main.cpp

/*  Copyright © 2007 Apple Inc. All Rights Reserved.
    
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// This is a simple test case of making an simple graph with a DLSSynth, Limiter and Ouput unit
 
// we're going to use a graph because its easier for it to just handle the setup and connections, etc...
 
#include <CoreServices/CoreServices.h> //for file stuff
#include <AudioUnit/AudioUnit.h>
#include <AudioToolbox/AudioToolbox.h> //for AUGraph
#include <unistd.h> // used for usleep...
 
// This call creates the Graph and the Synth unit...
OSStatus    CreateAUGraph (AUGraph &outGraph, AudioUnit &outSynth)
{
    OSStatus result;
    //create the nodes of the graph
    AUNode synthNode, limiterNode, outNode;
    
    AudioComponentDescription cd;
    cd.componentManufacturer = kAudioUnitManufacturer_Apple;
    cd.componentFlags = 0;
    cd.componentFlagsMask = 0;
 
    require_noerr (result = NewAUGraph (&outGraph), home);
 
    cd.componentType = kAudioUnitType_MusicDevice;
    cd.componentSubType = kAudioUnitSubType_DLSSynth;
 
    require_noerr (result = AUGraphAddNode (outGraph, &cd, &synthNode), home);
 
    cd.componentType = kAudioUnitType_Effect;
    cd.componentSubType = kAudioUnitSubType_PeakLimiter;  
 
    require_noerr (result = AUGraphAddNode (outGraph, &cd, &limiterNode), home);
 
    cd.componentType = kAudioUnitType_Output;
    cd.componentSubType = kAudioUnitSubType_DefaultOutput;  
    require_noerr (result = AUGraphAddNode (outGraph, &cd, &outNode), home);
    
    require_noerr (result = AUGraphOpen (outGraph), home);
    
    require_noerr (result = AUGraphConnectNodeInput (outGraph, synthNode, 0, limiterNode, 0), home);
    require_noerr (result = AUGraphConnectNodeInput (outGraph, limiterNode, 0, outNode, 0), home);
    
    // ok we're good to go - get the Synth Unit...
    require_noerr (result = AUGraphNodeInfo(outGraph, synthNode, 0, &outSynth), home);
 
home:
    return result;
}
 
 
// some MIDI constants:
enum {
    kMidiMessage_ControlChange      = 0xB,
    kMidiMessage_ProgramChange      = 0xC,
    kMidiMessage_BankMSBControl     = 0,
    kMidiMessage_BankLSBControl     = 32,
    kMidiMessage_NoteOn             = 0x9
};
 
int main (int argc, const char * argv[]) {
    AUGraph graph = 0;
    AudioUnit synthUnit;
    OSStatus result;
    char* bankPath = 0;
    
    UInt8 midiChannelInUse = 0; //we're using midi channel 1...
    
        // this is the only option to main that we have...
        // just the full path of the sample bank...
        
        // On OS X there are known places were sample banks can be stored
        // Library/Audio/Sounds/Banks - so you could scan this directory and give the user options
        // about which sample bank to use...
    if (argc > 1)
        bankPath = const_cast<char*>(argv[1]);
    
    require_noerr (result = CreateAUGraph (graph, synthUnit), home);
    
// if the user supplies a sound bank, we'll set that before we initialize and start playing
    if (bankPath) 
    {
        FSRef fsRef;
        require_noerr (result = FSPathMakeRef ((const UInt8*)bankPath, &fsRef, 0), home);
        
        printf ("Setting Sound Bank:%s\n", bankPath);
        
        require_noerr (result = AudioUnitSetProperty (synthUnit,
                                            kMusicDeviceProperty_SoundBankFSRef,
                                            kAudioUnitScope_Global, 0,
                                            &fsRef, sizeof(fsRef)), home);
    
    }
    
    // ok we're set up to go - initialize and start the graph
    require_noerr (result = AUGraphInitialize (graph), home);
 
        //set our bank
    require_noerr (result = MusicDeviceMIDIEvent(synthUnit, 
                                kMidiMessage_ControlChange << 4 | midiChannelInUse, 
                                kMidiMessage_BankMSBControl, 0,
                                0/*sample offset*/), home);
 
    require_noerr (result = MusicDeviceMIDIEvent(synthUnit, 
                                kMidiMessage_ProgramChange << 4 | midiChannelInUse, 
                                0/*prog change num*/, 0,
                                0/*sample offset*/), home);
 
    CAShow (graph); // prints out the graph so we can see what it looks like...
    
    require_noerr (result = AUGraphStart (graph), home);
 
    // we're going to play an octave of MIDI notes: one a second
    for (int i = 0; i < 13; i++) {
        UInt32 noteNum = i + 60;
        UInt32 onVelocity = 127;
        UInt32 noteOnCommand =  kMidiMessage_NoteOn << 4 | midiChannelInUse;
            
            printf ("Playing Note: Status: 0x%lX, Note: %ld, Vel: %ld\n", noteOnCommand, noteNum, onVelocity);
        
        require_noerr (result = MusicDeviceMIDIEvent(synthUnit, noteOnCommand, noteNum, onVelocity, 0), home);
        
            // sleep for a second
        usleep (1 * 1000 * 1000);
 
        require_noerr (result = MusicDeviceMIDIEvent(synthUnit, noteOnCommand, noteNum, 0, 0), home);
    }
    
    // ok we're done now
 
home:
    if (graph) {
        AUGraphStop (graph); // stop playback - AUGraphDispose will do that for us but just showing you what to do
        DisposeAUGraph (graph);
    }
    return result;
}