Nsound::FilterPhaser Class Reference

A class for filtering audio in the frequecy domain. More...

#include <Nsound/FilterPhaser.h>

Inheritance diagram for Nsound::FilterPhaser:

Public Member Functions
	FilterPhaser (const float64 &sample_rate, const uint32 n_stages, const float64 &frequency, const float64 &frequency_step_per_stage, const float64 &max_delay_in_seconds)
	FilterPhaser (const FilterPhaser &copy)
	~FilterPhaser ()
AudioStream	filter (const AudioStream &x)
Buffer	filter (const Buffer &x)
float64	filter (const float64 &x)
float64	filter (const float64 &x, const float64 &ignored)
FilterPhaser &	operator= (const FilterPhaser &rhs)
void	plot (boolean show_fc=false, boolean show_phase=false)
void	reset ()
void	setRealtime (bool flag)
AudioStream	filter (const AudioStream &x, const float64 &frequency)
AudioStream	filter (const AudioStream &x, const Buffer &frequencies)
Buffer	filter (const Buffer &x, const float64 &frequency)
Buffer	filter (const Buffer &x, const Buffer &frequencies)
Buffer	getFrequencyAxis (const uint32 n_fft=8192)
Buffer	getFrequencyResponse (const uint32 n_fft=8192)
Buffer	getImpulseResponse (const uint32 n_samples=8192)
virtual uint32	getKernelSize () const
Buffer	getPhaseResponse ()
float64	getSampleRate () const
void	plot (boolean show_phase=false)

Protected Attributes
uint32	n_stages_
float64	max_delay_
FilterAllPass **	filters_
std::vector< float64 >	frequencies_
Buffer *	waveform_
std::vector< float64 >	waveform_position_
float64	sample_rate_
float64	two_pi_over_sample_rate_
float64	sample_time_
uint32	kernel_size_
bool	is_realtime_

Detailed Description

A class for filtering audio in the frequecy domain.

Definition at line 49 of file FilterPhaser.h.

Constructor & Destructor Documentation

FilterPhaser::FilterPhaser	(	const float64 &	sample_rate,
		const uint32	n_stages,
		const float64 &	frequency,
		const float64 &	frequency_step_per_stage,
		const float64 &	max_delay_in_seconds
	)

Definition at line 47 of file FilterPhaser.cc.

References filters_, frequencies_, Nsound::Generator::generate(), M_ASSERT_VALUE, max_delay_, n_stages_, Nsound::Filter::sample_rate_, waveform_, and waveform_position_.

    :
    Filter(sample_rate),
    n_stages_(n_stages),
    max_delay_(max_delay_time_seconds),
    filters_(NULL),
    frequencies_(),
    waveform_(NULL),
    waveform_position_()
{
    M_ASSERT_VALUE(n_stages_, >, 0);
    M_ASSERT_VALUE(frequency, >, 0.0);
    M_ASSERT_VALUE(frequency_step_per_stage, >, 0.0);
    M_ASSERT_VALUE(max_delay_, >, 0.0);

    float64 f = frequency;

    if(f <= 0.0) f = 1.0;

    float64 fstep = frequency_step_per_stage;

    if(fstep <= 0.0) fstep = 1.0 / static_cast<float64>(n_stages_);

    if(max_delay_ <= 0.0) max_delay_ = 0.1;

    filters_= new FilterAllPass * [n_stages_];

    waveform_ = new Buffer(static_cast<uint32>(sample_rate_));

    Sine sin(sample_rate_);

    *waveform_ = (1.0 + sin.generate(1.0, 1.0)) / 2.0;

    for(uint32 i = 0; i < n_stages_; ++i)
    {
        filters_[i] = new FilterAllPass(sample_rate_, max_delay_, 0.5);
        waveform_position_.push_back(0.0);
        frequencies_.push_back(f + fstep * static_cast<float64>(i));
    }
}

FilterPhaser::FilterPhaser

(

const FilterPhaser &

copy

)

Definition at line 95 of file FilterPhaser.cc.

References filters_, max_delay_, n_stages_, Nsound::Filter::sample_rate_, waveform_, and waveform_position_.

