Re: CoreMidi and CoreAudio for software synth
Re: CoreMidi and CoreAudio for software synth
- Subject: Re: CoreMidi and CoreAudio for software synth
- From: Edwin Vane <email@hidden>
- Date: Wed, 5 Oct 2005 09:24:15 -0400
- Mail-followup-to: CoreAudio/Midi List <email@hidden>
After a delay, I've looked at the MusicSequence API. Just a couple of
questions that looking at the sample code and header files didn't
answer:
-The header mentions being able to set time units to be in seconds
instead of beats. What call(s) accomplish this? I'm trying to sync to
video so I've encoded all my music timestamps in milliseconds so
being able to work in seconds would be nice. For future work, I'll
probably change this to be more musician friendly...
-Can you modify the sequence that a player is attached to while it is
playing? I'm hoping it works like a buffer where QuickTime does the
feeding...
On Wed, Sep 21, 2005 at 12:12:33PM -0700, William Stewart wrote:
> You should look at the MusicSequence API - this is a much better
> (sample accurate) scheduler for events to ANY audio unit - see
> MusicPlayer.h in the AudioToolbox framework. There are a couple of
> examples of using this in the SDK as well (PlaySequence is one)
>
> Bill
>
> On 21/09/2005, at 11:38 AM, Edwin Vane wrote:
>
> >Hi,
> >
> >I'm still fairly new to CoreAudio/MIDI and finding the reading slow
> >since the documents seem pretty fragmented. Hopefully these questions
> >have easy answers.
> >
> >I currently have a software synthesizer that uses an AUGraph with a
> >synth unit in it (like the example in /Developer/...). I'm using
> >QuickTime to act as the timekeeper to trigger note events to be sent
> >through the graph. However, since the update interval in QuickTime
> >seems
> >to be about 20ms and it varies over time, I can hear slight
> >irregularities in any music produced. I thought perhaps the scheduling
> >part of CoreMIDI could help me out.
> >
> >So, is it possible to use the CoreMIDI scheduling to schedule notes
> >into
> >the short future (to cover the next update interval for instance) and
> >have CoreMIDI send info to the AUGraph for rendering? The documents
> >mention AUMIDIController which seem to provide glue between
> >CoreMIDI and
> >CoreAudio. Is that the right direction to go in? Also, are the
> >timestamps for events in CoreMIDI those of the system clock? In the
> >docs
> >it looks like we do the converting between the usual MIDI
> >timestamps and
> >host time.
> >
> >Finally, can CoreMIDI support the extended control protocol of
> >MusicDevices?
> >
> >--
> >
> >Edwin Vane
> > MMath Candidate
> > Computer Graphics Lab
> > School of Computer Science
> > University of Waterloo
> >
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--
Edwin Vane
MMath Candidate
Computer Graphics Lab
School of Computer Science
University of Waterloo
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