Signal analyzer: Fourier transformation of the recorded audio signal. More...

#include <signalanalyzer.h>

Inheritance diagram for SignalAnalyzer:

Collaboration diagram for SignalAnalyzer:

Public Member Functions
	SignalAnalyzer (AudioRecorderAdapter *recorder)
	Constructor of the SignalAnalyzer. More...

	~SignalAnalyzer ()

void	init ()
	Initializes the SignalAnalyzer and its components. More...

void	exit ()

virtual void	stop () override
	Stop the thread. More...

Public Member Functions inherited from SimpleThreadHandler
	SimpleThreadHandler ()
	Constructor. More...

virtual	~SimpleThreadHandler ()
	virtual destructor calls stop More...

virtual void	start ()
	Start the thread. More...

Public Member Functions inherited from MessageListener
	MessageListener (bool defaultActivation=true)

virtual	~MessageListener ()

bool	isMessageListenerActive () const

void	activateMessageListener ()

void	deactivateMessageListener ()

Static Public Attributes
static const int	AUDIO_BUFFER_SIZE_IN_SECONDS = 60
	Maximal size of the audio buffer. More...

static const int	MINIMAL_FFT_INTERVAL_IN_MILLISECONDS = 150
	Time interval for at most one FFT. More...

Private Types
enum	AnalyzerRole { ROLE_IDLE, ROLE_RECORD_KEYSTROKE, ROLE_ROLLING_FFT }

Private Member Functions
void	handleMessage (MessagePtr m) overridefinal
	Message receiver and dispatcer. More...

void	changeRole (AnalyzerRole role)
	Changes the current role of the signal analyzer. More...

void	updateDataBufferSize ()

void	workerFunction () overridefinal
	Thread function of the SignalAnalyzer. More...

void	recordSignal ()
	Record signal and perform FFT's in regular intervals. More...

void	analyzeSignal ()
	Analyze the final signal (in recording mode only) More...

void	recordPostprocessing ()
	Process the singal after recording has finsihed. More...

void	updateOverpull ()

double	signalPreprocessing (FFTWVector &signal)
	Function for signal preprocessing. More...

void	signalProcessing (FFTWVector &signal, int samplingrate)
	Function for signal processing. More...

bool	detectClipping (FFTWVector signal)
	Clipping detector. More...

void	PerformFFT (FFTWVector &signal, FFTWVector &powerspec)
	Perform fast Fourier transform. More...

void	createPolygon (const FFTWVector &powerspec, FFTPolygon &poly) const
	Create a polygon for drawing. More...

int	identifySelectedKey ()
	identify final key More...

virtual void	keyRecognized (int keyIndex, double frequency) overridefinal

void	WriteSignal (std::string filename, const FFTWVector &signal)

void	WriteFFT (std::string filename, const FFTWVector &fft)

Private Attributes
const Piano *	mPiano
	Pointer to the piano. More...

CircularBuffer< FFTWType >	mDataBuffer
	Local audio buffer. More...

std::mutex	mDataBufferMutex
	The data buffer might change its size during recording and key selection, lock it. More...

AudioRecorderAdapter *	mAudioRecorder
	Pointer to the audio recorder. More...

std::atomic< bool >	mRecording
	Flag indicating ongoing recording. More...

FFTWVector	mProprocessedSignal
	the current signal (after preprocessing) More...

FFTDataPointer	mPowerspectrum
	the last recorded powerspectrum More...

FFT_Implementation	mFFT
	Instance of the Fourier transformer. More...

FFTAnalyzer	mFFTAnalyser
	Instance of the FFT analyzer. More...

KeyRecognizer	mKeyRecognizer
	Instance of the Key recognizer. More...

OverpullEstimator	mOverpull
	Instance of the overpull estimator. More...

std::map< int, int >	mKeyCountStatistics
	Count which key is selected how often. More...

std::mutex	mKeyCountStatisticsMutex
	Corresponding mutex. More...

int	mSelectedKey
	The selected key by the user. More...

bool	mKeyForced
	Is the key selection forced. More...

std::atomic< AnalyzerRole >	mAnalyzerRole

Additional Inherited Members
Static Public Member Functions inherited from SimpleThreadHandler
static void	setThreadName (std::string s)
	Specify the name of the thread. More...

Protected Member Functions inherited from SimpleThreadHandler
virtual void	exceptionCaught (const EptException &e)
	EPT exception handling. More...

void	setCancelThread (bool b)
	Cancel-flag setter method, thread-safe. More...

bool	cancelThread () const
	Cancel-flag getter method, thread-safe. More...

void	msleep (double milliseconds)
	Sleep function for staying idle. More...

bool	isThreadRunning () const
	Flag to check if the thread is running. More...

Detailed Description

Signal analyzer: Fourier transformation of the recorded audio signal.

The signal analyzer receives the audio signal from the audio device. It contains another cyclic buffer which can hold audio data of about a minute. After detecting a keystroke, the AudioRecorderAdapter sends a message to start the SignalAnalyzer. During recording the SignalAnalyzer continuously performs Fourer transformations on the current signal. When the recording is finished, a final Fourier transformation is carried out. Various steps for signal preprocessing are included as well.

