public void InitializeAUGraph () { Debug.Print ("Initialize"); LoadFiles (); graph = new AUGraph (); // create two AudioComponentDescriptions for the AUs we want in the graph // output unit var outputNode = graph.AddNode (AudioComponentDescription.CreateOutput (AudioTypeOutput.Remote)); // mixer node var mixerNode = graph.AddNode (AudioComponentDescription.CreateMixer (AudioTypeMixer.MultiChannel)); // connect a node's output to a node's input if (graph.ConnnectNodeInput (mixerNode, 0, outputNode, 0) != AUGraphError.OK) throw new ApplicationException (); // open the graph AudioUnits are open but not initialized (no resource allocation occurs here) if (graph.TryOpen () != 0) throw new ApplicationException (); mixer = graph.GetNodeInfo (mixerNode); // set bus count const uint numbuses = 2; Debug.Print ("Set input bus count {0}", numbuses); if (mixer.SetElementCount (AudioUnitScopeType.Input, numbuses) != AudioUnitStatus.OK) throw new ApplicationException (); AudioStreamBasicDescription desc; for (uint i = 0; i < numbuses; ++i) { // setup render callback if (graph.SetNodeInputCallback (mixerNode, i, HandleRenderDelegate) != AUGraphError.OK) throw new ApplicationException (); // set input stream format to what we want desc = mixer.GetAudioFormat (AudioUnitScopeType.Input, i); //desc.ChangeNumberChannels(2, false); desc.SampleRate = GraphSampleRate; mixer.SetAudioFormat (desc, AudioUnitScopeType.Input, i); } // set output stream format to what we want desc = mixer.GetAudioFormat (AudioUnitScopeType.Output); //desc.ChangeNumberChannels(2, false); desc.SampleRate = GraphSampleRate; mixer.SetAudioFormat (desc, AudioUnitScopeType.Output); // now that we've set everything up we can initialize the graph, this will also validate the connections if (graph.Initialize () != AUGraphError.OK) throw new ApplicationException (); }