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