syedhali/EZAudio

NSArray *inputDevices = [EZAudioDevice inputDevices];

// On iOS this will default to the headset device or bottom microphone, while on OSX this will
// be your selected inpupt device from the Sound preferences
EZAudioDevice *currentInputDevice = [EZAudioDevice currentInputDevice];

NSArray *outputDevices = [EZAudioDevice outputDevices];

// On iOS this will default to the headset speaker, while on OSX this will be your selected
// output device from the Sound preferences
EZAudioDevice *currentOutputDevice = [EZAudioDevice currentOutputDevice];

// Declare the EZMicrophone as a strong property
@property (nonatomic, strong) EZMicrophone *microphone;

...

// Initialize the microphone instance and assign it a delegate to receive the audio data
// callbacks
self.microphone = [EZMicrophone microphoneWithDelegate:self];

// Assign a delegate to the shared instance of the microphone to receive the audio data
// callbacks
[EZMicrophone sharedMicrophone].delegate = self;

NSArray *inputs = [EZAudioDevice inputDevices];
[self.microphone setDevice:[inputs lastObject]];

- (void)microphone:(EZMicrophone *)microphone changedDevice:(EZAudioDevice *)device
{
    // This is not always guaranteed to occur on the main thread so make sure you
    // wrap it in a GCD block
    dispatch_async(dispatch_get_main_queue(), ^{
        // Update UI here
	    NSLog(@"Changed input device: %@", device);
    });
}

// Starts fetching audio from the default device microphone and sends data to EZMicrophoneDelegate
[self.microphone startFetchingAudio];

/**
 The microphone data represented as non-interleaved float arrays useful for:
    - Creating real-time waveforms using EZAudioPlot or EZAudioPlotGL
    - Creating any number of custom visualizations that utilize audio!
 */
-(void)   microphone:(EZMicrophone *)microphone
    hasAudioReceived:(float **)buffer
      withBufferSize:(UInt32)bufferSize
withNumberOfChannels:(UInt32)numberOfChannels
{
    __weak typeof (self) weakSelf = self;
	// Getting audio data as an array of float buffer arrays that can be fed into the
	// EZAudioPlot, EZAudioPlotGL, or whatever visualization you would like to do with
	// the microphone data.
	dispatch_async(dispatch_get_main_queue(),^{
		// Visualize this data brah, buffer[0] = left channel, buffer[1] = right channel
		[weakSelf.audioPlot updateBuffer:buffer[0] withBufferSize:bufferSize];
    });
}

/**
 The microphone data represented as CoreAudio's AudioBufferList useful for:
    - Appending data to an audio file via the EZRecorder
    - Playback via the EZOutput

 */
-(void)    microphone:(EZMicrophone *)microphone
        hasBufferList:(AudioBufferList *)bufferList
       withBufferSize:(UInt32)bufferSize
 withNumberOfChannels:(UInt32)numberOfChannels
{
	// Getting audio data as an AudioBufferList that can be directly fed into the EZRecorder
	// or EZOutput. Say whattt...
}

// Stop fetching audio
[self.microphone stopFetchingAudio];

// Resume fetching audio
[self.microphone startFetchingAudio];

// Stop fetching audio
self.microphone.microphoneOn = NO;

// Start fetching audio
self.microphone.microphoneOn = YES;

// The EZOutputDataSource should fill out the audioBufferList with the given frame count.
// The timestamp is provided for sample accurate calculation, but for basic use cases can
// be ignored.
- (OSStatus)        output:(EZOutput *)output
 shouldFillAudioBufferList:(AudioBufferList *)audioBufferList
        withNumberOfFrames:(UInt32)frames
                 timestamp:(const AudioTimeStamp *)timestamp;

// Declare the EZOutput as a strong property
@property (nonatomic, strong) EZOutput *output;
...

