Here is the (Objective C) documentation for Core Midi: https://developer.apple.com/documentation/coremidi
How can I learn what is expected of me to be able to utilize this in a C++ project?
(I guess a more fundamental question is also: Can I use Core MIDI in a C++ project? - but I've seen other stackoverflow questions where the answer appears to be "yes" [then again, those were from years ago...])
What do I need to do to get this set up- to the point where I can start using the API? The documentation doesn't so much as show what frameworks are used, what header files are required, etc...
So, what are the steps to get started?
Ideally, I'd like to be able to compile from a simple makefile.
The majority of the CoreMIDI API is plain old C. You can easily call it from C++ code without doing anything special.
(The Apple docs have a language toggle between "Swift" and "Objective-C", but don't take "Objective-C" literally. It really means "C family, either C or Objective-C". Toggling it to Swift shows you the same APIs, but in the translated form that's visible to Swift.)
Specifically, see CoreMIDI/MIDIServices.h.
The oldest and simplest piece of CoreMIDI sample code, "Echo.cpp", is in fact C++. It reads MIDI input from all sources and sends that MIDI data to the first available destination (on channel 1). It's very rough, but you have to start somewhere.
To compile:
clang Echo.cpp -framework CoreMIDI -framework CoreFoundation -o Echo
The code:
/* Copyright © 2007 Apple Inc. All Rights Reserved.
Disclaimer: IMPORTANT: This Apple software is supplied to you by
Apple Inc. ("Apple") in consideration of your agreement to the
following terms, and your use, installation, modification or
redistribution of this Apple software constitutes acceptance of these
terms. If you do not agree with these terms, please do not use,
install, modify or redistribute this Apple software.
In consideration of your agreement to abide by the following terms, and
subject to these terms, Apple grants you a personal, non-exclusive
license, under Apple's copyrights in this original Apple software (the
"Apple Software"), to use, reproduce, modify and redistribute the Apple
Software, with or without modifications, in source and/or binary forms;
provided that if you redistribute the Apple Software in its entirety and
without modifications, you must retain this notice and the following
text and disclaimers in all such redistributions of the Apple Software.
Neither the name, trademarks, service marks or logos of Apple Inc.
may be used to endorse or promote products derived from the Apple
Software without specific prior written permission from Apple. Except
as expressly stated in this notice, no other rights or licenses, express
or implied, are granted by Apple herein, including but not limited to
any patent rights that may be infringed by your derivative works or by
other works in which the Apple Software may be incorporated.
The Apple Software is provided by Apple on an "AS IS" basis. APPLE
MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND
OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.
IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL
OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,
MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED
AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),
STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/
#include <CoreMIDI/MIDIServices.h>
#include <CoreFoundation/CFRunLoop.h>
#include <stdio.h>
// ___________________________________________________________________________________________
// test program to echo MIDI In to Out
// ___________________________________________________________________________________________
MIDIPortRef gOutPort = NULL;
MIDIEndpointRef gDest = NULL;
int gChannel = 0;
static void MyReadProc(const MIDIPacketList *pktlist, void *refCon, void *connRefCon)
{
if (gOutPort != NULL && gDest != NULL) {
MIDIPacket *packet = (MIDIPacket *)pktlist->packet; // remove const (!)
for (unsigned int j = 0; j < pktlist->numPackets; ++j) {
for (int i = 0; i < packet->length; ++i) {
// printf("%02X ", packet->data[i]);
// rechannelize status bytes
if (packet->data[i] >= 0x80 && packet->data[i] < 0xF0)
packet->data[i] = (packet->data[i] & 0xF0) | gChannel;
}
// printf("\n");
packet = MIDIPacketNext(packet);
}
MIDISend(gOutPort, gDest, pktlist);
}
}
int main(int argc, char *argv[])
{
if (argc >= 2) {
// first argument, if present, is the MIDI channel number to echo to (1-16)
sscanf(argv[1], "%d", &gChannel);
if (gChannel < 1) gChannel = 1;
else if (gChannel > 16) gChannel = 16;
--gChannel; // convert to 0-15
}
// create client and ports
MIDIClientRef client = NULL;
MIDIClientCreate(CFSTR("MIDI Echo"), NULL, NULL, &client);
MIDIPortRef inPort = NULL;
MIDIInputPortCreate(client, CFSTR("Input port"), MyReadProc, NULL, &inPort);
MIDIOutputPortCreate(client, CFSTR("Output port"), &gOutPort);
// enumerate devices (not really related to purpose of the echo program
// but shows how to get information about devices)
int i, n;
CFStringRef pname, pmanuf, pmodel;
char name[64], manuf[64], model[64];
n = MIDIGetNumberOfDevices();
for (i = 0; i < n; ++i) {
MIDIDeviceRef dev = MIDIGetDevice(i);
MIDIObjectGetStringProperty(dev, kMIDIPropertyName, &pname);
MIDIObjectGetStringProperty(dev, kMIDIPropertyManufacturer, &pmanuf);
MIDIObjectGetStringProperty(dev, kMIDIPropertyModel, &pmodel);
CFStringGetCString(pname, name, sizeof(name), 0);
CFStringGetCString(pmanuf, manuf, sizeof(manuf), 0);
CFStringGetCString(pmodel, model, sizeof(model), 0);
CFRelease(pname);
CFRelease(pmanuf);
CFRelease(pmodel);
printf("name=%s, manuf=%s, model=%s\n", name, manuf, model);
}
// open connections from all sources
n = MIDIGetNumberOfSources();
printf("%d sources\n", n);
for (i = 0; i < n; ++i) {
MIDIEndpointRef src = MIDIGetSource(i);
MIDIPortConnectSource(inPort, src, NULL);
}
// find the first destination
n = MIDIGetNumberOfDestinations();
if (n > 0)
gDest = MIDIGetDestination(0);
if (gDest != NULL) {
MIDIObjectGetStringProperty(gDest, kMIDIPropertyName, &pname);
CFStringGetCString(pname, name, sizeof(name), 0);
CFRelease(pname);
printf("Echoing to channel %d of %s\n", gChannel + 1, name);
} else {
printf("No MIDI destinations present\n");
}
CFRunLoopRun();
// run until aborted with control-C
return 0;
}