Nsound::FilterLeastSquaresFIR Class Reference

A FIR filter that is defined as the least square error to the desired requency response. More...

#include <Nsound/FilterLeastSquaresFIR.h>

Inheritance diagram for Nsound::FilterLeastSquaresFIR:

Public Member Functions
	FilterLeastSquaresFIR (const float64 &sample_rate, uint32 kernel_size, const Buffer &freq_axis, const Buffer &amplitude_axis, const float64 &beta=5.0)
	FilterLeastSquaresFIR (const FilterLeastSquaresFIR &copy)
virtual	~FilterLeastSquaresFIR ()
Buffer	getKernel () const
void	setKernel (const Buffer &k)
Buffer	getKernelFrequencies ()
Buffer	getKernelAmplitudes ()
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)
float64	filter (const float64 &x, const float64 &frequency_Hz)
Buffer	getImpulseResponse ()
FilterLeastSquaresFIR &	operator= (const FilterLeastSquaresFIR &rhs)
void	plot (boolean show_fc=true, boolean show_phase=false)
void	reset ()
void	setWindow (WindowType type)
void	makeKernel (const Buffer &freq_axis, const Buffer &amplitude_axis)
void	setRealtime (bool flag)
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
float64 *	b_
float64 *	window_
float64 *	x_history_
float64 *	x_ptr_
float64 *	x_end_ptr_
Buffer *	f_axis_
Buffer *	a_axis_
float64	sample_rate_
float64	two_pi_over_sample_rate_
float64	sample_time_
uint32	kernel_size_
bool	is_realtime_

Detailed Description

A FIR filter that is defined as the least square error to the desired requency response.

Based on Matlab's firls function.

Definition at line 48 of file FilterLeastSquaresFIR.h.

Constructor & Destructor Documentation

FilterLeastSquaresFIR::FilterLeastSquaresFIR	(	const float64 &	sample_rate,
		uint32	kernel_size,
		const Buffer &	freq_axis,
		const Buffer &	amplitude_axis,
		const float64 &	beta = 5.0
	)

Definition at line 51 of file FilterLeastSquaresFIR.cc.

References a_axis_, b_, Nsound::Generator::drawWindowKaiser(), f_axis_, Nsound::Buffer::getPointer(), Nsound::Filter::kernel_size_, makeKernel(), reset(), window_, x_end_ptr_, x_history_, and x_ptr_.

    :
    Filter(sample_rate),
    b_(NULL),
    window_(NULL),
    x_history_(NULL),
    x_ptr_(NULL),
    x_end_ptr_(NULL),
    f_axis_(NULL),
    a_axis_(NULL)
{
    kernel_size_ = kernel_size;

    b_ = new float64[kernel_size_];

    x_history_ = new float64[kernel_size_ + 1];
    x_ptr_ = x_history_;
    x_end_ptr_ = x_history_ + kernel_size_ + 1;

    // Create the Kaiser window.
    window_ = new float64[kernel_size_];

    Generator gen(1.0);

    Buffer kaiser = gen.drawWindowKaiser(kernel_size_, beta);

    memcpy(window_, kaiser.getPointer(), sizeof(float64) * kernel_size_);

    // Allocate f & a axis.
    f_axis_ = new Buffer(16);
    a_axis_ = new Buffer(16);

    FilterLeastSquaresFIR::makeKernel(freq_axis, amplitude_axis);
    FilterLeastSquaresFIR::reset();
}

FilterLeastSquaresFIR::FilterLeastSquaresFIR

(

const FilterLeastSquaresFIR &

copy

)

Definition at line 95 of file FilterLeastSquaresFIR.cc.

References a_axis_, b_, f_axis_, Nsound::Filter::kernel_size_, window_, x_end_ptr_, x_history_, and x_ptr_.

