tentative bw_src
This commit is contained in:
parent
fd4db8fd4f
commit
db06874a17
215
include/bw_src.h
Normal file
215
include/bw_src.h
Normal file
@ -0,0 +1,215 @@
|
||||
/*
|
||||
* Brickworks
|
||||
*
|
||||
* Copyright (C) 2023 Orastron Srl unipersonale
|
||||
*
|
||||
* Brickworks is free software: you can redistribute it and/or modify
|
||||
* it under the terms of the GNU General Public License as published by
|
||||
* the Free Software Foundation, version 3 of the License.
|
||||
*
|
||||
* Brickworks is distributed in the hope that it will be useful,
|
||||
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
* GNU General Public License for more details.
|
||||
*
|
||||
* You should have received a copy of the GNU General Public License
|
||||
* along with Brickworks. If not, see <http://www.gnu.org/licenses/>.
|
||||
*
|
||||
* File author: Stefano D'Angelo
|
||||
*/
|
||||
|
||||
/*!
|
||||
* module_type {{{ dsp }}}
|
||||
* version {{{ 0.4.0 }}}
|
||||
* requires {{{ bw_config bw_common bw_math }}}
|
||||
* description {{{
|
||||
* Aribtrary-ratio IIR sample rate converter.
|
||||
* }}}
|
||||
* changelog {{{
|
||||
* <ul>
|
||||
* <li>Version <strong>0.4.0</strong>:
|
||||
* <ul>
|
||||
* <li>First release.</li>
|
||||
* </ul>
|
||||
* </li>
|
||||
* </ul>
|
||||
* }}}
|
||||
*/
|
||||
|
||||
#ifndef _BW_SRC_H
|
||||
#define _BW_SRC_H
|
||||
|
||||
#ifdef __cplusplus
|
||||
extern "C" {
|
||||
#endif
|
||||
|
||||
#include <bw_common.h>
|
||||
|
||||
/*! api {{{
|
||||
* #### bw_src_coeffs
|
||||
* ```>>> */
|
||||
typedef struct _bw_src_coeffs bw_src_coeffs;
|
||||
/*! <<<```
|
||||
* Coefficients and related.
|
||||
*
|
||||
* ### bw_src_state
|
||||
* ```>>> */
|
||||
typedef struct _bw_src_state bw_src_state;
|
||||
/*! <<<```
|
||||
* Internal state and related.
|
||||
*
|
||||
* #### bw_src_init()
|
||||
* ```>>> */
|
||||
static inline void bw_src_init(bw_src_coeffs *BW_RESTRICT coeffs, float ratio);
|
||||
/*! <<<```
|
||||
* Initializes input parameter values in `coeffs`.
|
||||
* XXX
|
||||
*
|
||||
* #### bw_src_reset_state()
|
||||
* ```>>> */
|
||||
static inline void bw_src_reset_state(const bw_src_coeffs *BW_RESTRICT coeffs, bw_src_state *BW_RESTRICT state, float x0);
|
||||
/*! <<<```
|
||||
* XXX
|
||||
*
|
||||
* #### bw_src_process()
|
||||
* ```>>> */
|
||||
static inline void bw_src_process(const bw_src_coeffs *BW_RESTRICT coeffs, bw_src_state *BW_RESTRICT state, const float *x, float *y, int *n_in_samples, int *n_out_samples);
|
||||
/*! <<<```
|
||||
* XXX
|
||||
* }}} */
|
||||
|
||||
/*** Implementation ***/
|
||||
|
||||
/* WARNING: This part of the file is not part of the public API. Its content may
|
||||
* change at any time in future versions. Please, do not use it directly. */
|
||||
|
||||
#include <bw_math.h>
|
||||
|
||||
struct _bw_src_coeffs {
|
||||
float r;
|
||||
float a1;
|
||||
float a2;
|
||||
float a3;
|
||||
float a4;
|
||||
float b0;
|
||||
float b1;
|
||||
float b2;
|
||||
float b3;
|
||||
float b4;
|
||||
};
|
||||
|
||||
struct _bw_src_state {
|
||||
float i;
|
||||
float z1;
|
||||
float z2;
|
||||
float z3;
|
||||
float z4;
|
||||
float xz1;
|
||||
float xz2;
|
||||
float xz3;
|
||||
};
|
||||
|
||||
static inline void bw_src_init(bw_src_coeffs *BW_RESTRICT coeffs, float ratio) {
|
||||
coeffs->k = ratio >= 0.f ? 1.f / ratio : ratio;
|
||||
// TODO: better filter, perhaps optimzied coefficients
|
||||
ratio = bw_absf(ratio);
|
||||
coeffs->a1 = (12.56637061435917f - 8.f * ratio) / (2.f * ratio + 3.141592653589793f);
|
||||
coeffs->a2 = (ratio * (24.f * ratio - 75.39822368615503f) + 59.21762640653615f) / (ratio * (4.f * ratio + 12.56637061435917f) + 9.869604401089358f);
|
||||
coeffs->a3 = (ratio * ((150.7964473723101f - 32.f * ratio) * ratio - 236.8705056261446f) + 124.0251067211993f) / (ratio * (ratio * (8.f * ratio + 37.69911184307752f) + 59.21762640653615f) + 31.00627668029982f);
|
||||