    :
    Filter(copy.sample_rate_),
    n_stages_(copy.n_stages_),
    max_delay_(copy.max_delay_),
    filters_(NULL),
    frequencies_(),
    waveform_(NULL),
    waveform_position_(copy.waveform_position_)
{
    filters_= new FilterAllPass * [n_stages_];

    waveform_ = new Buffer(static_cast<uint32>(sample_rate_));

    for(uint32 i = 0; i < n_stages_; ++i)
    {
        filters_[i] = new FilterAllPass(sample_rate_, max_delay_, 0.5);
        waveform_position_.push_back(0.0);
    }

    *this = copy;
}

FilterPhaser::~FilterPhaser

(

)

Definition at line 120 of file FilterPhaser.cc.

References filters_, n_stages_, and waveform_.

{
    for(uint32 i = 0; i < n_stages_; ++i)
    {
        delete filters_[i];
    }

    delete [] filters_;

    delete waveform_;
}

Member Function Documentation

AudioStream FilterPhaser::filter

(

const AudioStream &

x

)

Definition at line 134 of file FilterPhaser.cc.

References Nsound::Filter::filter().

Referenced by filter().

{
    return Filter::filter(x);
}

Buffer FilterPhaser::filter

(

const Buffer &

x

)

Definition at line 141 of file FilterPhaser.cc.

References Nsound::Filter::filter().

{
    return Filter::filter(x);
}

float64 FilterPhaser::filter ( const float64 &  x )

virtual

Implements Nsound::Filter.

Definition at line 148 of file FilterPhaser.cc.

References Nsound::FilterAllPass::filter(), filters_, frequencies_, max_delay_, n_stages_, Nsound::Filter::sample_rate_, and waveform_position_.

{
    float64 y = 0.0;

    for(uint32 i = 0; i < n_stages_; ++i)
    {
        float64 pos = waveform_position_[i]
                    + frequencies_[i];

        if(pos >= sample_rate_) pos -= sample_rate_;

        waveform_position_[i] = pos;

        float64 f = (*waveform_)[static_cast<uint32>(pos)];

        y += filters_[i]->filter(x, f * max_delay_);
    }

    y /= static_cast<float64>(n_stages_);

    return (y+x) / 2.0;
}

float64 Nsound::FilterPhaser::filter ( const float64 &  x, const float64 &  ignored  )

inlinevirtual

Implements Nsound::Filter.

Definition at line 74 of file FilterPhaser.h.

References filter().

    { return filter(x); };

FilterPhaser & FilterPhaser::operator=

(

const FilterPhaser &

rhs

)

Definition at line 174 of file FilterPhaser.cc.

References filters_, frequencies_, max_delay_, n_stages_, Nsound::Filter::sample_rate_, waveform_, and waveform_position_.

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

    sample_rate_       = rhs.sample_rate_;
    max_delay_         = rhs.max_delay_;
    *waveform_         = *rhs.waveform_;
    frequencies_       = rhs.frequencies_;
    waveform_position_ = rhs.waveform_position_;

    if(n_stages_ != rhs.n_stages_)
    {
        for(uint32 i = 0; i < n_stages_; ++i)
        {
            delete filters_[i];
        }

        delete [] filters_;

        n_stages_ = rhs.n_stages_;

        filters_ = new FilterAllPass * [n_stages_];

        for(uint32 i = 0; i < n_stages_; ++i)
        {
            filters_[i] = new FilterAllPass(sample_rate_, max_delay_, 0.5);
        }
    }

    for(uint32 i = 0; i < n_stages_; ++i)
    {
        *filters_[i] = *rhs.filters_[i];
    }

    return *this;
}

void FilterPhaser::plot	(	boolean	show_fc = false,
		boolean	show_phase = false
	)

Definition at line 216 of file FilterPhaser.cc.

References frequencies_, max_delay_, Nsound::Filter::plot(), Nsound::Filter::sample_rate_, Nsound::Plotter::subplot(), and Nsound::Plotter::title().

