James,
I
haven’t done this, but it looks like it would work. If you’re
willing to fiddle with the events in your tracks, you could do this by adding
UserEvents to a MusicSequence’s MusicTracks (at the same timestamps as
your NoteOn events). If you analyze the track before playback and know the
durations, you could add the duration info to these UserEvents. Then, with a
SequenceCallback registered, you will get alerted at every UserEvent with your duration
Info. See MusicSequence & MusicTrack references.
David
MusicSequenceSetUserCallback
Registers
a user callback function with a music sequence.
OSStatus MusicSequenceSetUserCallback (
MusicSequence inSequence,
MusicSequenceUserCallback inCallback,
void *inClientData
);
Parameters
inSequence
The music sequence
that you want to add a user callback function to.
inCallback
A reference to your
callback function. Use NULL to remove a registered callback function.
inClientData
Your data that the
music sequence provides back to your callback function when it is invoked.
Return
Value
A result code.
Discussion
The music sequence invokes your callback for each user
event added to any music track owned by the sequence. If there is a callback
registered, then UserEvents will be chased when MusicPlayerSetTime is called.
In that case the inStartSliceBeat and inEndSliceBeat will both be the same
value and will be the beat that the player is chasing to.
MusicTrackNewUserEvent
Adds an event of
type MusicEventUserData to a music track.
OSStatus MusicTrackNewUserEvent (
MusicTrack inTrack,
MusicTimeStamp inTimeStamp,
const MusicEventUserData *inUserData
);
From:
coreaudio-api-bounces+d.hicks=email@hidden
[mailto:coreaudio-api-bounces+d.hicks=email@hidden] On Behalf Of James Maxwell
Sent: Monday, February 27, 2012
10:01 PM
To: email@hidden
Subject: Grabbing MusicPlayer
events during playback
I'm wondering if there's a good way to grab MusicPlayer events within
an application, during playback, **without** using a MIDI
endpoint? I have a system that has to "listen" to its own playback,
but I don't want to use the actual MIDI
endpoint, in order to avoid feedback loops. Also, it would be great to be able
to get the duration info, which I wouldn't normally have in "live"
playback (i.e., I don't know when a note will end), but would have directly
from the sequence/track. Any way to do this?
------------------------------------------------------
Composer/Researcher/PhD
Candidate