static int tdav_consumer_audiounit_prepare(tmedia_consumer_t* self, const tmedia_codec_t* codec)
{
	static UInt32 flagOne = 1;
	AudioStreamBasicDescription audioFormat;
#define kOutputBus  0
	
	tdav_consumer_audiounit_t* consumer = (tdav_consumer_audiounit_t*)self;
	OSStatus status = noErr;
	
	if(!consumer || !codec || !codec->plugin){
		TSK_DEBUG_ERROR("Invalid parameter");
		return -1;
	}
	if(!consumer->audioUnitHandle){
		if(!(consumer->audioUnitHandle = tdav_audiounit_handle_create(TMEDIA_CONSUMER(consumer)->session_id))){
			TSK_DEBUG_ERROR("Failed to get audio unit instance for session with id=%lld", TMEDIA_CONSUMER(consumer)->session_id);
			return -3;
		}
	}

	// enable
	status = AudioUnitSetProperty(tdav_audiounit_handle_get_instance(consumer->audioUnitHandle), 
								  kAudioOutputUnitProperty_EnableIO, 
								  kAudioUnitScope_Output, 
								  kOutputBus,
								  &flagOne, 
								  sizeof(flagOne));
	if(status){
		TSK_DEBUG_ERROR("AudioUnitSetProperty(kAudioOutputUnitProperty_EnableIO) failed with status=%d", (int32_t)status);
		return -4;
	}
	else {
		
#if !TARGET_OS_IPHONE // strange: TARGET_OS_MAC is equal to '1' on Smulator
		UInt32 param;
		
		// disable input
		param = 0;
		status = AudioUnitSetProperty(tdav_audiounit_handle_get_instance(consumer->audioUnitHandle), kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Input, 1, &param, sizeof(UInt32));
		if(status != noErr){
			TSK_DEBUG_ERROR("AudioUnitSetProperty(kAudioOutputUnitProperty_EnableIO) failed with status=%ld", (signed long)status);
			return -4;
		}
		
		// set default audio device
		param = sizeof(AudioDeviceID);
		AudioDeviceID outputDeviceID;
		status = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice, &param, &outputDeviceID);
		if(status != noErr){
			TSK_DEBUG_ERROR("AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice) failed with status=%ld", (signed long)status);
			return -4;
		}
		
		// set the current device to the default input unit
		status = AudioUnitSetProperty(tdav_audiounit_handle_get_instance(consumer->audioUnitHandle), 
									  kAudioOutputUnitProperty_CurrentDevice, 
									  kAudioUnitScope_Global, 
									  0, 
									  &outputDeviceID, 
									  sizeof(AudioDeviceID));
		if(status != noErr){
			TSK_DEBUG_ERROR("AudioUnitSetProperty(kAudioOutputUnitProperty_CurrentDevice) failed with status=%ld", (signed long)status);
			return -4;
		}
		
#endif

		TMEDIA_CONSUMER(consumer)->audio.ptime = TMEDIA_CODEC_PTIME_AUDIO_DECODING(codec);
		TMEDIA_CONSUMER(consumer)->audio.in.channels = TMEDIA_CODEC_CHANNELS_AUDIO_DECODING(codec);
		TMEDIA_CONSUMER(consumer)->audio.in.rate = TMEDIA_CODEC_RATE_DECODING(codec);
        
        TSK_DEBUG_INFO("AudioUnit consumer: in.channels=%d, out.channles=%d, in.rate=%d, out.rate=%d, ptime=%d",
                       TMEDIA_CONSUMER(consumer)->audio.in.channels,
                       TMEDIA_CONSUMER(consumer)->audio.out.channels,
                       TMEDIA_CONSUMER(consumer)->audio.in.rate,
                       TMEDIA_CONSUMER(consumer)->audio.out.rate,
                       TMEDIA_CONSUMER(consumer)->audio.ptime);
		
