1 /*
2 * Copyright (c) 2019 The FFmpeg Project
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 #include "libavutil/avassert.h"
22 #include "libavutil/channel_layout.h"
23 #include "libavutil/opt.h"
24 #include "avfilter.h"
25 #include "audio.h"
26 #include "formats.h"
27
28 #define MAX_OVERSAMPLE 64
29
30 enum ASoftClipTypes {
31 ASC_HARD = -1,
32 ASC_TANH,
33 ASC_ATAN,
34 ASC_CUBIC,
35 ASC_EXP,
36 ASC_ALG,
37 ASC_QUINTIC,
38 ASC_SIN,
39 ASC_ERF,
40 NB_TYPES,
41 };
42
43 typedef struct Lowpass {
44 float fb0, fb1, fb2;
45 float fa0, fa1, fa2;
46
47 double db0, db1, db2;
48 double da0, da1, da2;
49 } Lowpass;
50
51 typedef struct ASoftClipContext {
52 const AVClass *class;
53
54 int type;
55 int oversample;
56 int64_t delay;
57 double threshold;
58 double output;
59 double param;
60
61 Lowpass lowpass[MAX_OVERSAMPLE];
62 AVFrame *frame[2];
63
64 void (*filter)(struct ASoftClipContext *s, void **dst, const void **src,
65 int nb_samples, int channels, int start, int end);
66 } ASoftClipContext;
67
68 #define OFFSET(x) offsetof(ASoftClipContext, x)
69 #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
70
71 static const AVOption asoftclip_options[] = {
72 { "type", "set softclip type", OFFSET(type), AV_OPT_TYPE_INT, {.i64=0}, -1, NB_TYPES-1, A, "types" },
73 { "hard", NULL, 0, AV_OPT_TYPE_CONST, {.i64=ASC_HARD}, 0, 0, A, "types" },
74 { "tanh", NULL, 0, AV_OPT_TYPE_CONST, {.i64=ASC_TANH}, 0, 0, A, "types" },
75 { "atan", NULL, 0, AV_OPT_TYPE_CONST, {.i64=ASC_ATAN}, 0, 0, A, "types" },
76 { "cubic", NULL, 0, AV_OPT_TYPE_CONST, {.i64=ASC_CUBIC}, 0, 0, A, "types" },
77 { "exp", NULL, 0, AV_OPT_TYPE_CONST, {.i64=ASC_EXP}, 0, 0, A, "types" },
78 { "alg", NULL, 0, AV_OPT_TYPE_CONST, {.i64=ASC_ALG}, 0, 0, A, "types" },
79 { "quintic", NULL, 0, AV_OPT_TYPE_CONST, {.i64=ASC_QUINTIC},0, 0, A, "types" },
80 { "sin", NULL, 0, AV_OPT_TYPE_CONST, {.i64=ASC_SIN}, 0, 0, A, "types" },
81 { "erf", NULL, 0, AV_OPT_TYPE_CONST, {.i64=ASC_ERF}, 0, 0, A, "types" },
82 { "threshold", "set softclip threshold", OFFSET(threshold), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0.000001, 1, A },
83 { "output", "set softclip output gain", OFFSET(output), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0.000001, 16, A },
84 { "param", "set softclip parameter", OFFSET(param), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0.01, 3, A },
85 { "oversample", "set oversample factor", OFFSET(oversample), AV_OPT_TYPE_INT, {.i64=1}, 1, MAX_OVERSAMPLE, A },
86 { NULL }
87 };
88
89 AVFILTER_DEFINE_CLASS(asoftclip);
90
get_lowpass(Lowpass * s,double frequency,double sample_rate)91 static void get_lowpass(Lowpass *s,
92 double frequency,
93 double sample_rate)
94 {
95 double w0 = 2 * M_PI * frequency / sample_rate;
96 double alpha = sin(w0) / (2 * 0.8);
97 double factor;
98
99 s->da0 = 1 + alpha;
100 s->da1 = -2 * cos(w0);
101 s->da2 = 1 - alpha;
102 s->db0 = (1 - cos(w0)) / 2;
103 s->db1 = 1 - cos(w0);
104 s->db2 = (1 - cos(w0)) / 2;
105
106 s->da1 /= s->da0;
107 s->da2 /= s->da0;
108 s->db0 /= s->da0;
109 s->db1 /= s->da0;
110 s->db2 /= s->da0;
111 s->da0 /= s->da0;
112
113 factor = (s->da0 + s->da1 + s->da2) / (s->db0 + s->db1 + s->db2);
114 s->db0 *= factor;
115 s->db1 *= factor;
116 s->db2 *= factor;
117
118 s->fa0 = s->da0;
119 s->fa1 = s->da1;
120 s->fa2 = s->da2;
121 s->fb0 = s->db0;
122 s->fb1 = s->db1;
123 s->fb2 = s->db2;
124 }
125