// Initialize the EZOutput instance and assign it a delegate to provide the output audio data
self.output = [EZOutput outputWithDataSource:self];

// Assign a delegate to the shared instance of the output to provide the output audio data
[EZOutput sharedOutput].delegate = self;

// By default the EZOutput uses the default output device, but you can change this at any time
EZAudioDevice *currentOutputDevice = [EZAudioDevice currentOutputDevice];
[self.output setDevice:currentOutputDevice];

- (void)output:(EZOutput *)output changedDevice:(EZAudioDevice *)device
{
    NSLog(@"Change output device to: %@", device);
}

// Set a mono, float format with a sample rate of 44.1 kHz
AudioStreamBasicDescription monoFloatFormat = [EZAudioUtilities monoFloatFormatWithSampleRate:44100.0f];
[self.output setInputFormat:monoFloatFormat];

- (OSStatus)        output:(EZOutput *)output
 shouldFillAudioBufferList:(AudioBufferList *)audioBufferList
        withNumberOfFrames:(UInt32)frames
                 timestamp:(const AudioTimeStamp *)timestamp
{
    if (self.audioFile)
    {
        UInt32 bufferSize; // amount of frames actually read
        BOOL eof; // end of file
        [self.audioFile readFrames:frames
                   audioBufferList:audioBufferList
                        bufferSize:&bufferSize
                               eof:&eof];
        if (eof && [self.delegate respondsToSelector:@selector(audioPlayer:reachedEndOfAudioFile:)])
        {
            [self.delegate audioPlayer:self reachedEndOfAudioFile:self.audioFile];
        }
        if (eof && self.shouldLoop)
        {
            [self seekToFrame:0];
        }
        else if (eof)
        {
            [self pause];
            [self seekToFrame:0];
            [[NSNotificationCenter defaultCenter] postNotificationName:EZAudioPlayerDidReachEndOfFileNotification
                                                                object:self];
        }
    }
    return noErr;
}

...
double const SAMPLE_RATE = 44100.0;

- (void)awakeFromNib
{
    //
    // Create EZOutput to play audio data with mono format (EZOutput will convert
    // this mono, float "inputFormat" to a clientFormat, i.e. the stereo output format).
    //
    AudioStreamBasicDescription inputFormat = [EZAudioUtilities monoFloatFormatWithSampleRate:SAMPLE_RATE];
    self.output = [EZOutput outputWithDataSource:self inputFormat:inputFormat];
    [self.output setDelegate:self];
    self.frequency = 200.0;
    self.sampleRate = SAMPLE_RATE;
    self.amplitude = 0.80;
}

- (OSStatus)        output:(EZOutput *)output
 shouldFillAudioBufferList:(AudioBufferList *)audioBufferList
        withNumberOfFrames:(UInt32)frames
                 timestamp:(const AudioTimeStamp *)timestamp
{
    Float32 *buffer = (Float32 *)audioBufferList->mBuffers[0].mData;
    size_t bufferByteSize = (size_t)audioBufferList->mBuffers[0].mDataByteSize;
    double theta = self.theta;
    double frequency = self.frequency;
    double thetaIncrement = 2.0 * M_PI * frequency / SAMPLE_RATE;
    if (self.type == GeneratorTypeSine)
    {
        for (UInt32 frame = 0; frame < frames; frame++)
        {
            buffer[frame] = self.amplitude * sin(theta);
            theta += thetaIncrement;
            if (theta > 2.0 * M_PI)
            {
                theta -= 2.0 * M_PI;
            }
        }
        self.theta = theta;
    }
    else if (... other shapes in full source)
}

/**
 The output data represented as non-interleaved float arrays useful for:
    - Creating real-time waveforms using EZAudioPlot or EZAudioPlotGL
    - Creating any number of custom visualizations that utilize audio!
 */
- (void)       output:(EZOutput *)output
          playedAudio:(float **)buffer
       withBufferSize:(UInt32)bufferSize
 withNumberOfChannels:(UInt32)numberOfChannels
{
    __weak typeof (self) weakSelf = self;
    dispatch_async(dispatch_get_main_queue(), ^{
	// Update plot, buffer[0] = left channel, buffer[1] = right channel
    });
}

// Stop fetching audio
[self.output stopPlayback];

// Resume fetching audio
[self.output startPlayback];

// By default this method connects the AUNode representing the input format converter to
// the mixer node. In subclasses you can add effects in the chain between the converter
// and mixer by creating additional AUNodes, adding them to the AUGraph provided below,
// and then connecting them together.
- (OSStatus)connectOutputOfSourceNode:(AUNode)sourceNode
                  sourceNodeOutputBus:(UInt32)sourceNodeOutputBus
                    toDestinationNode:(AUNode)destinationNode
              destinationNodeInputBus:(UInt32)destinationNodeInputBus
                              inGraph:(AUGraph)graph;

// In interface, declare delay node info property
@property (nonatomic, assign) EZAudioNodeInfo *delayNodeInfo;

