| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | /* | ||
| 2 | * IIR filter | ||
| 3 | * Copyright (c) 2008 Konstantin Shishkov | ||
| 4 | * | ||
| 5 | * This file is part of FFmpeg. | ||
| 6 | * | ||
| 7 | * FFmpeg is free software; you can redistribute it and/or | ||
| 8 | * modify it under the terms of the GNU Lesser General Public | ||
| 9 | * License as published by the Free Software Foundation; either | ||
| 10 | * version 2.1 of the License, or (at your option) any later version. | ||
| 11 | * | ||
| 12 | * FFmpeg is distributed in the hope that it will be useful, | ||
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
| 15 | * Lesser General Public License for more details. | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU Lesser General Public | ||
| 18 | * License along with FFmpeg; if not, write to the Free Software | ||
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | ||
| 20 | */ | ||
| 21 | |||
| 22 | /** | ||
| 23 | * @file | ||
| 24 | * different IIR filters implementation | ||
| 25 | */ | ||
| 26 | |||
| 27 | #include <math.h> | ||
| 28 | |||
| 29 | #include "config.h" | ||
| 30 | |||
| 31 | #include "libavutil/attributes.h" | ||
| 32 | #include "libavutil/common.h" | ||
| 33 | #include "libavutil/log.h" | ||
| 34 | #include "libavutil/mem.h" | ||
| 35 | |||
| 36 | #include "iirfilter.h" | ||
| 37 | |||
| 38 | /** | ||
| 39 | * IIR filter global parameters | ||
| 40 | */ | ||
| 41 | typedef struct FFIIRFilterCoeffs { | ||
| 42 | int order; | ||
| 43 | float gain; | ||
| 44 | int *cx; | ||
| 45 | float *cy; | ||
| 46 | } FFIIRFilterCoeffs; | ||
| 47 | |||
| 48 | /** | ||
| 49 | * IIR filter state | ||
| 50 | */ | ||
| 51 | typedef struct FFIIRFilterState { | ||
| 52 | float x[1]; | ||
| 53 | } FFIIRFilterState; | ||
| 54 | |||
| 55 | /// maximum supported filter order | ||
| 56 | #define MAXORDER 30 | ||
| 57 | |||
| 58 | 1 | static av_cold int butterworth_init_coeffs(void *avc, | |
| 59 | struct FFIIRFilterCoeffs *c, | ||
| 60 | enum IIRFilterMode filt_mode, | ||
| 61 | int order, float cutoff_ratio, | ||
| 62 | float stopband) | ||
| 63 | { | ||
| 64 | int i, j; | ||
| 65 | double wa; | ||
| 66 | double p[MAXORDER + 1][2]; | ||
| 67 | |||
| 68 |
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1 | if (filt_mode != FF_FILTER_MODE_LOWPASS) { |
| 69 | ✗ | av_log(avc, AV_LOG_ERROR, "Butterworth filter currently only supports " | |
| 70 | "low-pass filter mode\n"); | ||
| 71 | ✗ | return -1; | |
| 72 | } | ||
| 73 |
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1 | if (order & 1) { |
| 74 | ✗ | av_log(avc, AV_LOG_ERROR, "Butterworth filter currently only supports " | |
| 75 | "even filter orders\n"); | ||
| 76 | ✗ | return -1; | |
| 77 | } | ||
| 78 | |||
| 79 | 1 | wa = 2 * tan(M_PI * 0.5 * cutoff_ratio); | |
| 80 | |||
| 81 | 1 | c->cx[0] = 1; | |
| 82 |
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3 | for (i = 1; i < (order >> 1) + 1; i++) |
| 83 | 2 | c->cx[i] = c->cx[i - 1] * (order - i + 1LL) / i; | |
| 84 | |||
| 85 | 1 | p[0][0] = 1.0; | |
| 86 | 1 | p[0][1] = 0.0; | |
| 87 |
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5 | for (i = 1; i <= order; i++) |
| 88 | 4 | p[i][0] = p[i][1] = 0.0; | |