{
    char title[128];
    sprintf(title,
        "Phaser Frequency Response\n"
        "sr = %0.1f Hz, f = %0.1f Hz, delay = %0.3f ms",
        sample_rate_,
        frequencies_[0],
        max_delay_ * 1000.0);

    Filter::plot(show_phase);

    Plotter pylab;

    uint32 n_rows = 1;

    if(show_phase)
    {
        n_rows = 2;
    }

    if(show_fc)
    {
        pylab.subplot(n_rows, 1, 1);
    }

    pylab.title(title);
}

void FilterPhaser::reset ( )

virtual

Implements Nsound::Filter.

Definition at line 247 of file FilterPhaser.cc.

References filters_, n_stages_, Nsound::FilterAllPass::reset(), and waveform_position_.

{
    for(uint32 i = 0; i < n_stages_; ++i)
    {
        filters_[i]->reset();
        waveform_position_[i] = 0.0;
    }
}

void Nsound::Filter::setRealtime ( bool  flag )

inlineinherited

Definition at line 57 of file Filter.h.

References Nsound::Filter::is_realtime_.

{is_realtime_ = flag;}

AudioStream Filter::filter ( const AudioStream &  x, const float64 &  frequency  )

inherited

Definition at line 76 of file Filter.cc.

References Nsound::Filter::filter(), Nsound::AudioStream::getNChannels(), Nsound::AudioStream::getSampleRate(), Nsound::Filter::is_realtime_, M_THROW, and Nsound::Filter::reset().

{
    if(!is_realtime_) reset();

    uint32 n_channels = x.getNChannels();

    if(is_realtime_ && n_channels > 1)
    {
        M_THROW("In real-time mode, a filter per audio channel must be used!");
    }

    AudioStream y(x.getSampleRate(), n_channels);

    for(uint32 channel = 0; channel < n_channels; ++channel)
    {
        y[channel] = filter(x[channel], frequency);
    }

    return y;
}

AudioStream Filter::filter ( const AudioStream &  x, const Buffer &  frequencies  )

inherited

Definition at line 99 of file Filter.cc.

References Nsound::Filter::filter(), Nsound::AudioStream::getNChannels(), Nsound::AudioStream::getSampleRate(), Nsound::Filter::is_realtime_, M_THROW, and Nsound::Filter::reset().

{
    if(!is_realtime_) reset();

    uint32 n_channels = x.getNChannels();

    if(is_realtime_ && n_channels > 1)
    {
        M_THROW("In real-time mode, a filter per audio channel must be used!");
    }

    AudioStream y(x.getSampleRate(), n_channels);

    for(uint32 channel = 0; channel < n_channels; ++channel)
    {
        y[channel] = filter(x[channel], frequency);
    }

    return y;
}

Buffer Filter::filter ( const Buffer &  x, const float64 &  frequency  )

inherited

Definition at line 140 of file Filter.cc.

References Nsound::Buffer::begin(), Nsound::Buffer::end(), Nsound::Filter::filter(), Nsound::Buffer::getLength(), Nsound::Filter::is_realtime_, and Nsound::Filter::reset().

{
    if(!is_realtime_) reset();

    Buffer::const_iterator itor = x.begin();
    Buffer::const_iterator end = x.end();

    Buffer y(x.getLength());

    while(itor != end)
    {
        y << filter(*itor, frequency);

        ++itor;
    }

    return y;
}

Buffer Filter::filter ( const Buffer &  x, const Buffer &  frequencies  )

inherited

Definition at line 161 of file Filter.cc.

References Nsound::Buffer::begin(), Nsound::Buffer::cbegin(), Nsound::Buffer::end(), Nsound::Filter::filter(), Nsound::Buffer::getLength(), Nsound::Filter::is_realtime_, and Nsound::Filter::reset().

{
    if(!is_realtime_) reset();

    Buffer::const_circular_iterator freq = frequencies.cbegin();

    Buffer::const_iterator itor = x.begin();
    Buffer::const_iterator end = x.end();

    Buffer y(x.getLength());

    while(itor != end)
    {
        y << filter(*itor, *freq);

        ++itor;
        ++freq;
    }

    return y;
}

Buffer Filter::getFrequencyAxis ( const uint32  n_fft = 8192 )

inherited

Definition at line 185 of file Filter.cc.