// In implementation, overwrite the connection method
- (OSStatus)connectOutputOfSourceNode:(AUNode)sourceNode
                  sourceNodeOutputBus:(UInt32)sourceNodeOutputBus
                    toDestinationNode:(AUNode)destinationNode
              destinationNodeInputBus:(UInt32)destinationNodeInputBus
                              inGraph:(AUGraph)graph
{
    self.delayNodeInfo = (EZAudioNodeInfo *)malloc(sizeof(EZAudioNodeInfo));

    // A description for the time/pitch shifter Device
    AudioComponentDescription delayComponentDescription;
    delayComponentDescription.componentType = kAudioUnitType_Effect;
    delayComponentDescription.componentSubType = kAudioUnitSubType_Delay;
    delayComponentDescription.componentManufacturer = kAudioUnitManufacturer_Apple;
    delayComponentDescription.componentFlags = 0;
    delayComponentDescription.componentFlagsMask = 0;

    [EZAudioUtilities checkResult:AUGraphAddNode(graph,
                                                 &delayComponentDescription,
                                                 &self.delayNodeInfo->node)
                        operation:"Failed to add node for time shift"];

    // Get the time/pitch shifter Audio Unit from the node
    [EZAudioUtilities checkResult:AUGraphNodeInfo(graph,
                                                  self.delayNodeInfo->node,
                                                  NULL,
                                                  &self.delayNodeInfo->audioUnit)
                        operation:"Failed to get audio unit for delay node"];

    // connect the output of the input source node to the input of the time/pitch shifter node
    [EZAudioUtilities checkResult:AUGraphConnectNodeInput(graph,
                                                          sourceNode,
                                                          sourceNodeOutputBus,
                                                          self.delayNodeInfo->node,
                                                          0)
                        operation:"Failed to connect source node into delay node"];

    // connect the output of the time/pitch shifter node to the input of the destination node, thus completing the chain.
    [EZAudioUtilities checkResult:AUGraphConnectNodeInput(graph,
                                                          self.delayNodeInfo->node,
                                                          0,
                                                          destinationNode,
                                                          destinationNodeInputBus)
                        operation:"Failed to connect delay to destination node"];
    return noErr;
}

// Clean up
- (void)dealloc
{
    free(self.delayNodeInfo);
}

// Declare the EZAudioFile as a strong property
@property (nonatomic, strong) EZAudioFile *audioFile;

...

// Initialize the EZAudioFile instance and assign it a delegate to receive the read/seek callbacks
self.audioFile = [EZAudioFile audioFileWithURL:[NSURL fileURLWithPath:@"/path/to/your/file"] delegate:self];

__weak typeof (self) weakSelf = self;
// Get a waveform with 1024 points of data. We can adjust the number of points to whatever level
// of detail is needed by the application
[self.audioFile getWaveformDataWithNumberOfPoints:1024
                                  completionBlock:^(float **waveformData,
                                                    int length)
{
     [weakSelf.audioPlot updateBuffer:waveformData[0]
                       withBufferSize:length];
}];

// Allocate an AudioBufferList to hold the audio data (the client format is the non-compressed
// in-app format that is used for reading, it's different than the file format which is usually
// something compressed like an mp3 or m4a)
AudioStreamBasicDescription clientFormat = [self.audioFile clientFormat];
UInt32 numberOfFramesToRead = 512;
UInt32 channels = clientFormat.mChannelsPerFrame;
BOOL isInterleaved = [EZAudioUtilities isInterleaved:clientFormat];
AudioBufferList *bufferList = [EZAudioUtilities audioBufferListWithNumberOfFrames:numberOfFramesToRead
                                                                 numberOfChannels:channels
                                                                      interleaved:isInterleaved];

// Read the frames from the EZAudioFile into the AudioBufferList
UInt32 framesRead;
UInt32 isEndOfFile;
[self.audioFile readFrames:numberOfFramesToRead
           audioBufferList:bufferList
                bufferSize:&framesRead
                       eof:&isEndOfFile]

-(void)     audioFile:(EZAudioFile *)audioFile
            readAudio:(float **)buffer
       withBufferSize:(UInt32)bufferSize
 withNumberOfChannels:(UInt32)numberOfChannels
{
    __weak typeof (self) weakSelf = self;
    dispatch_async(dispatch_get_main_queue(), ^{
        [weakSelf.audioPlot updateBuffer:buffer[0]
                          withBufferSize:bufferSize];
    });
}