coeffs->a4 = (ratio * (ratio * (ratio * (16.f * ratio - 100.5309649148734f) + 236.8705056261446f) - 248.0502134423985f) + 97.40909103400242f) / (ratio * (ratio * (ratio * (16.f * ratio + 100.5309649148734f) + 236.8705056261446f) + 248.0502134423985f) + 97.40909103400242f);
|
||||
coeffs->b0 = 97.40909103400242f / (ratio * (ratio * (ratio * (16.f * ratio + 100.5309649148734f) + 236.8705056261446f) + 248.0502134423985f) + 97.40909103400242f);
|
||||
coeffs->b1 = 4.f * coeffs->b0;
|
||||
coeffs->b2 = 6.f * coeffs->b0;
|
||||
coeffs->b3 = coeffs->b1;
|
||||
coeffs->b4 = coeffs->b0;
|
||||
}
|
||||
|
||||
static inline void bw_src_reset_state(const bw_src_coeffs *BW_RESTRICT coeffs, bw_src_state *BW_RESTRICT state, float x0) {
|
||||
if (coeffs->ratio < 0) {
|
||||
// DF-II
|
||||
state->z1 = x0 / (1.f + coeffs->a1 + coeffs->a2 + coeffs->a3 + coeffs->a4);
|
||||
state->z2 = state->z1;
|
||||
state->z3 = state->z2;
|
||||
state->z4 = state->z3;
|
||||
state->i = 1.f;
|
||||
} else {
|
||||
// TDF-II
|
||||
state->z4 = (coeffs->b4 - coeffs->a4) * x0;
|
||||
state->z3 = (coeffs->b3 - coeffs->a3) * x0 + state->z4;
|
||||
state->z2 = (coeffs->b2 - coeffs->a2) * x0 + state->z3;
|
||||
state->z1 = (coeffs->b1 - coeffs->a1) * x0 + state->z2;
|
||||
state->i = 0.f;
|
||||
}
|
||||
state->xz1 = x0;
|
||||
state->xz2 = x0;
|
||||
state->xz3 = x0;
|
||||
}
|
||||
|
||||
static inline void bw_src_process(const bw_src_coeffs *BW_RESTRICT coeffs, bw_src_state *BW_RESTRICT state, const float *x, float *y, int *n_in_samples, int *n_out_samples) {
|
||||
int i = 0;
|
||||
int j = 0;
|
||||
if (coeffs->k < 0) {
|
||||
while (i < *n_in_samples && j < *n_out_samples) {
|
||||
// DF-II
|
||||
const float z0 = x[i] - coeffs->a1 * state->z1 - coeffs->a2 * state->z2 - coeffs->a3 * state->z3 - coeffs->a4 * state->z4;
|
||||
const float o = coeffs->b0 * z0 + coeffs->b1 * state->z1 + coeffs->b2 * state->z2 + coeffs->b3 * state->z3 + coeffs->b4 * state->z4;
|
||||
state->i -= 1.f;
|
||||
if (state->i <= 0.f) {
|
||||
// 3rd degree Lagrange interpolation + Horner's rule
|
||||
const float k1 = state->xz2 - state->xz1;
|
||||
const float k2 = 0.333333333333333f * (o - state->xz3);
|
||||
const float k3 = o + k1;
|
||||
const float k4 = k1 + o -> state->xz1;
|
||||
const float a = k4 + 0.5f * k4 + k2;
|
||||
const float b = k3 + k1 - 0.5f * (state->xz1 + state->xz3);
|
||||
const float c = 0.5f * (k1 + k2);
|
||||
y[j] = o + state->i * (a + state->i * (b + state->i * c));
|
||||
state->i -= coeffs->k;
|
||||
j++;
|
||||
}
|
||||
state->z4 = state->z3;
|
||||
state->z3 = state->z2;
|
||||
state->z2 = state->z1;
|
||||
state->z1 = z0;
|
||||
state->xz3 = state->xz2;
|
||||
state->xz2 = state->xz1;
|
||||
state->xz1 = o;
|
||||
i++;
|
||||
}
|
||||
} else {
|
||||
while (i < *n_in_samples && j < *n_out_samples) {
|
||||
for (int j = 0; j < coeffs->ratio; j++) {
|
||||
// 3rd degree Lagrange interpolation + Horner's rule
|
||||
const float k1 = state->xz2 - state->xz1;
|
||||
const float k2 = 0.333333333333333f * (x[i] - state->xz3);
|
||||
const float k3 = state->xz3 - k1;
|
||||
const float k4 = state->xz2 - k3;
|
||||
const float a = k4 + 0.5f * k4 + k2;
|
||||
const float b = k3 - k1 - 0.5f * (x[i] + state->xz2);
|
||||
const float c = 0.5f * (k1 + k2);
|
||||
const float o = state->xz3 + state->i * (a + state->i * (b + state->i * c));
|
||||
// TDF-II
|
||||
y[j] = coeffs->b0 * o + state->z1;
|
||||
state->z1 = coeffs->b1 * o - coeffs->a1 * y[j] + state->z2;
|
||||
state->z2 = coeffs->b2 * o - coeffs->a2 * y[j] + state->z3;
|
||||
state->z3 = coeffs->b3 * o - coeffs->a3 * y[j] + state->z4;
|
||||
state->z4 = coeffs->b4 * o - coeffs->a4 * y[j];
|
||||
state->i += coeffs->k;
|
||||
j++;
|
||||
}
|
||||
state->xz3 = state->xz2;
|
||||
state->xz2 = state->xz1;
|
||||
state->xz1 = x[i];
|
||||
state->i -= 1.f;
|
||||
i++;
|
||||
}
|
||||
}
|
||||
*n_in_samples = i;
|
||||
*n_out_sample = j;
|
||||
}
|
||||
|
||||
#ifdef __cplusplus
|
||||
}
|
||||
#endif
|
||||
|
||||
#endif
|
||||
Loading…
Reference in New Issue
Block a user