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Merge pull request #1302 from diizy/master

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More filter stuff
This commit is contained in:
Vesa V
2014-11-14 22:18:39 +02:00
parent 7c9ccf59db a5d95f0bdd
commit 6e027ae929
1 changed files with 19 additions and 46 deletions
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65
include/basic_filters.h
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@@ -112,17 +112,6 @@ public:
}
inline basicFilters( const sample_rate_t _sample_rate ) :
m_b0a0( 0.0f ),
m_b1a0( 0.0f ),
m_b2a0( 0.0f ),
m_a1a0( 0.0f ),
m_a2a0( 0.0f ),
m_rca( 0.0f ),
m_rcb( 1.0f ),
m_rcc( 0.0f ),
m_svf1( 0.0f ),
m_svf2( 0.0f ),
m_svq( 0.0f ),
m_doubleFilter( false ),
m_sampleRate( (float) _sample_rate ),
m_sampleRatio( 1.0f / m_sampleRate ),
@@ -143,8 +132,7 @@ public:
for( ch_cnt_t _chnl = 0; _chnl < CHANNELS; ++_chnl )
{
// reset in/out history for simple filters
m_ou1[_chnl] = m_ou2[_chnl] = m_in1[_chnl] =
m_in2[_chnl] = 0.0f;
m_z1[_chnl] = m_z2[_chnl] = 0.0f;
// reset in/out history for moog-filter
m_y1[_chnl] = m_y2[_chnl] = m_y3[_chnl] = m_y4[_chnl] =
@@ -544,19 +532,10 @@ public:
}
default:
// filter
out = m_b0a0*_in0 +
m_b1a0*m_in1[_chnl] +
m_b2a0*m_in2[_chnl] -
m_a1a0*m_ou1[_chnl] -
m_a2a0*m_ou2[_chnl];
// push in/out buffers
m_in2[_chnl] = m_in1[_chnl];
m_in1[_chnl] = _in0;
m_ou2[_chnl] = m_ou1[_chnl];
m_ou1[_chnl] = out;
// biquad filter in transposed form
out = m_z1[_chnl] + m_b0a0 * _in0;
m_z1[_chnl] = m_b1a0 * _in0 + m_z2[_chnl] - m_a1a0 * out;
m_z2[_chnl] = m_b2a0 * _in0 - m_a2a0 * out;
break;
}
@@ -584,11 +563,11 @@ public:
{
_freq = qBound( 50.0f, _freq, 20000.0f );
const float sr = m_sampleRatio * 0.25f;
const float f = ( _freq * 2.0f * F_PI );
const float f = 1.0f / ( _freq * F_2PI );
m_rca = 1.0f - sr / ( ( 1.0f / f ) + sr );
m_rca = 1.0f - sr / ( f + sr );
m_rcb = 1.0f - m_rca;
m_rcc = ( 1.0f / f ) / ( ( 1.0f / f ) + sr );
m_rcc = f / ( f + sr );
// Stretch Q/resonance, as self-oscillation reliably starts at a q of ~2.5 - ~2.6
m_rcq = _q * 0.25f;
@@ -617,32 +596,26 @@ public:
const float fract = vowelf - vowel;
// interpolate between formant frequencies
const float f0 = linearInterpolate( _f[vowel+0][0], _f[vowel+1][0], fract ) * 2.0f * F_PI;
const float f1 = linearInterpolate( _f[vowel+0][1], _f[vowel+1][1], fract ) * 2.0f * F_PI;
const float f0 = 1.0f / ( linearInterpolate( _f[vowel+0][0], _f[vowel+1][0], fract ) * F_2PI );
const float f1 = 1.0f / ( linearInterpolate( _f[vowel+0][1], _f[vowel+1][1], fract ) * F_2PI );
// samplerate coeff: depends on oversampling
const float sr = m_type == FastFormant ? m_sampleRatio : m_sampleRatio * 0.25f;
m_vfa[0] = 1.0f - sr /
( ( 1.0f / f0 ) + sr );
m_vfa[0] = 1.0f - sr / ( f0 + sr );
m_vfb[0] = 1.0f - m_vfa[0];
m_vfc[0] = ( 1.0f / f0 ) /
( ( 1.0f / f0 ) + sr );
m_vfa[1] = 1.0f - sr /
( ( 1.0f / f1 ) + sr );
m_vfc[0] = f0 / ( f0 + sr );
m_vfa[1] = 1.0f - sr / ( f1 + sr );
m_vfb[1] = 1.0f - m_vfa[1];
m_vfc[1] = ( 1.0f / f1 ) /
( ( 1.0f / f1 ) + sr );
m_vfc[1] = f1 / ( f1 + sr );
return;
}
if( m_type == Moog ||
m_type == DoubleMoog )
{
_freq = qBound( minFreq(), _freq, 20000.0f );
// [ 0 - 0.5 ]
const float f = _freq * m_sampleRatio;
const float f = qBound( minFreq(), _freq, 20000.0f ) * m_sampleRatio;
// (Empirical tunning)
m_p = ( 3.6f - 3.2f * f ) * f;
m_k = 2.0f * m_p - 1;
@@ -683,10 +656,10 @@ public:
// other filters
_freq = qBound( minFreq(), _freq, 20000.0f );
const float omega = F_2PI * _freq * m_sampleRatio;
const float tsin = sinf( omega );
const float tsin = sinf( omega ) * 0.5f;
const float tcos = cosf( omega );
const float alpha = 0.5f * tsin / _q;
const float alpha = tsin / _q;
const float a0 = 1.0f / ( 1.0f + alpha );
@@ -707,7 +680,7 @@ public:
break;
case BandPass_CSG:
m_b1a0 = 0.0f;
m_b0a0 = tsin * 0.5f * a0;
m_b0a0 = tsin * a0;
m_b2a0 = -m_b0a0;
break;
case BandPass_CZPG:
@@ -759,7 +732,7 @@ private:
typedef sample_t frame[CHANNELS];
// in/out history
frame m_ou1, m_ou2, m_in1, m_in2;
frame m_z1, m_z2;
// in/out history for moog-filter
frame m_y1, m_y2, m_y3, m_y4, m_oldx, m_oldy1, m_oldy2, m_oldy3;