Definition at line 54 of file signalanalyzer.h.

Member Enumeration Documentation

enum SignalAnalyzer::AnalyzerRole

private

Enumerator
ROLE_IDLE	Idle.
ROLE_RECORD_KEYSTROKE	Recording a key stroke in recording operation mode.
ROLE_ROLLING_FFT	Performing rolling ffts in tuning mode.

Definition at line 65 of file signalanalyzer.h.

Constructor & Destructor Documentation

SignalAnalyzer::SignalAnalyzer ( AudioRecorderAdapter * recorder )

Constructor of the SignalAnalyzer.

Parameters

recorder : pointer to the implementation of the AudioRecorder

Definition at line 56 of file signalanalyzer.cpp.

SignalAnalyzer::~SignalAnalyzer ( )

inline

Definition at line 74 of file signalanalyzer.h.

Member Function Documentation

void SignalAnalyzer::analyzeSignal ( )

private

Analyze the final signal (in recording mode only)

Definition at line 341 of file signalanalyzer.cpp.

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void SignalAnalyzer::changeRole ( AnalyzerRole role )

private

Changes the current role of the signal analyzer.

This will stop all current actions first, and then adjust all parameters.

Definition at line 164 of file signalanalyzer.cpp.

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void SignalAnalyzer::createPolygon	(	const FFTWVector &	powerspec,
		FFTPolygon &	poly
	)		const

private

Create a polygon for drawing.

Parameters

powerspec	: reference to the power spectrum rendered by the FFT
poly	: reference to a map relating frequency and power (f->I).

Definition at line 685 of file signalanalyzer.cpp.

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bool SignalAnalyzer::detectClipping ( FFTWVector signal )

private

Clipping detector.

The signature of an overdriven signal is the clipping at certain maximal amplitudes. This is recognized here by counting the PCM values which are close to the maximal amplitude.

Similarly, some audio devices transmit intermittent data with random strings of zeros in between. This is detected by counting the number of vanishing PCM amplitudes.

Parameters

signal : vector holding the incoming audio signal

Returns: true if a problem has been detected, false if not

Definition at line 647 of file signalanalyzer.cpp.

void SignalAnalyzer::exit ( )

inline

Definition at line 77 of file signalanalyzer.h.

void SignalAnalyzer::handleMessage ( MessagePtr m )

finaloverrideprivatevirtual

Message receiver and dispatcer.

Parameters

m	: pointer to the received message

Implements MessageListener.

Definition at line 101 of file signalanalyzer.cpp.

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int SignalAnalyzer::identifySelectedKey ( )

private

identify final key

Identify the selected key.

The KeyRecognizer has continuously sent messages containing the number of the recognized key. These results have beeen registered by the in the histogram mKeyCount. This function declares a key as selected if more it was recognized for more than 50%.

Returns: Number of the key, -1 if none.

Definition at line 733 of file signalanalyzer.cpp.

void SignalAnalyzer::init ( )

Initializes the SignalAnalyzer and its components.

This function will initialize the KeyRecognizer that could take a while if the fft transform shall be optimized.

Definition at line 75 of file signalanalyzer.cpp.

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void SignalAnalyzer::keyRecognized	(	int	keyIndex,
		double	frequency
	)

finaloverrideprivatevirtual

Implements KeyRecognizerCallback.

Definition at line 750 of file signalanalyzer.cpp.

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void SignalAnalyzer::PerformFFT	(	FFTWVector &	signal,
		FFTWVector &	powerspectrum
	)

private

Perform fast Fourier transform.

This function transforms the real-valued signal of length N to a complex-valued Fourier transform of length N/2+1. Then it computes the power spectrum by computing the intensities (squares).

Parameters

signal	: reference to the vector of the incoming audio signal.
powerspectrum	: reference to the resulting powerspectrum.

Definition at line 619 of file signalanalyzer.cpp.

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void SignalAnalyzer::recordPostprocessing ( )

private

Process the singal after recording has finsihed.

In ROLE_RECORD_KEYSTROKE this will perform the actual analysis of the complete recorded signal. in ROLE_ROLLING_FFT this wont do anything.

Definition at line 416 of file signalanalyzer.cpp.

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void SignalAnalyzer::recordSignal ( )

private

Record signal and perform FFT's in regular intervals.

Definition at line 249 of file signalanalyzer.cpp.

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double SignalAnalyzer::signalPreprocessing ( FFTWVector & signal )

private

Function for signal preprocessing.

This function performs several steps to make the input signal ready for the Fourier transformation:

Cut subsonic waves
Modify the input signal in such a way that the volume is constant.
Fade in and out at the end of the buffer
Parameters

signal : real-valued vector with PCM data

Returns
Average decay time of the envelope, serving as a rough estimate whether a very low or a very high key has been hit.

Definition at line 486 of file signalanalyzer.cpp.