-(void)audioFile:(EZAudioFile *)audioFile updatedPosition:(SInt64)framePosition
{
    __weak typeof (self) weakSelf = self;
    dispatch_async(dispatch_get_main_queue(), ^{
		// Update UI
    });
}

// Get the total number of frames for the audio file
SInt64 totalFrames = [self.audioFile totalFrames];

// Seeks halfway through the audio file
[self.audioFile seekToFrame:(totalFrames/2)];

// Alternatively, you can seek using seconds
NSTimeInterval duration = [self.audioFile duration];
[self.audioFile setCurrentTime:duration/2.0];

-(void)audioFile:(EZAudioFile *)audioFile updatedPosition:(SInt64)framePosition
{
    __weak typeof (self) weakSelf = self;
    dispatch_async(dispatch_get_main_queue(), ^{
		// Update UI
    });
}

// Declare the EZAudioFile as a strong property
@property (nonatomic, strong) EZAudioFile *audioFile;

...

// Create an EZAudioPlayer with a delegate that conforms to EZAudioPlayerDelegate
self.player = [EZAudioPlayer audioPlayerWithDelegate:self];

// Set the EZAudioFile for playback by setting the `audioFile` property
EZAudioFile *audioFile = [EZAudioFile audioFileWithURL:[NSURL fileURLWithPath:@"/path/to/your/file"]];
[self.player setAudioFile:audioFile];

// This, however, will not pause playback if a current file is playing. Instead
// it's encouraged to use `playAudioFile:` instead if you're swapping in a new
// audio file while playback is already running
EZAudioFile *audioFile = [EZAudioFile audioFileWithURL:[NSURL fileURLWithPath:@"/path/to/your/file"]];
[self.player playAudioFile:audioFile];

- (void)  audioPlayer:(EZAudioPlayer *)audioPlayer
          playedAudio:(float **)buffer
       withBufferSize:(UInt32)bufferSize
 withNumberOfChannels:(UInt32)numberOfChannels
          inAudioFile:(EZAudioFile *)audioFile
{
    __weak typeof (self) weakSelf = self;
    // Update an EZAudioPlot or EZAudioPlotGL to reflect the audio data coming out
    // of the EZAudioPlayer (post volume and pan)
    dispatch_async(dispatch_get_main_queue(), ^{
        [weakSelf.audioPlot updateBuffer:buffer[0]
                          withBufferSize:bufferSize];
    });
}

//------------------------------------------------------------------------------

- (void)audioPlayer:(EZAudioPlayer *)audioPlayer
    updatedPosition:(SInt64)framePosition
        inAudioFile:(EZAudioFile *)audioFile
{
    __weak typeof (self) weakSelf = self;
    // Update any UI controls including sliders and labels
    // display current time/duration
    dispatch_async(dispatch_get_main_queue(), ^{
        if (!weakSelf.positionSlider.highlighted)
        {
            weakSelf.positionSlider.floatValue = (float)framePosition;
            weakSelf.positionLabel.integerValue = framePosition;
        }
    });
}

// Get the total number of frames and seek halfway
SInt64 totalFrames = [self.player totalFrames];
[self.player seekToFrame:(totalFrames/2)];

// Alternatively, you can seek using seconds
NSTimeInterval duration = [self.player duration];
[self.player setCurrentTime:duration/2.0];

// Make it half as loud, 0 = silence, 1 = full volume. Default is 1.
[self.player setVolume:0.5];

// Make it only play on the left, -1 = left, 1 = right. Default is 0.0 (center)
[self.player setPan:-1.0];

NSTimeInterval  currentTime          = [self.player currentTime];
NSTimeInterval  duration             = [self.player duration];
NSString       *formattedCurrentTime = [self.player formattedCurrentTime]; // MM:SS formatted
NSString       *formattedDuration    = [self.player formattedDuration];    // MM:SS formatted
SInt64          frameIndex           = [self.player frameIndex];
SInt64          totalFrames          = [self.player totalFrames];

EZAudioDevice *outputDevice = [self.player device];
BOOL 	       isPlaying    = [self.player isPlaying];
float          pan          = [self.player pan];
float          volume       = [self.player volume];

/**
 Notification that occurs whenever the EZAudioPlayer changes its `audioFile` property. Check the new value using the EZAudioPlayer's `audioFile` property.
 */
FOUNDATION_EXPORT NSString * const EZAudioPlayerDidChangeAudioFileNotification;

