Apple

I am updating an app that plays audio files with iLBC stream description. This new implementation is a simple Audio Graph with an Audio Converter node connected to a RemoteIO Node.

Setting the input asbd to the Audio Converter ("soundFileDataFormat" below) fails with -10868 (format not supported) with simulator and devices above iOS 4.0 and succeeds below 4.0. My dump of the parameters ([self logASBD:]) at the end of the snippet below verifies that.

Is there no longer support for this codec in the AudioConverter? Using the AudioQueue services approach works in all iOS so the codec is in the iPhone, but I need Audio Units for latency issues that can't be solved with AudioQueue.

Code Snippet:

NSLog(@"Start Play");

OSStatus status;

// set output data format

UInt32 formatFlags = (0

| kAudioFormatFlagIsPacked

| kAudioFormatFlagIsSignedInteger

| kAudioFormatFlagsNativeEndian

);

dataFormat.mFormatID = kAudioFormatLinearPCM;

dataFormat.mFormatFlags = formatFlags;

dataFormat.mSampleRate = 44100;

dataFormat.mBitsPerChannel = 16;

dataFormat.mChannelsPerFrame = 2;

dataFormat.mBytesPerFrame = 4;

dataFormat.mFramesPerPacket = 1;

dataFormat.mBytesPerPacket = 4;

soundFileDataFormat.mFormatID = kAudioFormatiLBC;

soundFileDataFormat.mFormatFlags = 0;

soundFileDataFormat.mSampleRate = 8000.0;

soundFileDataFormat.mBitsPerChannel = 0;

soundFileDataFormat.mChannelsPerFrame = 1;

soundFileDataFormat.mBytesPerFrame = 0;

soundFileDataFormat.mFramesPerPacket = 160;

soundFileDataFormat.mBytesPerPacket = 38;

NewAUGraph(&playGraph);

// Add Remote IO output node

AudioComponentDescription outputUnitDescription;

outputUnitDescription.componentType = kAudioUnitType_Output;

outputUnitDescription.componentSubType = kAudioUnitSubType_RemoteIO;

outputUnitDescription.componentManufacturer = kAudioUnitManufacturer_Apple;

AUGraphAddNode(playGraph, &outputUnitDescription, &outputNode);

// Add Converter

AudioComponentDescription converterUnitDescription;

converterUnitDescription.componentType = kAudioUnitType_FormatConverter;

converterUnitDescription.componentSubType = kAudioUnitSubType_AUConverter;

converterUnitDescription.componentManufacturer = kAudioUnitManufacturer_Apple;

AUGraphAddNode(playGraph, &converterUnitDescription, &outputConverterNode);

// Connect the nodes

AUGraphConnectNodeInput(playGraph, outputConverterNode, 0,

outputNode, 0);

// Open the graph

AUGraphOpen(playGraph);

status = AUGraphNodeInfo(playGraph, outputConverterNode,

NULL, &converterAudioUnit);

if (status != noErr) {

NSLog(@"Status = %ld", status);

return FALSE;

}

outputConverter = (AudioConverterRef)converterAudioUnit;

status = AudioUnitSetProperty(converterAudioUnit,

kAudioUnitProperty_StreamFormat,

kAudioUnitScope_Input,

&soundFileDataFormat,

sizeof(soundFileDataFormat));

if (status != noErr) {

NSLog(@"Status = %ld", status);

// return FALSE;

}

UInt32 sizeofdata = sizeof(asbd);

status = AudioUnitGetProperty(converterAudioUnit,

kAudioUnitProperty_StreamFormat,

kAudioUnitScope_Input,

&asbd,

&sizeofdata);

[self logASBD:asbd];