| 89 |
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5 | for (i = 0; i < order; i++) { |
| 90 | double zp[2]; | ||
| 91 | 4 | double th = (i + (order >> 1) + 0.5) * M_PI / order; | |
| 92 | double a_re, a_im, c_re, c_im; | ||
| 93 | 4 | zp[0] = cos(th) * wa; | |
| 94 | 4 | zp[1] = sin(th) * wa; | |
| 95 | 4 | a_re = zp[0] + 2.0; | |
| 96 | 4 | c_re = zp[0] - 2.0; | |
| 97 | 4 | a_im = | |
| 98 | 4 | c_im = zp[1]; | |
| 99 | 4 | zp[0] = (a_re * c_re + a_im * c_im) / (c_re * c_re + c_im * c_im); | |
| 100 | 4 | zp[1] = (a_im * c_re - a_re * c_im) / (c_re * c_re + c_im * c_im); | |
| 101 | |||
| 102 |
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20 | for (j = order; j >= 1; j--) { |
| 103 | 16 | a_re = p[j][0]; | |
| 104 | 16 | a_im = p[j][1]; | |
| 105 | 16 | p[j][0] = a_re * zp[0] - a_im * zp[1] + p[j - 1][0]; | |
| 106 | 16 | p[j][1] = a_re * zp[1] + a_im * zp[0] + p[j - 1][1]; | |
| 107 | } | ||
| 108 | 4 | a_re = p[0][0] * zp[0] - p[0][1] * zp[1]; | |
| 109 | 4 | p[0][1] = p[0][0] * zp[1] + p[0][1] * zp[0]; | |
| 110 | 4 | p[0][0] = a_re; | |
| 111 | } | ||
| 112 | 1 | c->gain = p[order][0]; | |
| 113 |
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5 | for (i = 0; i < order; i++) { |
| 114 | 4 | c->gain += p[i][0]; | |
| 115 | 4 | c->cy[i] = (-p[i][0] * p[order][0] + -p[i][1] * p[order][1]) / | |
| 116 | 4 | (p[order][0] * p[order][0] + p[order][1] * p[order][1]); | |
| 117 | } | ||
| 118 | 1 | c->gain /= 1 << order; | |
| 119 | |||
| 120 | 1 | return 0; | |
| 121 | } | ||
| 122 | |||
| 123 | ✗ | static av_cold int biquad_init_coeffs(void *avc, struct FFIIRFilterCoeffs *c, | |
| 124 | enum IIRFilterMode filt_mode, int order, | ||
| 125 | float cutoff_ratio, float stopband) | ||
| 126 | { | ||
| 127 | double cos_w0, sin_w0; | ||
| 128 | double a0, x0, x1; | ||
| 129 | |||
| 130 | ✗ | if (filt_mode != FF_FILTER_MODE_HIGHPASS && | |
| 131 | filt_mode != FF_FILTER_MODE_LOWPASS) { | ||
| 132 | ✗ | av_log(avc, AV_LOG_ERROR, "Biquad filter currently only supports " | |
| 133 | "high-pass and low-pass filter modes\n"); | ||
| 134 | ✗ | return -1; | |
| 135 | } | ||
| 136 | ✗ | if (order != 2) { | |
| 137 | ✗ | av_log(avc, AV_LOG_ERROR, "Biquad filter must have order of 2\n"); | |
| 138 | ✗ | return -1; | |
| 139 | } | ||
| 140 | |||
| 141 | ✗ | cos_w0 = cos(M_PI * cutoff_ratio); | |
| 142 | ✗ | sin_w0 = sin(M_PI * cutoff_ratio); | |
| 143 | |||
| 144 | ✗ | a0 = 1.0 + (sin_w0 / 2.0); | |
| 145 | |||
| 146 | ✗ | if (filt_mode == FF_FILTER_MODE_HIGHPASS) { | |
| 147 | ✗ | c->gain = ((1.0 + cos_w0) / 2.0) / a0; | |
| 148 | ✗ | x0 = ((1.0 + cos_w0) / 2.0) / a0; | |
| 149 | ✗ | x1 = (-(1.0 + cos_w0)) / a0; | |
| 150 | } else { // FF_FILTER_MODE_LOWPASS | ||
| 151 | ✗ | c->gain = ((1.0 - cos_w0) / 2.0) / a0; | |
| 152 | ✗ | x0 = ((1.0 - cos_w0) / 2.0) / a0; | |
| 153 | ✗ | x1 = (1.0 - cos_w0) / a0; | |
| 154 | } | ||
| 155 | ✗ | c->cy[0] = (-1.0 + (sin_w0 / 2.0)) / a0; | |
| 156 | ✗ | c->cy[1] = (2.0 * cos_w0) / a0; | |
| 157 | |||
| 158 | // divide by gain to make the x coeffs integers. | ||
| 159 | // during filtering, the delay state will include the gain multiplication | ||
| 160 | ✗ | c->cx[0] = lrintf(x0 / c->gain); | |
| 161 | ✗ | c->cx[1] = lrintf(x1 / c->gain); | |