    :
    Filter(copy.sample_rate_),
    b_(NULL),
    window_(NULL),
    x_history_(NULL),
    x_ptr_(NULL),
    x_end_ptr_(NULL),
    f_axis_(NULL),
    a_axis_(NULL)
{
    kernel_size_ = copy.kernel_size_;

    b_ = new float64[kernel_size_];

    x_history_ = new float64[kernel_size_ + 1];
    x_ptr_ = x_history_;
    x_end_ptr_ = x_history_ + kernel_size_ + 1;

    // Create the Kaiser window.
    window_ = new float64[kernel_size_];

    // Allocate f & a axis.
    f_axis_ = new Buffer(16);
    a_axis_ = new Buffer(16);

    // do the rest in the oprator=()
    *this = copy;
}

FilterLeastSquaresFIR::~FilterLeastSquaresFIR ( )

virtual

Definition at line 127 of file FilterLeastSquaresFIR.cc.

References a_axis_, b_, f_axis_, window_, and x_history_.

{
    delete [] b_;
    delete [] window_;
    delete [] x_history_;
    delete f_axis_;
    delete a_axis_;
}

Member Function Documentation

Buffer FilterLeastSquaresFIR::getKernel

(

)

const

Definition at line 138 of file FilterLeastSquaresFIR.cc.

References b_, and Nsound::Filter::kernel_size_.

Referenced by Nsound::Buffer::_get_resample().

{
    Buffer k(kernel_size_);
    for(uint32 i = 0; i < kernel_size_; ++i)
    {
        k << b_[i];
    }

    return k;
}

void FilterLeastSquaresFIR::setKernel

(

const Buffer &

k

)

Definition at line 151 of file FilterLeastSquaresFIR.cc.

References b_, Nsound::Generator::drawWindowKaiser(), Nsound::Buffer::getLength(), Nsound::Buffer::getPointer(), Nsound::Filter::kernel_size_, reset(), window_, x_end_ptr_, x_history_, and x_ptr_.

Referenced by Nsound::Buffer::_get_resample().

{
    if(k.getLength() != kernel_size_)
    {
        delete [] b_;
        delete [] window_;
        delete [] x_history_;

        kernel_size_ = k.getLength();

        b_ = new float64[kernel_size_];

        x_history_ = new float64[kernel_size_ + 1];
        x_ptr_ = x_history_;
        x_end_ptr_ = x_history_ + kernel_size_ + 1;

        // Create the Kaiser window.
        window_ = new float64[kernel_size_];

        Generator gen(1.0);

        Buffer kaiser = gen.drawWindowKaiser(kernel_size_, 5.0);

        memcpy(window_, kaiser.getPointer(), sizeof(float64) * kernel_size_);

        FilterLeastSquaresFIR::reset();
    }

    for(uint32 i = 0; i < kernel_size_; ++i)
    {
        b_[i] = k[i];
    }

    return;
}

Buffer FilterLeastSquaresFIR::getKernelFrequencies

(

)

Definition at line 189 of file FilterLeastSquaresFIR.cc.

References f_axis_.

{
    return *f_axis_;
}

Buffer FilterLeastSquaresFIR::getKernelAmplitudes

(

)

Definition at line 196 of file FilterLeastSquaresFIR.cc.

References a_axis_.

{
    return *a_axis_;
}

AudioStream FilterLeastSquaresFIR::filter

(

const AudioStream &

x

)

Definition at line 203 of file FilterLeastSquaresFIR.cc.

References Nsound::Filter::filter().

Referenced by Nsound::Buffer::_get_resample(), filter(), and FilterLeastSquaresFIR_UnitTest().

{
    return Filter::filter(x);
}

AudioStream Nsound::FilterLeastSquaresFIR::filter ( const AudioStream &  x, const float64 &  frequency  )

inline

Definition at line 80 of file FilterLeastSquaresFIR.h.

References filter().

    { return filter(x); };

AudioStream Nsound::FilterLeastSquaresFIR::filter ( const AudioStream &  x, const Buffer &  frequencies  )

inline

Definition at line 85 of file FilterLeastSquaresFIR.h.

References filter().

    { return filter(x); };

Buffer FilterLeastSquaresFIR::filter

(

const Buffer &

x

)

Definition at line 210 of file FilterLeastSquaresFIR.cc.

References Nsound::Filter::filter().

