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change bp polarity + limit prewarp in bw_svf + cosmetics

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This commit is contained in:
Stefano D'Angelo 2023-09-05 09:46:09 +02:00
parent a16cdd9c73
commit e12db3795a
4 changed files with 18 additions and 12 deletions
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3
TODO
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@ -11,17 +11,14 @@ code:
* mem req -> return value of set sample rate? or sample rate argument of mem req?
* c++ get coeffs/state? or public? src nIn/OutSamples case (array vs single value), delay read/write, process1? process single?
* common smoothing policy (as control rate as possible?) - smoothing control?
* check unititialized warnings (check fxpp_comp in particular vs fxpp_satur)
* IMPLEMENTATION prepocessor def???
semi-specific:
* osc post filter (and one pole init, slew rate, etc.) val from input? set state instead?
* audio rate optional pulse width/slope inputs?
* max_delay -> set sample rate? see reverb
specific:
* svf bandpass out polarity too confusing (inverted in mm2)?
* bw_comb: should also modulate feedback?
* bw_comb: integer target delay values?
* bw_svf/lp1 automatically limited (max) prewarp frequency to avoid instability?
* prewarp control in all derived filtering modules
* src inside distortions? w/ control from outside?
* peak gain + Q ???

3
include/bw_lp1.h
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@ -32,6 +32,7 @@
* <ul>
* <li>Version <strong>1.0.0</strong>:
* <ul>
* <li>Limited actual prewarping frequency to prevent instability.</li>
* <li>Added <code>bw_lp1_reset_state_multi()</code> and updated C++
* API in this regard.</li>
* <li>Now <code>bw_lp1_reset_state()</code> returns the initial output
@ -380,7 +381,7 @@ static inline void bw_lp1_do_update_coeffs(
if (prewarp_freq_changed || cutoff_changed) {
if (prewarp_freq_changed) {
prewarp_freq_cur = bw_one_pole_process1_sticky_rel(&coeffs->smooth_coeffs, &coeffs->smooth_prewarp_freq_state, prewarp_freq);
coeffs->t = bw_tanf(bw_minf(coeffs->t_k * prewarp_freq_cur, 1.569796326794897f));
coeffs->t = bw_tanf(bw_minf(coeffs->t_k * prewarp_freq_cur, 1.567654734141306f)); // max = 0.499 * fs
}
if (cutoff_changed) {
cutoff_cur = bw_one_pole_process1_sticky_rel(&coeffs->smooth_coeffs, &coeffs->smooth_cutoff_state, coeffs->cutoff);

2
include/bw_mm2.h
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@ -352,7 +352,7 @@ static inline void bw_mm2_set_coeff_lp(bw_mm2_coeffs *BW_RESTRICT coeffs, float
}
static inline void bw_mm2_set_coeff_bp(bw_mm2_coeffs *BW_RESTRICT coeffs, float value) {
bw_gain_set_gain_lin(&coeffs->gain_bp_coeffs, -value);
bw_gain_set_gain_lin(&coeffs->gain_bp_coeffs, value);
}
static inline void bw_mm2_set_coeff_hp(bw_mm2_coeffs *BW_RESTRICT coeffs, float value) {

22
include/bw_svf.h
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@ -37,6 +37,9 @@
* <ul>
* <li>Version <strong>1.0.0</strong>:
* <ul>
* <li>Changed model to get positive polarity at the bandpass
* output.</li>
* <li>Limited actual prewarping frequency to prevent instability.</li>
* <li>Added <code>bw_svf_reset_state_multi()</code> and updated C++
* API in this regard.</li>
* <li>Now <code>bw_svf_reset_state()</code> returns the initial output
@ -364,6 +367,7 @@ struct bw_svf_coeffs {
// Coefficients
float t_k;
float prewarp_freq_max;
float t;
float kf;
@ -424,6 +428,7 @@ static inline void bw_svf_set_sample_rate(
bw_one_pole_set_sample_rate(&coeffs->smooth_coeffs, sample_rate);
bw_one_pole_reset_coeffs(&coeffs->smooth_coeffs);
coeffs->t_k = 3.141592653589793f / sample_rate;
coeffs->prewarp_freq_max = 0.499f * sample_rate;
#ifdef BW_DEBUG_DEEP
coeffs->state = bw_svf_coeffs_state_set_sample_rate;
@ -448,8 +453,9 @@ static inline void bw_svf_do_update_coeffs(
cutoff_cur = bw_one_pole_process1_sticky_rel(&coeffs->smooth_coeffs, &coeffs->smooth_cutoff_state, coeffs->cutoff);
if (prewarp_freq_changed) {
prewarp_freq_cur = bw_one_pole_process1_sticky_rel(&coeffs->smooth_coeffs, &coeffs->smooth_prewarp_freq_state, prewarp_freq);
coeffs->t = bw_tanf(coeffs->t_k * prewarp_freq_cur);
coeffs->kf = coeffs->t * bw_rcpf(prewarp_freq_cur);
const float f = bw_minf(prewarp_freq_cur, coeffs->prewarp_freq_max);
coeffs->t = bw_tanf(coeffs->t_k * f);
coeffs->kf = coeffs->t * bw_rcpf(f);
}
coeffs->kbl = coeffs->kf * cutoff_cur;
}
@ -629,11 +635,11 @@ static inline void bw_svf_process1(
BW_ASSERT(y_hp != NULL);
const float kk = coeffs->kf * state->cutoff_z1;
const float lp_xz1 = state->lp_z1 - kk * state->bp_z1;
const float bp_xz1 = state->bp_z1 - kk * state->hp_z1;
*y_hp = coeffs->hp_x * (x + coeffs->hp_hb * bp_xz1 - lp_xz1);
*y_bp = bp_xz1 - coeffs->kbl * *y_hp;
*y_lp = lp_xz1 - coeffs->kbl * *y_bp;
const float lp_xz1 = state->lp_z1 + kk * state->bp_z1;
const float bp_xz1 = state->bp_z1 + kk * state->hp_z1;
*y_hp = coeffs->hp_x * (x - coeffs->hp_hb * bp_xz1 - lp_xz1);
*y_bp = bp_xz1 + coeffs->kbl * *y_hp;
*y_lp = lp_xz1 + coeffs->kbl * *y_bp;
state->hp_z1 = *y_hp;
state->lp_z1 = *y_lp;
state->bp_z1 = *y_bp;
@ -938,6 +944,8 @@ static inline char bw_svf_coeffs_is_valid(
if (coeffs->state >= bw_svf_coeffs_state_set_sample_rate) {
if (!bw_is_finite(coeffs->t_k) || coeffs->t_k <= 0.f)
return 0;
if (!bw_is_finite(coeffs->prewarp_freq_max) || coeffs->prewarp_freq_max <= 0.f)
return 0;
}
if (coeffs->state >= bw_svf_coeffs_state_reset_coeffs) {