328 lines
12 KiB
C
328 lines
12 KiB
C
|
/*
|
||
|
|
* IIR filter
|
||
|
|
* Copyright (c) 2008 Konstantin Shishkov
|
||
|
|
*
|
||
|
|
* This file is part of FFmpeg.
|
||
|
|
*
|
||
|
|
* FFmpeg is free software; you can redistribute it and/or
|
||
|
|
* modify it under the terms of the GNU Lesser General Public
|
||
|
|
* License as published by the Free Software Foundation; either
|
||
|
|
* version 2.1 of the License, or (at your option) any later version.
|
||
|
|
*
|
||
|
|
* FFmpeg 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
|
||
|
|
* Lesser General Public License for more details.
|
||
|
|
*
|
||
|
|
* You should have received a copy of the GNU Lesser General Public
|
||
|
|
* License along with FFmpeg; if not, write to the Free Software
|
||
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
||
|
|
*/
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @file
|
||
|
|
* different IIR filters implementation
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <math.h>
|
||
|
|
|
||
|
|
#include "libavutil/attributes.h"
|
||
|
|
#include "libavutil/common.h"
|
||
|
|
|
||
|
|
#include "iirfilter.h"
|
||
|
|
|
||
|
|
/**
|
||
|
|
* IIR filter global parameters
|
||
|
|
*/
|
||
|
|
typedef struct FFIIRFilterCoeffs {
|
||
|
|
int order;
|
||
|
|
float gain;
|
||
|
|
int *cx;
|
||
|
|
float *cy;
|
||
|
|
} FFIIRFilterCoeffs;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* IIR filter state
|
||
|
|
*/
|
||
|
|
typedef struct FFIIRFilterState {
|
||
|
|
float x[1];
|
||
|
|
} FFIIRFilterState;
|
||
|
|
|
||
|
|
/// maximum supported filter order
|
||
|
|
#define MAXORDER 30
|
||
|
|
|
||
|
|
static av_cold int butterworth_init_coeffs(void *avc,
|
||
|
|
struct FFIIRFilterCoeffs *c,
|
||
|
|
enum IIRFilterMode filt_mode,
|
||
|
|
int order, float cutoff_ratio,
|
||
|
|
float stopband)
|
||
|
|
{
|
||
|
|
int i, j;
|
||
|
|
double wa;
|
||
|
|
double p[MAXORDER + 1][2];
|
||
|
|
|
||
|
|
if (filt_mode != FF_FILTER_MODE_LOWPASS) {
|
||
|
|
av_log(avc, AV_LOG_ERROR, "Butterworth filter currently only supports "
|
||
|
|
"low-pass filter mode\n");
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
if (order & 1) {
|
||
|
|
av_log(avc, AV_LOG_ERROR, "Butterworth filter currently only supports "
|
||
|
|
"even filter orders\n");
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
|
||
|
|
wa = 2 * tan(M_PI * 0.5 * cutoff_ratio);
|
||
|
|
|
||
|
|
c->cx[0] = 1;
|
||
|
|
for (i = 1; i < (order >> 1) + 1; i++)
|
||
|
|
c->cx[i] = c->cx[i - 1] * (order - i + 1LL) / i;
|
||
|
|
|
||
|
|
p[0][0] = 1.0;
|
||
|
|
p[0][1] = 0.0;
|
||
|
|
