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/opt.h"
  66 #include "libavutil/avassert.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     HZ,
  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     enum WidthType 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, const char *args)
 120 {
 121     BiquadsContext *p = ctx->priv;
 122     int ret;
 123
 124     av_opt_set_defaults(p);
 125
 126     if ((ret = av_set_options_string(p, args, "=", ":")) < 0)
 127         return ret;
 128
 129     if (p->filter_type != biquad) {
 130         if (p->frequency <= 0 || p->width <= 0) {
 131             av_log(ctx, AV_LOG_ERROR, "Invalid frequency %f and/or width %f <= 0\n",
 132                    p->frequency, p->width);
 133             return AVERROR(EINVAL);
 134         }
 135     }
 136
 137     return 0;
 138 }
 139
 140 static int query_formats(AVFilterContext *ctx)
 141 {
 142     AVFilterFormats *formats;
 143     AVFilterChannelLayouts *layouts;
 144     static const enum AVSampleFormat sample_fmts[] = {
 145         AV_SAMPLE_FMT_S16P,
 146         AV_SAMPLE_FMT_S32P,
 147         AV_SAMPLE_FMT_FLTP,
 148         AV_SAMPLE_FMT_DBLP,
 149         AV_SAMPLE_FMT_NONE
 150     };
 151
 152     layouts = ff_all_channel_layouts();
 153     if (!layouts)
 154         return AVERROR(ENOMEM);
 155     ff_set_common_channel_layouts(ctx, layouts);
 156
 157     formats = ff_make_format_list(sample_fmts);
 158     if (!formats)
 159         return AVERROR(ENOMEM);
 160     ff_set_common_formats(ctx, formats);
 161
 162     formats = ff_all_samplerates();
 163     if (!formats)
 164         return AVERROR(ENOMEM);
 165     ff_set_common_samplerates(ctx, formats);
 166
 167     return 0;
 168 }
 169
 170 #define BIQUAD_FILTER(name, type, min, max)                                   \
 171 static void biquad_## name (const void *input, void *output, int len,         \
 172                             double *in1, double *in2,                         \
 173                             double *out1, double *out2,                       \
 174                             double b0, double b1, double b2,                  \
 175                             double a1, double a2)                             \
 176 {                                                                             \
 177     const type *ibuf = input;                                                 \
 178     type *obuf = output;                                                      \
 179     double i1 = *in1;                                                         \
 180     double i2 = *in2;                                                         \
 181     double o1 = *out1;                                                        \
 182     double o2 = *out2;                                                        \
 183     int i;                                                                    \
 184     a1 = -a1;                                                                 \
 185     a2 = -a2;                                                                 \
 186                                                                               \
 187     for (i = 0; i+1 < len; i++) {                                             \
 188         o2 = i2 * b2 + i1 * b1 + ibuf[i] * b0 + o2 * a2 + o1 * a1;            \
 189         i2 = ibuf[i];                                                         \
 190         if (o2 < min) {                                                       \
 191             av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
 192             obuf[i] = min;                                                    \
 193         } else if (o2 > max) {                                                \
 194             av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
 195             obuf[i] = max;                                                    \
 196         } else {                                                              \
 197             obuf[i] = o2;                                                     \
 198         }                                                                     \
 199         i++;                                                                  \
 200         o1 = i1 * b2 + i2 * b1 + ibuf[i] * b0 + o1 * a2 + o2 * a1;            \
 201         i1 = ibuf[i];                                                         \
 202         if (o1 < min) {                                                       \
 203             av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
 204             obuf[i] = min;                                                    \
 205         } else if (o1 > max) {                                                \
 206             av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
 207             obuf[i] = max;                                                    \
 208         } else {                                                              \
 209             obuf[i] = o1;                                                     \
 210         }                                                                     \
 211     }                                                                         \
 212     if (i < len) {                                                            \
 213         double o0 = ibuf[i] * b0 + i1 * b1 + i2 * b2 + o1 * a1 + o2 * a2;     \
 214         i2 = i1;                                                              \
 215         i1 = ibuf[i];                                                         \
 216         o2 = o1;                                                              \
 217         o1 = o0;                                                              \
 218         if (o0 < min) {                                                       \
 219             av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
 220             obuf[i] = min;                                                    \
 221         } else if (o0 > max) {                                                \
 222             av_log(NULL, AV_LOG_WARNING, "clipping\n");                       \
 223             obuf[i] = max;                                                    \
 224         } else {                                                              \
 225             obuf[i] = o0;                                                     \
 226         }                                                                     \
 227     }                                                                         \
 228     *in1  = i1;                                                               \
 229     *in2  = i2;                                                               \
 230     *out1 = o1;                                                               \
 231     *out2 = o2;                                                               \
