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 int64_t duration; ///< minimum duration of silence until notification
39 int mono; ///< mono mode : check each channel separately (default = check when ALL channels are silent)
40 int channels; ///< number of channels
41 int independent_channels; ///< number of entries in following arrays (always 1 in mono mode)
42 int64_t *nb_null_samples; ///< (array) current number of continuous zero samples
43 int64_t *start; ///< (array) if silence is detected, this value contains the time of the first zero sample (default/unset = INT64_MIN)
44 int64_t frame_end; ///< pts of the end of the current frame (used to compute duration of silence at EOS)
45 int last_sample_rate; ///< last sample rate to check for sample rate changes
46 AVRational time_base; ///< time_base
47
48 void (*silencedetect)(struct SilenceDetectContext *s, AVFrame *insamples,
49 int nb_samples, int64_t nb_samples_notify,
50 AVRational time_base);
51 } SilenceDetectContext;
52
53 #define MAX_DURATION (24*3600*1000000LL)
54 #define OFFSET(x) offsetof(SilenceDetectContext, x)
55 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_AUDIO_PARAM
56 static const AVOption silencedetect_options[] = {
57 { "n", "set noise tolerance", OFFSET(noise), AV_OPT_TYPE_DOUBLE, {.dbl=0.001}, 0, DBL_MAX, FLAGS },
58 { "noise", "set noise tolerance", OFFSET(noise), AV_OPT_TYPE_DOUBLE, {.dbl=0.001}, 0, DBL_MAX, FLAGS },
59 { "d", "set minimum duration in seconds", OFFSET(duration), AV_OPT_TYPE_DURATION, {.i64=2000000}, 0, MAX_DURATION,FLAGS },
60 { "duration", "set minimum duration in seconds", OFFSET(duration), AV_OPT_TYPE_DURATION, {.i64=2000000}, 0, MAX_DURATION,FLAGS },
61 { "mono", "check each channel separately", OFFSET(mono), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },
62 { "m", "check each channel separately", OFFSET(mono), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },
63 { NULL }
64 };
65
66 AVFILTER_DEFINE_CLASS(silencedetect);
67
set_meta(AVFrame * insamples,int channel,const char * key,char * value)68 static void set_meta(AVFrame *insamples, int channel, const char *key, char *value)
69 {
70 char key2[128];
71
72 if (channel)
73 snprintf(key2, sizeof(key2), "lavfi.%s.%d", key, channel);
74 else
75 snprintf(key2, sizeof(key2), "lavfi.%s", key);
76 av_dict_set(&insamples->metadata, key2, value, 0);
77 }
update(SilenceDetectContext * s,AVFrame * insamples,int is_silence,int current_sample,int64_t nb_samples_notify,AVRational time_base)78 static av_always_inline void update(SilenceDetectContext *s, AVFrame *insamples,
79 int is_silence, int current_sample, int64_t nb_samples_notify,
80 AVRational time_base)
81 {
82 int channel = current_sample % s->independent_channels;
83 if (is_silence) {
84 if (s->start[channel] == INT64_MIN) {
85 s->nb_null_samples[channel]++;
86 if (s->nb_null_samples[channel] >= nb_samples_notify) {
87 s->start[channel] = insamples->pts + av_rescale_q(current_sample / s->channels + 1 - nb_samples_notify * s->independent_channels / s->channels,
88 (AVRational){ 1, s->last_sample_rate }, time_base);
89 set_meta(insamples, s->mono ? channel + 1 : 0, "silence_start",
90 av_ts2timestr(s->start[channel], &time_base));
91 if (s->mono)
92 av_log(s, AV_LOG_INFO, "channel: %d | ", channel);
93 av_log(s, AV_LOG_INFO, "silence_start: %s\n",
94 av_ts2timestr(s->start[channel], &time_base));
95 }
96 }
97 } else {
98 if (s->start[channel] > INT64_MIN) {
99 int64_t end_pts = insamples ? insamples->pts + av_rescale_q(current_sample / s->channels,
100 (AVRational){ 1, s->last_sample_rate }, time_base)
101 : s->frame_end;
102 int64_t duration_ts = end_pts - s->start[channel];
103 if (insamples) {
104 set_meta(insamples, s->mono ? channel + 1 : 0, "silence_end",
105 av_ts2timestr(end_pts, &time_base));
106 set_meta(insamples, s->mono ? channel + 1 : 0, "silence_duration",
107 av_ts2timestr(duration_ts, &time_base));
108 }
109 if (s->mono)
110 av_log(s, AV_LOG_INFO, "channel: %d | ", channel);
111 av_log(s, AV_LOG_INFO, "silence_end: %s | silence_duration: %s\n",
112 av_ts2timestr(end_pts, &time_base),
113 av_ts2timestr(duration_ts, &time_base));
114 }
115 s->nb_null_samples[channel] = 0;
116 s->start[channel] = INT64_MIN;
117 }
118 }
119
120 #define SILENCE_DETECT(name, type) \
121 static void silencedetect_##name(SilenceDetectContext *s, AVFrame *insamples, \
122 int nb_samples, int64_t nb_samples_notify, \
123 AVRational time_base) \
124 { \
125 const type *p = (const type *)insamples->data[0]; \
