Mixer AudioUnit to RemoteIO AudioUnit

Question

I have an AudioUnit with correspondent Callback working properly, But now, I need to send it to a RemoteIO, cause i'm implementing some framework who needs an RemoteIO AudioUnit to work.

THen... I need the same output i'm getting with this audiounit mixer but with another audiounit with type kAudioUnitSubType_RemoteIO.

Please, help!

EDIT ... This is the code I'm trying... EDIT 2- iOUnitDescription Added

AudioComponentDescription iOUnitDescription;
iOUnitDescription.componentType          = kAudioUnitType_Output;
iOUnitDescription.componentSubType       = kAudioUnitSubType_RemoteIO;
iOUnitDescription.componentManufacturer  = kAudioUnitManufacturer_Apple;
iOUnitDescription.componentFlags         = 0;
iOUnitDescription.componentFlagsMask     = 0;


AudioComponent foundIoUnitReference = AudioComponentFindNext (
                                                              NULL,
                                                              &iOUnitDescription
                                                              );
AudioComponentInstanceNew (
                           foundIoUnitReference,
                           &audioUnit
                           );

result = AudioUnitSetProperty (
                               audioUnit,
                               kAudioUnitProperty_StreamFormat,
                               kAudioUnitScope_Input,
                               guitarBus,
                               &stereoStreamFormat,
                               sizeof (stereoStreamFormat)
                               );

if (noErr != result) {[self printErrorMessage: @"AudioUnitSetProperty (set mixer unit guitar input bus stream format)" withStatus: result];return;}
result = AudioUnitSetProperty (
                               audioUnit,
                               kAudioUnitProperty_SampleRate,
                               kAudioUnitScope_Output,
                               0,
                               &graphSampleRate,
                               sizeof (graphSampleRate)
                               );
if (noErr != result) {[self printErrorMessage: @"AudioUnitSetProperty (set AUDIOUNIT unit output stream format)" withStatus: result]; return;}


AudioUnitElement mixerUnitOutputBus  = 0;
AudioUnitElement ioUnitOutputElement = 0;

AudioUnitConnection mixerOutToIoUnitIn;
mixerOutToIoUnitIn.sourceAudioUnit    = mixerUnit;
mixerOutToIoUnitIn.sourceOutputNumber = mixerUnitOutputBus;
mixerOutToIoUnitIn.destInputNumber    = ioUnitOutputElement;

AudioUnitSetProperty (
                      audioUnit,                     // connection destination
                      kAudioUnitProperty_MakeConnection,  // property key
                      kAudioUnitScope_Input,              // destination scope
                      ioUnitOutputElement,                // destination element
                      &mixerOutToIoUnitIn,                // connection definition
                      sizeof (mixerOutToIoUnitIn)
                      );

Post some code of your AudioUnit setup, it's literally a case of adding the additional AudioUnit and making the correct connections. — MDB983

MDB983 MDB983 · Accepted Answer · 2014-08-02T17:00:04

I really need more info. From the above, i see you have a mixer somewhere, a guitarBus which presumably is your input (and seemingly a stream). What is the definition of &iOUnitDescription. More importantly, where are you hooking your renderCallback to, what are you doing in the callback and what does the framework expect?

Typically, when i need to process Audio, I build my own graph; I make this it's own class for better portability. This should be a good starting point for you

Here is how I implement such a solution.

 // header file

  @interface MDMixerGraph : NSObject{
    AUGraph graph;
    AudioUnit mixerUnit;
    AudioUnit inputUnit;
    AudioUnit rioUnit;
   }
  -(void) setupAUGraph;
  @end

  // implementation

  @implementation MDMixerGraph

  // exception Helper 
  void MDThrowOnError(OSStatus status){
  if (status != noErr) {
      @throw [NSException exceptionWithName:@"MDMixerException"
                                   reason:[NSString stringWithFormat:@"Status Error %d).", (int)status]
                                    userInfo:nil];
     }
  }


   // helper method for setting up graph nodes
   OSStatus MDAdAUGraphdNode(OSType inComponentType, OSType inComponentSubType, AUGraph inGraph, AUNode *outNode)
   {
     AudioComponentDescription desc;
     desc.componentType = inComponentType;
     desc.componentSubType = inComponentSubType;
     desc.componentFlags = 0;
     desc.componentFlagsMask = 0;
     desc.componentManufacturer = kAudioUnitManufacturer_Apple;
     return AUGraphAddNode(inGraph, &desc, outNode);
   }

   // setup method to init and start AUGraph
   -(void) setupAUGraph{

    //Create the Graph
    MDThrowOnError(NewAUGraph(&graph));

   // setup AU Units
   // Add Audio Units (Nodes) to the graph
   AUNode inputNode, rioNode, mixerNode;

//Input Node -- this may need to be a different type to accept your Stream (not enough info above) 
MDThrowOnError(MDAdAUGraphdNode(kAudioUnitType_Output, kAudioUnitSubType_RemoteIO, graph, &inputUnit));

//Remote IO Node - your output node
MDThrowOnError(MDAdAUGraphdNode(kAudioUnitType_Output, kAudioUnitSubType_RemoteIO, graph, &rioNode));

//mixerNode - Depending on output and input change the mixer sub-type here
// you can configure additional nodes depending on your needs for inputs and outputs
MDThrowOnError(MDAdAUGraphdNode(kAudioUnitType_Mixer, kAudioUnitSubType_AU3DMixerEmbedded, graph, &mixerNode));

// open graph
MDThrowOnError(AUGraphOpen(graph));

// we need a ref to the Audio Units so lets grab all of them here

MDThrowOnError(AUGraphNodeInfo(graph, inputNode, NULL, &inputUnit));
MDThrowOnError(AUGraphNodeInfo(graph, rioNode, NULL, &rioUnit));
MDThrowOnError(AUGraphNodeInfo(graph, mixerNode, NULL, &mixerUnit));

// setup the connections here, input to output of the graph.
/// the graph looks like inputNode->mixerNode->rioNode

MDThrowOnError(AUGraphConnectNodeInput(graph, inputNode, 0, mixerNode, 0));
MDThrowOnError(AUGraphConnectNodeInput(graph, mixerNode, 0, rioNode, 0));

// Init the graph

MDThrowOnError(AUGraphInitialize(graph));

//do any other setup here for your stream    

// Finally, Start the graph

MDThrowOnError(AUGraphStart(graph));

}

In your View Controller extension you simply;

  // define the MDMixerGraph Class
  // @property (nonatomic) MDMixerGraph *mixer;

And in the implementation

  self.mixer = [[MDMixerGraph alloc]init];
 [self.mixer setupAUGraph];

And you have reference to the rioUnit to pass to your framework (self.mixer.rioUnit); Without knowing more about your requirements connection/processing this is the best i can do for you.

Cheers!

Mixer AudioUnit to RemoteIO AudioUnit

1 Answers