run_lowpassf(const Lowpass * const s,float src,float * w)126 static inline float run_lowpassf(const Lowpass *const s,
127 float src, float *w)
128 {
129 float dst;
130
131 dst = src * s->fb0 + w[0];
132 w[0] = s->fb1 * src + w[1] - s->fa1 * dst;
133 w[1] = s->fb2 * src - s->fa2 * dst;
134
135 return dst;
136 }
137
filter_flt(ASoftClipContext * s,void ** dptr,const void ** sptr,int nb_samples,int channels,int start,int end)138 static void filter_flt(ASoftClipContext *s,
139 void **dptr, const void **sptr,
140 int nb_samples, int channels,
141 int start, int end)
142 {
143 const int oversample = s->oversample;
144 const int nb_osamples = nb_samples * oversample;
145 const float scale = oversample > 1 ? oversample * 0.5f : 1.f;
146 float threshold = s->threshold;
147 float gain = s->output * threshold;
148 float factor = 1.f / threshold;
149 float param = s->param;
150
151 for (int c = start; c < end; c++) {
152 float *w = (float *)(s->frame[0]->extended_data[c]) + 2 * (oversample - 1);
153 const float *src = sptr[c];
154 float *dst = dptr[c];
155
156 for (int n = 0; n < nb_samples; n++) {
157 dst[oversample * n] = src[n];
158
159 for (int m = 1; m < oversample; m++)
160 dst[oversample * n + m] = 0.f;
161 }
162
163 for (int n = 0; n < nb_osamples && oversample > 1; n++)
164 dst[n] = run_lowpassf(&s->lowpass[oversample - 1], dst[n], w);
165
166 switch (s->type) {
167 case ASC_HARD:
168 for (int n = 0; n < nb_osamples; n++) {
169 dst[n] = av_clipf(dst[n] * factor, -1.f, 1.f);
170 dst[n] *= gain;
171 }
172 break;
173 case ASC_TANH:
174 for (int n = 0; n < nb_osamples; n++) {
175 dst[n] = tanhf(dst[n] * factor * param);
176 dst[n] *= gain;
177 }
178 break;
179 case ASC_ATAN:
180 for (int n = 0; n < nb_osamples; n++) {
181 dst[n] = 2.f / M_PI * atanf(dst[n] * factor * param);
182 dst[n] *= gain;
183 }
184 break;
185 case ASC_CUBIC:
186 for (int n = 0; n < nb_osamples; n++) {
187 float sample = dst[n] * factor;
188
189 if (FFABS(sample) >= 1.5f)
190 dst[n] = FFSIGN(sample);
191 else
192 dst[n] = sample - 0.1481f * powf(sample, 3.f);
193 dst[n] *= gain;
194 }
195 break;
196 case ASC_EXP:
197 for (int n = 0; n < nb_osamples; n++) {
198 dst[n] = 2.f / (1.f + expf(-2.f * dst[n] * factor)) - 1.;
199 dst[n] *= gain;
200 }
201 break;
202 case ASC_ALG:
203 for (int n = 0; n < nb_osamples; n++) {
204 float sample = dst[n] * factor;
205
206 dst[n] = sample / (sqrtf(param + sample * sample));
207 dst[n] *= gain;
208 }
209 break;
210 case ASC_QUINTIC:
211 for (int n = 0; n < nb_osamples; n++) {
212 float sample = dst[n] * factor;
213
214 if (FFABS(sample) >= 1.25)
215 dst[n] = FFSIGN(sample);
216 else
217 dst[n] = sample - 0.08192f * powf(sample, 5.f);
218 dst[n] *= gain;
219 }
220 break;
221 case ASC_SIN:
222 for (int n = 0; n < nb_osamples; n++) {
223 float sample = dst[n] * factor;
224
225 if (FFABS(sample) >= M_PI_2)
226 dst[n] = FFSIGN(sample);
227 else
228 dst[n] = sinf(sample);
229 dst[n] *= gain;
230 }
231 break;
232 case ASC_ERF:
233 for (int n = 0; n < nb_osamples; n++) {
234 dst[n] = erff(dst[n] * factor);
235 dst[n] *= gain;
236 }
237 break;
238 default:
239 av_assert0(0);
240 }
241
242 w = (float *)(s->frame[1]->extended_data[c]) + 2 * (oversample - 1);
243 for (int n = 0; n < nb_osamples && oversample > 1; n++)
244 dst[n] = run_lowpassf(&s->lowpass[oversample - 1], dst[n], w);
245
246 for (int n = 0; n < nb_samples; n++)
247 dst[n] = dst[n * oversample] * scale;
248 }
249 }
250
run_lowpassd(const Lowpass * const s,double src,double * w)251 static inline double run_lowpassd(const Lowpass *const s,
