Nsound::Filter Class Reference

Base class for IIR Filters, defines the interface. More...

#include <Nsound/Filter.h>

Inheritance diagram for Nsound::Filter:

Public Member Functions
	Filter (const float64 &sample_rate)
virtual	~Filter ()
void	setRealtime (bool flag)
AudioStream	filter (const AudioStream &x)
AudioStream	filter (const AudioStream &x, const float64 &frequency)
AudioStream	filter (const AudioStream &x, const Buffer &frequencies)
Buffer	filter (const Buffer &x)
Buffer	filter (const Buffer &x, const float64 &frequency)
Buffer	filter (const Buffer &x, const Buffer &frequencies)
virtual float64	filter (const float64 &x)=0
virtual float64	filter (const float64 &x, const float64 &frequency)=0
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)
virtual void	reset ()=0

Protected Attributes
float64	sample_rate_
float64	two_pi_over_sample_rate_
float64	sample_time_
uint32	kernel_size_
bool	is_realtime_

Detailed Description

Base class for IIR Filters, defines the interface.

Definition at line 49 of file Filter.h.

Constructor & Destructor Documentation

Filter::Filter

(

const float64 &

sample_rate

)

Definition at line 41 of file Filter.cc.

    :
    sample_rate_(sample_rate),
    two_pi_over_sample_rate_(2.0 * M_PI / sample_rate),
    sample_time_(1.0 / sample_rate),
    kernel_size_(0),
    is_realtime_(false)
{
}

virtual Nsound::Filter::~Filter ( )

inlinevirtual

Definition at line 55 of file Filter.h.

{};

Member Function Documentation

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

inline

Definition at line 57 of file Filter.h.

References is_realtime_.

{is_realtime_ = flag;}

AudioStream Filter::filter

(

const AudioStream &

x

)

Definition at line 53 of file Filter.cc.

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

Referenced by Nsound::FilterHighPassIIR::filter(), Nsound::FilterHighPassFIR::filter(), Nsound::FilterLowPassFIR::filter(), Nsound::FilterLowPassIIR::filter(), Nsound::FilterTone::filter(), Nsound::FilterDelay::filter(), Nsound::FilterAllPass::filter(), Nsound::FilterMovingAverage::filter(), Nsound::FilterFlanger::filter(), filter(), Nsound::FilterCombLowPassFeedback::filter(), Nsound::FilterBandPassVocoder::filter(), Nsound::FilterPhaser::filter(), Nsound::FilterBandPassFIR::filter(), Nsound::FilterBandRejectFIR::filter(), Nsound::FilterBandRejectIIR::filter(), Nsound::FilterBandPassIIR::filter(), Nsound::FilterStageIIR::filter(), Nsound::FilterLeastSquaresFIR::filter(), Nsound::FilterIIR::filter(), and getImpulseResponse().

{
    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]);
    }

    return y;
}

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

Definition at line 76 of file Filter.cc.

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

Definition at line 99 of file Filter.cc.

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

)

Definition at line 122 of file Filter.cc.

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

{
    if(!is_realtime_) reset();

    Buffer y(x.getLength());

    uint32 x_samples = x.getLength();

    for(uint32 i = 0; i < x_samples; ++i)
    {
        y << filter(x[i]);
    }

    return y;
}

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

Definition at line 140 of file Filter.cc.

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

Definition at line 161 of file Filter.cc.

References Nsound::Buffer::begin(), Nsound::Buffer::cbegin(), Nsound::Buffer::end(), filter(), Nsound::Buffer::getLength(), is_realtime_, and 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;
}

virtual float64 Nsound::Filter::filter ( const float64 &  x )

pure virtual

Implemented in Nsound::FilterParametricEqualizer, Nsound::FilterBandPassIIR, Nsound::FilterBandRejectIIR, Nsound::FilterIIR, Nsound::FilterBandPassFIR, Nsound::FilterBandRejectFIR, Nsound::FilterFlanger, Nsound::FilterLeastSquaresFIR, Nsound::FilterBandPassVocoder, Nsound::FilterStageIIR, Nsound::FilterAllPass, Nsound::FilterMovingAverage, Nsound::FilterDelay, Nsound::FilterSlinky, Nsound::FilterCombLowPassFeedback, Nsound::FilterLowPassIIR, Nsound::FilterLowPassFIR, Nsound::FilterHighPassFIR, Nsound::FilterHighPassIIR, Nsound::FilterPhaser, Nsound::FilterTone, and Nsound::FilterLowPassMoogVcf.

