git.sesse.net Git - ffmpeg/blob - libavfilter/af_biquads.c

   1 /*
   2  * Copyright (c) 2013 Paul B Mahol
   3  * Copyright (c) 2006-2008 Rob Sykes <robs@users.sourceforge.net>
   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  * 2-pole filters designed by Robert Bristow-Johnson <rbj@audioimagination.com>
  24  *   see http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt
  25  *
  26  * 1-pole filters based on code (c) 2000 Chris Bagwell <cbagwell@sprynet.com>
  27  *   Algorithms: Recursive single pole low/high pass filter
  28  *   Reference: The Scientist and Engineer's Guide to Digital Signal Processing
  29  *
  30  *   low-pass: output[N] = input[N] * A + output[N-1] * B
  31  *     X = exp(-2.0 * pi * Fc)
  32  *     A = 1 - X
  33  *     B = X
  34  *     Fc = cutoff freq / sample rate
  35  *
  36  *     Mimics an RC low-pass filter:
  37  *
  38  *     ---/\/\/\/\----------->
  39  *                   |
  40  *                  --- C
  41  *                  ---
  42  *                   |
  43  *                   |
  44  *                   V
  45  *
  46  *   high-pass: output[N] = A0 * input[N] + A1 * input[N-1] + B1 * output[N-1]
  47  *     X  = exp(-2.0 * pi * Fc)
  48  *     A0 = (1 + X) / 2
  49  *     A1 = -(1 + X) / 2
  50  *     B1 = X
  51  *     Fc = cutoff freq / sample rate
  52  *
  53  *     Mimics an RC high-pass filter:
  54  *
  55  *         || C
  56  *     ----||--------->
  57  *         ||    |
  58  *               <
  59  *               > R
  60  *               <
  61  *               |
  62  *               V
  63  */
  64
  65 #include "libavutil/avassert.h"
  66 #include "libavutil/opt.h"
  67 #include "audio.h"
  68 #include "avfilter.h"
  69 #include "internal.h"
  70
  71 enum FilterType {
  72     biquad,
  73     equalizer,
  74     bass,
  75     treble,
  76     band,
  77     bandpass,
  78     bandreject,
  79     allpass,
  80     highpass,
  81     lowpass,
  82 };
  83
  84 enum WidthType {
  85     NONE,
  86     HERTZ,
  87     OCTAVE,
  88     QFACTOR,
  89     SLOPE,
  90 };
  91
  92 typedef struct ChanCache {
  93     double i1, i2;
  94     double o1, o2;
  95 } ChanCache;
  96
  97 typedef struct {
  98     const AVClass *class;
  99
 100     enum FilterType filter_type;
 101     int width_type;
 102     int poles;
 103     int csg;
 104
 105     double gain;
 106     double frequency;
 107     double width;
 108
 109     double a0, a1, a2;
 110     double b0, b1, b2;
 111
 112     ChanCache *cache;
 113
 114     void (*filter)(const void *ibuf, void *obuf, int len,
 115                    double *i1, double *i2, double *o1, double *o2,
 116                    double b0, double b1, double b2, double a1, double a2);
 117 } BiquadsContext;
 118
 119 static av_cold int init(AVFilterContext *ctx)
 120 {
 121     BiquadsContext *s = ctx->priv;
 122
 123     if (s->filter_type != biquad) {
 124         if (s->frequency <= 0 || s->width <= 0) {
 125             av_log(ctx, AV_LOG_ERROR, "Invalid frequency %f and/or width %f <= 0\n",
 126                    s->frequency, s->width);
 127             return AVERROR(EINVAL);
 128         }
 129     }
 130
 131     return 0;
 132 }
 133
 134 static int query_formats(AVFilterContext *ctx)
 135 {
 136     AVFilterFormats *formats;
 137     AVFilterChannelLayouts *layouts;
 138     static const enum AVSampleFormat sample_fmts[] = {
 139         AV_SAMPLE_FMT_S16P,
 140         AV_SAMPLE_FMT_S32P,
 141         AV_SAMPLE_FMT_FLTP,
 142         AV_SAMPLE_FMT_DBLP,
 143         AV_SAMPLE_FMT_NONE
 144     };
 145     int ret;
 146
 147     layouts = ff_all_channel_layouts();
 148     if (!layouts)
 149         return AVERROR(ENOMEM);
 150     ret = ff_set_common_channel_layouts(ctx, layouts);
 151     if (ret < 0)
 152         return ret;
 153
 154     formats = ff_make_format_list(sample_fmts);
 155     if (!formats)
 156         return AVERROR(ENOMEM);
 157     ret = ff_set_common_formats(ctx, formats);
 158     if (ret < 0)
 159         return ret;
 160
 161     formats = ff_all_samplerates();
 162     if (!formats)
 163         return AVERROR(ENOMEM);
 164     return ff_set_common_samplerates(ctx, formats);
 165 }
 166
 167 #define BIQUAD_FILTER(name, type, min, max, need_clipping)                    \
 168 static void biquad_## name (const void *input, void *output, int len,         \
 169                             double *in1, double *in2,                         \
 170                             double *out1, double *out2,                       \
 171                             double b0, double b1, double b2,                  \