252 double src, double *w)
253 {
254 double dst;
255
256 dst = src * s->db0 + w[0];
257 w[0] = s->db1 * src + w[1] - s->da1 * dst;
258 w[1] = s->db2 * src - s->da2 * dst;
259
260 return dst;
261 }
262
filter_dbl(ASoftClipContext * s,void ** dptr,const void ** sptr,int nb_samples,int channels,int start,int end)263 static void filter_dbl(ASoftClipContext *s,
264 void **dptr, const void **sptr,
265 int nb_samples, int channels,
266 int start, int end)
267 {
268 const int oversample = s->oversample;
269 const int nb_osamples = nb_samples * oversample;
270 const double scale = oversample > 1 ? oversample * 0.5 : 1.;
271 double threshold = s->threshold;
272 double gain = s->output * threshold;
273 double factor = 1. / threshold;
274 double param = s->param;
275
276 for (int c = start; c < end; c++) {
277 double *w = (double *)(s->frame[0]->extended_data[c]) + 2 * (oversample - 1);
278 const double *src = sptr[c];
279 double *dst = dptr[c];
280
281 for (int n = 0; n < nb_samples; n++) {
282 dst[oversample * n] = src[n];
283
284 for (int m = 1; m < oversample; m++)
285 dst[oversample * n + m] = 0.f;
286 }
287
288 for (int n = 0; n < nb_osamples && oversample > 1; n++)
289 dst[n] = run_lowpassd(&s->lowpass[oversample - 1], dst[n], w);
290
291 switch (s->type) {
292 case ASC_HARD:
293 for (int n = 0; n < nb_osamples; n++) {
294 dst[n] = av_clipd(dst[n] * factor, -1., 1.);
295 dst[n] *= gain;
296 }
297 break;
298 case ASC_TANH:
299 for (int n = 0; n < nb_osamples; n++) {
300 dst[n] = tanh(dst[n] * factor * param);
301 dst[n] *= gain;
302 }
303 break;
304 case ASC_ATAN:
305 for (int n = 0; n < nb_osamples; n++) {
306 dst[n] = 2. / M_PI * atan(dst[n] * factor * param);
307 dst[n] *= gain;
308 }
309 break;
310 case ASC_CUBIC:
311 for (int n = 0; n < nb_osamples; n++) {
312 double sample = dst[n] * factor;
313
314 if (FFABS(sample) >= 1.5)
315 dst[n] = FFSIGN(sample);
316 else
317 dst[n] = sample - 0.1481 * pow(sample, 3.);
318 dst[n] *= gain;
319 }
320 break;
321 case ASC_EXP:
322 for (int n = 0; n < nb_osamples; n++) {
323 dst[n] = 2. / (1. + exp(-2. * dst[n] * factor)) - 1.;
324 dst[n] *= gain;
325 }
326 break;
327 case ASC_ALG:
328 for (int n = 0; n < nb_osamples; n++) {
329 double sample = dst[n] * factor;
330
331 dst[n] = sample / (sqrt(param + sample * sample));
332 dst[n] *= gain;
333 }
334 break;
335 case ASC_QUINTIC:
336 for (int n = 0; n < nb_osamples; n++) {
337 double sample = dst[n] * factor;
338
339 if (FFABS(sample) >= 1.25)
340 dst[n] = FFSIGN(sample);
341 else
342 dst[n] = sample - 0.08192 * pow(sample, 5.);
343 dst[n] *= gain;
344 }
345 break;
346 case ASC_SIN:
347 for (int n = 0; n < nb_osamples; n++) {
348 double sample = dst[n] * factor;
349
350 if (FFABS(sample) >= M_PI_2)
351 dst[n] = FFSIGN(sample);
352 else
353 dst[n] = sin(sample);
354 dst[n] *= gain;
355 }
356 break;
357 case ASC_ERF:
358 for (int n = 0; n < nb_osamples; n++) {
359 dst[n] = erf(dst[n] * factor);
360 dst[n] *= gain;
361 }
362 break;
363 default:
364 av_assert0(0);
365 }
366
367 w = (double *)(s->frame[1]->extended_data[c]) + 2 * (oversample - 1);
368 for (int n = 0; n < nb_osamples && oversample > 1; n++)
369 dst[n] = run_lowpassd(&s->lowpass[oversample - 1], dst[n], w);
370
371 for (int n = 0; n < nb_samples; n++)
372 dst[n] = dst[n * oversample] * scale;
373 }
374 }
375
config_input(AVFilterLink * inlink)376 static int config_input(AVFilterLink *inlink)
