Apple

OSStatus result = noErr;

AudioUnit outputUnit = 0;

AudioUnit converterUnit = 0;

AudioUnit decoderUnit = 0;

// Create a graph

result = NewAUGraph(&audioGraph);

// Add an output node

AudioComponentDescription outputNodeDesc = {kAudioUnitType_Output, kAudioUnitSubType_DefaultOutput, kAudioUnitManufacturer_Apple, 0, 0};

result = AUGraphAddNode(audioGraph, &outputNodeDesc, &outputNode);

AudioComponentDescription decoderNodeDesc = {kAudioDecoderComponentType, 'ima4', 'appl', 0, 0};

result = AUGraphAddNode(audioGraph, &decoderNodeDesc, &decoderNode);

// Add a converter to get things in the correct LPCM format

AudioComponentDescription converterNodeDesc = {kAudioUnitType_FormatConverter, kAudioUnitSubType_AUConverter, kAudioUnitManufacturer_Apple, 0, 0};

result = AUGraphAddNode(audioGraph, &converterNodeDesc, &converterNode);

// Open the graph

result = AUGraphOpen(audioGraph);

// Get the converter unit

result = AUGraphNodeInfo(audioGraph, converterNode, &converterNodeDesc, &converterUnit);

// Get the decoder unit

result = AUGraphNodeInfo(audioGraph, decoderNode, &decoderNodeDesc, &decoderUnit);

// Get the output unit

result = AUGraphNodeInfo(audioGraph, outputNode, &outputNodeDesc, &outputUnit);

AudioStreamBasicDescription outputFormat;

bzero(&outputFormat, sizeof(outputFormat));

outputFormat.mSampleRate = 44100.0;

outputFormat.mFormatID = kAudioFormatLinearPCM;

outputFormat.mFormatFlags = kAudioFormatFlagsNativeEndian | kLinearPCMFormatFlagIsSignedInteger | kLinearPCMFormatFlagIsPacked;

outputFormat.mChannelsPerFrame = 2;

outputFormat.mBitsPerChannel = 16;

outputFormat.mBytesPerPacket = outputFormat.mChannelsPerFrame * (outputFormat.mBitsPerChannel / 8);

outputFormat.mFramesPerPacket = 1;

outputFormat.mBytesPerFrame = outputFormat.mBytesPerPacket;

// Configure the decoder unit output

result = AudioUnitSetProperty(converterUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, 0, &outputFormat, sizeof(outputFormat));

// Configure the converter unit output

result = AudioUnitSetProperty(converterUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, 0, &outputFormat, sizeof(outputFormat));

// Configure the output unit's input format

result = AudioUnitSetProperty(outputUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, 0, &outputFormat, sizeof(outputFormat));

// Connect the decoder node as the input of the converter node

result = AUGraphConnectNodeInput (audioGraph, decoderNode, 0, converterNode, 0);

// Connect the converter node as the input of the output node

result = AUGraphConnectNodeInput (audioGraph, converterNode, 0, outputNode, 0);

// Initialize the graph

result = AUGraphInitialize(audioGraph);

… rest of code omitted since we don't get that far

References:
	>Why does this code crash in AUGraphInitialize? (From: Dave Camp <email@hidden>)