{
    return Filter::filter(x);
}

Buffer Nsound::FilterLeastSquaresFIR::filter ( const Buffer &  x, const float64 &  frequency  )

inline

Definition at line 93 of file FilterLeastSquaresFIR.h.

References filter().

    { return filter(x); };

Buffer Nsound::FilterLeastSquaresFIR::filter ( const Buffer &  x, const Buffer &  frequencies  )

inline

Definition at line 98 of file FilterLeastSquaresFIR.h.

References filter().

    { return filter(x); };

float64 FilterLeastSquaresFIR::filter ( const float64 &  x )

virtual

Implements Nsound::Filter.

Definition at line 217 of file FilterLeastSquaresFIR.cc.

References b_, Nsound::Filter::kernel_size_, x_end_ptr_, x_history_, and x_ptr_.

{
    // Write x to history
    *x_ptr_ = x;

    // Increment history pointer
    ++x_ptr_;

    // Bounds check.
    if(x_ptr_ >= x_end_ptr_)
    {
        x_ptr_ = x_history_;
    }

    // Perform the convolution.

    // y[n] = kernel_[0] * x[n]
    //      + kernel_[1] * x[n - 1]
    //      + kernel_[2] * x[n - 2]
    //      ...
    //      + kernel_[N] * x[n - N]

    float64 y = 0.0;
    float64 * history = x_ptr_;
    for(float64 * b = b_; b != b_ + kernel_size_; ++b)
    {
        // When we enter this loop, history is pointing at x[n + 1].
        --history;

        // Bounds check
        if(history < x_history_)
        {
            history = x_end_ptr_ - 1;
        }

        y += *b * *history;
    }

    return y;
}

float64 Nsound::FilterLeastSquaresFIR::filter ( const float64 &  x, const float64 &  frequency_Hz  )

inlinevirtual

Implements Nsound::Filter.

Definition at line 107 of file FilterLeastSquaresFIR.h.

References filter().

    { return filter(x); };

Buffer Nsound::FilterLeastSquaresFIR::getImpulseResponse ( )

inline

Definition at line 112 of file FilterLeastSquaresFIR.h.

References Nsound::Filter::getImpulseResponse().

    {return Filter::getImpulseResponse();};

FilterLeastSquaresFIR & FilterLeastSquaresFIR::operator=

(

const FilterLeastSquaresFIR &

rhs

)

Definition at line 628 of file FilterLeastSquaresFIR.cc.

References a_axis_, b_, f_axis_, Nsound::Filter::kernel_size_, reset(), Nsound::Filter::sample_rate_, window_, x_end_ptr_, x_history_, and x_ptr_.

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

    if(kernel_size_ != rhs.kernel_size_)
    {
        delete [] b_;
        delete [] window_;
        delete [] x_history_;

        kernel_size_ = rhs.kernel_size_;

        b_ = new float64[kernel_size_];

        x_history_ = new float64[kernel_size_ + 1];
        x_ptr_ = x_history_;
        x_end_ptr_ = x_history_ + kernel_size_ + 1;

        // Create the Kaiser window.
        window_ = new float64[kernel_size_];
    }

    sample_rate_ = rhs.sample_rate_;

    *f_axis_ = *rhs.f_axis_;
    *a_axis_ = *rhs.a_axis_;

    memcpy(b_,      rhs.b_,      sizeof(float64) * kernel_size_);
    memcpy(window_, rhs.window_, sizeof(float64) * kernel_size_);

    FilterLeastSquaresFIR::reset();

    return *this;
}

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

Definition at line 668 of file FilterLeastSquaresFIR.cc.

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

{
    char title[256];
    sprintf(title,
        "Least Square FIR Frequency Response\n"
        "order = %d, sr = %0.1f Hz",
        kernel_size_, 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.title(title);
    }
}

void FilterLeastSquaresFIR::reset ( )

virtual

Resets interal history buffer and sets the cut off frequency to the one used at declaration.

Implements Nsound::Filter.

Definition at line 697 of file FilterLeastSquaresFIR.cc.

References Nsound::Filter::kernel_size_, x_history_, and x_ptr_.