| 162 | |||
| 163 | ✗ | return 0; | |
| 164 | } | ||
| 165 | |||
| 166 | 1 | av_cold struct FFIIRFilterCoeffs *ff_iir_filter_init_coeffs(void *avc, | |
| 167 | enum IIRFilterType filt_type, | ||
| 168 | enum IIRFilterMode filt_mode, | ||
| 169 | int order, float cutoff_ratio, | ||
| 170 | float stopband, float ripple) | ||
| 171 | { | ||
| 172 | FFIIRFilterCoeffs *c; | ||
| 173 | 1 | int ret = 0; | |
| 174 | |||
| 175 |
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1 | if (order <= 0 || order > MAXORDER || cutoff_ratio >= 1.0) |
| 176 | ✗ | return NULL; | |
| 177 | |||
| 178 |
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1 | if (!(c = av_mallocz(sizeof(*c))) || |
| 179 |
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1 | !(c->cx = av_malloc (sizeof(c->cx[0]) * ((order >> 1) + 1))) || |
| 180 |
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1 | !(c->cy = av_malloc (sizeof(c->cy[0]) * order))) |
| 181 | ✗ | goto free; | |
| 182 | 1 | c->order = order; | |
| 183 | |||
| 184 |
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1 | switch (filt_type) { |
| 185 | 1 | case FF_FILTER_TYPE_BUTTERWORTH: | |
| 186 | 1 | ret = butterworth_init_coeffs(avc, c, filt_mode, order, cutoff_ratio, | |
| 187 | stopband); | ||
| 188 | 1 | break; | |
| 189 | ✗ | case FF_FILTER_TYPE_BIQUAD: | |
| 190 | ✗ | ret = biquad_init_coeffs(avc, c, filt_mode, order, cutoff_ratio, | |
| 191 | stopband); | ||
| 192 | ✗ | break; | |
| 193 | ✗ | default: | |
| 194 | ✗ | av_log(avc, AV_LOG_ERROR, "filter type is not currently implemented\n"); | |
| 195 | ✗ | goto free; | |
| 196 | } | ||
| 197 | |||
| 198 |
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1 | if (!ret) |
| 199 | 1 | return c; | |
| 200 | ✗ | free: | |
| 201 | ✗ | ff_iir_filter_free_coeffsp(&c); | |
| 202 | ✗ | return NULL; | |
| 203 | } | ||
| 204 | |||
| 205 | 1 | av_cold struct FFIIRFilterState *ff_iir_filter_init_state(int order) | |
| 206 | { | ||
| 207 | 1 | FFIIRFilterState *s = av_mallocz(sizeof(FFIIRFilterState) + sizeof(s->x[0]) * (order - 1)); | |
| 208 | 1 | return s; | |
| 209 | } | ||
| 210 | |||
| 211 | #define CONV_S16(dest, source) dest = av_clip_int16(lrintf(source)); | ||
| 212 | |||
| 213 | #define CONV_FLT(dest, source) dest = source; | ||
| 214 | |||
| 215 | #define FILTER_BW_O4_1(i0, i1, i2, i3, fmt) \ | ||
| 216 | in = *src0 * c->gain + \ | ||
| 217 | c->cy[0] * s->x[i0] + \ | ||
| 218 | c->cy[1] * s->x[i1] + \ | ||
| 219 | c->cy[2] * s->x[i2] + \ | ||
| 220 | c->cy[3] * s->x[i3]; \ | ||
| 221 | res = (s->x[i0] + in) * 1 + \ | ||
| 222 | (s->x[i1] + s->x[i3]) * 4 + \ | ||
| 223 | s->x[i2] * 6; \ | ||
| 224 | CONV_ ## fmt(*dst0, res) \ | ||
| 225 | s->x[i0] = in; \ | ||
| 226 | src0 += sstep; \ | ||
| 227 | dst0 += dstep; | ||
| 228 | |||
| 229 | #define FILTER_BW_O4(type, fmt) { \ | ||
| 230 | int i; \ | ||
| 231 | const type *src0 = src; \ | ||
| 232 | type *dst0 = dst; \ | ||
| 233 | for (i = 0; i < size; i += 4) { \ | ||
| 234 | float in, res; \ | ||
| 235 | FILTER_BW_O4_1(0, 1, 2, 3, fmt); \ | ||
| 236 | FILTER_BW_O4_1(1, 2, 3, 0, fmt); \ | ||
| 237 | FILTER_BW_O4_1(2, 3, 0, 1, fmt); \ | ||
| 238 | FILTER_BW_O4_1(3, 0, 1, 2, fmt); \ | ||
| 239 | } \ | ||