 172                             double a1, double a2)                             \
 173 {                                                                             \
 174     const type *ibuf = input;                                                 \
 175     type *obuf = output;                                                      \
 176     double i1 = *in1;                                                         \
 177     double i2 = *in2;                                                         \
 178     double o1 = *out1;                                                        \
 179     double o2 = *out2;                                                        \
 180     int i;                                                                    \
 181     a1 = -a1;                                                                 \
 182     a2 = -a2;                                                                 \
 183                                                                               \
 184     for (i = 0; i+1 < len; i++) {                                             \
 185         o2 = i2 * b2 + i1 * b1 + ibuf[i] * b0 + o2 * a2 + o1 * a1;            \
 186         i2 = ibuf[i];                                                         \
 187         if (need_clipping && o2 < min) {                                      \
 188             av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
 189             obuf[i] = min;                                                    \
 190         } else if (need_clipping && o2 > max) {                               \
 191             av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
 192             obuf[i] = max;                                                    \
 193         } else {                                                              \
 194             obuf[i] = o2;                                                     \
 195         }                                                                     \
 196         i++;                                                                  \
 197         o1 = i1 * b2 + i2 * b1 + ibuf[i] * b0 + o1 * a2 + o2 * a1;            \
 198         i1 = ibuf[i];                                                         \
 199         if (need_clipping && o1 < min) {                                      \
 200             av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
 201             obuf[i] = min;                                                    \
 202         } else if (need_clipping && o1 > max) {                               \
 203             av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
 204             obuf[i] = max;                                                    \
 205         } else {                                                              \
 206             obuf[i] = o1;                                                     \
 207         }                                                                     \
 208     }                                                                         \
 209     if (i < len) {                                                            \
 210         double o0 = ibuf[i] * b0 + i1 * b1 + i2 * b2 + o1 * a1 + o2 * a2;     \
 211         i2 = i1;                                                              \
 212         i1 = ibuf[i];                                                         \
 213         o2 = o1;                                                              \
 214         o1 = o0;                                                              \
 215         if (need_clipping && o0 < min) {                                      \
 216             av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
 217             obuf[i] = min;                                                    \
 218         } else if (need_clipping && o0 > max) {                               \
 219             av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
 220             obuf[i] = max;                                                    \
 221         } else {                                                              \
 222             obuf[i] = o0;                                                     \
 223         }                                                                     \
 224     }                                                                         \
 225     *in1  = i1;                                                               \
 226     *in2  = i2;                                                               \
 227     *out1 = o1;                                                               \