Referenced by FilterLeastSquaresFIR(), makeKernel(), operator=(), and setKernel().

{
    memset(x_history_, 0, sizeof(float64) * (kernel_size_ + 1));
    x_ptr_ = x_history_;
}

void FilterLeastSquaresFIR::setWindow

(

WindowType

type

)

Definition at line 705 of file FilterLeastSquaresFIR.cc.

References a_axis_, Nsound::Generator::drawWindow(), f_axis_, Nsound::Buffer::getPointer(), Nsound::Filter::kernel_size_, makeKernel(), Nsound::Filter::sample_rate_, and window_.

Referenced by FilterLeastSquaresFIR_UnitTest().

{
    Generator gen(1.0);

    Buffer window = gen.drawWindow(kernel_size_, type);

    memcpy(window_, window.getPointer(), sizeof(float64)*kernel_size_);

    // Make new kernel with window.
    Buffer f(*f_axis_);
    Buffer a(*a_axis_);

    f *= 0.5 * sample_rate_;

    makeKernel(f, a);
}

void FilterLeastSquaresFIR::makeKernel	(	const Buffer &	freq_axis,
		const Buffer &	amplitude_axis
	)

Definition at line 260 of file FilterLeastSquaresFIR.cc.

References a_axis_, b_, Nsound::Generator::drawLine(), f_axis_, Nsound::Buffer::getDerivative(), Nsound::Buffer::getLength(), Nsound::Buffer::getMin(), Nsound::Buffer::getPointer(), Nsound::Buffer::getReverse(), Nsound::Filter::kernel_size_, M_PI, M_THROW, reset(), Nsound::Filter::sample_rate_, Nsound::Buffer::subbuffer(), and window_.

Referenced by FilterLeastSquaresFIR(), FilterLeastSquaresFIR_UnitTest(), and setWindow().

{
    // Reset the buffers.
    *f_axis_ = Buffer(16);
    *a_axis_ = Buffer(16);

    float64 max_freq = sample_rate_ / 2.0;

    // Validate freq_axis and amplitude_axis.
    if(freq_axis.getLength() != amplitude_axis.getLength() ||
       freq_axis.getLength() % 2 != 0)
    {
        M_THROW("FilterLeastSquaresFIR::makeKernel(): "
            << "freq_axis and amplitude_axis must be same length and even!");

        *f_axis_ << 0.0 << max_freq;
        *a_axis_ << 1.0 << 1.0;

        FilterLeastSquaresFIR::reset();
        return;
    }

    // Veirfy all samples inf freq_axis are in assending order.
    if(freq_axis[0] != 0.0)
    {
        M_THROW("FilterLeastSquaresFIR::makeKernel(): "
             << "freq_axis[0] must be 0.0!");

        *f_axis_ << 0.0 << max_freq;
        *a_axis_ << 1.0 << 1.0;

        FilterLeastSquaresFIR::reset();
        return;
    }

    if(freq_axis[freq_axis.getLength() -1 ] != max_freq)
    {
        M_THROW("FilterLeastSquaresFIR::makeKernel(): "
             << "freq_axis[end] (" << freq_axis[freq_axis.getLength() -1 ]
             << ") must be " << max_freq << "!");

        *f_axis_ << 0.0 << max_freq;
        *a_axis_ << 1.0 << 1.0;

        FilterLeastSquaresFIR::reset();
        return;
    }

    // Test all samples are in assending order.
    Buffer df = freq_axis.getDerivative(1);
    if(df.getMin() < 0.0)
    {
        M_THROW("FilterLeastSquaresFIR::makeKernel(): "
             << "Frequencies in freq_axis must be increasing!");

        *f_axis_ << 0.0 << max_freq;
        *a_axis_ << 1.0 << 1.0;

        FilterLeastSquaresFIR::reset();
        return;
    }

    // All is okay.

