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biquad.js
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export default {
lp1 (x0,freq=1000,amt=1) {
var b = _biquads[_filter_i++],
{y1,y2,x1,x2} = b,
w0 = pi2 * freq/sampleRate,
a1 = -Math.exp(-w0),
a2 = 0.0,
b0 = 1.0 + a1,
b1 = 0.0,
b2 = 0.0,
y0 = (x0*b0+x1*b1+x2*b2-y1*a1-y2*a2)
b.y1=y0; b.y2=y1; b.x1=x0; b.x2=x1;
return x0*(1-amt) + y0*amt
},
hp1 (x0,freq=1000,amt=1) {
var b = _biquads[_filter_i++],
{y1,y2,x1,x2} = b,
w0 = pi2 * freq/sampleRate,
a1 = -Math.exp(-w0),
a2 = 0.0,
b0 = (1.0 - a1) / 2.0,
b1 = -b0,
b2 = 0.0,
y0 = (x0*b0+x1*b1+x2*b2-y1*a1-y2*a2)
b.y1=y0; b.y2=y1; b.x1=x0; b.x2=x1;
return x0*(1-amt) + y0*amt
},
lp (x0, freq=1000, Q=1, amt=1) {
var b = _biquads[_filter_i++],
{y1,y2,x1,x2} = b,
w0 = pi2 * freq/sampleRate,
sin_w0 = Math.sin(w0),
cos_w0 = Math.cos(w0),
alpha = sin_w0 / (2.0 * Q),
b0 = (1.0 - cos_w0) / 2.0,
b1 = 1.0 - cos_w0,
b2 = b0,
a0 = 1.0 + alpha,
a1 = -2.0 * cos_w0,
a2 = 1.0 - alpha,
y0 = (x0*b0+x1*b1+x2*b2-y1*a1-y2*a2)/a0
b.y1=y0; b.y2=y1; b.x1=x0; b.x2=x1;
return x0*(1-amt) + y0*amt
},
hp (x0, freq=1000, Q=1, amt=1) {
var b = _biquads[_filter_i++],
{y1,y2,x1,x2} = b,
w0 = pi2 * freq/sampleRate,
sin_w0 = Math.sin(w0),
cos_w0 = Math.cos(w0),
alpha = sin_w0 / (2.0 * Q),
b0 = (1.0 + cos_w0) / 2.0,
b1 = -(1.0 + cos_w0),
b2 = b0,
a0 = 1.0 + alpha,
a1 = -2.0 * cos_w0,
a2 = 1.0 - alpha,
y0 = (x0*b0+x1*b1+x2*b2-y1*a1-y2*a2)/a0
b.y1=y0; b.y2=y1; b.x1=x0; b.x2=x1;
return x0*(1-amt) + y0*amt
},
bp (x0, freq=1000, Q=1, amt=1) {
var b = _biquads[_filter_i++],
{y1,y2,x1,x2} = b,
w0 = pi2 * freq/sampleRate,
sin_w0 = Math.sin(w0),
cos_w0 = Math.cos(w0),
alpha = sin_w0 / (2.0 * Q),
b0 = sin_w0 / 2.0,
b1 = 0.0,
b2 = -b0,
a0 = 1.0 + alpha,
a1 = -2.0 * cos_w0,
a2 = 1.0 - alpha,
y0 = (x0*b0+x1*b1+x2*b2-y1*a1-y2*a2)/a0
b.y1=y0; b.y2=y1; b.x1=x0; b.x2=x1;
return x0*(1-amt) + y0*amt
},
bpp (x0, freq=1000, Q=1, amt=1) {
var b = _biquads[_filter_i++],
{y1,y2,x1,x2} = b,
w0 = pi2 * freq/sampleRate,
sin_w0 = Math.sin(w0),
cos_w0 = Math.cos(w0),
alpha = sin_w0 / (2.0 * Q),
b0 = alpha,
b1 = 0.0,
b2 = -alpha,
a0 = 1.0 + alpha,
a1 = -2.0 * cos_w0,
a2 = 1.0 - alpha,
y0 = (x0*b0+x1*b1+x2*b2-y1*a1-y2*a2)/a0
b.y1=y0; b.y2=y1; b.x1=x0; b.x2=x1;
return x0*(1-amt) + y0*amt
},
not (x0, freq=1000, Q=1, amt=1) {
var b = _biquads[_filter_i++],
{y1,y2,x1,x2} = b,
w0 = pi2 * freq/sampleRate,