377 {
378 AVFilterContext *ctx = inlink->dst;
379 ASoftClipContext *s = ctx->priv;
380
381 switch (inlink->format) {
382 case AV_SAMPLE_FMT_FLTP: s->filter = filter_flt; break;
383 case AV_SAMPLE_FMT_DBLP: s->filter = filter_dbl; break;
384 default: av_assert0(0);
385 }
386
387 s->frame[0] = ff_get_audio_buffer(inlink, 2 * MAX_OVERSAMPLE);
388 s->frame[1] = ff_get_audio_buffer(inlink, 2 * MAX_OVERSAMPLE);
389 if (!s->frame[0] || !s->frame[1])
390 return AVERROR(ENOMEM);
391
392 for (int i = 0; i < MAX_OVERSAMPLE; i++) {
393 get_lowpass(&s->lowpass[i], inlink->sample_rate / 2, inlink->sample_rate * (i + 1));
394 }
395
396 return 0;
397 }
398
399 typedef struct ThreadData {
400 AVFrame *in, *out;
401 int nb_samples;
402 int channels;
403 } ThreadData;
404
filter_channels(AVFilterContext * ctx,void * arg,int jobnr,int nb_jobs)405 static int filter_channels(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
406 {
407 ASoftClipContext *s = ctx->priv;
408 ThreadData *td = arg;
409 AVFrame *out = td->out;
410 AVFrame *in = td->in;
411 const int channels = td->channels;
412 const int nb_samples = td->nb_samples;
413 const int start = (channels * jobnr) / nb_jobs;
414 const int end = (channels * (jobnr+1)) / nb_jobs;
415
416 s->filter(s, (void **)out->extended_data, (const void **)in->extended_data,
417 nb_samples, channels, start, end);
418
419 return 0;
420 }
421
filter_frame(AVFilterLink * inlink,AVFrame * in)422 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
423 {
424 AVFilterContext *ctx = inlink->dst;
425 ASoftClipContext *s = ctx->priv;
426 AVFilterLink *outlink = ctx->outputs[0];
427 int nb_samples, channels;
428 ThreadData td;
429 AVFrame *out;
430
431 if (av_frame_is_writable(in) && s->oversample == 1) {
432 out = in;
433 } else {
434 out = ff_get_audio_buffer(outlink, in->nb_samples * s->oversample);
435 if (!out) {
436 av_frame_free(&in);
437 return AVERROR(ENOMEM);
438 }
439 av_frame_copy_props(out, in);
440 }
441
442 nb_samples = in->nb_samples;
443 channels = in->ch_layout.nb_channels;
444
445 td.in = in;
446 td.out = out;
447 td.nb_samples = nb_samples;
448 td.channels = channels;
449 ff_filter_execute(ctx, filter_channels, &td, NULL,
450 FFMIN(channels, ff_filter_get_nb_threads(ctx)));
451
452 if (out != in)
453 av_frame_free(&in);
454
455 out->nb_samples /= s->oversample;
456 return ff_filter_frame(outlink, out);
457 }
458
uninit(AVFilterContext * ctx)459 static av_cold void uninit(AVFilterContext *ctx)
460 {
461 ASoftClipContext *s = ctx->priv;
462
463 av_frame_free(&s->frame[0]);
464 av_frame_free(&s->frame[1]);
465 }
466
467 static const AVFilterPad inputs[] = {
468 {
469 .name = "default",
470 .type = AVMEDIA_TYPE_AUDIO,
471 .filter_frame = filter_frame,
472 .config_props = config_input,
473 },
474 };
475
476 static const AVFilterPad outputs[] = {
477 {
478 .name = "default",
479 .type = AVMEDIA_TYPE_AUDIO,
480 },
481 };
482
483 const AVFilter ff_af_asoftclip = {
484 .name = "asoftclip",
485 .description = NULL_IF_CONFIG_SMALL("Audio Soft Clipper."),
486 .priv_size = sizeof(ASoftClipContext),
487 .priv_class = &asoftclip_class,
488 FILTER_INPUTS(inputs),
489 FILTER_OUTPUTS(outputs),
490 FILTER_SAMPLEFMTS(AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_DBLP),
491 .uninit = uninit,
492 .process_command = ff_filter_process_command,
493 .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
494 AVFILTER_FLAG_SLICE_THREADS,
495 };
496