    *f_axis_ << (freq_axis / max_freq);
    *a_axis_ << amplitude_axis;

//~    // Debug
//~    std::cout << "faxis:" << *f_axis_ << std::endl;

    Generator gen(1.0);

    Buffer f(*f_axis_/2.0);
    Buffer a(*a_axis_);

    Buffer w = gen.drawLine(freq_axis.getLength() / 2, 1.0, 1.0);

//~    cout << "N = " << kernel_size_ << endl
//~         << "F = " << endl;
//~
//~    for(uint32 i = 0; i < f.getLength(); ++i)
//~    {
//~        cout << "    " << f[i] << endl;
//~    }

//~    cout << "M = " << endl;
//~
//~    for(uint32 i = 0; i < a.getLength(); ++i)
//~    {
//~        cout << "    " << a[i] << endl;
//~    }

//~    cout << "W = " << endl;
//~
//~    for(uint32 i = 0; i < w.getLength(); ++i)
//~    {
//~        cout << "    " << w[i] << endl;
//~    }

    df = f.getDerivative(1);

    // throw out last value
    df = df.subbuffer(0, df.getLength() -1);

//~    cout << "dF = " << endl;

//~    for(uint32 i = 0; i < df.getLength(); ++i)
//~    {
//~        cout << "    " << df[i] << endl;
//~    }

    // Check for full band

    boolean fullband = true;

//~    cerr << CERR_HEADER << endl;

    if(df.getLength() > 1)
    {
        for(uint32 i = 1; i < df.getLength() - 1; i += 2)
        {

//~            cerr << "df[" << i << "] = " << df[i] << endl;

            if(df[i] != 0.0)
            {
                fullband = false;
                break;
            }
        }
    }

//~    cout << "fullband = " << fullband << endl;

    int32 L = (kernel_size_ - 1) / 2;

//~    cout << "L = " << L << endl;

    boolean is_odd = true;

    if(kernel_size_ % 2 == 0)
    {
        is_odd = false;
    }

//~    cout << "Nodd = " << is_odd << endl;

    Buffer m;

    if(L > 0)
    {
        m = gen.drawLine(L, 0, L);
    }

    m << L;

    if(!is_odd)
    {
        m += 0.5;
    }

//~    cout << "length(m) = " << m.getLength() << endl;
//~    cout << "m[0]   = " << m[0] << endl;
//~    cout << "m[end] = " << m[m.getLength()-1] << endl;

    boolean need_matrix = ! fullband;

//~    cout << "need_matrix = " << need_matrix << endl;

    if(need_matrix)
    {
        M_THROW("FilterLeastSquaresFIR::makeKernel(): "
             << "FIXME: need_matix is true!");
    }

    Buffer k(m);

    float64 b0 = 0.0;

    if(is_odd)
    {
        k = m.subbuffer(1, m.getLength()-1);
    }

//~    cout << "length(k) = " << k.getLength() << endl;
//~    cout << "k[0]   = " << k[0] << endl;
//~    cout << "k[end] = " << k[k.getLength()-1] << endl;

    float64 PI_x_2 = 2.0 * M_PI;
//~    float64 PI_x_4 = 4.0 * M_PI;
    float64 PI_x_PI_x_4 = 4.0 * M_PI * M_PI;

    Buffer b = 0.0 * k;
    Buffer kk = k * k;

    for(uint32 i = 0; i < f.getLength(); i += 2)
    {
        float64 t_df = f[i+1] - f[i];

        float64 mm = 0.0;
        float64 b1 = 0.0;

        mm = (a[i+1] - a[i]) / t_df;    // slope
        b1 = a[i] - mm * f[i];          // y-intercept

//~        cout << endl;
//~        cout << "s = " << i+1 << endl;
//~        cout << "m = " << mm << endl;
//~        cout << "b1 = " << b1 << endl;

        if(is_odd)
        {
            b0 += (b1 * t_df + mm / 2.0 * (f[i+1] * f[i+1] - f[i]*f[i]))
                * w[(i+1)/2] * w[(i+1)/2];
        }

//~        cout << "b0 = " << b0 << endl;

        Buffer f1 = PI_x_2 * k * f[i+1];
        Buffer f2 = PI_x_2 * k * f[i];

        std::stringstream ss;

        float64 abs_w2 = std::fabs(w[(i+1)/2] * w[(i+1)/2]);