 228     *out2 = o2;                                                               \
 229 }
 230
 231 BIQUAD_FILTER(s16, int16_t, INT16_MIN, INT16_MAX, 1)
 232 BIQUAD_FILTER(s32, int32_t, INT32_MIN, INT32_MAX, 1)
 233 BIQUAD_FILTER(flt, float,   -1., 1., 0)
 234 BIQUAD_FILTER(dbl, double,  -1., 1., 0)
 235
 236 static int config_output(AVFilterLink *outlink)
 237 {
 238     AVFilterContext *ctx    = outlink->src;
 239     BiquadsContext *s       = ctx->priv;
 240     AVFilterLink *inlink    = ctx->inputs[0];
 241     double A = exp(s->gain / 40 * log(10.));
 242     double w0 = 2 * M_PI * s->frequency / inlink->sample_rate;
 243     double alpha;
 244
 245     if (w0 > M_PI) {
 246         av_log(ctx, AV_LOG_ERROR,
 247                "Invalid frequency %f. Frequency must be less than half the sample-rate %d.\n",
 248                s->frequency, inlink->sample_rate);
 249         return AVERROR(EINVAL);
 250     }
 251
 252     switch (s->width_type) {
 253     case NONE:
 254         alpha = 0.0;
 255         break;
 256     case HERTZ:
 257         alpha = sin(w0) / (2 * s->frequency / s->width);
 258         break;
 259     case OCTAVE:
 260         alpha = sin(w0) * sinh(log(2.) / 2 * s->width * w0 / sin(w0));
 261         break;
 262     case QFACTOR:
 263         alpha = sin(w0) / (2 * s->width);
 264         break;
 265     case SLOPE:
 266         alpha = sin(w0) / 2 * sqrt((A + 1 / A) * (1 / s->width - 1) + 2);
 267         break;
 268     default:
 269         av_assert0(0);
 270     }
 271
 272     switch (s->filter_type) {
 273     case biquad:
 274         break;
 275     case equalizer:
 276         s->a0 =   1 + alpha / A;
 277         s->a1 =  -2 * cos(w0);
 278         s->a2 =   1 - alpha / A;
 279         s->b0 =   1 + alpha * A;
 280         s->b1 =  -2 * cos(w0);
 281         s->b2 =   1 - alpha * A;
 282         break;
 283     case bass:
 284         s->a0 =          (A + 1) + (A - 1) * cos(w0) + 2 * sqrt(A) * alpha;
 285         s->a1 =    -2 * ((A - 1) + (A + 1) * cos(w0));
 286         s->a2 =          (A + 1) + (A - 1) * cos(w0) - 2 * sqrt(A) * alpha;
 287         s->b0 =     A * ((A + 1) - (A - 1) * cos(w0) + 2 * sqrt(A) * alpha);
 288         s->b1 = 2 * A * ((A - 1) - (A + 1) * cos(w0));
 289         s->b2 =     A * ((A + 1) - (A - 1) * cos(w0) - 2 * sqrt(A) * alpha);
 290         break;
 291     case treble:
 292         s->a0 =          (A + 1) - (A - 1) * cos(w0) + 2 * sqrt(A) * alpha;
 293         s->a1 =     2 * ((A - 1) - (A + 1) * cos(w0));
 294         s->a2 =          (A + 1) - (A - 1) * cos(w0) - 2 * sqrt(A) * alpha;
 295         s->b0 =     A * ((A + 1) + (A - 1) * cos(w0) + 2 * sqrt(A) * alpha);
 296         s->b1 =-2 * A * ((A - 1) + (A + 1) * cos(w0));
 297         s->b2 =     A * ((A + 1) + (A - 1) * cos(w0) - 2 * sqrt(A) * alpha);
 298         break;
 299     case bandpass:
 300         if (s->csg) {
 301             s->a0 =  1 + alpha;
 302             s->a1 = -2 * cos(w0);
 303             s->a2 =  1 - alpha;
 304             s->b0 =  sin(w0) / 2;
 305             s->b1 =  0;
 306             s->b2 = -sin(w0) / 2;
 307         } else {
 308             s->a0 =  1 + alpha;
 309             s->a1 = -2 * cos(w0);
 310             s->a2 =  1 - alpha;
 311             s->b0 =  alpha;
 312             s->b1 =  0;
 313             s->b2 = -alpha;
 314         }
 315         break;
 316     case bandreject:
 317         s->a0 =  1 + alpha;
 318         s->a1 = -2 * cos(w0);
 319         s->a2 =  1 - alpha;
 320         s->b0 =  1;
 321         s->b1 = -2 * cos(w0);
 322         s->b2 =  1;
 323         break;
 324     case lowpass:
 325         if (s->poles == 1) {
 326             s->a0 = 1;
 327             s->a1 = -exp(-w0);
 328             s->a2 = 0;
 329             s->b0 = 1 + s->a1;
 330             s->b1 = 0;
 331             s->b2 = 0;
 332         } else {
 333             s->a0 =  1 + alpha;
 334             s->a1 = -2 * cos(w0);
 335             s->a2 =  1 - alpha;
 336             s->b0 = (1 - cos(w0)) / 2;
 337             s->b1 =  1 - cos(w0);
 338             s->b2 = (1 - cos(w0)) / 2;
 339         }
 340         break;
 341     case highpass:
 342         if (s->poles == 1) {
 343             s->a0 = 1;
 344             s->a1 = -exp(-w0);
 345             s->a2 = 0;
 346             s->b0 = (1 - s->a1) / 2;
 347             s->b1 = -s->b0;
 348             s->b2 = 0;
 349         } else {
 350             s->a0 =   1 + alpha;
 351             s->a1 =  -2 * cos(w0);
 352             s->a2 =   1 - alpha;
 353             s->b0 =  (1 + cos(w0)) / 2;
 354             s->b1 = -(1 + cos(w0));