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void SignalAnalyzer::signalProcessing	(	FFTWVector &	signal,
		int	samplingrate
	)

private

Function for signal processing.

Create an FFT vector and perform the FFT.

On ROLE_ROLLING_FFT this will permanentely send FinalFFT On ROLE_RECORD_KEYSTRO this will peramaentely send NewFFT

Definition at line 569 of file signalanalyzer.cpp.

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void SignalAnalyzer::stop ( )

overridevirtual

Stop the thread.

Mark the thread for cancellation. This function waits for termination of the thread, i.e. it blocks until the thread has been shut down. This waiting time will depend on the implementation of the workerFunction.

Reimplemented from SimpleThreadHandler.

Definition at line 87 of file signalanalyzer.cpp.

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void SignalAnalyzer::updateDataBufferSize ( )

private

Definition at line 175 of file signalanalyzer.cpp.

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void SignalAnalyzer::updateOverpull ( )

private

Definition at line 447 of file signalanalyzer.cpp.

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void SignalAnalyzer::workerFunction ( )

finaloverrideprivatevirtual

Thread function of the SignalAnalyzer.

This is the main function of the SignalAnalyzer which is running in an independent thread. It is started by a message from the AudioRecorder when the recording begins. By calling the AudioRecorder via the readAll function the actual data is read and processed.

Implements SimpleThreadHandler.

Definition at line 218 of file signalanalyzer.cpp.

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void SignalAnalyzer::WriteFFT	(	std::string	filename,
		const FFTWVector &	fft
	)

private

Definition at line 777 of file signalanalyzer.cpp.

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void SignalAnalyzer::WriteSignal	(	std::string	filename,
		const FFTWVector &	signal
	)

private

Definition at line 791 of file signalanalyzer.cpp.

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Member Data Documentation

const int SignalAnalyzer::AUDIO_BUFFER_SIZE_IN_SECONDS = 60

static

Maximal size of the audio buffer.

Definition at line 60 of file signalanalyzer.h.

std::atomic<AnalyzerRole> SignalAnalyzer::mAnalyzerRole

private

Definition at line 128 of file signalanalyzer.h.

AudioRecorderAdapter* SignalAnalyzer::mAudioRecorder

private

Pointer to the audio recorder.

Definition at line 113 of file signalanalyzer.h.

CircularBuffer<FFTWType> SignalAnalyzer::mDataBuffer

private

Local audio buffer.

Definition at line 111 of file signalanalyzer.h.

std::mutex SignalAnalyzer::mDataBufferMutex

private

The data buffer might change its size during recording and key selection, lock it.

Definition at line 112 of file signalanalyzer.h.

FFT_Implementation SignalAnalyzer::mFFT

private

Instance of the Fourier transformer.

Definition at line 118 of file signalanalyzer.h.

FFTAnalyzer SignalAnalyzer::mFFTAnalyser

private

Instance of the FFT analyzer.

Definition at line 120 of file signalanalyzer.h.

const int SignalAnalyzer::MINIMAL_FFT_INTERVAL_IN_MILLISECONDS = 150

static

Time interval for at most one FFT.

Definition at line 61 of file signalanalyzer.h.

std::map<int,int> SignalAnalyzer::mKeyCountStatistics

private

Count which key is selected how often.

Definition at line 123 of file signalanalyzer.h.

std::mutex SignalAnalyzer::mKeyCountStatisticsMutex

private

Corresponding mutex.

Definition at line 124 of file signalanalyzer.h.

bool SignalAnalyzer::mKeyForced

private

Is the key selection forced.

Definition at line 126 of file signalanalyzer.h.

KeyRecognizer SignalAnalyzer::mKeyRecognizer

private

Instance of the Key recognizer.

Definition at line 121 of file signalanalyzer.h.

OverpullEstimator SignalAnalyzer::mOverpull

private

Instance of the overpull estimator.

Definition at line 122 of file signalanalyzer.h.

const Piano* SignalAnalyzer::mPiano

private

Pointer to the piano.

Definition at line 110 of file signalanalyzer.h.

FFTDataPointer SignalAnalyzer::mPowerspectrum

private

the last recorded powerspectrum

Definition at line 116 of file signalanalyzer.h.

FFTWVector SignalAnalyzer::mProprocessedSignal

private

the current signal (after preprocessing)

Definition at line 115 of file signalanalyzer.h.

std::atomic<bool> SignalAnalyzer::mRecording

private

Flag indicating ongoing recording.

Definition at line 114 of file signalanalyzer.h.

int SignalAnalyzer::mSelectedKey

private

The selected key by the user.

Definition at line 125 of file signalanalyzer.h.

The documentation for this class was generated from the following files:

/home/hinrichsen/Dokumente/Aktuell/EPT/Entropy-Piano-Tuner/core/analyzers/signalanalyzer.h
/home/hinrichsen/Dokumente/Aktuell/EPT/Entropy-Piano-Tuner/core/analyzers/signalanalyzer.cpp

Public Member Functions

Static Public Attributes

Private Types

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation