Nsound::FFTChunk Class Reference

Results of performing an FFT are stored in this class. More...

#include <Nsound/FFTChunk.h>

Public Member Functions
	FFTChunk (uint32 size=32, uint32 sample_rate=44100, uint32 original_size=0)
	FFTChunk (const FFTChunk &copy)
	~FFTChunk ()
Buffer	getFrequencyAxis () const
Buffer	getReal () const
Buffer	getImaginary () const
Buffer	getMagnitude () const
uint32	getOriginalSize () const
Buffer	getPhase () const
boolean	isPolar () const
FFTChunk &	operator= (const FFTChunk &rhs)
void	plot (const std::string &title="", boolean dB=true, boolean show_phase=false) const
void	setCartesian (const Buffer &real, const Buffer &imaginary)
	Sets up an FFTChunk to use the provided real & imaginary. More...
void	setPolar (const Buffer &magnitude, const Buffer &phase)
	Sets up an FFTChunk to use the provided magnitude & phase. More...
void	toPolar ()
	convertes the real & imaginary unit to plor form: magnitude & phase More...
void	toCartesian ()
	convertes the magnitude & phase to cartesian form: real & imaginary More...
uint32	getSampleRate () const

Public Attributes
Buffer *	real_
Buffer *	imag_

Protected Attributes
uint32	sample_rate_
uint32	original_size_
boolean	is_polar_

Detailed Description

Results of performing an FFT are stored in this class.

Definition at line 49 of file FFTChunk.h.

Constructor & Destructor Documentation

FFTChunk::FFTChunk	(	uint32	size = 32,
		uint32	sample_rate = 44100,
		uint32	original_size = 0
	)

Definition at line 46 of file FFTChunk.cc.

References imag_, original_size_, and real_.

    :
    real_(NULL),
    imag_(NULL),
    sample_rate_(sample_rate),
    original_size_(original_size),
    is_polar_(false)
{
    real_ = new Buffer(size);
    imag_  = new Buffer(size);

    if(original_size_ == 0)
    {
        original_size_ = size;
    }
}

FFTChunk::FFTChunk

(

const FFTChunk &

copy

)

Definition at line 65 of file FFTChunk.cc.

    :
    real_(new Buffer(copy.real_->getLength())),
    imag_(new Buffer(copy.real_->getLength())),
    sample_rate_(copy.sample_rate_),
    original_size_(copy.original_size_),
    is_polar_(copy.is_polar_)
{
    // Call operator =
    *this = copy;
}

FFTChunk::~FFTChunk

(

)

Definition at line 79 of file FFTChunk.cc.

References imag_, and real_.

{
    delete real_;
    delete imag_;
}

Member Function Documentation

Buffer FFTChunk::getFrequencyAxis

(

)

const

Definition at line 109 of file FFTChunk.cc.

References Nsound::Generator::drawLine(), Nsound::Buffer::getLength(), real_, and sample_rate_.

Referenced by plot().

{
    // Create the x axis based on Hz.

    uint32 chunk_size = real_->getLength();

    uint32 n_samples = chunk_size / 2 + 1;

    float64 x_step = static_cast<float64>(sample_rate_)
                   / static_cast<float64>(chunk_size);

    Generator gen(1);

    return gen.drawLine(n_samples, 0.0, x_step * n_samples);
}

Buffer FFTChunk::getReal

(

)

const

Definition at line 127 of file FFTChunk.cc.

References Nsound::Buffer::getLength(), imag_, is_polar_, real_, and Nsound::Buffer::subbuffer().

Referenced by FFTransform_UnitTest().

{
    if(!is_polar_)
    {
        return real_->subbuffer(0, real_->getLength() / 2);
    }

    uint32 n_samples = real_->getLength();

    Buffer out(n_samples / 2);

    for(uint32 i = 0; i < n_samples / 2; ++i)
    {
        //      mag * cos(phase)
        out << (*real_)[i] * std::cos((*imag_)[i]);
    }

    return out;
}

Buffer FFTChunk::getImaginary

(

)

const

Definition at line 87 of file FFTChunk.cc.

References Nsound::Buffer::getLength(), imag_, is_polar_, real_, and Nsound::Buffer::subbuffer().

Referenced by FFTransform_UnitTest().

{
    if(!is_polar_)
    {
        return imag_->subbuffer(0, imag_->getLength() / 2);
    }

    Buffer out;

    uint32 n_samples = real_->getLength();

    for(uint32 i = 0; i < n_samples / 2; ++i)
    {
        //      mag * sin(phase)
        out << (*real_)[i] * std::sin((*imag_)[i]);
    }

    return out;
}

Buffer FFTChunk::getMagnitude

(

)

const

Definition at line 149 of file FFTChunk.cc.

References Nsound::Buffer::getLength(), is_polar_, real_, and Nsound::Buffer::subbuffer().

Referenced by plot().

{
    uint32 n_samples = real_->getLength();

    if(is_polar_)
    {
        return real_->subbuffer(0, n_samples / 2 + 1);
    }

    float64 x = 0.0;
    float64 y = 0.0;

    Buffer out(n_samples / 2 + 1);

    for(uint32 i = 0; i < n_samples / 2 + 1; ++i)
    {
        x = (*real_)[i];
        y = (*imag_)[i];
        out << std::sqrt(x*x + y*y);
    }

    return out;
}

uint32 Nsound::FFTChunk::getOriginalSize ( ) const

inline

Definition at line 72 of file FFTChunk.h.

References original_size_.

{ return original_size_; };

Buffer FFTChunk::getPhase

(

)

const

Definition at line 175 of file FFTChunk.cc.

References Nsound::Buffer::getLength(), imag_, is_polar_, M_PI, real_, and Nsound::Buffer::subbuffer().

Referenced by plot().

{
    if(is_polar_)
    {
        return imag_->subbuffer(0, imag_->getLength() / 2 + 1);
    }

    uint32 n_samples = real_->getLength();

    float64 r = 0.0;
    float64 i = 0.0;
    float64 phase = 0.0;

    Buffer out(n_samples / 2 + 1);

    for(uint32 j = 0; j < n_samples / 2 + 1; ++j)
    {
        r = (*real_)[j];
        i = (*imag_)[j];

        //if(r == 0.0) r = 1e-20;

        phase = std::atan(i/r);

        if(r < 0.0)
        {
            if(i <  0.0) phase -= M_PI;
            else phase += M_PI;
        }

        out << phase;
    }

    return out;
}

boolean Nsound::FFTChunk::isPolar ( ) const

inline

Definition at line 78 of file FFTChunk.h.

References is_polar_.

Referenced by Nsound::FFTransform::ifft().

{ return is_polar_; };

FFTChunk & FFTChunk::operator=

(

const FFTChunk &

rhs

)

Definition at line 214 of file FFTChunk.cc.

References imag_, is_polar_, original_size_, real_, and sample_rate_.

{
    if(this == &rhs)
    {
        return *this;
    }

    *real_ = *rhs.real_;
    *imag_  = *rhs.imag_;
    sample_rate_ = rhs.sample_rate_;
    original_size_ = rhs.original_size_;
    is_polar_ = rhs.is_polar_;

    return *this;
}

void FFTChunk::plot	(	const std::string &	title = "",
		boolean	dB = true,
		boolean	show_phase = false
	)		const

Definition at line 232 of file FFTChunk.cc.

References Nsound::Buffer::dB(), Nsound::Plotter::figure(), getFrequencyAxis(), Nsound::Buffer::getLength(), getMagnitude(), getPhase(), Nsound::Plotter::plot(), real_, Nsound::Buffer::subbuffer(), Nsound::Plotter::subplot(), Nsound::Plotter::title(), Nsound::Plotter::xlabel(), and Nsound::Plotter::ylabel().

{
    //~    // Create the x axis based on Hz.
    //~
    //~    uint32 chunk_size = real_->getLength();

    uint32 n_samples = real_->getLength() / 2 + 1;

    //~
    //~    float64 x_step = (1.0 / (static_cast<float64>(chunk_size) / 2.0))
    //~                   * (static_cast<float64>(sample_rate_) / 2.0);
    //~
    //~    Buffer x;
    //~
    //~    float64 tx = 0.0;
    //~
    //~    for(uint32 i = 0; i < n_samples; ++i)
    //~    {
    //~        x << tx;
    //~        tx += x_step;
    //~    }

    Buffer x = getFrequencyAxis();

    // Calculate the magnitude for the signal:
    //
    // magnitude = sqrt(x*x + y*y);
    //
    Buffer magnitude = getMagnitude();

    Plotter pylab;

    pylab.figure();

    if(show_phase)
    {
        pylab.subplot(2, 1, 1);
    }

    if(title.length() <= 0)
    {
        pylab.title("Magnitude");
    }
    else
    {
        pylab.title(title);
    }

    if(dB)
    {
        magnitude.dB();
        pylab.ylabel("Magnitude dB");
    }
    else
    {
        pylab.ylabel("Magnitude");
    }

    pylab.plot(x,magnitude.subbuffer(0,n_samples));

    if(show_phase)
    {
        Buffer phase = getPhase().subbuffer(0,n_samples);

        pylab.subplot(2, 1, 2);
        pylab.title("Phase");
        pylab.plot(x,phase);
        pylab.ylabel("Phase Radians");
    }

    pylab.xlabel("Frequency Hz");
}

void FFTChunk::setCartesian	(	const Buffer &	real,
		const Buffer &	imaginary
	)

Sets up an FFTChunk to use the provided real & imaginary.