for (i = 1; i <= order; i++)
|
||
|
|
p[i][0] = p[i][1] = 0.0;
|
||
|
|
for (i = 0; i < order; i++) {
|
||
|
|
double zp[2];
|
||
|
|
double th = (i + (order >> 1) + 0.5) * M_PI / order;
|
||
|
|
double a_re, a_im, c_re, c_im;
|
||
|
|
zp[0] = cos(th) * wa;
|
||
|
|
zp[1] = sin(th) * wa;
|
||
|
|
a_re = zp[0] + 2.0;
|
||
|
|
c_re = zp[0] - 2.0;
|
||
|
|
a_im =
|
||
|
|
c_im = zp[1];
|
||
|
|
zp[0] = (a_re * c_re + a_im * c_im) / (c_re * c_re + c_im * c_im);
|
||
|
|
zp[1] = (a_im * c_re - a_re * c_im) / (c_re * c_re + c_im * c_im);
|
||
|
|
|
||
|
|
for (j = order; j >= 1; j--) {
|
||
|
|
a_re = p[j][0];
|
||
|
|
a_im = p[j][1];
|
||
|
|
p[j][0] = a_re * zp[0] - a_im * zp[1] + p[j - 1][0];
|
||
|
|
p[j][1] = a_re * zp[1] + a_im * zp[0] + p[j - 1][1];
|
||
|
|
}
|
||
|
|
a_re = p[0][0] * zp[0] - p[0][1] * zp[1];
|
||
|
|
p[0][1] = p[0][0] * zp[1] + p[0][1] * zp[0];
|
||
|
|
p[0][0] = a_re;
|
||
|
|
}
|
||
|
|
c->gain = p[order][0];
|
||
|
|
for (i = 0; i < order; i++) {
|
||
|
|
c->gain += p[i][0];
|
||
|
|
c->cy[i] = (-p[i][0] * p[order][0] + -p[i][1] * p[order][1]) /
|
||
|
|
(p[order][0] * p[order][0] + p[order][1] * p[order][1]);
|
||
|
|
}
|
||
|
|
c->gain /= 1 << order;
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static av_cold int biquad_init_coeffs(void *avc, struct FFIIRFilterCoeffs *c,
|
||
|
|
enum IIRFilterMode filt_mode, int order,
|
||
|
|
float cutoff_ratio, float stopband)
|
||
|
|
{
|
||
|
|
double cos_w0, sin_w0;
|
||
|
|
double a0, x0, x1;
|
||
|
|
|
||
|
|
if (filt_mode != FF_FILTER_MODE_HIGHPASS &&
|
||
|
|
filt_mode != FF_FILTER_MODE_LOWPASS) {
|
||
|
|
av_log(avc, AV_LOG_ERROR, "Biquad filter currently only supports "
|
||
|
|
"high-pass and low-pass filter modes\n");
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
if (order != 2) {
|
||
|
|
av_log(avc, AV_LOG_ERROR, "Biquad filter must have order of 2\n");
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
|
||
|
|
cos_w0 = cos(M_PI * cutoff_ratio);
|
||
|
|
sin_w0 = sin(M_PI * cutoff_ratio);
|
||
|
|
|
||
|
|
a0 = 1.0 + (sin_w0 / 2.0);
|
||
|
|
|
||
|
|
if (filt_mode == FF_FILTER_MODE_HIGHPASS) {
|
||
|
|
c->gain = ((1.0 + cos_w0) / 2.0) / a0;
|
||
|
|
x0 = ((1.0 + cos_w0) / 2.0) / a0;
|
||
|
|
x1 = (-(1.0 + cos_w0)) / a0;
|
||
|
|
} else { // FF_FILTER_MODE_LOWPASS
|
||
|
|
c->gain = ((1.0 - cos_w0) / 2.0) / a0;
|
||
|
|
x0 = ((1.0 - cos_w0) / 2.0) / a0;
|
||
|
|
x1 = (1.0 - cos_w0) / a0;
|
||
|
|
}
|
||
|
|
c->cy[0] = (-1.0 + (sin_w0 / 2.0)) / a0;
|
||
|
|
c->cy[1] = (2.0 * cos_w0) / a0;
|
||
|
|
|
||
|
|
// divide by gain to make the x coeffs integers.
