[wdmaudiodev] Re: Strange Delay with MIDI Filter Creation Times (AVStream)

  • From: Basileios Bu <basileiosbu@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Tue, 12 Jun 2012 11:54:29 -0400

Thank you for your reply.  Actually, as far as I see, Skype makes kernel
debugging completely impossible, and my observations were made using WPP
traces on WinXP systems with kernel debugging disabled.

On Mon, Jun 11, 2012 at 8:45 PM, Sam Tertzakian <sam@xxxxxxxxxxx> wrote:

> Not sure if this is the cause but…****
> ** **
> Skype does very strange things when it is run on a machine that is enabled
> for kernel debugging. If your machine is in that state, I would change that
> single  variable and see if by chance it solves your issue. ****
> ** **
> From what I have seen in the past, a machine capable of being debugged is
> virtually unusable for more than a few minutes if Skype is running.****
> ** **
> ** **
> *From:* wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:
> wdmaudiodev-bounce@xxxxxxxxxxxxx] *On Behalf Of *Basileios Bu
> *Sent:* Friday, June 08, 2012 2:07 PM
> *To:* wdmaudiodev@xxxxxxxxxxxxx
> *Subject:* [wdmaudiodev] Strange Delay with MIDI Filter Creation Times
> (AVStream)****
> ** **
> Hello,****
> We have a high speed USB audio device which exposes audio in(4)/out(4) and
> MIDI in(1)/out(1), and we use AVStream as a driver model, which creates 4
> KS filters, 2 audio, and 2 MIDI.  I am experiencing a strange issue with
> the creation time of one of our MIDI filters when Skype is running in the
> background (even when its told not to target our device), only on Windows
> XP.  When Skype is not executing, there is no delay; I create my filter
> factories without incident, and very soon after PostStart, our filters are
> created by the system.  However, when Skype is executing in the background
> (even when told never to address our devices), there is a delay (5-7
> seconds!) between creation of the audio/MIDI input filters and  the
> remaining MIDI output filter.  Even if I don't create the audio filter
> factories, the aforementioned delay remains with respect to the last MIDI
> filter.  I see this delay in the timestamps of WPP traces in my filter
> creation calls (the last such filter created is long delayed when Skype is
> in the background).  I see quite clearly in KS Studio that under the
> category "KSCATEGORY_AUDIO_DEVICE" that one instance out of four lags in
> creation time (which I assume to be the MIDI output instance in the general
> case in which I create all 4 filters).****
> Note that for all cases when I create my 4 filter factories the DDI
> KsCreateFilterFactory returns success, as does
> KsFilterFactorySetDeviceClassesState.  I tried moving filter factory
> creation and enabling to AVStrMiniDevicePostStart
> from AVStrMiniDeviceStart because the docs say that
> IoRegisterDeviceInterface (which is done prior to the creation of the
> filter factories) must be done in the context of a system thread, which
> AVStrMiniDevicePostStart seems to guarantee, but that had no effect.  The
> filters are created in the context of work items, which are a limited
> resource, and I tried increasing the number of work items via the registry,
> but this had no effect.****
> Now there were some topology differences between the MS MIDI filters and
> our MIDI filters, but even when I applied most of the differences, there
> was no effect.  For example, I used the category "KSCATEGORY_AUDIO" instead
> sum nodes, but there was no effect whatsoever, so it does not seem (to me,
> at least) to be a topology issue.  On significant difference which I could
> not test is that MS uses just one filter with multiple pin factories, while
> the we have multiple filters with two pins factories each.  This is not a
> trivial change to implement at this point, and note that the input and
> output audio filter creation times are *not* similarly delayed, at least as
> far as I can tell from WPP trace timestamps.****
> Would anyone have any idea as to the cause?  Is there any way to speed up
> filter creation?  Am I possibly missing some INF registry entries?  Without
> Skype, there are no large delays whatsoever. Very Strange.****
> Thank you for any help or insight.****

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