Definition at line 310 of file FFTChunk.cc.

References imag_, is_polar_, and real_.

Referenced by FFTransform_UnitTest().

{
    Buffer zeros = 0.0 * real;

    *real_ = 2.0 * real;
    *real_ << zeros;

    *imag_ = 2.0 * img;
    *imag_ << zeros;

    is_polar_ = false;
}

void FFTChunk::setPolar	(	const Buffer &	magnitude,
		const Buffer &	phase
	)

Sets up an FFTChunk to use the provided magnitude & phase.

Definition at line 325 of file FFTChunk.cc.

References imag_, is_polar_, and real_.

Referenced by FFTransform_UnitTest().

{
    Buffer zeros = 0.0 * mag;

    *real_ = 2.0 * mag;
    *real_ << zeros;

    *imag_ = 2.0 * phase;
    *imag_ << zeros;

    is_polar_ = true;
}

void FFTChunk::toPolar

(

)

convertes the real & imaginary unit to plor form: magnitude & phase

Definition at line 362 of file FFTChunk.cc.

References Nsound::Buffer::getLength(), is_polar_, M_PI, and real_.

{
    if(is_polar_) return;

    uint32 n_samples = real_->getLength();

    float64 r = 0.0;
    float64 i = 0.0;

    for(uint32 j = 0; j < n_samples; ++j)
    {
        r = (*real_)[j];
        i = (*imag_)[j];

        (*real_)[j] = std::sqrt(r*r + i*i);
        (*imag_)[j]  = std::atan(i / r);

        if(i <  0.0 && r < 0.0) (*imag_)[j] -= M_PI;
        if(i >= 0.0 && r < 0.0) (*imag_)[j] += M_PI;
    }

    is_polar_ = true;
}

void FFTChunk::toCartesian

(

)

convertes the magnitude & phase to cartesian form: real & imaginary

Definition at line 340 of file FFTChunk.cc.

References Nsound::Buffer::getLength(), is_polar_, and real_.

Referenced by Nsound::FFTransform::ifft().

{
    if(!is_polar_) return;

    uint32 n_samples = real_->getLength();

    float64 m = 0.0;
    float64 p = 0.0;

    for(uint32 j = 0; j < n_samples; ++j)
    {
        m = (*real_)[j];
        p = (*imag_)[j];
        (*real_)[j] = m * std::cos(p);
        (*imag_)[j]  = m * std::sin(p);
    }

    is_polar_ = false;
}

uint32 Nsound::FFTChunk::getSampleRate ( ) const

inline

Definition at line 108 of file FFTChunk.h.

{return sample_rate_;};

Member Data Documentation

Buffer* Nsound::FFTChunk::real_

Definition at line 105 of file FFTChunk.h.

Referenced by FFTChunk(), getFrequencyAxis(), getImaginary(), getMagnitude(), getPhase(), getReal(), Nsound::FFTransform::ifft(), operator=(), plot(), setCartesian(), setPolar(), toCartesian(), toPolar(), and ~FFTChunk().

Buffer* Nsound::FFTChunk::imag_

Definition at line 106 of file FFTChunk.h.

Referenced by FFTChunk(), getImaginary(), getPhase(), getReal(), Nsound::FFTransform::ifft(), operator=(), setCartesian(), setPolar(), and ~FFTChunk().

uint32 Nsound::FFTChunk::sample_rate_

protected

Definition at line 108 of file FFTChunk.h.

Referenced by getFrequencyAxis(), and operator=().

uint32 Nsound::FFTChunk::original_size_

protected

Definition at line 113 of file FFTChunk.h.

Referenced by FFTChunk(), getOriginalSize(), and operator=().

boolean Nsound::FFTChunk::is_polar_

protected

Definition at line 114 of file FFTChunk.h.

Referenced by getImaginary(), getMagnitude(), getPhase(), getReal(), isPolar(), operator=(), setCartesian(), setPolar(), toCartesian(), and toPolar().

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

• Nsound/FFTChunk.h
• Nsound/FFTChunk.cc