|
||
|
|
// during filtering, the delay state will include the gain multiplication
|
||
|
|
c->cx[0] = lrintf(x0 / c->gain);
|
||
|
|
c->cx[1] = lrintf(x1 / c->gain);
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
av_cold struct FFIIRFilterCoeffs *ff_iir_filter_init_coeffs(void *avc,
|
||
|
|
enum IIRFilterType filt_type,
|
||
|
|
enum IIRFilterMode filt_mode,
|
||
|
|
int order, float cutoff_ratio,
|
||
|
|
float stopband, float ripple)
|
||
|
|
{
|
||
|
|
FFIIRFilterCoeffs *c;
|
||
|
|
int ret = 0;
|
||
|
|
|
||
|
|
if (order <= 0 || order > MAXORDER || cutoff_ratio >= 1.0)
|
||
|
|
return NULL;
|
||
|
|
|
||
|
|
FF_ALLOCZ_OR_GOTO(avc, c, sizeof(FFIIRFilterCoeffs),
|
||
|
|
init_fail);
|
||
|
|
FF_ALLOC_OR_GOTO(avc, c->cx, sizeof(c->cx[0]) * ((order >> 1) + 1),
|
||
|
|
init_fail);
|
||
|
|
FF_ALLOC_OR_GOTO(avc, c->cy, sizeof(c->cy[0]) * order,
|
||
|
|
init_fail);
|
||
|
|
c->order = order;
|
||
|
|
|
||
|
|
switch (filt_type) {
|
||
|
|
case FF_FILTER_TYPE_BUTTERWORTH:
|
||
|
|
ret = butterworth_init_coeffs(avc, c, filt_mode, order, cutoff_ratio,
|
||
|
|
stopband);
|
||
|
|
break;
|
||
|
|
case FF_FILTER_TYPE_BIQUAD:
|
||
|
|
ret = biquad_init_coeffs(avc, c, filt_mode, order, cutoff_ratio,
|
||
|
|
stopband);
|
||
|
|
break;
|
||
|
|
default:
|
||
|
|
av_log(avc, AV_LOG_ERROR, "filter type is not currently implemented\n");
|
||
|
|
goto init_fail;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (!ret)
|
||
|
|
return c;
|
||
|
|
|
||
|
|
init_fail:
|
||
|
|
ff_iir_filter_free_coeffsp(&c);
|
||
|
|
return NULL;
|
||
|
|
}
|
||
|
|
|
||
|
|
av_cold struct FFIIRFilterState *ff_iir_filter_init_state(int order)
|
||
|
|
{
|
||
|
|
FFIIRFilterState *s = av_mallocz(sizeof(FFIIRFilterState) + sizeof(s->x[0]) * (order - 1));
|
||
|
|
return s;
|
||
|
|
}
|
||
|
|
|
||
|
|
#define CONV_S16(dest, source) dest = av_clip_int16(lrintf(source));
|
||
|
|
|
||
|
|
#define CONV_FLT(dest, source) dest = source;
|
||
|
|
|
||
|
|
#define FILTER_BW_O4_1(i0, i1, i2, i3, fmt) \
|
||
|
|
in = *src0 * c->gain + \
|
||
|
|
c->cy[0] * s->x[i0] + \
|
||
|
|
c->cy[1] * s->x[i1] + \
|
||
|
|
c->cy[2] * s->x[i2] + \
|
||
|
|
c->cy[3] * s->x[i3]; \
|
||
|
|
res = (s->x[i0] + in) * 1 + \
|
||
|
|
(s->x[i1] + s->x[i3]) * 4 + \
|
||
|
|
s->x[i2] * 6; \
|
||
|
|
CONV_ ## fmt(*dst0, res) \
|
||
|
|
s->x[i0] = in; \
|
||
|
|
src0 += sstep; \
|
||
|
|
dst0 += dstep;
|
||
|
|
|
||
|
|
#define FILTER_BW_O4(type, fmt) { \
|
||
|
|
int i; \
|
||
|
|
const type *src0 = src; \
|
||
|
|
type *dst0 = dst; \
|
||
|
|
for (i = 0; i < size; i += 4) { \
|
||
|
|
float in, res; \
|
||
|
|
FILTER_BW_O4_1(0, 1, 2, 3, fmt); \
|
||
|
|
FILTER_BW_O4_1(1, 2, 3, 0, fmt); \
|
||
|
|
FILTER_BW_O4_1(2, 3, 0, 1, fmt); \
|
||
|
|
FILTER_BW_O4_1(3, 0, 1, 2, fmt); \
|