//~        cout << "W[" << i << "] = " << w[(i+1)/2] << endl;
//~        cout << "abs(W^2) = " << abs_w2 << endl;


        for(uint32 j = 0; j < b.getLength(); ++j)
        {
            b[j] += (mm / PI_x_PI_x_4
                        * (std::cos(f1[j]) - std::cos(f2[j]))
                        / (k[j] * k[j])
                    ) * abs_w2;
        }

        float64 fi  = f[i];
        float64 fi1 = f[i+1];

//~        ss.str("");
//~        ss << "s = " << (i+1) << ", b1";
//~        b.plot(ss.str());

//~        cout << "F[" << (i)   << "] = " << fi  << endl;
//~        cout << "F[" << (i+1) << "] = " << fi1 << endl;

//~        // DEBUG
//~        Buffer SINC;
//~        for(uint32 j = 0; j < b.getLength(); ++j)
//~        {
//~            float64 x = PI_x_2 * k[j] * fi1;
//~
//~            if(x == 0.0) x = M_PI;
//~
//~            SINC << std::sin(x) / x;
//~        }
//~
//~        ss.str("");
//~        ss << "s = " << (i+1) << ", sinc";
//~        SINC.plot(ss.str());

        for(uint32 j = 0; j < b.getLength(); ++j)
        {
            float64 t = PI_x_2 * k[j];
            float64 x = 0.0;
            float64 sinc = 0.0;
            float64 sinc1 = 0.0;

            x = t*fi;

            if(x == 0.0) x = M_PI;

            sinc = std::sin(x) / x;

            x = t*fi1;

            if(x == 0.0) x = M_PI;

            sinc1 = std::sin(x) / x;

            b[j] += (  fi1 * (mm * fi1 + b1) * sinc1
                     - fi  * (mm * fi  + b1) * sinc )
                  * abs_w2;
        }

//~        ss << "s = " << (i+1) << ", f1";
//~        f1.plot(ss.str());
//~        ss.str("");
//~        ss << "s = " << (i+1) << ", f2";
//~        f2.plot(ss.str());
//~
//~        ss.str("");
//~        ss << "s = " << (i+1) << ", b2";
//~        b.plot(ss.str());

    }

//~    cout << "below loop" << endl
//~         << "b0 = " << b0 << endl;

//~    b.plot("below loop: b");

    if(is_odd)
    {
        Buffer t;
        t << b0 << b;
        b = t;
    }

//~    b.plot("below loop: b2");

//~    a = b;
    Buffer h;

    if(! need_matrix)
    {
        a = w[0] * w[0] * 4.0 * b;

        if(is_odd)
        {
            a[0] *= 0.5;
        }
    }

    if(is_odd)
    {
        float64 a0 = a[0];
        Buffer a2 = 0.5 * a.subbuffer(1, a.getLength());
        h = a2.getReverse() << a0 << a2;
    }
    else
    {
        h = a.getReverse() << a;

        h *= 0.5;
    }

//~    h.plot("h");
//~    Plotter::show();

    if(kernel_size_ != h.getLength())
    {
        M_THROW("FilterLeastSquaresFIR::makeKernel(): "
             << "kernel_size_ != h.getLength()!");

        for(uint32 i = 0; i < kernel_size_; ++i)
        {
            b_[i] = 0.0;
        }
    }
    else
    {
        memcpy(b_, h.getPointer(), sizeof(float64)*kernel_size_);
    }

    // Apply window
    for(uint32 i = 0; i < kernel_size_; ++i)
    {
        b_[i] *= window_[i];
    }
}

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

inlineinherited

Definition at line 57 of file Filter.h.

References Nsound::Filter::is_realtime_.

{is_realtime_ = flag;}

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(), 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(), Nsound::FilterCombLowPassFeedback::plot(), Nsound::FilterLowPassIIR::plot(), Nsound::FilterLowPassFIR::plot(), Nsound::FilterHighPassFIR::plot(), Nsound::FilterAllPass::plot(), Nsound::FilterBandPassVocoder::plot(), Nsound::FilterBandPassFIR::plot(), 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

float64* Nsound::FilterLeastSquaresFIR::b_

protected

Definition at line 136 of file FilterLeastSquaresFIR.h.