 232 }
 233
 234 BIQUAD_FILTER(s16, int16_t, INT16_MIN, INT16_MAX)
 235 BIQUAD_FILTER(s32, int32_t, INT32_MIN, INT32_MAX)
 236 BIQUAD_FILTER(flt, float,   -1., 1.)
 237 BIQUAD_FILTER(dbl, double,  -1., 1.)
 238
 239 static int config_output(AVFilterLink *outlink)
 240 {
 241     AVFilterContext *ctx    = outlink->src;
 242     BiquadsContext *p       = ctx->priv;
 243     AVFilterLink *inlink    = ctx->inputs[0];
 244     double A = exp(p->gain / 40 * log(10.));
 245     double w0 = 2 * M_PI * p->frequency / inlink->sample_rate;
 246     double alpha;
 247
 248     if (w0 > M_PI) {
 249         av_log(ctx, AV_LOG_ERROR,
 250                "Invalid frequency %f. Frequency must be less than half the sample-rate %d.\n",
 251                p->frequency, inlink->sample_rate);
 252         return AVERROR(EINVAL);
 253     }
 254
 255     switch (p->width_type) {
 256     case NONE:
 257         alpha = 0.0;
 258         break;
 259     case HZ:
 260         alpha = sin(w0) / (2 * p->frequency / p->width);
 261         break;
 262     case OCTAVE:
 263         alpha = sin(w0) * sinh(log(2.) / 2 * p->width * w0 / sin(w0));
 264         break;
 265     case QFACTOR:
 266         alpha = sin(w0) / (2 * p->width);
 267         break;
 268     case SLOPE:
 269         alpha = sin(w0) / 2 * sqrt((A + 1 / A) * (1 / p->width - 1) + 2);
 270         break;
 271     default:
 272         av_assert0(0);
 273     }
 274
 275     switch (p->filter_type) {
 276     case biquad:
 277         break;
 278     case equalizer:
 279         p->a0 =   1 + alpha / A;
 280         p->a1 =  -2 * cos(w0);
 281         p->a2 =   1 - alpha / A;
 282         p->b0 =   1 + alpha * A;
 283         p->b1 =  -2 * cos(w0);
 284         p->b2 =   1 - alpha * A;
 285         break;
 286     case bass:
 287         p->a0 =          (A + 1) + (A - 1) * cos(w0) + 2 * sqrt(A) * alpha;
 288         p->a1 =    -2 * ((A - 1) + (A + 1) * cos(w0));
 289         p->a2 =          (A + 1) + (A - 1) * cos(w0) - 2 * sqrt(A) * alpha;
 290         p->b0 =     A * ((A + 1) - (A - 1) * cos(w0) + 2 * sqrt(A) * alpha);
 291         p->b1 = 2 * A * ((A - 1) - (A + 1) * cos(w0));
 292         p->b2 =     A * ((A + 1) - (A - 1) * cos(w0) - 2 * sqrt(A) * alpha);
 293         break;
 294     case treble:
 295         p->a0 =          (A + 1) - (A - 1) * cos(w0) + 2 * sqrt(A) * alpha;
 296         p->a1 =     2 * ((A - 1) - (A + 1) * cos(w0));
 297         p->a2 =          (A + 1) - (A - 1) * cos(w0) - 2 * sqrt(A) * alpha;
 298         p->b0 =     A * ((A + 1) + (A - 1) * cos(w0) + 2 * sqrt(A) * alpha);
 299         p->b1 =-2 * A * ((A - 1) + (A + 1) * cos(w0));
 300         p->b2 =     A * ((A + 1) + (A - 1) * cos(w0) - 2 * sqrt(A) * alpha);
 301         break;
 302     case bandpass:
 303         if (p->csg) {
 304             p->a0 =  1 + alpha;
 305             p->a1 = -2 * cos(w0);
 306             p->a2 =  1 - alpha;
 307             p->b0 =  sin(w0) / 2;
 308             p->b1 =  0;
 309             p->b2 = -sin(w0) / 2;
 310         } else {
 311             p->a0 =  1 + alpha;
 312             p->a1 = -2 * cos(w0);
 313             p->a2 =  1 - alpha;
 314             p->b0 =  alpha;
 315             p->b1 =  0;
 316             p->b2 = -alpha;
 317         }
 318         break;
 319     case bandreject:
 320         p->a0 =  1 + alpha;
 321         p->a1 = -2 * cos(w0);
 322         p->a2 =  1 - alpha;
 323         p->b0 =  1;
 324         p->b1 = -2 * cos(w0);
 325         p->b2 =  1;
 326         break;
 327     case lowpass:
 328         if (p->poles == 1) {
 329             p->a0 = 1;
 330             p->a1 = -exp(-w0);
 331             p->a2 = 0;
 332             p->b0 = 1 + p->a1;
 333             p->b1 = 0;
