MusicTrackSetDestNode Repaired Sampler Sound for Old Musictracks

I am creating a music app where you can add new instruments to an existing sequencer. These instruments are separate AudioUnitSamplers stored in an array, so when a new instrument and track is loaded, it must load the sound that this track will use.

This is how I am now adding a track to AUGraph.

// Return count as an id for the new track
- (int) addMusicTrack: (MusicTrack)musicTrack withNode:(AUNode)newSamplerNode withAudioUnit:(AudioUnit)newSamplerUnit {

    tracksCount++;
    int trackId = tracksCount;

    MusicPlayerStop(_musicPlayer);
    status = MusicSequenceNewTrack(sequence, &tracks[trackId]);
    MusicSequenceSetAUGraph(sequence, graph);

    if(status){
        printf("Error adding main track: %d", (int)status);
        status = 0;
    }

    timeDiff = 32.f/_tempo;

    [self setLoopDuration:DEFAULT_LOOP_DURATION forTrack:trackId];
    currentOctaveNumber = 59;

    AudioComponentDescription samplerNodeDesc;
    samplerNodeDesc.componentManufacturer = (OSType)kAudioUnitManufacturer_Apple;
    samplerNodeDesc.componentType = (OSType)kAudioUnitType_MusicDevice;
    samplerNodeDesc.componentSubType = (OSType)kAudioUnitSubType_Sampler;
    samplerNodeDesc.componentFlags = 0;
    samplerNodeDesc.componentFlagsMask = 0;
    status = AUGraphAddNode(graph, &samplerNodeDesc, &auSampleNodes[trackId]);

    AudioComponentDescription splitterNodeDesc;
    splitterNodeDesc.componentManufacturer = (OSType)kAudioUnitManufacturer_Apple;
    splitterNodeDesc.componentType = (OSType)kAudioUnitType_FormatConverter;
    splitterNodeDesc.componentSubType = (OSType)kAudioUnitSubType_Splitter;
    splitterNodeDesc.componentFlags = 0;
    splitterNodeDesc.componentFlagsMask = 0;
    status = AUGraphAddNode(graph, &splitterNodeDesc, &splitterNodes[trackId]);

    // node info
    status = AUGraphNodeInfo(graph, auSampleNodes[trackId], 0, &auSampleUnits[trackId]);
    status = AUGraphNodeInfo(graph, splitterNodes[trackId], 0, &splitterUnits[trackId]);

    // connecting nodes samplernode ==> Splitter ==> Mixer
    status = AUGraphConnectNodeInput(graph, auSampleNodes[trackId], 0, splitterNodes[trackId], 0);
    status = AUGraphConnectNodeInput(graph, splitterNodes[trackId], 0, mixerNode, trackId);

    status = MusicTrackSetDestNode(tracks[trackId], auSampleNodes[trackId]);

    status = AUGraphUpdate(graph, NULL);
    if (status) {printf("Error updating graph: %ld\n", status);}

    MusicPlayerStart(_musicPlayer);

    return trackId;
}

      

        
        
        
      

    

And this is how I load the sound for this track:

[self samplerUnit:auSampleUnits[trackId] loadFromDLSOrSoundFont:url withPatch:patchNumber];

      

        
        
        
      

    

soundfont Download:

- (OSStatus)samplerUnit:(AudioUnit)sampler loadFromDLSOrSoundFont:(NSURL *)bankURL withPatch:(int)presetNumber{

    OSStatus result = noErr;

    // Fill out the sampler instrument data structure
    AUSamplerInstrumentData insdata;
    insdata.fileURL = (__bridge CFURLRef) bankURL;
    insdata.bankMSB  = kAUSampler_DefaultMelodicBankMSB;
    insdata.bankLSB  = (UInt8)0;
    insdata.presetID = (UInt8) presetNumber;
    insdata.instrumentType = kInstrumentType_DLSPreset; // DLS and SF2 are the same enum values

    // Load the instrument
    result = AudioUnitSetProperty(sampler,
                                  kAUSamplerProperty_LoadInstrument,
                                  kAudioUnitScope_Global,
                                  0,
                                  &insdata,
                                  sizeof(insdata));

    NSCAssert (result == noErr,
               @"Unable to set the preset property on the Sampler. Error code: %d",
               (int) result);

    return result;
}

      

        
        
        
      

    

The corresponding audio is currently loaded for the newly added track, but the audio for older tracks is now the default AudioUnitSampler audio waveform.

I'm trying to fix this after about a day, but haven't found a way around it, any solutions out there?

Greetings !!!