Hello, 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 > of "KSNODETYPE_SPEAKER/KSNODETYPE_LINE_CONNECTOR", and removed our internal > 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.**** >