[wdmaudiodev] Re: MIDI Capture Timestamping

Setting the masterclock can be done with IDirectMusic::SetMasterClock(). The
input for this function is the GUID of the masterclock. How you add a
masterclock to the system is unclear to me. Can't find it in the
documentation either.

Evert





----- Original Message -----
From: "Mathieu Routhier" <MRouthier@xxxxxxxxxxxxx>
To: <wdmaudiodev@xxxxxxxxxxxxx>
Sent: Wednesday, August 06, 2003 3:01 PM
Subject: [wdmaudiodev] Re: MIDI Capture Timestamping


> I should have given this address in the first place:
> http://forum.cubase.net/forum/Forum2/HTML/038028.html
>
> It describes the problems that people have seen with sonar and cubase.  It
> does not refer to DirectMusic drivers; this is mostly a musician's forum.
I
> am not sure about this but I guess legacy midi drivers are also affected.
>
> You must be right when you say it is possible to use a different master
> clock.  Can you explain how to do this?  It's probably done by connecting
> things in the filter graph.  Is it?
>
> Mat
>
> -----Original Message-----
> From: Evert van der Poll [mailto:e.j.van.der.poll@xxxxxxxxx]
> Sent: Tuesday, August 05, 2003 5:46 PM
> To: wdmaudiodev@xxxxxxxxxxxxx
> Subject: [wdmaudiodev] Re: MIDI Capture Timestamping
>
> Hi,
>
> I'm currently developing a DirectMusic driver for a MIDI device and I got
a
> little confused by your answers. It was my understanding that it was
> possible for an application to provide it's own masterclock, which would
> then be used by all active DirectMusic devices. This can be very useful,
for
> instance if you want to link everything to the samplerate of an audio
> device.
> I am curious about the problem you described with Sonar and Cubase. I have
> noticed some strange things with the timestamping of input messages
myself.
> My driver sends the incoming MIDI data as unprocessed bytes. Somewhere in
> the internals of the DirectMusic API these loose bytes are made into full
> MIDI messages. These I can then receive by calling
IDirectMusicPort::Read().
> But the timestamp I get with that function is not the timestamp that the
> driver gave the incoming MIDI bytes. I would suspect that the full MIDI
> message would get the timestamp of either the first or the last byte of
> which it consists. But apparently that is not the case.
> You mention that the applications (Cubase or Sonar) can be configured to
> ignore timestamps? How is that done?
>
> Evert
>
>
>
>
> ----- Original Message -----
> From: "Mathieu Routhier" <MRouthier@xxxxxxxxxxxxx>
> To: <wdmaudiodev@xxxxxxxxxxxxx>
> Sent: Tuesday, August 05, 2003 11:00 PM
> Subject: [wdmaudiodev] Re: MIDI Capture Timestamping
>
>
> > The master clock is provided to you as a reference clock.  When the note
> > comes in from your hardware, the time stamp should be relative to this
> clock
> > depending on how you want it time-stamped (how long before or after the
> > current time, if that applies).  Why do you need to use another clock?
> >
> > Btw, lately, we had to debug our midi input port timestamps because of a
> > problem we noticed with sonar: there seems to be an increasing skew
> between
> > the application clock and the midi timestamps.  The longer the
application
> > was opened, the longer it took for a note to be processed by the
> > application.  Restarting the application reset the skew.  When the
> > application was configured to ignore the timestamps, the problem
> > disappeared.  We finally found out that the problem was in the
> application's
> > way to handle the timestamps.  Apparently Cubase has the same problem.
> >
> > I suppose some of you already dealt with this (or at least heard about
> this
> > issue).  I was wondering if there was something you'd like to add to the
> > discussion.
> >
> > Mat
> >
> > -----Original Message-----
> > From: BlazeAudio Developer [mailto:developer@xxxxxxxxxxxxxx]
> > Sent: Tuesday, August 05, 2003 3:09 PM
> > To: wdmaudiodev@xxxxxxxxxxxxx
> > Subject: [wdmaudiodev] MIDI Capture Timestamping
> >
> > Can anybody tell what the ullPresTime100Ns in DMUS_KERNEL_EVENT is
> supposed
> > to be?
> >
> > It's in 100 ns units - but is it the absolute system time or is it
> relative
> > to some other event.
> >
> > We have a MIDI capture driver(portclass miniport) where we cannot just
use
> > the MasterClock object provided in IMiniPortDMus::NewStream call.
> >
> > Thanks.
> > Devendra.
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