| 240 | } | ||
| 241 | |||
| 242 | #define FILTER_DIRECT_FORM_II(type, fmt) { \ | ||
| 243 | int i; \ | ||
| 244 | const type *src0 = src; \ | ||
| 245 | type *dst0 = dst; \ | ||
| 246 | for (i = 0; i < size; i++) { \ | ||
| 247 | int j; \ | ||
| 248 | float in, res; \ | ||
| 249 | in = *src0 * c->gain; \ | ||
| 250 | for (j = 0; j < c->order; j++) \ | ||
| 251 | in += c->cy[j] * s->x[j]; \ | ||
| 252 | res = s->x[0] + in + s->x[c->order >> 1] * c->cx[c->order >> 1]; \ | ||
| 253 | for (j = 1; j < c->order >> 1; j++) \ | ||
| 254 | res += (s->x[j] + s->x[c->order - j]) * c->cx[j]; \ | ||
| 255 | for (j = 0; j < c->order - 1; j++) \ | ||
| 256 | s->x[j] = s->x[j + 1]; \ | ||
| 257 | CONV_ ## fmt(*dst0, res) \ | ||
| 258 | s->x[c->order - 1] = in; \ | ||
| 259 | src0 += sstep; \ | ||
| 260 | dst0 += dstep; \ | ||
| 261 | } \ | ||
| 262 | } | ||
| 263 | |||
| 264 | #define FILTER_O2(type, fmt) { \ | ||
| 265 | int i; \ | ||
| 266 | const type *src0 = src; \ | ||
| 267 | type *dst0 = dst; \ | ||
| 268 | for (i = 0; i < size; i++) { \ | ||
| 269 | float in = *src0 * c->gain + \ | ||
| 270 | s->x[0] * c->cy[0] + \ | ||
| 271 | s->x[1] * c->cy[1]; \ | ||
| 272 | CONV_ ## fmt(*dst0, s->x[0] + in + s->x[1] * c->cx[1]) \ | ||
| 273 | s->x[0] = s->x[1]; \ | ||
| 274 | s->x[1] = in; \ | ||
| 275 | src0 += sstep; \ | ||
| 276 | dst0 += dstep; \ | ||
| 277 | } \ | ||
| 278 | } | ||
| 279 | |||
| 280 | /** | ||
| 281 | * Perform IIR filtering on floating-point input samples. | ||
| 282 | * | ||
| 283 | * @param coeffs pointer to filter coefficients | ||
| 284 | * @param state pointer to filter state | ||
| 285 | * @param size input length | ||
| 286 | * @param src source samples | ||
| 287 | * @param sstep source stride | ||
| 288 | * @param dst filtered samples (destination may be the same as input) | ||
| 289 | * @param dstep destination stride | ||
| 290 | */ | ||
| 291 | ✗ | static void iir_filter_flt(const struct FFIIRFilterCoeffs *c, | |
| 292 | struct FFIIRFilterState *s, int size, | ||
| 293 | const float *src, ptrdiff_t sstep, | ||
| 294 | float *dst, ptrdiff_t dstep) | ||
| 295 | { | ||
| 296 | ✗ | if (c->order == 2) { | |
| 297 | ✗ | FILTER_O2(float, FLT) | |
| 298 | ✗ | } else if (c->order == 4) { | |
| 299 | ✗ | FILTER_BW_O4(float, FLT) | |
| 300 | } else { | ||
| 301 | ✗ | FILTER_DIRECT_FORM_II(float, FLT) | |
| 302 | } | ||
| 303 | ✗ | } | |
| 304 | |||
| 305 | 1 | av_cold void ff_iir_filter_free_statep(struct FFIIRFilterState **state) | |
| 306 | { | ||
| 307 | 1 | av_freep(state); | |
| 308 | 1 | } | |
| 309 | |||
| 310 | 11 | av_cold void ff_iir_filter_free_coeffsp(struct FFIIRFilterCoeffs **coeffsp) | |
| 311 | { | ||
| 312 | 11 | struct FFIIRFilterCoeffs *coeffs = *coeffsp; | |
| 313 |
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11 | if (coeffs) { |
| 314 | 1 | av_freep(&coeffs->cx); | |
| 315 | 1 | av_freep(&coeffs->cy); | |
| 316 | } | ||
| 317 | 11 | av_freep(coeffsp); | |
| 318 | 11 | } | |
| 319 | |||
| 320 | 10 | void ff_iir_filter_init(FFIIRFilterContext *f) { | |
| 321 | 10 | f->filter_flt = iir_filter_flt; | |
| 322 | |||
| 323 | #if HAVE_MIPSFPU | ||
| 324 | ff_iir_filter_init_mips(f); | ||
| 325 | #endif | ||
| 326 | 10 | } | |
| 327 |