References Nsound::FFTransform::roundUp2(), and Nsound::Filter::sample_rate_.

Referenced by main(), Nsound::Filter::plot(), and Nsound::FilterIIR::savePlot().

{
    uint32 fft_chunk_size = FFTransform::roundUp2(
        static_cast<int32>(n_fft));

    uint32 n_samples = fft_chunk_size / 2 + 1;

    float64 f_step = (1.0 / (static_cast<float64>(fft_chunk_size) / 2.0))
                   * (sample_rate_ / 2.0);

    Buffer f_axis;

    float64 f = 0.0;

    for(uint32 i = 0; i < n_samples; ++i)
    {
        f_axis << f;
        f += f_step;
    }

    return f_axis;
};

Buffer Filter::getFrequencyResponse ( const uint32  n_fft = 8192 )

inherited

Definition at line 210 of file Filter.cc.

References Nsound::FFTransform::fft(), Nsound::Filter::getImpulseResponse(), and Nsound::Filter::sample_rate_.

Referenced by Nsound::FilterBandPassIIR::FilterBandPassIIR(), FilterLeastSquaresFIR_UnitTest(), Nsound::FilterIIR::getRMS(), main(), Nsound::Filter::plot(), and Nsound::FilterIIR::savePlot().

{
    FFTransform fft(sample_rate_);

//~    fft.setWindow(HANNING);

    FFTChunkVector vec;

    vec = fft.fft(getImpulseResponse(), n_fft);

    return vec[0].getMagnitude();
}

Buffer Filter::getImpulseResponse ( const uint32  n_samples = 8192 )

inherited

Definition at line 225 of file Filter.cc.

References Nsound::Filter::filter(), Nsound::Filter::is_realtime_, and Nsound::Filter::reset().

Referenced by Nsound::Filter::getFrequencyResponse(), Nsound::FilterHighPassFIR::getImpulseResponse(), Nsound::FilterLowPassFIR::getImpulseResponse(), Nsound::FilterLeastSquaresFIR::getImpulseResponse(), Nsound::FilterIIR::getImpulseResponse(), and Nsound::Filter::getPhaseResponse().

{
    if(!is_realtime_) reset();

    Buffer response(n_samples);

    response << filter(1.0);

    for(uint32 i = 1; i < n_samples; ++i)
    {
        response << filter(0.0);
    }

    if(!is_realtime_) reset();

    return response;
}

virtual uint32 Nsound::Filter::getKernelSize ( ) const

inlinevirtualinherited

Reimplemented in Nsound::FilterIIR, and Nsound::FilterTone.

Definition at line 96 of file Filter.h.

References Nsound::Filter::kernel_size_.

Referenced by Nsound::FilterBandPassIIR::FilterBandPassIIR(), Nsound::FilterBandPassFIR::plot(), Nsound::FilterBandPassIIR::plot(), and Nsound::FilterBandRejectIIR::plot().

{return kernel_size_;};

Buffer Filter::getPhaseResponse ( )

inherited

Definition at line 245 of file Filter.cc.

References Nsound::FFTransform::fft(), Nsound::Filter::getImpulseResponse(), Nsound::Buffer::getLength(), Nsound::Filter::sample_rate_, and Nsound::Buffer::subbuffer().

Referenced by Nsound::Filter::plot().

{
    uint32 n_samples = static_cast<uint32>(sample_rate_ * 2);

    FFTransform fft(n_samples);

    FFTChunkVector vec;

    vec = fft.fft(getImpulseResponse(), n_samples);

    Buffer phase = vec[0].getPhase();

    return phase.subbuffer(0, phase.getLength() / 2 + 1);
}

float64 Nsound::Filter::getSampleRate ( ) const

inlineinherited

Definition at line 102 of file Filter.h.

References Nsound::Filter::sample_rate_.

{ return sample_rate_; };

void Filter::plot ( boolean  show_phase = false )

inherited

Definition at line 262 of file Filter.cc.

