Nsound::FilterCombLowPassFeedback Class Reference

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

#include <Nsound/FilterCombLowPassFeedback.h>

Inheritance diagram for Nsound::FilterCombLowPassFeedback:

Public Member Functions
	FilterCombLowPassFeedback (const float64 &sample_rate, const float64 &delay_time_seconds, const float64 &feedback_gain, const float64 &low_pass_frequency_Hz)
	FilterCombLowPassFeedback (const FilterCombLowPassFeedback &copy)
virtual	~FilterCombLowPassFeedback ()
AudioStream	filter (const AudioStream &x)
AudioStream	filter (const AudioStream &x, const Buffer &frequencies)
Buffer	filter (const Buffer &x)
Buffer	filter (const Buffer &x, const Buffer &frequencies)
float64	filter (const float64 &x)
float64	filter (const float64 &x, const float64 &frequency)
FilterCombLowPassFeedback &	operator= (const FilterCombLowPassFeedback &rhs)
void	plot (boolean show_fc=true, boolean show_phase=false)
void	reset ()
void	setRealtime (bool flag)
AudioStream	filter (const AudioStream &x, const float64 &frequency)
Buffer	filter (const Buffer &x, const float64 &frequency)
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
FilterDelay *	delay_
float64	feedback_gain_
float64	damp1_
float64	damp2_
float64	y_history_
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 48 of file FilterCombLowPassFeedback.h.

Constructor & Destructor Documentation

FilterCombLowPassFeedback::FilterCombLowPassFeedback	(	const float64 &	sample_rate,
		const float64 &	delay_time_seconds,
		const float64 &	feedback_gain,
		const float64 &	low_pass_frequency_Hz
	)

Definition at line 48 of file FilterCombLowPassFeedback.cc.

References damp1_, damp2_, delay_, feedback_gain_, reset(), and Nsound::Filter::sample_rate_.

    :
    Filter(sample_rate),
    delay_(NULL),
    feedback_gain_(feedback_gain),
    damp1_(0.0),
    damp2_(0.0),
    y_history_(0.0)
{
    delay_ = new FilterDelay(sample_rate_, delay_time_seconds);

    FilterCombLowPassFeedback::reset();

    if(feedback_gain_ < 0.0)
    {
        feedback_gain_ = 0.0;
    }

    if(feedback_gain_ >= 1.0)
    {
        feedback_gain_ = 0.999999;
    }

    damp1_ = low_pass_frequency_Hz / sample_rate_;

    if(damp1_ > 0.5)
    {
        damp1_ = 0.5;
    }

    damp2_ = 1.0 - damp1_;
}

FilterCombLowPassFeedback::FilterCombLowPassFeedback

(

const FilterCombLowPassFeedback &

copy

)

Definition at line 87 of file FilterCombLowPassFeedback.cc.

    :
    Filter(copy.sample_rate_),
    delay_(new FilterDelay(*copy.delay_)),
    feedback_gain_(copy.feedback_gain_),
    damp1_(copy.damp1_),
    damp2_(copy.damp2_),
    y_history_(copy.y_history_)
{
}

FilterCombLowPassFeedback::~FilterCombLowPassFeedback ( )

virtual

Definition at line 101 of file FilterCombLowPassFeedback.cc.

References delay_.

{
    delete delay_;
}

Member Function Documentation

AudioStream FilterCombLowPassFeedback::filter

(

const AudioStream &

x

)

Definition at line 108 of file FilterCombLowPassFeedback.cc.

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

Referenced by filter(), Nsound::ReverberationRoom::filter(), and FilterCombLowPassFeedback_UnitTest().

{
    FilterCombLowPassFeedback::reset();
    return Filter::filter(x);
}

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

Definition at line 116 of file FilterCombLowPassFeedback.cc.

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

{
    FilterCombLowPassFeedback::reset();
    return Filter::filter(x, frequencies);
}

Buffer FilterCombLowPassFeedback::filter

(

const Buffer &

x

)

Definition at line 124 of file FilterCombLowPassFeedback.cc.

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

{
    FilterCombLowPassFeedback::reset();
    return Filter::filter(x);
}

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

Definition at line 132 of file FilterCombLowPassFeedback.cc.

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

{
    FilterCombLowPassFeedback::reset();
    return Filter::filter(x, frequencies);
}

float64 FilterCombLowPassFeedback::filter ( const float64 &  x )

virtual

Implements Nsound::Filter.

Definition at line 140 of file FilterCombLowPassFeedback.cc.

