My driver doesn't run at the internal clock, but at an external PTP master
as I'm going to send the audio data to a RTP network stream. Although PTP is
quite close it's not the same but something like a factor of 1.00002
compared to the internal clock (taken from performance counter). Now on some
systems this runs correct for hours and days without over- or underruns, but
on others I can see both over- and underruns. Both can occur even at the
same time on the same PC as my driver runs in multiple instances and one
seems to be a little slow while another is slightly too fast (on a HP Dual
Xeon Workstation). I had no explanation and so I started digging into the
APIs the applications are using and whether this could be the reason for
this behavior. I also wrote a little application myself that can handle all
the APIs to check the clocking and do some bit transparency tests. What I've
learned from you so far makes me think it's not the API itself, but
exclusive mode or not. And non exclusive mode seems to introduce a lot of
trouble with its format conversion, its limiter and its SRC if you expect
bit transparency and audio without any glitches for hours and days. And both
is expected as we're in the field of 24/7 pro audio broadcasting. So
probably I have to recommend our customers to prefer exclusive mode for this
kind of pro audio applications?
Von: wdmaudiodev-bounce@xxxxxxxxxxxxx <wdmaudiodev-bounce@xxxxxxxxxxxxx> Im
Auftrag von Matthew van Eerde (Redacted sender "Matthew.van.Eerde" for
DMARC)
Gesendet: Mittwoch, 22. August 2018 14:42
An: wdmaudiodev@xxxxxxxxxxxxx
Betreff: [wdmaudiodev] Re: AW: Re: AW: Re: bit transparency from app to WDM
audio driver depending from API?
I could better answer your questions if I understood where you were going
with this. Why do you ask? What is your scenario? These don't really sound
like "how do I write a driver" questions.
In Windows, the burden falls on the application to either invoke their own
micro-sample-rate-converter, or adjust Windows' built-in
micro-sample-rate-converter (e.g. via the IAudioClockAdjustment API.)
_____
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
<mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx> <wdmaudiodev-bounce@xxxxxxxxxxxxx
<mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx> > on behalf of Johannes Freyberger
<jfreyberger@xxxxxxxxxxxxxxxxxxxx <mailto:jfreyberger@xxxxxxxxxxxxxxxxxxxx>
Sent: Wednesday, August 22, 2018 2:03:14 AM