References Nsound::Plotter::figure(), Nsound::Buffer::getdB(), Nsound::Filter::getFrequencyAxis(), Nsound::Filter::getFrequencyResponse(), Nsound::Buffer::getMax(), Nsound::Filter::getPhaseResponse(), Nsound::Plotter::plot(), Nsound::Plotter::subplot(), Nsound::Plotter::xlabel(), Nsound::Plotter::ylabel(), and Nsound::Plotter::ylim().

Referenced by main(), Nsound::FilterLowPassMoogVcf::plot(), plot(), Nsound::FilterTone::plot(), Nsound::FilterHighPassIIR::plot(), Nsound::FilterCombLowPassFeedback::plot(), Nsound::FilterLowPassIIR::plot(), Nsound::FilterLowPassFIR::plot(), Nsound::FilterHighPassFIR::plot(), Nsound::FilterAllPass::plot(), Nsound::FilterBandPassVocoder::plot(), Nsound::FilterBandPassFIR::plot(), Nsound::FilterLeastSquaresFIR::plot(), Nsound::FilterFlanger::plot(), Nsound::FilterBandRejectFIR::plot(), Nsound::FilterBandRejectIIR::plot(), Nsound::FilterBandPassIIR::plot(), and Nsound::FilterParametricEqualizer::plot().

{
    Buffer x = getFrequencyAxis();
    Buffer fr = getFrequencyResponse().getdB();

    Plotter pylab;

    pylab.figure();

    uint32 n_rows = 1;
    uint32 n_cols = 1;

    if(show_phase)
    {
        n_rows = 2;
    }

    pylab.subplot(n_rows, n_cols, 1);

    // Frequency response
    pylab.plot(x,fr, "blue");

    pylab.xlabel("Frequency (Hz)");
    pylab.ylabel("Frequency Response (dB)");

    // Phase response
    if(show_phase)
    {
        pylab.subplot(n_rows, n_cols, 2);

        Buffer pr = getPhaseResponse().getdB();

        pylab.plot(x,pr);

        pylab.xlabel("Frequency (Hz)");
        pylab.ylabel("Phase Response (dB)");
    }

    float64 ymax = fr.getMax();
    float64 height = ymax - -60.0;

    pylab.ylim(-60.0, ymax + 0.05 * height);
}

Member Data Documentation

uint32 Nsound::FilterPhaser::n_stages_

protected

Definition at line 88 of file FilterPhaser.h.

Referenced by filter(), FilterPhaser(), operator=(), reset(), and ~FilterPhaser().

float64 Nsound::FilterPhaser::max_delay_

protected

Definition at line 89 of file FilterPhaser.h.

Referenced by filter(), FilterPhaser(), operator=(), and plot().

FilterAllPass** Nsound::FilterPhaser::filters_

protected

Definition at line 90 of file FilterPhaser.h.

Referenced by filter(), FilterPhaser(), operator=(), reset(), and ~FilterPhaser().

std::vector<float64> Nsound::FilterPhaser::frequencies_

protected

Definition at line 91 of file FilterPhaser.h.

Referenced by filter(), FilterPhaser(), operator=(), and plot().

Buffer* Nsound::FilterPhaser::waveform_

protected

Definition at line 92 of file FilterPhaser.h.

Referenced by FilterPhaser(), operator=(), and ~FilterPhaser().

std::vector<float64> Nsound::FilterPhaser::waveform_position_

protected

Definition at line 93 of file FilterPhaser.h.

Referenced by filter(), FilterPhaser(), operator=(), and reset().

float64 Nsound::Filter::sample_rate_

protectedinherited

Definition at line 113 of file Filter.h.

