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