References damp1_, damp2_, delay_, feedback_gain_, Nsound::FilterDelay::filter(), and y_history_.

{
    float64 d = delay_->filter(x + y_history_ * feedback_gain_);

    y_history_ = d * damp2_ + y_history_ * damp1_;

    return d;
}

float64 FilterCombLowPassFeedback::filter ( const float64 &  x, const float64 &  frequency  )

virtual

Implements Nsound::Filter.

Definition at line 151 of file FilterCombLowPassFeedback.cc.

References damp1_, damp2_, filter(), and Nsound::Filter::sample_rate_.

{
    damp1_ = frequency_Hz / sample_rate_;

    if(damp1_ > 0.5)
    {
        damp1_ = 0.5;
    }

    damp2_ = 1.0 - damp1_;

    return FilterCombLowPassFeedback::filter(x);
}

FilterCombLowPassFeedback & FilterCombLowPassFeedback::operator=

(

const FilterCombLowPassFeedback &

rhs

)

Definition at line 168 of file FilterCombLowPassFeedback.cc.

References damp1_, damp2_, delay_, feedback_gain_, and y_history_.

{
    *delay_ = *rhs.delay_;
    feedback_gain_ = rhs.feedback_gain_;
    damp1_ = rhs.damp1_;
    damp2_ = rhs.damp2_;
    y_history_ = rhs.y_history_;

    return *this;
}

void FilterCombLowPassFeedback::plot	(	boolean	show_fc = true,
		boolean	show_phase = false
	)

Definition at line 181 of file FilterCombLowPassFeedback.cc.

References Nsound::Plotter::axvline(), damp1_, Nsound::Filter::plot(), Nsound::Filter::sample_rate_, Nsound::Plotter::subplot(), and Nsound::Plotter::title().

{
    char title[128];
    sprintf(title,
        "Comb Low Pass Feedback Frequency Response\n"
        "order = %d, fc = %0.1f Hz, sr = %0.1f Hz",
        2,
        damp1_ * sample_rate_,
        sample_rate_);

    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.axvline(damp1_ * sample_rate_,"color='red'");

        pylab.title(title);
    }
}

void FilterCombLowPassFeedback::reset ( )

virtual

Implements Nsound::Filter.

Definition at line 214 of file FilterCombLowPassFeedback.cc.

References delay_, Nsound::FilterDelay::reset(), and y_history_.

Referenced by filter(), FilterCombLowPassFeedback(), and Nsound::ReverberationRoom::reset().

{
    delay_->reset();
    y_history_ = 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;
}

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::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(), Nsound::FilterPhaser::plot(), Nsound::FilterTone::plot(), Nsound::FilterHighPassIIR::plot(), 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

FilterDelay* Nsound::FilterCombLowPassFeedback::delay_

protected

Definition at line 92 of file FilterCombLowPassFeedback.h.

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

float64 Nsound::FilterCombLowPassFeedback::feedback_gain_

protected

Definition at line 94 of file FilterCombLowPassFeedback.h.

Referenced by filter(), FilterCombLowPassFeedback(), and operator=().

float64 Nsound::FilterCombLowPassFeedback::damp1_

protected

Definition at line 96 of file FilterCombLowPassFeedback.h.

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

float64 Nsound::FilterCombLowPassFeedback::damp2_

protected

Definition at line 97 of file FilterCombLowPassFeedback.h.

Referenced by filter(), FilterCombLowPassFeedback(), and operator=().

float64 Nsound::FilterCombLowPassFeedback::y_history_

protected

Definition at line 99 of file FilterCombLowPassFeedback.h.

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

float64 Nsound::Filter::sample_rate_

protectedinherited

Definition at line 113 of file Filter.h.

Referenced by Nsound::FilterPhaser::filter(), filter(), Nsound::FilterDelay::filter(), Nsound::FilterAllPass::FilterAllPass(), FilterCombLowPassFeedback(), Nsound::FilterDelay::FilterDelay(), Nsound::FilterFlanger::FilterFlanger(), Nsound::FilterPhaser::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(), Nsound::FilterPhaser::operator=(), Nsound::FilterLeastSquaresFIR::operator=(), Nsound::FilterFlanger::operator=(), Nsound::FilterIIR::operator=(), Nsound::FilterLowPassMoogVcf::plot(), Nsound::FilterPhaser::plot(), Nsound::FilterTone::plot(), Nsound::FilterHighPassIIR::plot(), 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/FilterCombLowPassFeedback.h
• Nsound/FilterCombLowPassFeedback.cc