 355             s->b2 =  (1 + cos(w0)) / 2;
 356         }
 357         break;
 358     case allpass:
 359         s->a0 =  1 + alpha;
 360         s->a1 = -2 * cos(w0);
 361         s->a2 =  1 - alpha;
 362         s->b0 =  1 - alpha;
 363         s->b1 = -2 * cos(w0);
 364         s->b2 =  1 + alpha;
 365         break;
 366     default:
 367         av_assert0(0);
 368     }
 369
 370     s->a1 /= s->a0;
 371     s->a2 /= s->a0;
 372     s->b0 /= s->a0;
 373     s->b1 /= s->a0;
 374     s->b2 /= s->a0;
 375
 376     s->cache = av_realloc_f(s->cache, sizeof(ChanCache), inlink->channels);
 377     if (!s->cache)
 378         return AVERROR(ENOMEM);
 379     memset(s->cache, 0, sizeof(ChanCache) * inlink->channels);
 380
 381     switch (inlink->format) {
 382     case AV_SAMPLE_FMT_S16P: s->filter = biquad_s16; break;
 383     case AV_SAMPLE_FMT_S32P: s->filter = biquad_s32; break;
 384     case AV_SAMPLE_FMT_FLTP: s->filter = biquad_flt; break;
 385     case AV_SAMPLE_FMT_DBLP: s->filter = biquad_dbl; break;
 386     default: av_assert0(0);
 387     }
 388
 389     return 0;
 390 }
 391
 392 static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
 393 {
 394     BiquadsContext *s       = inlink->dst->priv;
 395     AVFilterLink *outlink   = inlink->dst->outputs[0];
 396     AVFrame *out_buf;
 397     int nb_samples = buf->nb_samples;
 398     int ch;
 399
 400     if (av_frame_is_writable(buf)) {
 401         out_buf = buf;
 402     } else {
 403         out_buf = ff_get_audio_buffer(inlink, nb_samples);
 404         if (!out_buf)
 405             return AVERROR(ENOMEM);
 406         av_frame_copy_props(out_buf, buf);
 407     }
 408
 409     for (ch = 0; ch < av_frame_get_channels(buf); ch++)
 410         s->filter(buf->extended_data[ch],
 411                   out_buf->extended_data[ch], nb_samples,
 412                   &s->cache[ch].i1, &s->cache[ch].i2,
 413                   &s->cache[ch].o1, &s->cache[ch].o2,
 414                   s->b0, s->b1, s->b2, s->a1, s->a2);
 415
 416     if (buf != out_buf)
 417         av_frame_free(&buf);
 418
 419     return ff_filter_frame(outlink, out_buf);
 420 }
 421
 422 static av_cold void uninit(AVFilterContext *ctx)
 423 {
 424     BiquadsContext *s = ctx->priv;
 425
 426     av_freep(&s->cache);
 427 }
 428
 429 static const AVFilterPad inputs[] = {
 430     {
 431         .name         = "default",
 432         .type         = AVMEDIA_TYPE_AUDIO,
 433         .filter_frame = filter_frame,
 434     },
 435     { NULL }
 436 };
 437
 438 static const AVFilterPad outputs[] = {
 439     {
 440         .name         = "default",
 441         .type         = AVMEDIA_TYPE_AUDIO,
 442         .config_props = config_output,
 443     },
 444     { NULL }
 445 };
 446
 447 #define OFFSET(x) offsetof(BiquadsContext, x)
 448 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 449
 450 #define DEFINE_BIQUAD_FILTER(name_, description_)                       \
 451 AVFILTER_DEFINE_CLASS(name_);                                           \
 452 static av_cold int name_##_init(AVFilterContext *ctx) \
 453 {                                                                       \
 454     BiquadsContext *s = ctx->priv;                                      \
 455     s->class = &name_##_class;                                          \
 456     s->filter_type = name_;                                             \
 457     return init(ctx);                                             \
 458 }                                                                       \
 459                                                          \
 460 AVFilter ff_af_##name_ = {                         \
 461     .name          = #name_,                             \
 462     .description   = NULL_IF_CONFIG_SMALL(description_), \
 463     .priv_size     = sizeof(BiquadsContext),             \
 464     .init          = name_##_init,                       \
 465     .uninit        = uninit,                             \
 466     .query_formats = query_formats,                      \
 467     .inputs        = inputs,                             \
 468     .outputs       = outputs,                            \
 469     .priv_class    = &name_##_class,                     \
 470 }
 471
 472 #if CONFIG_EQUALIZER_FILTER
 473 static const AVOption equalizer_options[] = {
 474     {"frequency", "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=0}, 0, 999999, FLAGS},
 475     {"f",         "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=0}, 0, 999999, FLAGS},
 476     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HERTZ, SLOPE, FLAGS, "width_type"},