virtual float64 Nsound::Filter::filter ( const float64 &  x, const float64 &  frequency  )

pure virtual

Implemented in Nsound::FilterParametricEqualizer, Nsound::FilterBandPassIIR, Nsound::FilterBandRejectIIR, Nsound::FilterIIR, Nsound::FilterBandPassFIR, Nsound::FilterBandRejectFIR, Nsound::FilterLeastSquaresFIR, Nsound::FilterFlanger, Nsound::FilterBandPassVocoder, Nsound::FilterStageIIR, Nsound::FilterMovingAverage, Nsound::FilterAllPass, Nsound::FilterDelay, Nsound::FilterSlinky, Nsound::FilterCombLowPassFeedback, Nsound::FilterLowPassIIR, Nsound::FilterLowPassFIR, Nsound::FilterHighPassFIR, Nsound::FilterHighPassIIR, Nsound::FilterPhaser, Nsound::FilterTone, and Nsound::FilterLowPassMoogVcf.

Buffer Filter::getFrequencyAxis

(

const uint32

n_fft = 8192

)

Definition at line 185 of file Filter.cc.

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

Referenced by main(), 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

)

Definition at line 210 of file Filter.cc.

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

Referenced by Nsound::FilterBandPassIIR::FilterBandPassIIR(), FilterLeastSquaresFIR_UnitTest(), Nsound::FilterIIR::getRMS(), main(), 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

)

Definition at line 225 of file Filter.cc.

References filter(), is_realtime_, and reset().

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

inlinevirtual

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

Definition at line 96 of file Filter.h.

References kernel_size_.

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

{return kernel_size_;};

Buffer Filter::getPhaseResponse

(

)

Definition at line 245 of file Filter.cc.

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

Referenced by 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

inline

Definition at line 102 of file Filter.h.

References sample_rate_.

{ return sample_rate_; };

void Filter::plot

(

boolean

show_phase = false

)

Definition at line 262 of file Filter.cc.

References Nsound::Plotter::figure(), Nsound::Buffer::getdB(), getFrequencyAxis(), getFrequencyResponse(), Nsound::Buffer::getMax(), 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(), 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::FilterBandPassIIR::plot(), Nsound::FilterBandRejectIIR::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);
}

virtual void Nsound::Filter::reset ( )

pure virtual

Implemented in Nsound::FilterParametricEqualizer, Nsound::FilterBandPassIIR, Nsound::FilterBandRejectIIR, Nsound::FilterIIR, Nsound::FilterBandRejectFIR, Nsound::FilterLeastSquaresFIR, Nsound::FilterBandPassFIR, Nsound::FilterFlanger, Nsound::FilterBandPassVocoder, Nsound::FilterStageIIR, Nsound::FilterHighPassFIR, Nsound::FilterLowPassFIR, Nsound::FilterAllPass, Nsound::FilterMovingAverage, Nsound::FilterCombLowPassFeedback, Nsound::FilterLowPassIIR, Nsound::FilterDelay, Nsound::FilterTone, Nsound::FilterHighPassIIR, Nsound::FilterPhaser, Nsound::FilterSlinky, and Nsound::FilterLowPassMoogVcf.

Referenced by filter(), and getImpulseResponse().

Member Data Documentation

float64 Nsound::Filter::sample_rate_

protected

Definition at line 113 of file Filter.h.

Referenced by Nsound::FilterPhaser::filter(), Nsound::FilterCombLowPassFeedback::filter(), Nsound::FilterDelay::filter(), Nsound::FilterAllPass::FilterAllPass(), Nsound::FilterCombLowPassFeedback::FilterCombLowPassFeedback(), Nsound::FilterDelay::FilterDelay(), Nsound::FilterFlanger::FilterFlanger(), Nsound::FilterPhaser::FilterPhaser(), Nsound::FilterSlinky::FilterSlinky(), getFrequencyAxis(), getFrequencyResponse(), getPhaseResponse(), 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(), Nsound::FilterLowPassIIR::plot(), Nsound::FilterCombLowPassFeedback::plot(), Nsound::FilterLowPassFIR::plot(), Nsound::FilterHighPassFIR::plot(), Nsound::FilterAllPass::plot(), Nsound::FilterBandPassFIR::plot(), Nsound::FilterLeastSquaresFIR::plot(), Nsound::FilterFlanger::plot(), Nsound::FilterBandRejectFIR::plot(), Nsound::FilterBandRejectIIR::plot(), Nsound::FilterBandPassIIR::plot(), Nsound::FilterParametricEqualizer::plot(), Nsound::FilterLowPassIIR::setCutoff(), and Nsound::FilterLeastSquaresFIR::setWindow().

float64 Nsound::Filter::two_pi_over_sample_rate_

protected

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_

protected

Definition at line 115 of file Filter.h.

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

uint32 Nsound::Filter::kernel_size_

protected

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(), 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_

protected

Definition at line 118 of file Filter.h.

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

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

• Nsound/Filter.h
• Nsound/Filter.cc