on 3/19/08 3:46 PM, Devon McDormand <[EMAIL PROTECTED]> wrote:
> The archives from June 2007 had a thread entitled "Device disconnected while
> playing". The original problem: "We are trying to get a notification when the
> current MIDI device gets disconnected." Roger said they look into it, and
> suggested where they should look, and what they might look for.
>
> Notification on disconnect is of interest to me, so I took a quick look, and
> sure enough, code I insert into the MIM_CLOSE case in winmm_in_callback() from
> pmwinmm.c gets run shortly after I disconnect or power down a USB midi device.
> Before I decide how I'm going to make it so this notification is passed back
> to my client application, I want to make sure I can catch this same situation
> on OSX. I've found reference to a constant
> "kAudioDevicePropertyDeviceIsAlive" but being completely unfamiliar with
> CoreMIDI, I don't yet know how to make use of this tiny nugget of information.
> Any suggestions?
I've used CoreMIDI in limited ways only, but knew vaguely where to look.
Before creating input/output ports it is necessary to call MIDIClientCreate
which specifies a device notification proc, which can receive the following
notifications (from the headers, but not the latest version):
/*
@enum MIDINotificationMessageID
@abstract Signifies the type of a MIDINotification.
@constant kMIDIMsgSetupChanged Some aspect of the current
MIDISetup
has changed. No data. Should
ignore this
message if messages 2-6 are handled.
@constant kMIDIMsgObjectAdded A device, entity or endpoint was
added.
Structure is
MIDIObjectAddRemoveNotification.
New for CoreMIDI 1.3.
@constant kMIDIMsgObjectRemoved A device, entity or endpoint was
removed.
Structure is
MIDIObjectAddRemoveNotification.
New for CoreMIDI 1.3.
@constant kMIDIMsgPropertyChanged An object's property was
changed.
Structure is
MIDIObjectPropertyChangeNotification.
New for CoreMIDI 1.3.
@constant kMIDIMsgThruConnectionsChanged A persistent MIDI Thru
connection was created
or destroyed. No data. New for
CoreMIDI 1.3.
@constant kMIDIMsgSerialPortOwnerChanged A persistent MIDI Thru
connection was created
or destroyed. No data. New for
CoreMIDI 1.3.
@constant kMIDIMsgIOError A driver I/O error occurred.
*/
enum { // MIDINotificationMessageID
kMIDIMsgSetupChanged = 1,
kMIDIMsgObjectAdded = 2,
kMIDIMsgObjectRemoved = 3,
kMIDIMsgPropertyChanged = 4,
kMIDIMsgThruConnectionsChanged = 5,
kMIDIMsgSerialPortOwnerChanged = 6,
kMIDIMsgIOError = 7
};
typedef SInt32 MIDINotificationMessageID;
So I suspect you want to look for kMIDIMsgObjectRemoved, rather than polling
for kAudioDevicePropertyDeviceIsAlive (which I didn't look at).
The device notify proc is a MIDINotifyProc which takes a MIDINotification*
argument. MIDINotification is a struct with a MIDINotificationMessageID
field.
See MIDIServices.h
HTH,
Kurt
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