CoreMIDI refCon passed to MIDIReadProc

Question

I need to understand how to return the source of a MIDI packet when using multiple MIDI devices.

I have all my sources connected by using the following loop:

ItemCount sourceCount = MIDIGetNumberOfSources();
for (ItemCount i = 0 ; i < sourceCount ; ++i) {

MIDIEndpointRef source = MIDIGetSource(i);
MIDISourceConnectPort( inPort, source, &i);

}

I understand that the last parameter in MIDISourceConnectPort() is a context to identify the source that is sent to the MIDIReadProc callback. So I'm trying to send the index of the source to MIDIReadProc.

void MIDIReadProc (const MIDIPacketList   *pktlist,
                 void                   *readProcRefCon,
                 void                   *srcConnRefCon)
{

\\ How do I access the source index passed in the conRef by using *srcConnRefSource?

}

The reason I need to know this is that I'm trying to send LED feedback to devices and I need to know which device sent the packets so I can send the feedback to the correct device.

Answer 1

The code below assumes you have already set up the MIDIClient and the MIDIPortRef for both input and output:

-(void)connectMidiSources{

MIDIEndpointRef src;

ItemCount sourceCount = MIDIGetNumberOfSources();

for (int i = 0; i < sourceCount; ++i) {

    src = MIDIGetSource(i);
    CFStringRef endpointName = NULL;
    MIDIUniqueID sourceUniqueID = NULL;

    CheckError(MIDIObjectGetStringProperty(src, kMIDIPropertyName, &endpointName), "Unable to get property Name");
    CheckError(MIDIObjectGetIntegerProperty(src, kMIDIPropertyUniqueID, &sourceUniqueID), "Unable to get property UniqueID");

    NSLog(@"Source: %u; Name: %@; UniqueID: %u", i, endpointName, sourceUniqueID);

    // *** The last paramenter in this function is a pointer to srcConnRefCon ***
    CheckError(MIDIPortConnectSource(clientInputPort, src, (void*)sourceUniqueID), "Couldn't connect MIDI port");


    }

}

And to access the source refCon context in MIDIReadProc:

void midiReadProc (const MIDIPacketList *pktlist, void *readProcRefCon, void *srcConnRefCon){

//make a reference to the class you have the MIDIReadProc implemented within
MidiManager *midiListener = (MidiManager*)readProcRefCon;

//print the UniqueID for the source MIDIEndpointRef
int sourceUniqueID = (int*)srcConnRefCon;
NSLog(@"Note On sourceIdx: %u", sourceUniqueID);

// the rest of your code here...

}