 334             p->b2 = 0;
 335         } else {
 336             p->a0 =  1 + alpha;
 337             p->a1 = -2 * cos(w0);
 338             p->a2 =  1 - alpha;
 339             p->b0 = (1 - cos(w0)) / 2;
 340             p->b1 =  1 - cos(w0);
 341             p->b2 = (1 - cos(w0)) / 2;
 342         }
 343         break;
 344     case highpass:
 345         if (p->poles == 1) {
 346             p->a0 = 1;
 347             p->a1 = -exp(-w0);
 348             p->a2 = 0;
 349             p->b0 = (1 - p->a1) / 2;
 350             p->b1 = -p->b0;
 351             p->b2 = 0;
 352         } else {
 353             p->a0 =   1 + alpha;
 354             p->a1 =  -2 * cos(w0);
 355             p->a2 =   1 - alpha;
 356             p->b0 =  (1 + cos(w0)) / 2;
 357             p->b1 = -(1 + cos(w0));
 358             p->b2 =  (1 + cos(w0)) / 2;
 359         }
 360         break;
 361     case allpass:
 362         p->a0 =  1 + alpha;
 363         p->a1 = -2 * cos(w0);
 364         p->a2 =  1 - alpha;
 365         p->b0 =  1 - alpha;
 366         p->b1 = -2 * cos(w0);
 367         p->b2 =  1 + alpha;
 368         break;
 369     default:
 370         av_assert0(0);
 371     }
 372
 373     p->a1 /= p->a0;
 374     p->a2 /= p->a0;
 375     p->b0 /= p->a0;
 376     p->b1 /= p->a0;
 377     p->b2 /= p->a0;
 378
 379     p->cache = av_realloc_f(p->cache, sizeof(ChanCache), inlink->channels);
 380     if (!p->cache)
 381         return AVERROR(ENOMEM);
 382
 383     switch (inlink->format) {
 384     case AV_SAMPLE_FMT_S16P: p->filter = biquad_s16; break;
 385     case AV_SAMPLE_FMT_S32P: p->filter = biquad_s32; break;
 386     case AV_SAMPLE_FMT_FLTP: p->filter = biquad_flt; break;
 387     case AV_SAMPLE_FMT_DBLP: p->filter = biquad_dbl; break;
 388     default: av_assert0(0);
 389     }
 390
 391     return 0;
 392 }
 393
 394 static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *buf)
 395 {
 396     BiquadsContext *p       = inlink->dst->priv;
 397     AVFilterLink *outlink   = inlink->dst->outputs[0];
 398     AVFilterBufferRef *out_buf;
 399     int nb_samples = buf->audio->nb_samples;
 400     int ch;
 401
 402     if (buf->perms & AV_PERM_WRITE) {
 403         out_buf = buf;
 404     } else {
 405         out_buf = ff_get_audio_buffer(inlink, AV_PERM_WRITE, nb_samples);
 406         if (!out_buf)
 407             return AVERROR(ENOMEM);
 408         out_buf->pts = buf->pts;
 409     }
 410
 411     for (ch = 0; ch < buf->audio->channels; ch++)
 412         p->filter(buf->extended_data[ch],
 413                   out_buf->extended_data[ch], nb_samples,
 414                   &p->cache[ch].i1, &p->cache[ch].i2,
 415                   &p->cache[ch].o1, &p->cache[ch].o2,
 416                   p->b0, p->b1, p->b2, p->a1, p->a2);
 417
 418     if (buf != out_buf)
 419         avfilter_unref_buffer(buf);
 420
 421     return ff_filter_frame(outlink, out_buf);
 422 }
 423
 424 static av_cold void uninit(AVFilterContext *ctx)
 425 {
 426     BiquadsContext *p = ctx->priv;
 427
 428     av_freep(&p->cache);
 429     av_opt_free(p);
 430 }
 431
 432 static const AVFilterPad inputs[] = {
 433     {
 434         .name         = "default",
 435         .type         = AVMEDIA_TYPE_AUDIO,
 436         .filter_frame = filter_frame,
 437     },
 438     { NULL }
 439 };
 440
 441 static const AVFilterPad outputs[] = {
 442     {
 443         .name         = "default",
 444         .type         = AVMEDIA_TYPE_AUDIO,
 445         .config_props = config_output,
 446     },
 447     { NULL }
 448 };
 449
 450 #define OFFSET(x) offsetof(BiquadsContext, x)
 451 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 452
 453 #define DEFINE_BIQUAD_FILTER(name_, description_)                       \