||
|
|
} \
|
||
|
|
}
|
||
|
|
|
||
|
|
#define FILTER_DIRECT_FORM_II(type, fmt) { \
|
||
|
|
int i; \
|
||
|
|
const type *src0 = src; \
|
||
|
|
type *dst0 = dst; \
|
||
|
|
for (i = 0; i < size; i++) { \
|
||
|
|
int j; \
|
||
|
|
float in, res; \
|
||
|
|
in = *src0 * c->gain; \
|
||
|
|
for (j = 0; j < c->order; j++) \
|
||
|
|
in += c->cy[j] * s->x[j]; \
|
||
|
|
res = s->x[0] + in + s->x[c->order >> 1] * c->cx[c->order >> 1]; \
|
||
|
|
for (j = 1; j < c->order >> 1; j++) \
|
||
|
|
res += (s->x[j] + s->x[c->order - j]) * c->cx[j]; \
|
||
|
|
for (j = 0; j < c->order - 1; j++) \
|
||
|
|
s->x[j] = s->x[j + 1]; \
|
||
|
|
CONV_ ## fmt(*dst0, res) \
|
||
|
|
s->x[c->order - 1] = in; \
|
||
|
|
src0 += sstep; \
|
||
|
|
dst0 += dstep; \
|
||
|
|
} \
|
||
|
|
}
|
||
|
|
|
||
|
|
#define FILTER_O2(type, fmt) { \
|
||
|
|
int i; \
|
||
|
|
const type *src0 = src; \
|
||
|
|
type *dst0 = dst; \
|
||
|
|
for (i = 0; i < size; i++) { \
|
||
|
|
float in = *src0 * c->gain + \
|
||
|
|
s->x[0] * c->cy[0] + \
|
||
|
|
s->x[1] * c->cy[1]; \
|
||
|
|
CONV_ ## fmt(*dst0, s->x[0] + in + s->x[1] * c->cx[1]) \
|
||
|
|
s->x[0] = s->x[1]; \
|
||
|
|
s->x[1] = in; \
|
||
|
|
src0 += sstep; \
|
||
|
|
dst0 += dstep; \
|
||
|
|
} \
|
||
|
|
}
|
||
|
|
|
||
|
|
void ff_iir_filter(const struct FFIIRFilterCoeffs *c,
|
||
|
|
struct FFIIRFilterState *s, int size,
|
||
|
|
const int16_t *src, ptrdiff_t sstep,
|
||
|
|
int16_t *dst, ptrdiff_t dstep)
|
||
|
|
{
|
||
|
|
if (c->order == 2) {
|
||
|
|
FILTER_O2(int16_t, S16)
|
||
|
|
} else if (c->order == 4) {
|
||
|
|
FILTER_BW_O4(int16_t, S16)
|
||
|
|
} else {
|
||
|
|
FILTER_DIRECT_FORM_II(int16_t, S16)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
void ff_iir_filter_flt(const struct FFIIRFilterCoeffs *c,
|
||
|
|
struct FFIIRFilterState *s, int size,
|
||
|
|
const float *src, ptrdiff_t sstep,
|
||
|
|
float *dst, ptrdiff_t dstep)
|
||
|
|
{
|
||
|
|
if (c->order == 2) {
|
||
|
|
FILTER_O2(float, FLT)
|
||
|
|
} else if (c->order == 4) {
|
||
|
|
FILTER_BW_O4(float, FLT)
|
||
|
|
} else {
|
||
|
|
FILTER_DIRECT_FORM_II(float, FLT)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
av_cold void ff_iir_filter_free_statep(struct FFIIRFilterState **state)
|
||
|
|
{
|
||
|
|
av_freep(state);
|
||
|
|
}
|
||
|
|
|
||
|
|
av_cold void ff_iir_filter_free_coeffsp(struct FFIIRFilterCoeffs **coeffsp)
|
||
|
|
{
|
||
|
|
struct FFIIRFilterCoeffs *coeffs = *coeffsp;
|
||
|
|
if (coeffs) {
|
||
|
|
av_freep(&coeffs->cx);
|
||
|
|
av_freep(&coeffs->cy);
|
||
|
|
}
|
||
|
|
av_freep(coeffsp);
|
||
|
|
}
|
||
|
|
|
||
|
|
void ff_iir_filter_init(FFIIRFilterContext *f) {
|
||
|
|
f->filter_flt = ff_iir_filter_flt;
|
||
|
|
|
||
|
|
if (HAVE_MIPSFPU)
|
||
|
|
ff_iir_filter_init_mips(f);
|
||
|
|
}
|