 477     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HERTZ}, 0, 0, FLAGS, "width_type"},
 478     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 479     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 480     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 481     {"width", "set band-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 999, FLAGS},
 482     {"w",     "set band-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 999, FLAGS},
 483     {"gain", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
 484     {"g",    "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
 485     {NULL}
 486 };
 487
 488 DEFINE_BIQUAD_FILTER(equalizer, "Apply two-pole peaking equalization (EQ) filter.");
 489 #endif  /* CONFIG_EQUALIZER_FILTER */
 490 #if CONFIG_BASS_FILTER
 491 static const AVOption bass_options[] = {
 492     {"frequency", "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=100}, 0, 999999, FLAGS},
 493     {"f",         "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=100}, 0, 999999, FLAGS},
 494     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HERTZ, SLOPE, FLAGS, "width_type"},
 495     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HERTZ}, 0, 0, FLAGS, "width_type"},
 496     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 497     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 498     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 499     {"width", "set shelf transition steep", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 99999, FLAGS},
 500     {"w",     "set shelf transition steep", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 99999, FLAGS},
 501     {"gain", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
 502     {"g",    "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
 503     {NULL}
 504 };
 505
 506 DEFINE_BIQUAD_FILTER(bass, "Boost or cut lower frequencies.");
 507 #endif  /* CONFIG_BASS_FILTER */
 508 #if CONFIG_TREBLE_FILTER
 509 static const AVOption treble_options[] = {
 510     {"frequency", "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 511     {"f",         "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 512     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HERTZ, SLOPE, FLAGS, "width_type"},
 513     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HERTZ}, 0, 0, FLAGS, "width_type"},
 514     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 515     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 516     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 517     {"width", "set shelf transition steep", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 99999, FLAGS},
 518     {"w",     "set shelf transition steep", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 99999, FLAGS},
 519     {"gain", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
 520     {"g",    "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
 521     {NULL}
 522 };
 523
 524 DEFINE_BIQUAD_FILTER(treble, "Boost or cut upper frequencies.");
 525 #endif  /* CONFIG_TREBLE_FILTER */
 526 #if CONFIG_BANDPASS_FILTER
 527 static const AVOption bandpass_options[] = {
 528     {"frequency", "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 529     {"f",         "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 530     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HERTZ, SLOPE, FLAGS, "width_type"},
 531     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HERTZ}, 0, 0, FLAGS, "width_type"},
 532     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 533     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 534     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 535     {"width", "set band-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 999, FLAGS},
 536     {"w",     "set band-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 999, FLAGS},
 537     {"csg",   "use constant skirt gain", OFFSET(csg), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, FLAGS},
 538     {NULL}
 539 };
 540
 541 DEFINE_BIQUAD_FILTER(bandpass, "Apply a two-pole Butterworth band-pass filter.");
 542 #endif  /* CONFIG_BANDPASS_FILTER */
 543 #if CONFIG_BANDREJECT_FILTER
 544 static const AVOption bandreject_options[] = {
 545     {"frequency", "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 546     {"f",         "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 547     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HERTZ, SLOPE, FLAGS, "width_type"},
 548     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HERTZ}, 0, 0, FLAGS, "width_type"},