 454 AVFILTER_DEFINE_CLASS(name_);                                           \
 455 static av_cold int name_##_init(AVFilterContext *ctx, const char *args) \
 456 {                                                                       \
 457     BiquadsContext *p = ctx->priv;                                      \
 458     p->class = &name_##_class;                                          \
 459     p->filter_type = name_;                                             \
 460     return init(ctx, args);                                             \
 461 }                                                                       \
 462                                                          \
 463 AVFilter avfilter_af_##name_ = {                         \
 464     .name          = #name_,                             \
 465     .description   = NULL_IF_CONFIG_SMALL(description_), \
 466     .priv_size     = sizeof(BiquadsContext),             \
 467     .init          = name_##_init,                       \
 468     .uninit        = uninit,                             \
 469     .query_formats = query_formats,                      \
 470     .inputs        = inputs,                             \
 471     .outputs       = outputs,                            \
 472     .priv_class    = &name_##_class,                     \
 473 }
 474
 475 #if CONFIG_EQUALIZER_FILTER
 476 static const AVOption equalizer_options[] = {
 477     {"frequency", "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=0}, 0, 999999, FLAGS},
 478     {"f",         "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=0}, 0, 999999, FLAGS},
 479     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HZ, SLOPE, FLAGS, "width_type"},
 480     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HZ}, 0, 0, FLAGS, "width_type"},
 481     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 482     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 483     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 484     {"width", "set band-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 999, FLAGS},
 485     {"w",     "set band-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 999, FLAGS},
 486     {"gain", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
 487     {"g",    "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
 488     {NULL},
 489 };
 490
 491 DEFINE_BIQUAD_FILTER(equalizer, "Apply two-pole peaking equalization (EQ) filter.");
 492 #endif  /* CONFIG_EQUALIZER_FILTER */
 493 #if CONFIG_BASS_FILTER
 494 static const AVOption bass_options[] = {
 495     {"frequency", "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=100}, 0, 999999, FLAGS},
 496     {"f",         "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=100}, 0, 999999, FLAGS},
 497     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HZ, SLOPE, FLAGS, "width_type"},
 498     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HZ}, 0, 0, FLAGS, "width_type"},
 499     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 500     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 501     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 502     {"width", "set shelf transition steep", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 99999, FLAGS},
 503     {"w",     "set shelf transition steep", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 99999, FLAGS},
 504     {"gain", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
 505     {"g",    "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
 506     {NULL},
 507 };
 508
 509 DEFINE_BIQUAD_FILTER(bass, "Boost or cut lower frequencies.");
 510 #endif  /* CONFIG_BASS_FILTER */
 511 #if CONFIG_TREBLE_FILTER
