PitchDetector Class Reference

Generates a PitchEvent whenever a notable frequency is detected using FFT. More...

#include <PitchDetector.h>

Inheritance diagram for PitchDetector:

[legend]

Detailed Description

Generates a PitchEvent whenever a notable frequency is detected using FFT.

Definition at line 10 of file PitchDetector.h.

List of all members.

Classes
struct	PitchInfo
	stores info about the pitch currently being detected More...
Public Member Functions
	PitchDetector ()
	constructor
	~PitchDetector ()
	destructor, asserts that pitch_info and pitch_bin have been deleted by doStop()
virtual void	doStart ()
	allocates and sets up pitch_info and pitch_bin, relies on EventGeneratorBase to manage event subscriptions
virtual void	doStop ()
	deletes pitch_info and pitch_bin
virtual void	doEvent ()
	Delegate function for event processing, the event itself is pointed to (only for the duration of the doEvent() call!) by event.
virtual std::string	getDescription () const
	Gives a short description of what this particular instantiation does (in case a more specific description is needed on an individual basis).
Static Public Member Functions
static std::string	getClassDescription ()
	Gives a short description of what this class of behaviors does... you should override this (but don't have to).
Static Public Attributes
static const unsigned int	fft_frames = 4
	number frames to use for fft
static const unsigned int	num_pitches = 60
	5 octaves, 12 pitches per octave
static const float	base_pitch = 110.0f
	two octaves below tuning A (440)
static const float	half_step = 1.0594630943593f
	twelfth root of two: $\sqrt[12]{2}$
static const float	sqrt_2_pi = 2.506628274631f
	set to $\sqrt{2\pi}$
Protected Member Functions
float	confidence (unsigned int p, float strength)
	returns a confidence estimate of a pitch in bin p... (actual computation used is not obvious, you'll have to stare at the code /ejt)
Static Protected Member Functions
static bool	is_pitch (float conf)
	returns true if the confidence is above a threshold obtained from configuration
static float	gaussian_pdf (float mu, float sigma, float x)
	returns the value at x of a gaussian with the parameters mu and sigma
static const char *	pitch_name (unsigned int i)
	returns a string representing the musical note of a given frequency
static void	hamming (NEWMAT::ColumnVector &v)
	unknown calculation, does some kind of rescaling of v (/ejt)
Protected Attributes
NEWMAT::ColumnVector	left
	the waveform of the left channel
NEWMAT::ColumnVector	right
	the waveform of the right channel
NEWMAT::ColumnVector	iml
	imaginary outputs of the FFT for left channel
NEWMAT::ColumnVector	imr
	imaginary outputs of the FFT for right channel
NEWMAT::ColumnVector	rel
	real outputs of the FFT for the left channel
NEWMAT::ColumnVector	rer
	real outputs of the FFT for the right channel
NEWMAT::ColumnVector	pol
	absolute value (magnitude) of results of FFT for left channel
NEWMAT::ColumnVector	por
	absolute value (magnitude) of results of FFT for right channel
NEWMAT::ColumnVector	po
	average of pol and por for each bin
unsigned int	frame_sz
	number of samples given by system for each frame (assumed that once started, this won't change)
unsigned int	win_sz
	number of samples to be recorded before running FFT (frame_sz * fft_frames)
unsigned int	rate
	sampling frequence (Hz)
unsigned int	cur_frame
	the current frame index to be filled in next, up to fft_frames, when the FFT is run
unsigned int	local_maxes
	number of individual peaks
PitchInfo *	pitch_info
	an array of PitchInfos, one for each of num_pitches, allocated for scope spanning doStart()/doStop()
float *	pitch_bin
	array, holds current amplitude for each num_pitches (mono)
bool	have_fft
	set to true after FFT has been computed, differentiates first filling of buffers from subsequent rewrites
Private Member Functions
	PitchDetector (const PitchDetector &)
	don't call (copy constructor)
PitchDetector &	operator= (const PitchDetector &)
	don't call (assignment operator)

Constructor & Destructor Documentation

PitchDetector::PitchDetector ( )

constructor

Definition at line 19 of file PitchDetector.h.

PitchDetector::~PitchDetector ( )

destructor, asserts that pitch_info and pitch_bin have been deleted by doStop()

Definition at line 25 of file PitchDetector.cc.

PitchDetector::PitchDetector ( const PitchDetector & ) [private]

don't call (copy constructor)

Member Function Documentation

float PitchDetector::confidence	(	unsigned int	p,
		float	strength
	)			`[protected]`

returns a confidence estimate of a pitch in bin p... (actual computation used is not obvious, you'll have to stare at the code /ejt)

Definition at line 79 of file PitchDetector.h.

Referenced by doEvent().

void PitchDetector::doEvent ( ) [virtual]

Delegate function for event processing, the event itself is pointed to (only for the duration of the doEvent() call!) by event.

Default implementation watches for 'private' text message events (those forwarded by a BehaviorSwitchControl from ControllerGUI input) and will publically rebroadcast them. The idea is that your own processEvent gets first dibs, but if the behavior doesn't handle the text message, it will be handed off for others.

Reimplemented from BehaviorBase.

Definition at line 67 of file PitchDetector.cc.

void PitchDetector::doStart ( ) [virtual]

allocates and sets up pitch_info and pitch_bin, relies on EventGeneratorBase to manage event subscriptions

Reimplemented from EventGeneratorBase.

Definition at line 30 of file PitchDetector.cc.

void PitchDetector::doStop ( ) [virtual]

deletes pitch_info and pitch_bin

Reimplemented from EventGeneratorBase.

Definition at line 54 of file PitchDetector.cc.

static float PitchDetector::gaussian_pdf	(	float	mu,
		float	sigma,
		float	x
	)			`[static, protected]`

returns the value at x of a gaussian with the parameters mu and sigma

Definition at line 95 of file PitchDetector.h.

Referenced by doEvent().

static std::string PitchDetector::getClassDescription ( ) [static]

Gives a short description of what this class of behaviors does... you should override this (but don't have to).

If you do override this, also consider overriding getDescription() to return it

Reimplemented from BehaviorBase.

Definition at line 34 of file PitchDetector.h.

Referenced by getDescription().

virtual std::string PitchDetector::getDescription ( ) const [virtual]

Gives a short description of what this particular instantiation does (in case a more specific description is needed on an individual basis).

By default simply returns getName(), because any calls from a BehaviorBase function to getClassDescription() are going to call BehaviorBase::getClassDescription(), not ~YourSubClass~getClassDescription(), because static functions can't be virtual in C++ (doh!)

This means that getDescription called on a pointer to a BehaviorBase of unknown subtype would always return an empty string, which is pretty useless. So instead we return the name in this situation. If you want getDescription to return getClassDescription, you'll have to override it in your subclass to do so.

Reimplemented from BehaviorBase.

Definition at line 35 of file PitchDetector.h.

static void PitchDetector::hamming ( NEWMAT::ColumnVector & v ) [static, protected]

unknown calculation, does some kind of rescaling of v (/ejt)

Definition at line 110 of file PitchDetector.h.

Referenced by doEvent().

bool PitchDetector::is_pitch ( float conf ) [static, protected]

returns true if the confidence is above a threshold obtained from configuration

Definition at line 209 of file PitchDetector.cc.

Referenced by doEvent().

PitchDetector& PitchDetector::operator= ( const PitchDetector & ) [private]

don't call (assignment operator)