		audioFormat.mSampleRate = TMEDIA_CONSUMER(consumer)->audio.out.rate ? TMEDIA_CONSUMER(consumer)->audio.out.rate : TMEDIA_CONSUMER(consumer)->audio.in.rate;
		audioFormat.mFormatID = kAudioFormatLinearPCM;
		audioFormat.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
		audioFormat.mChannelsPerFrame = TMEDIA_CONSUMER(consumer)->audio.in.channels;
		audioFormat.mFramesPerPacket = 1;
		audioFormat.mBitsPerChannel = TMEDIA_CONSUMER(consumer)->audio.bits_per_sample;
		audioFormat.mBytesPerPacket = audioFormat.mBitsPerChannel / 8 * audioFormat.mChannelsPerFrame;
		audioFormat.mBytesPerFrame = audioFormat.mBytesPerPacket;
		audioFormat.mReserved = 0;
		status = AudioUnitSetProperty(tdav_audiounit_handle_get_instance(consumer->audioUnitHandle), 
									  kAudioUnitProperty_StreamFormat, 
									  kAudioUnitScope_Input, 
									  kOutputBus, 
									  &audioFormat, 
									  sizeof(audioFormat));
		
		if(status){
			TSK_DEBUG_ERROR("AudioUnitSetProperty(kAudioUnitProperty_StreamFormat) failed with status=%ld", (signed long)status);
			return -5;
		}
		else {
			// configure
			if(tdav_audiounit_handle_configure(consumer->audioUnitHandle, tsk_true, TMEDIA_CONSUMER(consumer)->audio.ptime, &audioFormat)){
				TSK_DEBUG_ERROR("tdav_audiounit_handle_set_rate(%d) failed", TMEDIA_CONSUMER(consumer)->audio.out.rate);
				return -4;
			}
			
			// set callback function
			AURenderCallbackStruct callback;
			callback.inputProc = __handle_output_buffer;
			callback.inputProcRefCon = consumer;
			status = AudioUnitSetProperty(tdav_audiounit_handle_get_instance(consumer->audioUnitHandle), 
										  kAudioUnitProperty_SetRenderCallback, 
										  kAudioUnitScope_Input, 
										  kOutputBus,
										  &callback, 
										  sizeof(callback));
			if(status){
				TSK_DEBUG_ERROR("AudioUnitSetProperty(kAudioOutputUnitProperty_SetInputCallback) failed with status=%ld", (signed long)status);
				return -6;
			}
		}
	}
	
	// allocate the chunck buffer and create the ring
	consumer->ring.chunck.size = (TMEDIA_CONSUMER(consumer)->audio.ptime * audioFormat.mSampleRate * audioFormat.mBytesPerFrame) / 1000;
	consumer->ring.size = kRingPacketCount * consumer->ring.chunck.size;
	if(!(consumer->ring.chunck.buffer = tsk_realloc(consumer->ring.chunck.buffer, consumer->ring.chunck.size))){
		TSK_DEBUG_ERROR("Failed to allocate new buffer");
		return -7;
	}
	if(!consumer->ring.buffer){
		consumer->ring.buffer = speex_buffer_init(consumer->ring.size);
	}
	else {
		int ret;
		if((ret = speex_buffer_resize(consumer->ring.buffer, consumer->ring.size)) < 0){
			TSK_DEBUG_ERROR("speex_buffer_resize(%d) failed with error code=%d", consumer->ring.size, ret);
			return ret;
		}
	}
	if(!consumer->ring.buffer){
		TSK_DEBUG_ERROR("Failed to create a new ring buffer with size = %d", consumer->ring.size);
		return -8;
	}
	if(!consumer->ring.mutex && !(consumer->ring.mutex = tsk_mutex_create_2(tsk_false))){
		TSK_DEBUG_ERROR("Failed to create mutex");
		return -9;
	}

	// set maximum frames per slice as buffer size
	//UInt32 numFrames = (UInt32)consumer->ring.chunck.size;
	//status = AudioUnitSetProperty(tdav_audiounit_handle_get_instance(consumer->audioUnitHandle), 
	//							  kAudioUnitProperty_MaximumFramesPerSlice,
	//							  kAudioUnitScope_Global, 
	//							  0, 
	//							  &numFrames, 
	//							  sizeof(numFrames));
	//if(status){
	//	TSK_DEBUG_ERROR("AudioUnitSetProperty(kAudioUnitProperty_MaximumFramesPerSlice, %u) failed with status=%d", (unsigned)numFrames, (int32_t)status);
	//	return -6;
	//}
	
	TSK_DEBUG_INFO("AudioUnit consumer prepared");
    return tdav_audiounit_handle_signal_consumer_prepared(consumer->audioUnitHandle);
}
static int tdav_producer_audiounit_prepare(tmedia_producer_t* self, const tmedia_codec_t* codec)
{
	static UInt32 flagOne = 1;
	UInt32 param;
	// static UInt32 flagZero = 0;
#define kInputBus  1
	
	tdav_producer_audiounit_t* producer = (tdav_producer_audiounit_t*)self;
	OSStatus status = noErr;
	AudioStreamBasicDescription audioFormat;
	AudioStreamBasicDescription	deviceFormat;
	
	if(!producer || !codec || !codec->plugin){
		TSK_DEBUG_ERROR("Invalid parameter");
		return -1;
	}
	if(!producer->audioUnitHandle){
		if(!(producer->audioUnitHandle = tdav_audiounit_handle_create(TMEDIA_PRODUCER(producer)->session_id))){
			TSK_DEBUG_ERROR("Failed to get audio unit instance for session with id=%lld", TMEDIA_PRODUCER(producer)->session_id);
			return -3;
		}
	}
	
	// enable
	status = AudioUnitSetProperty(tdav_audiounit_handle_get_instance(producer->audioUnitHandle), 
								  kAudioOutputUnitProperty_EnableIO, 
								  kAudioUnitScope_Input, 
								  kInputBus,
								  &flagOne, 
								  sizeof(flagOne));
	if(status != noErr){
		TSK_DEBUG_ERROR("AudioUnitSetProperty(kAudioOutputUnitProperty_EnableIO) failed with status=%ld", (signed long)status);
		return -4;
	}
	else {
#if !TARGET_OS_IPHONE // strange: TARGET_OS_MAC is equal to '1' on Smulator
		// disable output
		param = 0;
		status = AudioUnitSetProperty(tdav_audiounit_handle_get_instance(producer->audioUnitHandle), 
									  kAudioOutputUnitProperty_EnableIO, 
									  kAudioUnitScope_Output, 
									  0, 
									  &param, 
									  sizeof(UInt32));
		if(status != noErr){
			TSK_DEBUG_ERROR("AudioUnitSetProperty(kAudioOutputUnitProperty_EnableIO) failed with status=%ld", (signed long)status);
			return -4;
		}
		
		// set default audio device
		param = sizeof(AudioDeviceID);
		AudioDeviceID inputDeviceID;
		status = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultInputDevice, &param, &inputDeviceID);
		if(status != noErr){
			TSK_DEBUG_ERROR("AudioHardwareGetProperty(kAudioHardwarePropertyDefaultInputDevice) failed with status=%ld", (signed long)status);
			return -4;
		}
		
		// set the current device to the default input unit
		status = AudioUnitSetProperty(tdav_audiounit_handle_get_instance(producer->audioUnitHandle), 
									  kAudioOutputUnitProperty_CurrentDevice, 
									  kAudioUnitScope_Output, 
									  0, 
									  &inputDeviceID, 
									  sizeof(AudioDeviceID));
		if(status != noErr){
			TSK_DEBUG_ERROR("AudioUnitSetProperty(kAudioOutputUnitProperty_CurrentDevice) failed with status=%ld", (signed long)status);
			return -4;
		}
#endif /* TARGET_OS_MAC */
		
		/* codec should have ptime */
		TMEDIA_PRODUCER(producer)->audio.channels = codec->plugin->audio.channels;
		TMEDIA_PRODUCER(producer)->audio.rate = codec->plugin->rate;
		TMEDIA_PRODUCER(producer)->audio.ptime = codec->plugin->audio.ptime;
		
		// get device format
		param = sizeof(AudioStreamBasicDescription);
		status = AudioUnitGetProperty(tdav_audiounit_handle_get_instance(producer->audioUnitHandle), 
								   kAudioUnitProperty_StreamFormat, 
								   kAudioUnitScope_Input, 
								   kInputBus, 
								   &deviceFormat, &param);
		if(status == noErr && deviceFormat.mSampleRate){
#if TARGET_OS_IPHONE
			// iOS support 8Khz, 16kHz and 32kHz => do not override the sampleRate
#elif TARGET_OS_MAC
			// For example, iSight supports only 48kHz
			TMEDIA_PRODUCER(producer)->audio.rate = deviceFormat.mSampleRate;
#endif
		}
		