 512 static const AVOption treble_options[] = {
 513     {"frequency", "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 514     {"f",         "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 515     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HZ, SLOPE, FLAGS, "width_type"},
 516     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HZ}, 0, 0, FLAGS, "width_type"},
 517     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 518     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 519     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 520     {"width", "set shelf transition steep", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 99999, FLAGS},
 521     {"w",     "set shelf transition steep", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 99999, FLAGS},
 522     {"gain", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
 523     {"g",    "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
 524     {NULL},
 525 };
 526
 527 DEFINE_BIQUAD_FILTER(treble, "Boost or cut upper frequencies.");
 528 #endif  /* CONFIG_TREBLE_FILTER */
 529 #if CONFIG_BANDPASS_FILTER
 530 static const AVOption bandpass_options[] = {
 531     {"frequency", "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 532     {"f",         "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 533     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HZ, SLOPE, FLAGS, "width_type"},
 534     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HZ}, 0, 0, FLAGS, "width_type"},
 535     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 536     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 537     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 538     {"width", "set band-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 999, FLAGS},
 539     {"w",     "set band-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 999, FLAGS},
 540     {"csg",   "use constant skirt gain", OFFSET(csg), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, FLAGS},
 541     {NULL},
 542 };
 543
 544 DEFINE_BIQUAD_FILTER(bandpass, "Apply a two-pole Butterworth band-pass filter.");
 545 #endif  /* CONFIG_BANDPASS_FILTER */
 546 #if CONFIG_BANDREJECT_FILTER
 547 static const AVOption bandreject_options[] = {
 548     {"frequency", "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 549     {"f",         "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 550     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HZ, SLOPE, FLAGS, "width_type"},
 551     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HZ}, 0, 0, FLAGS, "width_type"},
 552     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 553     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 554     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 555     {"width", "set band-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 999, FLAGS},
 556     {"w",     "set band-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 999, FLAGS},
 557     {NULL},
 558 };
 559
 560 DEFINE_BIQUAD_FILTER(bandreject, "Apply a two-pole Butterworth band-reject filter.");
 561 #endif  /* CONFIG_BANDREJECT_FILTER */
 562 #if CONFIG_LOWPASS_FILTER
 563 static const AVOption lowpass_options[] = {
 564     {"frequency", "set frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=500}, 0, 999999, FLAGS},
 565     {"f",         "set frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=500}, 0, 999999, FLAGS},
 566     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HZ, SLOPE, FLAGS, "width_type"},
 567     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HZ}, 0, 0, FLAGS, "width_type"},
