock on the physical sound card.
MSVad's clock needs to be synchronized with that. Regardless of how accurate of
clock you are using in terms of "world time" if it does not match the playback
rate of your audio card, you will end up not being fed by WMP at the correct
rate. Ideally, you would query the position of the card that is playing back
the audio and return those values to WMP since that reflects the true position
of the audio. Regarding the other issue you describe below (21ms delay in
getting data from WMP), you can always check functionality against the original
msvad and confirm that it is working correctly with WMP. This will help you
determine if a problem you are seeing is something introduced by changes you
have made or not.
-Rich
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Bosser Frédéric
Sent: Monday, October 17, 2005 7:13 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: MSVAD: synchronization of MSVAD and WMP with a real
soundcard
hi all,
I have measured the delay between timer notifications of MSVAD. It is 10.742 ms
(instead of 10 ms).this delay is constant. I don't think that the problem is
here. The timer is constant and simulates a notification esach 10.742 ms.
But regularly, it seems that WMP misses a notification and therefore sends 10
ms of data with a delay of 21.48 ms!
I suppose (but it is just an idea) that WMP thinks it has sent too many data
before, but it is not true!
does anyone know an explanation for this? why WMP misses a notification or
ignore it?
thanks
fred
Marc Titinger <titinger@xxxxxxxxxxxx> a écrit :
I'm not sure this is related, but we where using a timer DPC
(KeInitializeTimerEx) of 10ms in a driver, until we figured out that on some
systems it would occure every 15ms instead of the expected 10ms. So we had to
move back to using a real PCI IRQ to trigger the service routines. Have you
actually measured 10ms between your timer notifications ?
Marc.
-----Message d'origine-----
De : wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx]De la part de Bosser Frédéric
Envoyé : vendredi 14 octobre 2005 11:16
À : wdmaudiodev@xxxxxxxxxxxxx
Objet : [wdmaudiodev] Re: MSVAD: synchronization of MSVAD and
WMP with a real soundcard
hello Richard,
I am agree with you when you say that WMP will send the data
based on the clock time returned by the driver it has opened. And there is no
problem when WMP opens the driver of a REAL soundcard.
And what you have described then sounds exactly like my
scenario. The clock time returned by the driver that WMP has opened is running
at a different rate then the clock that represents actual audio playback.
I join a diagram of my software with this mail.
To be more accurate, WMP is synchronized with a VIRTUAL driver
MSVAD. So WMP will send the data based on the clock time returned by the MSVAD
driver. You must know that, in MSVAD, the REAL interrupt notifications are
simulated with a periodic timer each 10 ms. So WMP is synchronized with this
timer.
If you look at the diagram I have joined, you will see that I
send then these sound data in a proprietary software (visioconference). This
proprietary software is synchronized with the real soundcard. And my problem is
that my MSVAD driver and the proprietary software are not synchronized.
So, how can I simulate in a very accurate way (more accurate
that the one in MSVAD sample), in the MSVAD driver, the clock of the real
soundcard? As I have said in my last email, I think WMP does not really send
the data each 10ms.
I hope that you understand my explanation. It is a very
blocking problem.
Thank you
fred
Richard Fricks <Richard.Fricks@xxxxxxxxxxxxx> a écrit :
WMP will send the data based on the clock time returned by the
driver it has opened. If that clock is running at a different rate then the
clock that represents actual audio playback I could see where you would get the
condition you are describing below. Is what I am describing sound like your
scenario?
Richard Fricks
Technical Lead, Microsoft DDK
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Bosser Frédéric
Sent: Wednesday, October 12, 2005 8:38 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] MSVAD: synchronization of MSVAD and WMP
with a real soundcard
hello,
I am developping a virtual audio driver based on the MSVAD
sample. The goal is to get the sound coming from windows media player (for
example...) in the driver and add it to the speech in a visioconference
application. I have modified the CopyTo function and I have the sound buffers
in my application ( I used shared buffer between kernel and user mode). In my
visioconference application, I put the sound buffer in a FIFO and add the
"music" sound buffer with the speech coming from the visioconference.
My problem is that my driver seems to not be synchronized! If I
play a sound file at the same frequency that the one used by the real soundcard
(used by the visioconference application) my FIFO becomes nearly EMPTY! Then I
miss some "music" sound buffers when I add the speech samples (from
visioconference) with the music samples*.
So my conclusion is that WMP sends the sound data (10 ms. We
cannot change this value, can we?) too slowly. Since MSVAD is virtual, the
interrupt notification are not hardware but software with a timer. Each 10 ms
this timer simulates the real harware interrupt. This timer doesn't seem to be
accurate enougth...
So, here are my questions:
- Can I use multimedia timers in the driver? I think they are
more accurate.I would like to use them in my driver in order to tell WMP to
send 10ms of sound date EACH 7ms (for example). Is it possible?
- How can I synchronize WMP with my soundcard? but it is
important to know that the sound coming from WMP passes by my virtual driver ,
THEN by my visioconference application, and FINALLY by the soundcard.
Tell me if you want more details.
thank you for your answers.
Fred
Software engineer
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