[wdmaudiodev] Re: AVStream: sound quality depends on the usage, why?

  • From: "alexander ivash" <elderorb@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Wed, 29 Jun 2016 02:15:15 +0300

Thank you for your time, Tim!

Are you getting different audio formats selected in those four cases?
For what it's worth, I have seen the same behavior with audio drivers.
I suspect it is a timing issue.  How are you doing the timing?  Are you
returning data as soon as it is demanded, or are you delaying to
simulate a real hardware stream?

Incorrect format usage is really the simplest explanation for sound distortion and this is what I'll check. But what is not clear for me, is why even in graphedit the same filter sounds differently if selected as 'WDM Capture' (good) and 'Audio Capture' (delayed, cropped). Could it be the case that 'mic' bridge pin introduces its own delays? I hope it is not, because I thought it is required only to make sysvad happy and should have no any impact on the overall performance..

I'm still using DPC (like in original avssamp), which calls KsFilterAttemptProcessing every tick, and probably there are no any reasons to continue using it.. But it worked fine until I registered driver as virtual mic so haven't changed that part yet.

Just in case here is my framing config:

    2 * PAGE_SIZE,
    2 * PAGE_SIZE

Probably this is suboptimal or even wrong, but still not clear why does it work in one scenario and doesn't in other. By the way, if I decide to get rid of DPC / KsFilterAttemptProcessing, what is the other mechanism of triggering Filter::Process ?

Regards, Alexander

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