 568     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 569     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 570     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 571     {"width", "set width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.707}, 0, 99999, FLAGS},
 572     {"w",     "set width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.707}, 0, 99999, FLAGS},
 573     {"poles", "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, FLAGS},
 574     {"p",     "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, FLAGS},
 575     {NULL},
 576 };
 577
 578 DEFINE_BIQUAD_FILTER(lowpass, "Apply a low-pass filter with 3dB point frequency.");
 579 #endif  /* CONFIG_LOWPASS_FILTER */
 580 #if CONFIG_HIGHPASS_FILTER
 581 static const AVOption highpass_options[] = {
 582     {"frequency", "set frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 583     {"f",         "set frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 584     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=QFACTOR}, HZ, SLOPE, FLAGS, "width_type"},
 585     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HZ}, 0, 0, FLAGS, "width_type"},
 586     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 587     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 588     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 589     {"width", "set width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.707}, 0, 99999, FLAGS},
 590     {"w",     "set width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.707}, 0, 99999, FLAGS},
 591     {"poles", "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, FLAGS},
 592     {"p",     "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, FLAGS},
 593     {NULL},
 594 };
 595
 596 DEFINE_BIQUAD_FILTER(highpass, "Apply a high-pass filter with 3dB point frequency.");
 597 #endif  /* CONFIG_HIGHPASS_FILTER */
 598 #if CONFIG_ALLPASS_FILTER
 599 static const AVOption allpass_options[] = {
 600     {"frequency", "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 601     {"f",         "set central frequency", OFFSET(frequency), AV_OPT_TYPE_DOUBLE, {.dbl=3000}, 0, 999999, FLAGS},
 602     {"width_type", "set filter-width type", OFFSET(width_type), AV_OPT_TYPE_INT, {.i64=HZ}, HZ, SLOPE, FLAGS, "width_type"},
 603     {"h", "Hz", 0, AV_OPT_TYPE_CONST, {.i64=HZ}, 0, 0, FLAGS, "width_type"},
 604     {"q", "Q-Factor", 0, AV_OPT_TYPE_CONST, {.i64=QFACTOR}, 0, 0, FLAGS, "width_type"},
 605     {"o", "octave", 0, AV_OPT_TYPE_CONST, {.i64=OCTAVE}, 0, 0, FLAGS, "width_type"},
 606     {"s", "slope", 0, AV_OPT_TYPE_CONST, {.i64=SLOPE}, 0, 0, FLAGS, "width_type"},
 607     {"width", "set filter-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=707.1}, 0, 99999, FLAGS},
 608     {"w",     "set filter-width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=707.1}, 0, 99999, FLAGS},
 609     {NULL},
 610 };
 611
 612 DEFINE_BIQUAD_FILTER(allpass, "Apply a two-pole all-pass filter.");
 613 #endif  /* CONFIG_ALLPASS_FILTER */
 614 #if CONFIG_BIQUAD_FILTER
 615 static const AVOption biquad_options[] = {
 616     {"a0", NULL, OFFSET(a0), AV_OPT_TYPE_DOUBLE, {.dbl=1}, INT16_MAX, INT16_MAX, FLAGS},
 617     {"a1", NULL, OFFSET(a1), AV_OPT_TYPE_DOUBLE, {.dbl=1}, INT16_MAX, INT16_MAX, FLAGS},
 618     {"a2", NULL, OFFSET(a2), AV_OPT_TYPE_DOUBLE, {.dbl=1}, INT16_MAX, INT16_MAX, FLAGS},
 619     {"b0", NULL, OFFSET(b0), AV_OPT_TYPE_DOUBLE, {.dbl=1}, INT16_MAX, INT16_MAX, FLAGS},
 620     {"b1", NULL, OFFSET(b1), AV_OPT_TYPE_DOUBLE, {.dbl=1}, INT16_MAX, INT16_MAX, FLAGS},
 621     {"b2", NULL, OFFSET(b2), AV_OPT_TYPE_DOUBLE, {.dbl=1}, INT16_MAX, INT16_MAX, FLAGS},
 622     {NULL},
 623 };
 624
 625 DEFINE_BIQUAD_FILTER(biquad, "Apply a biquad IIR filter with the given coefficients.");
 626 #endif  /* CONFIG_BIQUAD_FILTER */