Referenced by filter(), Nsound::FilterCombLowPassFeedback::filter(), Nsound::FilterDelay::filter(), Nsound::FilterAllPass::FilterAllPass(), Nsound::FilterCombLowPassFeedback::FilterCombLowPassFeedback(), Nsound::FilterDelay::FilterDelay(), Nsound::FilterFlanger::FilterFlanger(), FilterPhaser(), Nsound::FilterSlinky::FilterSlinky(), Nsound::Filter::getFrequencyAxis(), Nsound::Filter::getFrequencyResponse(), Nsound::Filter::getPhaseResponse(), Nsound::Filter::getSampleRate(), Nsound::FilterStageIIR::makeIIRKernelHelper(), Nsound::FilterHighPassFIR::makeKernel(), Nsound::FilterStageIIR::makeKernel(), Nsound::FilterBandPassVocoder::makeKernel(), Nsound::FilterLeastSquaresFIR::makeKernel(), Nsound::FilterParametricEqualizer::makeKernel(), operator=(), Nsound::FilterLeastSquaresFIR::operator=(), Nsound::FilterFlanger::operator=(), Nsound::FilterIIR::operator=(), Nsound::FilterLowPassMoogVcf::plot(), plot(), Nsound::FilterTone::plot(), Nsound::FilterHighPassIIR::plot(), Nsound::FilterCombLowPassFeedback::plot(), Nsound::FilterLowPassIIR::plot(), Nsound::FilterLowPassFIR::plot(), Nsound::FilterAllPass::plot(), Nsound::FilterHighPassFIR::plot(), Nsound::FilterBandPassFIR::plot(), Nsound::FilterLeastSquaresFIR::plot(), Nsound::FilterFlanger::plot(), Nsound::FilterBandRejectFIR::plot(), Nsound::FilterBandPassIIR::plot(), Nsound::FilterBandRejectIIR::plot(), Nsound::FilterParametricEqualizer::plot(), Nsound::FilterLowPassIIR::setCutoff(), and Nsound::FilterLeastSquaresFIR::setWindow().

float64 Nsound::Filter::two_pi_over_sample_rate_

protectedinherited

Definition at line 114 of file Filter.h.

Referenced by Nsound::FilterTone::makeKernel(), Nsound::FilterLowPassFIR::makeKernel(), and Nsound::FilterParametricEqualizer::makeKernel().

float64 Nsound::Filter::sample_time_

protectedinherited

Definition at line 115 of file Filter.h.

Referenced by Nsound::FilterLowPassMoogVcf::_make_filter().

uint32 Nsound::Filter::kernel_size_

protectedinherited

Definition at line 116 of file Filter.h.

Referenced by Nsound::FilterLowPassFIR::filter(), Nsound::FilterLeastSquaresFIR::filter(), Nsound::FilterBandPassFIR::FilterBandPassFIR(), Nsound::FilterBandPassIIR::FilterBandPassIIR(), Nsound::FilterBandRejectIIR::FilterBandRejectIIR(), Nsound::FilterHighPassIIR::FilterHighPassIIR(), Nsound::FilterLeastSquaresFIR::FilterLeastSquaresFIR(), Nsound::FilterLowPassFIR::FilterLowPassFIR(), Nsound::FilterLowPassIIR::FilterLowPassIIR(), Nsound::FilterLeastSquaresFIR::getKernel(), Nsound::Filter::getKernelSize(), Nsound::FilterHighPassFIR::makeKernel(), Nsound::FilterLowPassFIR::makeKernel(), Nsound::FilterBandRejectFIR::makeKernel(), Nsound::FilterLeastSquaresFIR::makeKernel(), Nsound::FilterLeastSquaresFIR::operator=(), Nsound::FilterLowPassFIR::plot(), Nsound::FilterHighPassFIR::plot(), Nsound::FilterLeastSquaresFIR::plot(), Nsound::FilterBandRejectFIR::plot(), Nsound::FilterLowPassFIR::reset(), Nsound::FilterHighPassFIR::reset(), Nsound::FilterLeastSquaresFIR::reset(), Nsound::FilterLeastSquaresFIR::setKernel(), Nsound::FilterLeastSquaresFIR::setWindow(), and Nsound::FilterHighPassFIR::spectraReversal_().

bool Nsound::Filter::is_realtime_

protectedinherited

Definition at line 118 of file Filter.h.

Referenced by Nsound::Filter::filter(), Nsound::FilterBandRejectIIR::filter(), Nsound::FilterBandRejectFIR::filter(), Nsound::Filter::getImpulseResponse(), and Nsound::Filter::setRealtime().

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

• Nsound/FilterPhaser.h
• Nsound/FilterPhaser.cc