126 const type noise = s->noise; \
127 int i; \
128 \
129 for (i = 0; i < nb_samples; i++, p++) \
130 update(s, insamples, *p < noise && *p > -noise, i, \
131 nb_samples_notify, time_base); \
132 }
133
SILENCE_DETECT(dbl,double)134 SILENCE_DETECT(dbl, double)
135 SILENCE_DETECT(flt, float)
136 SILENCE_DETECT(s32, int32_t)
137 SILENCE_DETECT(s16, int16_t)
138
139 static int config_input(AVFilterLink *inlink)
140 {
141 AVFilterContext *ctx = inlink->dst;
142 SilenceDetectContext *s = ctx->priv;
143 int c;
144
145 s->channels = inlink->channels;
146 s->duration = av_rescale(s->duration, inlink->sample_rate, AV_TIME_BASE);
147 s->independent_channels = s->mono ? s->channels : 1;
148 s->nb_null_samples = av_mallocz_array(sizeof(*s->nb_null_samples), s->independent_channels);
149 if (!s->nb_null_samples)
150 return AVERROR(ENOMEM);
151 s->start = av_malloc_array(sizeof(*s->start), s->independent_channels);
152 if (!s->start)
153 return AVERROR(ENOMEM);
154 for (c = 0; c < s->independent_channels; c++)
155 s->start[c] = INT64_MIN;
156
157 switch (inlink->format) {
158 case AV_SAMPLE_FMT_DBL: s->silencedetect = silencedetect_dbl; break;
159 case AV_SAMPLE_FMT_FLT: s->silencedetect = silencedetect_flt; break;
160 case AV_SAMPLE_FMT_S32:
161 s->noise *= INT32_MAX;
162 s->silencedetect = silencedetect_s32;
163 break;
164 case AV_SAMPLE_FMT_S16:
165 s->noise *= INT16_MAX;
166 s->silencedetect = silencedetect_s16;
167 break;
168 }
169
170 return 0;
171 }
172
filter_frame(AVFilterLink * inlink,AVFrame * insamples)173 static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
174 {
175 SilenceDetectContext *s = inlink->dst->priv;
176 const int nb_channels = inlink->channels;
177 const int srate = inlink->sample_rate;
178 const int nb_samples = insamples->nb_samples * nb_channels;
179 const int64_t nb_samples_notify = s->duration * (s->mono ? 1 : nb_channels);
180 int c;
181
182 // scale number of null samples to the new sample rate
183 if (s->last_sample_rate && s->last_sample_rate != srate)
184 for (c = 0; c < s->independent_channels; c++) {
185 s->nb_null_samples[c] = srate * s->nb_null_samples[c] / s->last_sample_rate;
186 }
187 s->last_sample_rate = srate;
188 s->time_base = inlink->time_base;
189 s->frame_end = insamples->pts + av_rescale_q(insamples->nb_samples,
190 (AVRational){ 1, s->last_sample_rate }, inlink->time_base);
191
192 s->silencedetect(s, insamples, nb_samples, nb_samples_notify,
193 inlink->time_base);
194
195 return ff_filter_frame(inlink->dst->outputs[0], insamples);
196 }
197
query_formats(AVFilterContext * ctx)198 static int query_formats(AVFilterContext *ctx)
199 {
200 AVFilterFormats *formats = NULL;
201 AVFilterChannelLayouts *layouts = NULL;
202 static const enum AVSampleFormat sample_fmts[] = {
203 AV_SAMPLE_FMT_DBL,
204 AV_SAMPLE_FMT_FLT,
205 AV_SAMPLE_FMT_S32,
206 AV_SAMPLE_FMT_S16,
207 AV_SAMPLE_FMT_NONE
208 };
209 int ret;
210
211 layouts = ff_all_channel_layouts();
212 if (!layouts)
213 return AVERROR(ENOMEM);
214 ret = ff_set_common_channel_layouts(ctx, layouts);
215 if (ret < 0)
216 return ret;
217
218 formats = ff_make_format_list(sample_fmts);
219 if (!formats)
220 return AVERROR(ENOMEM);
221 ret = ff_set_common_formats(ctx, formats);
222 if (ret < 0)
223 return ret;
224
225 formats = ff_all_samplerates();
226 if (!formats)
227 return AVERROR(ENOMEM);
228 return ff_set_common_samplerates(ctx, formats);
229 }
230
uninit(AVFilterContext * ctx)231 static av_cold void uninit(AVFilterContext *ctx)
232 {
233 SilenceDetectContext *s = ctx->priv;
234 int c;
235
236 for (c = 0; c < s->independent_channels; c++)
237 if (s->start[c] > INT64_MIN)
238 update(s, NULL, 0, c, 0, s->time_base);
239 av_freep(&s->nb_null_samples);
240 av_freep(&s->start);
241 }
242
243 static const AVFilterPad silencedetect_inputs[] = {
244 {
245 .name = "default",
246 .type = AVMEDIA_TYPE_AUDIO,
247 .config_props = config_input,
248 .filter_frame = filter_frame,
249 },
250 { NULL }
251 };
252
253 static const AVFilterPad silencedetect_outputs[] = {
254 {
255 .name = "default",
256 .type = AVMEDIA_TYPE_AUDIO,
257 },
258 { NULL }
259 };
260
261 AVFilter ff_af_silencedetect = {
262 .name = "silencedetect",
263 .description = NULL_IF_CONFIG_SMALL("Detect silence."),
264 .priv_size = sizeof(SilenceDetectContext),
265 .query_formats = query_formats,
266 .uninit = uninit,
267 .inputs = silencedetect_inputs,
268 .outputs = silencedetect_outputs,
269 .priv_class = &silencedetect_class,
270 };
271