/**
 Notification that occurs whenever the EZAudioPlayer changes its `device` property. Check the new value using the EZAudioPlayer's `device` property.
 */
FOUNDATION_EXPORT NSString * const EZAudioPlayerDidChangeOutputDeviceNotification;

/**
 Notification that occurs whenever the EZAudioPlayer changes its `output` component's `pan` property. Check the new value using the EZAudioPlayer's `pan` property.
 */
FOUNDATION_EXPORT NSString * const EZAudioPlayerDidChangePanNotification;

/**
 Notification that occurs whenever the EZAudioPlayer changes its `output` component's play state. Check the new value using the EZAudioPlayer's `isPlaying` property.
 */
FOUNDATION_EXPORT NSString * const EZAudioPlayerDidChangePlayStateNotification;

/**
 Notification that occurs whenever the EZAudioPlayer changes its `output` component's `volume` property. Check the new value using the EZAudioPlayer's `volume` property.
 */
FOUNDATION_EXPORT NSString * const EZAudioPlayerDidChangeVolumeNotification;

/**
 Notification that occurs whenever the EZAudioPlayer has reached the end of a file and its `shouldLoop` property has been set to NO.
 */
FOUNDATION_EXPORT NSString * const EZAudioPlayerDidReachEndOfFileNotification;

/**
 Notification that occurs whenever the EZAudioPlayer performs a seek via the `seekToFrame` method or `setCurrentTime:` property setter. Check the new `currentTime` or `frameIndex` value using the EZAudioPlayer's `currentTime` or `frameIndex` property, respectively.
 */
FOUNDATION_EXPORT NSString * const EZAudioPlayerDidSeekNotification;

// Provide a file path url to write to, a client format (always linear PCM, this is the format
// coming from another component like the EZMicrophone's audioStreamBasicDescription property),
// and a EZRecorderFileType constant representing either a wav (EZRecorderFileTypeWAV),
// aiff (EZRecorderFileTypeAIFF), or m4a (EZRecorderFileTypeM4A) file format. The advantage of
// this is that the `fileFormat` property will be automatically filled out for you.
+ (instancetype)recorderWithURL:(NSURL *)url
                   clientFormat:(AudioStreamBasicDescription)clientFormat
                       fileType:(EZRecorderFileType)fileType;

// Alternatively, you can provide a file path url to write to, a client format (always linear
// PCM, this is the format coming from another component like the EZMicrophone's
// audioStreamBasicDescription property), a `fileFormat` representing your custom
// AudioStreamBasicDescription, and an AudioFileTypeID that corresponds with your `fileFormat`.
+ (instancetype)recorderWithURL:(NSURL *)url
                   clientFormat:(AudioStreamBasicDescription)clientFormat
                     fileFormat:(AudioStreamBasicDescription)fileFormat
                audioFileTypeID:(AudioFileTypeID)audioFileTypeID;

// Declare the EZRecorder as a strong property
@property (nonatomic, strong) EZRecorder *recorder;

// Example using an EZMicrophone and a string called kAudioFilePath representing a file
// path location on your computer to write out a M4A file.
self.recorder = [EZRecorder recorderWithURL:[NSURL fileURLWithPath:@"/path/to/your/file.m4a"]
                               clientFormat:[self.microphone audioStreamBasicDescription]
                                   fileType:EZRecorderFileTypeM4A];

// Example using an EZMicrophone, a string called kAudioFilePath representing a file
// path location on your computer, and an iLBC file format.
AudioStreamBasicDescription iLBCFormat = [EZAudioUtilities iLBCFormatWithSampleRate:8000];
self.recorder = [EZRecorder recorderWithURL:[NSURL fileURLWithPath:@"/path/to/your/file.caf"]
                               clientFormat:[self.microphone audioStreamBasicDescription]
                                 fileFormat:iLBCFormat
                            audioFileTypeID:kAudioFileCAFType];

// Append the microphone data coming as a AudioBufferList with the specified buffer size
// to the recorder
-(void)    microphone:(EZMicrophone *)microphone
        hasBufferList:(AudioBufferList *)bufferList
       withBufferSize:(UInt32)bufferSize
 withNumberOfChannels:(UInt32)numberOfChannels
{
    // Getting audio data as a buffer list that can be directly fed into the EZRecorder. This is
    // happening on the audio thread - any UI updating needs a GCD main queue block.
    if (self.isRecording)
    {
        // Since we set the recorder's client format to be that of the EZMicrophone instance,
        // the audio data coming in represented by the AudioBufferList can directly be provided
        // to the EZRecorder. The EZRecorder will internally convert the audio data from the
        // `clientFormat` to `fileFormat`.
        [self.recorder appendDataFromBufferList:bufferList
                                 withBufferSize:bufferSize];
    }
}

