void BandFilter::setup(){
LOUDIA_DEBUG("BANDFILTER: Setting up...");
_filter.setChannelCount( _channelCount, false );
LOUDIA_DEBUG("BANDFILTER: Getting zpk");
// Get the lowpass z, p, k
MatrixXC zeros, poles;
Real gain;
switch( _filterType ){
case CHEBYSHEVI:
chebyshev1(_order, _passRipple, _channelCount, &zeros, &poles, &gain);
break;
case CHEBYSHEVII:
chebyshev2(_order, _stopAttenuation, _channelCount, &zeros, &poles, &gain);
break;
case BUTTERWORTH:
butterworth(_order, _channelCount, &zeros, &poles, &gain);
break;
case BESSEL:
bessel(_order, _channelCount, &zeros, &poles, &gain);
break;
}
LOUDIA_DEBUG("BANDFILTER: zeros:" << zeros );
LOUDIA_DEBUG("BANDFILTER: poles:" << poles );
LOUDIA_DEBUG("BANDFILTER: gain:" << gain );
// Convert zpk to ab coeffs
MatrixXC a;
MatrixXC b;
zpkToCoeffs(zeros, poles, gain, &b, &a);
LOUDIA_DEBUG("BANDFILTER: Calculated the coeffs");
// Since we cannot create matrices of Nx0
// we have created at least one Zero in 0
if ( zeros == MatrixXC::Zero(zeros.rows(), zeros.cols()) ){
// Now we must remove the last coefficient from b
MatrixXC temp = b.block(0, 0, b.rows(), b.cols()-1);
b = temp;
}
// Get the warped critical frequency
Real fs = 2.0;
Real warped = 2.0 * fs * tan( M_PI * _lowFrequency / fs );
Real warpedStop = 2.0 * fs * tan( M_PI * _highFrequency / fs );
Real warpedCenter = sqrt(warped * warpedStop);
Real warpedBandwidth = warpedStop - warped;
// Warpped coeffs
MatrixXC wa;
MatrixXC wb;
LOUDIA_DEBUG("BANDFILTER: Create the band type filter from the analog prototype");
switch( _bandType ){
case LOWPASS:
lowPassToLowPass(b, a, warped, &wb, &wa);
break;
case HIGHPASS:
lowPassToHighPass(b, a, warped, &wb, &wa);
break;
case BANDPASS:
lowPassToBandPass(b, a, warpedCenter, warpedBandwidth, &wb, &wa);
break;
case BANDSTOP:
lowPassToBandStop(b, a, warpedCenter, warpedBandwidth, &wb, &wa);
break;
}
LOUDIA_DEBUG("BANDFILTER: Calculated the low pass to band pass");
// Digital coeffs
MatrixXR da;
MatrixXR db;
bilinear(wb, wa, fs, &db, &da);
LOUDIA_DEBUG("BANDFILTER: setup the coeffs");
// Set the coefficients to the filter
_filter.setA( da.transpose() );
_filter.setB( db.transpose() );
_filter.setup();
LOUDIA_DEBUG("BANDFILTER: Finished set up...");
}