Referenced by filter(), FilterLeastSquaresFIR(), getKernel(), makeKernel(), operator=(), setKernel(), and ~FilterLeastSquaresFIR().

float64* Nsound::FilterLeastSquaresFIR::window_

protected

Definition at line 137 of file FilterLeastSquaresFIR.h.

Referenced by FilterLeastSquaresFIR(), makeKernel(), operator=(), setKernel(), setWindow(), and ~FilterLeastSquaresFIR().

float64* Nsound::FilterLeastSquaresFIR::x_history_

protected

Definition at line 139 of file FilterLeastSquaresFIR.h.

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

float64* Nsound::FilterLeastSquaresFIR::x_ptr_

protected

Definition at line 140 of file FilterLeastSquaresFIR.h.

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

float64* Nsound::FilterLeastSquaresFIR::x_end_ptr_

protected

Definition at line 141 of file FilterLeastSquaresFIR.h.

Referenced by filter(), FilterLeastSquaresFIR(), operator=(), and setKernel().

Buffer* Nsound::FilterLeastSquaresFIR::f_axis_

protected

Definition at line 143 of file FilterLeastSquaresFIR.h.

Referenced by FilterLeastSquaresFIR(), getKernelFrequencies(), makeKernel(), operator=(), setWindow(), and ~FilterLeastSquaresFIR().

Buffer* Nsound::FilterLeastSquaresFIR::a_axis_

protected

Definition at line 144 of file FilterLeastSquaresFIR.h.

Referenced by FilterLeastSquaresFIR(), getKernelAmplitudes(), makeKernel(), operator=(), setWindow(), and ~FilterLeastSquaresFIR().

float64 Nsound::Filter::sample_rate_

protectedinherited

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(), Nsound::Filter::getFrequencyAxis(), Nsound::Filter::getFrequencyResponse(), Nsound::Filter::getPhaseResponse(), Nsound::Filter::getSampleRate(), Nsound::FilterStageIIR::makeIIRKernelHelper(), Nsound::FilterHighPassFIR::makeKernel(), Nsound::FilterStageIIR::makeKernel(), Nsound::FilterBandPassVocoder::makeKernel(), makeKernel(), Nsound::FilterParametricEqualizer::makeKernel(), Nsound::FilterPhaser::operator=(), operator=(), Nsound::FilterFlanger::operator=(), Nsound::FilterIIR::operator=(), Nsound::FilterLowPassMoogVcf::plot(), Nsound::FilterPhaser::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(), plot(), Nsound::FilterFlanger::plot(), Nsound::FilterBandRejectFIR::plot(), Nsound::FilterBandPassIIR::plot(), Nsound::FilterBandRejectIIR::plot(), Nsound::FilterParametricEqualizer::plot(), Nsound::FilterLowPassIIR::setCutoff(), and 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(), filter(), Nsound::FilterBandPassFIR::FilterBandPassFIR(), Nsound::FilterBandPassIIR::FilterBandPassIIR(), Nsound::FilterBandRejectIIR::FilterBandRejectIIR(), Nsound::FilterHighPassIIR::FilterHighPassIIR(), FilterLeastSquaresFIR(), Nsound::FilterLowPassFIR::FilterLowPassFIR(), Nsound::FilterLowPassIIR::FilterLowPassIIR(), getKernel(), Nsound::Filter::getKernelSize(), Nsound::FilterHighPassFIR::makeKernel(), Nsound::FilterLowPassFIR::makeKernel(), Nsound::FilterBandRejectFIR::makeKernel(), makeKernel(), operator=(), Nsound::FilterLowPassFIR::plot(), Nsound::FilterHighPassFIR::plot(), plot(), Nsound::FilterBandRejectFIR::plot(), Nsound::FilterLowPassFIR::reset(), Nsound::FilterHighPassFIR::reset(), reset(), setKernel(), 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/FilterLeastSquaresFIR.h
• Nsound/FilterLeastSquaresFIR.cc