// Triggers after the EZRecorder's `appendDataFromBufferList:withBufferSize:` method is called
// so you can update your interface accordingly.
- (void)recorderUpdatedCurrentTime:(EZRecorder *)recorder
{
    __weak typeof (self) weakSelf = self;
    // This will get triggerd on the thread that the write occured on so be sure to wrap your UI
    // updates in a GCD main queue block! However, I highly recommend you first pull the values
    // you'd like to update the interface with before entering the GCD block to avoid trying to
    // fetch a value after the audio file has been closed.
    NSString *formattedCurrentTime = [recorder formattedCurrentTime]; // MM:SS formatted
    dispatch_async(dispatch_get_main_queue(), ^{
    	// Update label
        weakSelf.currentTimeLabel.stringValue = formattedCurrentTime;
    });
}

// Close the EZRecorder's audio file BEFORE reading
[self.recorder closeAudioFile];

- (void)recorderDidClose:(EZRecorder *)recorder
{
    recorder.delegate = nil;
}

// Programmatically create an audio plot
EZAudioPlot *audioPlot = [[EZAudioPlot alloc] initWithFrame:self.view.frame];
[self.view addSubview:audioPlot];

// Background color (use UIColor for iOS)
audioPlot.backgroundColor = [NSColor colorWithCalibratedRed:0.816
                                                      green:0.349
                                                       blue:0.255
                                                      alpha:1];
// Waveform color (use UIColor for iOS)
audioPlot.color = [NSColor colorWithCalibratedRed:1.000
                                            green:1.000
                                             blue:1.000
                                            alpha:1];
// Plot type
audioPlot.plotType = EZPlotTypeBuffer;
// Fill
audioPlot.shouldFill = YES;
// Mirror
audioPlot.shouldMirror = YES;

// The microphone component provides audio data to its delegate as an array of float buffer arrays.
- (void)   microphone:(EZMicrophone *)microphone
     hasAudioReceived:(float **)buffer
       withBufferSize:(UInt32)bufferSize
 withNumberOfChannels:(UInt32)numberOfChannels
{
    /**
     Update the audio plot using the float array provided by the microphone:
       buffer[0] = left channel
       buffer[1] = right channel
     Note: Audio updates happen asynchronously so we need to make sure
         sure to update the plot on the main thread
     */
    __weak typeof (self) weakSelf = self;
    dispatch_async(dispatch_get_main_queue(), ^{
        [weakSelf.audioPlot updateBuffer:buffer[0] withBufferSize:bufferSize];
    });
}

// Programmatically create an audio plot
EZAudioPlotGL *audioPlotGL = [[EZAudioPlotGL alloc] initWithFrame:self.view.frame];
[self.view addSubview:audioPlotGL];

// Background color (use UIColor for iOS)
audioPlotGL.backgroundColor = [NSColor colorWithCalibratedRed:0.816
                                                        green:0.349
                                                         blue:0.255
                                                        alpha:1];
// Waveform color (use UIColor for iOS)
audioPlotGL.color = [NSColor colorWithCalibratedRed:1.000
                                              green:1.000
                                               blue:1.000
                                              alpha:1];
// Plot type
audioPlotGL.plotType = EZPlotTypeBuffer;
// Fill
audioPlotGL.shouldFill = YES;
// Mirror
audioPlotGL.shouldMirror = YES;

// The microphone component provides audio data to its delegate as an array of float buffer arrays.
- (void)   microphone:(EZMicrophone *)microphone
     hasAudioReceived:(float **)buffer
       withBufferSize:(UInt32)bufferSize
 withNumberOfChannels:(UInt32)numberOfChannels
{
    /**
     Update the audio plot using the float array provided by the microphone:
       buffer[0] = left channel
       buffer[1] = right channel
     Note: Audio updates happen asynchronously so we need to make sure
         sure to update the plot on the main thread
     */
    __weak typeof (self) weakSelf = self;
    dispatch_async(dispatch_get_main_queue(), ^{
        [weakSelf.audioPlotGL updateBuffer:buffer[0] withBufferSize:bufferSize];
    });
}