sin_w0 = Math.sin(w0),
cos_w0 = Math.cos(w0),
alpha = sin_w0 / (2.0 * Q),
b0 = 1.0,
b1 = -2.0 * cos_w0,
b2 = 1.0,
a0 = 1.0 + alpha,
a1 = b1,
a2 = 1.0 - alpha,
y0 = (x0*b0+x1*b1+x2*b2-y1*a1-y2*a2)/a0
b.y1=y0; b.y2=y1; b.x1=x0; b.x2=x1;
return x0*(1-amt) + y0*amt
},
ap (x0, freq=1000, Q=1, amt=1) {
var b = _biquads[_filter_i++],
{y1,y2,x1,x2} = b,
w0 = pi2 * freq/sampleRate,
sin_w0 = Math.sin(w0),
cos_w0 = Math.cos(w0),
alpha = sin_w0 / (2.0 * Q),
b0 = 1.0 - alpha,
b1 = -2.0 * cos_w0,
b2 = 1.0 + alpha,
a0 = b2,
a1 = b1,
a2 = b0,
y0 = (x0*b0+x1*b1+x2*b2-y1*a1-y2*a2)/a0
b.y1=y0; b.y2=y1; b.x1=x0; b.x2=x1;
return x0*(1-amt) + y0*amt
},
pk (x0, freq=1000, Q=1, gain=1, amt=1) {
var b = _biquads[_filter_i++],
{y1,y2,x1,x2} = b,
w0 = pi2 * freq/sampleRate,
sin_w0 = Math.sin(w0),
cos_w0 = Math.cos(w0),
alpha = sin_w0 / (2.0 * Q),
a = Math.pow(10.0, gain / 40.0),
b0 = 1.0 + alpha * a,
b1 = -2.0 * cos_w0,
b2 = 1.0 - alpha * a,
a0 = 1.0 + alpha / a,
a1 = b1,
a2 = 1.0 - alpha / a,
y0 = (x0*b0+x1*b1+x2*b2-y1*a1-y2*a2)/a0
b.y1=y0; b.y2=y1; b.x1=x0; b.x2=x1;
return x0*(1-amt) + y0*amt
},
ls (x0, freq=1000, Q=1, gain=1, amt=1) {
var b = _biquads[_filter_i++],
{y1,y2,x1,x2} = b,
w0 = pi2 * freq/sampleRate,
sin_w0 = Math.sin(w0),
cos_w0 = Math.cos(w0),
alpha = sin_w0 / (2.0 * Q),
a = Math.pow(10.0, gain / 40.0),
c = 2.0 * Math.sqrt(a) * alpha,
b0 = a * ((a + 1.0) - (a - 1.0) * cos_w0 + c),
b1 = 2.0 * a * ((a - 1.0) - (a + 1.0) * cos_w0),
b2 = a * ((a + 1.0) - (a - 1.0) * cos_w0 - c),
a0 = (a + 1.0) + (a - 1.0) * cos_w0 + c,
a1 = -2.0 * ((a - 1.0) + (a + 1.0) * cos_w0),
a2 = (a + 1.0) + (a - 1.0) * cos_w0 - c,
y0 = (x0*b0+x1*b1+x2*b2-y1*a1-y2*a2)/a0
b.y1=y0; b.y2=y1; b.x1=x0; b.x2=x1;
return x0*(1-amt) + y0*amt
},
hs (x0, freq=1000, Q=1, gain=1, amt=1) {
var b = _biquads[_filter_i++],
{y1,y2,x1,x2} = b,
w0 = pi2 * freq/sampleRate,
sin_w0 = Math.sin(w0),
cos_w0 = Math.cos(w0),
alpha = sin_w0 / (2.0 * Q),
a = Math.pow(10.0, gain / 40.0),
c = 2.0 * Math.sqrt(a) * alpha,
b0 = a * ((a + 1.0) + (a - 1.0) * cos_w0 + c),
b1 = -2.0 * a * ((a - 1.0) + (a + 1.0) * cos_w0),
b2 = a * ((a + 1.0) + (a - 1.0) * cos_w0 - c),
a0 = (a + 1.0) - (a - 1.0) * cos_w0 + c,
a1 = 2.0 * ((a - 1.0) - (a + 1.0) * cos_w0),
a2 = (a + 1.0) - (a - 1.0) * cos_w0 - c,
y0 = (x0*b0+x1*b1+x2*b2-y1*a1-y2*a2)/a0
b.y1=y0; b.y2=y1; b.x1=x0; b.x2=x1;
return x0*(1-amt) + y0*amt
}
}