 549     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 550     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 551     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 552     {"width", "set band-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 999, FLAGS},
 553     {"w",     "set band-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 999, FLAGS},
 554     {NULL}
 555 };
 556
 557 DEFINE_BIQUAD_FILTER(bandreject, "Apply a two-pole Butterworth band-reject filter.");
 558 #endif  /* CONFIG_BANDREJECT_FILTER */
 559 #if CONFIG_LOWPASS_FILTER
 560 static const AVOption lowpass_options[] = {
 561     {"frequency", "set frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=500}, 0, 999999, FLAGS},
 562     {"f",         "set frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=500}, 0, 999999, FLAGS},
 563     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HERTZ, SLOPE, FLAGS, "width_type"},
 564     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HERTZ}, 0, 0, FLAGS, "width_type"},
 565     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 566     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 567     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 568     {"width", "set width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.707}, 0, 99999, FLAGS},
 569     {"w",     "set width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.707}, 0, 99999, FLAGS},
 570     {"poles", "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, FLAGS},
 571     {"p",     "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, FLAGS},
 572     {NULL}
 573 };
 574
 575 DEFINE_BIQUAD_FILTER(lowpass, "Apply a low-pass filter with 3dB point frequency.");
 576 #endif  /* CONFIG_LOWPASS_FILTER */
 577 #if CONFIG_HIGHPASS_FILTER
 578 static const AVOption highpass_options[] = {
 579     {"frequency", "set frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 580     {"f",         "set frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 581     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HERTZ, SLOPE, FLAGS, "width_type"},
 582     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HERTZ}, 0, 0, FLAGS, "width_type"},
 583     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 584     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 585     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 586     {"width", "set width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.707}, 0, 99999, FLAGS},
 587     {"w",     "set width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.707}, 0, 99999, FLAGS},
 588     {"poles", "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, FLAGS},
 589     {"p",     "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, FLAGS},
 590     {NULL}
 591 };
 592
 593 DEFINE_BIQUAD_FILTER(highpass, "Apply a high-pass filter with 3dB point frequency.");
 594 #endif  /* CONFIG_HIGHPASS_FILTER */
 595 #if CONFIG_ALLPASS_FILTER
 596 static const AVOption allpass_options[] = {
 597     {"frequency", "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 598     {"f",         "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 599     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=HERTZ}, HERTZ, SLOPE, FLAGS, "width_type"},
 600     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HERTZ}, 0, 0, FLAGS, "width_type"},
 601     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 602     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 603     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 604     {"width", "set filter-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=707.1}, 0, 99999, FLAGS},
 605     {"w",     "set filter-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=707.1}, 0, 99999, FLAGS},
 606     {NULL}
 607 };
 608
 609 DEFINE_BIQUAD_FILTER(allpass, "Apply a two-pole all-pass filter.");
 610 #endif  /* CONFIG_ALLPASS_FILTER */
 611 #if CONFIG_BIQUAD_FILTER
 612 static const AVOption biquad_options[] = {
 613     {"a0", NULL, OFFSET(a0), AV_OPT_TYPE_DOUBLE, {.dbl=1}, INT16_MIN, INT16_MAX, FLAGS},
 614     {"a1", NULL, OFFSET(a1), AV_OPT_TYPE_DOUBLE, {.dbl=1}, INT16_MIN, INT16_MAX, FLAGS},
 615     {"a2", NULL, OFFSET(a2), AV_OPT_TYPE_DOUBLE, {.dbl=1}, INT16_MIN, INT16_MAX, FLAGS},
 616     {"b0", NULL, OFFSET(b0), AV_OPT_TYPE_DOUBLE, {.dbl=1}, INT16_MIN, INT16_MAX, FLAGS},
 617     {"b1", NULL, OFFSET(b1), AV_OPT_TYPE_DOUBLE, {.dbl=1}, INT16_MIN, INT16_MAX, FLAGS},
 618     {"b2", NULL, OFFSET(b2), AV_OPT_TYPE_DOUBLE, {.dbl=1}, INT16_MIN, INT16_MAX, FLAGS},
 619     {NULL}
 620 };
 621
 622 DEFINE_BIQUAD_FILTER(biquad, "Apply a biquad IIR filter with the given coefficients.");
 623 #endif  /* CONFIG_BIQUAD_FILTER */