		// set format
		audioFormat.mSampleRate = TMEDIA_PRODUCER(producer)->audio.rate;
		audioFormat.mFormatID = kAudioFormatLinearPCM;
		audioFormat.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked | kAudioFormatFlagIsNonInterleaved;
		audioFormat.mChannelsPerFrame = TMEDIA_PRODUCER(producer)->audio.channels;
		audioFormat.mFramesPerPacket = 1;
		audioFormat.mBitsPerChannel = TMEDIA_PRODUCER(producer)->audio.bits_per_sample;
		audioFormat.mBytesPerPacket = audioFormat.mBitsPerChannel / 8 * audioFormat.mChannelsPerFrame;
		audioFormat.mBytesPerFrame = audioFormat.mBytesPerPacket;
		audioFormat.mReserved = 0;
		if(audioFormat.mFormatID == kAudioFormatLinearPCM && audioFormat.mChannelsPerFrame  == 1){
			audioFormat.mFormatFlags &= ~kLinearPCMFormatFlagIsNonInterleaved;
		}
		status = AudioUnitSetProperty(tdav_audiounit_handle_get_instance(producer->audioUnitHandle), 
									  kAudioUnitProperty_StreamFormat, 
									  kAudioUnitScope_Output, 
									  kInputBus, 
									  &audioFormat, 
								sizeof(audioFormat));
		if(status){
			TSK_DEBUG_ERROR("AudioUnitSetProperty(kAudioUnitProperty_StreamFormat) failed with status=%ld", (signed long)status);
			return -5;
		}
		else {
			
			// configure
			if(tdav_audiounit_handle_configure(producer->audioUnitHandle, tsk_false, TMEDIA_PRODUCER(producer)->audio.ptime, &audioFormat)){
				TSK_DEBUG_ERROR("tdav_audiounit_handle_set_rate(%d) failed", TMEDIA_PRODUCER(producer)->audio.rate);
				return -4;
			}
			
			// set callback function
			AURenderCallbackStruct callback;
			callback.inputProc = __handle_input_buffer;
			callback.inputProcRefCon = producer;
			status = AudioUnitSetProperty(tdav_audiounit_handle_get_instance(producer->audioUnitHandle), 
										  kAudioOutputUnitProperty_SetInputCallback, 
										  kAudioUnitScope_Output, 
										  kInputBus, 
										  &callback, 
										  sizeof(callback));
			if(status){
				TSK_DEBUG_ERROR("AudioUnitSetProperty(kAudioOutputUnitProperty_SetInputCallback) failed with status=%ld", (signed long)status);
				return -6;
			}
			else {
				// disbale buffer allocation as we will provide ours
				//status = AudioUnitSetProperty(tdav_audiounit_handle_get_instance(producer->audioUnitHandle), 
				//							  kAudioUnitProperty_ShouldAllocateBuffer,
				//							  kAudioUnitScope_Output, 
				//							  kInputBus,
				//							  &flagZero, 
				//							  sizeof(flagZero));
				
				int packetperbuffer = (1000 / codec->plugin->audio.ptime);
				producer->ring.chunck.size = audioFormat.mSampleRate * audioFormat.mBytesPerFrame / packetperbuffer;
				// allocate our chunck buffer
				if(!(producer->ring.chunck.buffer = tsk_realloc(producer->ring.chunck.buffer, producer->ring.chunck.size))){
					TSK_DEBUG_ERROR("Failed to allocate new buffer");
					return -7;
				}
				// create mutex for ring buffer
				if(!producer->ring.mutex && !(producer->ring.mutex = tsk_mutex_create_2(tsk_false))){
					TSK_DEBUG_ERROR("Failed to create new mutex");
					return -8;
				}
				// create ringbuffer
				producer->ring.size = kRingPacketCount * producer->ring.chunck.size;
				if(!producer->ring.buffer){
					producer->ring.buffer = speex_buffer_init(producer->ring.size);
				}
				else {
					int ret;
					if((ret = speex_buffer_resize(producer->ring.buffer, producer->ring.size)) < 0){
						TSK_DEBUG_ERROR("speex_buffer_resize(%d) failed with error code=%d", producer->ring.size, ret);
						return ret;
					}
				}
				if(!producer->ring.buffer){
					TSK_DEBUG_ERROR("Failed to create a new ring buffer with size = %d", producer->ring.size);
					return -9;
				}
			}

		}
	}
	
	TSK_DEBUG_INFO("AudioUnit producer prepared");
	return tdav_audiounit_handle_signal_producer_prepared(producer->audioUnitHandle);
}