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af_silencedetect.c
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1 /*
2  * Copyright (c) 2012 Clément Bœsch <u pkh me>
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 /**
22  * @file
23  * Audio silence detector
24  */
25 
26 #include <float.h> /* DBL_MAX */
27 
28 #include "libavutil/opt.h"
29 #include "libavutil/timestamp.h"
30 #include "audio.h"
31 #include "formats.h"
32 #include "avfilter.h"
33 #include "internal.h"
34 
35 typedef struct SilenceDetectContext {
36  const AVClass *class;
37  double noise; ///< noise amplitude ratio
38  double duration; ///< minimum duration of silence until notification
39  int64_t nb_null_samples; ///< current number of continuous zero samples
40  int64_t start; ///< if silence is detected, this value contains the time of the first zero sample
41  int last_sample_rate; ///< last sample rate to check for sample rate changes
42 
44  int nb_samples, int64_t nb_samples_notify,
45  AVRational time_base);
47 
48 #define OFFSET(x) offsetof(SilenceDetectContext, x)
49 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_AUDIO_PARAM
50 static const AVOption silencedetect_options[] = {
51  { "n", "set noise tolerance", OFFSET(noise), AV_OPT_TYPE_DOUBLE, {.dbl=0.001}, 0, DBL_MAX, FLAGS },
52  { "noise", "set noise tolerance", OFFSET(noise), AV_OPT_TYPE_DOUBLE, {.dbl=0.001}, 0, DBL_MAX, FLAGS },
53  { "d", "set minimum duration in seconds", OFFSET(duration), AV_OPT_TYPE_DOUBLE, {.dbl=2.}, 0, 24*60*60, FLAGS },
54  { "duration", "set minimum duration in seconds", OFFSET(duration), AV_OPT_TYPE_DOUBLE, {.dbl=2.}, 0, 24*60*60, FLAGS },
55  { NULL }
56 };
57 
59 
60 static char *get_metadata_val(AVFrame *insamples, const char *key)
61 {
62  AVDictionaryEntry *e = av_dict_get(insamples->metadata, key, NULL, 0);
63  return e && e->value ? e->value : NULL;
64 }
65 
67  int is_silence, int64_t nb_samples_notify,
68  AVRational time_base)
69 {
70  if (is_silence) {
71  if (!s->start) {
72  s->nb_null_samples++;
73  if (s->nb_null_samples >= nb_samples_notify) {
74  s->start = insamples->pts - (int64_t)(s->duration / av_q2d(time_base) + .5);
75  av_dict_set(&insamples->metadata, "lavfi.silence_start",
76  av_ts2timestr(s->start, &time_base), 0);
77  av_log(s, AV_LOG_INFO, "silence_start: %s\n",
78  get_metadata_val(insamples, "lavfi.silence_start"));
79  }
80  }
81  } else {
82  if (s->start) {
83  av_dict_set(&insamples->metadata, "lavfi.silence_end",
84  av_ts2timestr(insamples->pts, &time_base), 0);
85  av_dict_set(&insamples->metadata, "lavfi.silence_duration",
86  av_ts2timestr(insamples->pts - s->start, &time_base), 0);
88  "silence_end: %s | silence_duration: %s\n",
89  get_metadata_val(insamples, "lavfi.silence_end"),
90  get_metadata_val(insamples, "lavfi.silence_duration"));
91  }
92  s->nb_null_samples = s->start = 0;
93  }
94 }
95 
96 #define SILENCE_DETECT(name, type) \
97 static void silencedetect_##name(SilenceDetectContext *s, AVFrame *insamples, \
98  int nb_samples, int64_t nb_samples_notify, \
99  AVRational time_base) \
100 { \
101  const type *p = (const type *)insamples->data[0]; \
102  const type noise = s->noise; \
103  int i; \
104  \
105  for (i = 0; i < nb_samples; i++, p++) \
106  update(s, insamples, *p < noise && *p > -noise, \
107  nb_samples_notify, time_base); \
108 }
109 
110 SILENCE_DETECT(dbl, double)
111 SILENCE_DETECT(flt, float)
113 SILENCE_DETECT(s16, int16_t)
114 
115 static int config_input(AVFilterLink *inlink)
116 {
117  AVFilterContext *ctx = inlink->dst;
118  SilenceDetectContext *s = ctx->priv;
119 
120  switch (inlink->format) {
121  case AV_SAMPLE_FMT_DBL: s->silencedetect = silencedetect_dbl; break;
122  case AV_SAMPLE_FMT_FLT: s->silencedetect = silencedetect_flt; break;
123  case AV_SAMPLE_FMT_S32:
124  s->noise *= INT32_MAX;
125  s->silencedetect = silencedetect_s32;
126  break;
127  case AV_SAMPLE_FMT_S16:
128  s->noise *= INT16_MAX;
129  s->silencedetect = silencedetect_s16;
130  break;
131  }
132 
133  return 0;
134 }
135 
136 static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
137 {
138  SilenceDetectContext *s = inlink->dst->priv;
139  const int nb_channels = inlink->channels;
140  const int srate = inlink->sample_rate;
141  const int nb_samples = insamples->nb_samples * nb_channels;
142  const int64_t nb_samples_notify = srate * s->duration * nb_channels;
143 
144  // scale number of null samples to the new sample rate
145  if (s->last_sample_rate && s->last_sample_rate != srate)
146  s->nb_null_samples = srate * s->nb_null_samples / s->last_sample_rate;
147  s->last_sample_rate = srate;
148 
149  // TODO: document metadata
150  s->silencedetect(s, insamples, nb_samples, nb_samples_notify,
151  inlink->time_base);
152 
153  return ff_filter_frame(inlink->dst->outputs[0], insamples);
154 }
155 
157 {
160  static const enum AVSampleFormat sample_fmts[] = {
166  };
167  int ret;
168 
169  layouts = ff_all_channel_layouts();
170  if (!layouts)
171  return AVERROR(ENOMEM);
172  ret = ff_set_common_channel_layouts(ctx, layouts);
173  if (ret < 0)
174  return ret;
175 
176  formats = ff_make_format_list(sample_fmts);
177  if (!formats)
178  return AVERROR(ENOMEM);
179  ret = ff_set_common_formats(ctx, formats);
180  if (ret < 0)
181  return ret;
182 
183  formats = ff_all_samplerates();
184  if (!formats)
185  return AVERROR(ENOMEM);
186  return ff_set_common_samplerates(ctx, formats);
187 }
188 
190  {
191  .name = "default",
192  .type = AVMEDIA_TYPE_AUDIO,
193  .config_props = config_input,
194  .filter_frame = filter_frame,
195  },
196  { NULL }
197 };
198 
200  {
201  .name = "default",
202  .type = AVMEDIA_TYPE_AUDIO,
203  },
204  { NULL }
205 };
206 
208  .name = "silencedetect",
209  .description = NULL_IF_CONFIG_SMALL("Detect silence."),
210  .priv_size = sizeof(SilenceDetectContext),
212  .inputs = silencedetect_inputs,
213  .outputs = silencedetect_outputs,
214  .priv_class = &silencedetect_class,
215 };