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
134 #define SILENCE_DETECT_PLANAR(name, type) \
135 static void silencedetect_##name(SilenceDetectContext *s, AVFrame *insamples, \
136 int nb_samples, int64_t nb_samples_notify, \
137 AVRational time_base) \
138 { \
139 const int channels = insamples->ch_layout.nb_channels; \
140 const type noise = s->noise; \
141 \
142 nb_samples /= channels; \
143 for (int i = 0; i < nb_samples; i++) { \
144 for (int ch = 0; ch < insamples->ch_layout.nb_channels; ch++) { \
145 const type *p = (const type *)insamples->extended_data[ch]; \
146 update(s, insamples, p[i] < noise && p[i] > -noise, \
147 channels * i + ch, \
148 nb_samples_notify, time_base); \
149 } \
150 } \
151 }
152
SILENCE_DETECT(dbl,double)153 SILENCE_DETECT(dbl, double)
154 SILENCE_DETECT(flt, float)
155 SILENCE_DETECT(s32, int32_t)
156 SILENCE_DETECT(s16, int16_t)
157
158 SILENCE_DETECT_PLANAR(dblp, double)
159 SILENCE_DETECT_PLANAR(fltp, float)
160 SILENCE_DETECT_PLANAR(s32p, int32_t)
161 SILENCE_DETECT_PLANAR(s16p, int16_t)
162
163 static int config_input(AVFilterLink *inlink)
164 {
165 AVFilterContext *ctx = inlink->dst;
166 SilenceDetectContext *s = ctx->priv;
167 int c;
168
169 s->channels = inlink->ch_layout.nb_channels;
170 s->duration = av_rescale(s->duration, inlink->sample_rate, AV_TIME_BASE);
171 s->independent_channels = s->mono ? s->channels : 1;
172 s->nb_null_samples = av_calloc(s->independent_channels,
173 sizeof(*s->nb_null_samples));
174 if (!s->nb_null_samples)
175 return AVERROR(ENOMEM);
176 s->start = av_malloc_array(sizeof(*s->start), s->independent_channels);
177 if (!s->start)
178 return AVERROR(ENOMEM);
179 for (c = 0; c < s->independent_channels; c++)
180 s->start[c] = INT64_MIN;
181
182 switch (inlink->format) {
183 case AV_SAMPLE_FMT_DBL: s->silencedetect = silencedetect_dbl; break;
184 case AV_SAMPLE_FMT_FLT: s->silencedetect = silencedetect_flt; break;
185 case AV_SAMPLE_FMT_S32:
186 s->noise *= INT32_MAX;
187 s->silencedetect = silencedetect_s32;
188 break;
189 case AV_SAMPLE_FMT_S16:
190 s->noise *= INT16_MAX;
191 s->silencedetect = silencedetect_s16;
192 break;
193 case AV_SAMPLE_FMT_DBLP: s->silencedetect = silencedetect_dblp; break;
194 case AV_SAMPLE_FMT_FLTP: s->silencedetect = silencedetect_fltp; break;
195 case AV_SAMPLE_FMT_S32P:
196 s->noise *= INT32_MAX;
197 s->silencedetect = silencedetect_s32p;
198 break;
199 case AV_SAMPLE_FMT_S16P:
200 s->noise *= INT16_MAX;
201 s->silencedetect = silencedetect_s16p;
202 break;
203 default:
204 return AVERROR_BUG;
205 }
206
207 return 0;
208 }
209
filter_frame(AVFilterLink * inlink,AVFrame * insamples)210 static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
211 {
212 SilenceDetectContext *s = inlink->dst->priv;
213 const int nb_channels = inlink->ch_layout.nb_channels;
214 const int srate = inlink->sample_rate;
215 const int nb_samples = insamples->nb_samples * nb_channels;
216 const int64_t nb_samples_notify = s->duration * (s->mono ? 1 : nb_channels);
217 int c;
218
219 // scale number of null samples to the new sample rate
220 if (s->last_sample_rate && s->last_sample_rate != srate)
221 for (c = 0; c < s->independent_channels; c++) {
222 s->nb_null_samples[c] = srate * s->nb_null_samples[c] / s->last_sample_rate;
223 }
224 s->last_sample_rate = srate;
225 s->time_base = inlink->time_base;
226 s->frame_end = insamples->pts + av_rescale_q(insamples->nb_samples,
227 (AVRational){ 1, s->last_sample_rate }, inlink->time_base);
228
229 s->silencedetect(s, insamples, nb_samples, nb_samples_notify,
230 inlink->time_base);
231
232 return ff_filter_frame(inlink->dst->outputs[0], insamples);
233 }
234
uninit(AVFilterContext * ctx)235 static av_cold void uninit(AVFilterContext *ctx)
236 {
237 SilenceDetectContext *s = ctx->priv;
238 int c;
239
240 for (c = 0; c < s->independent_channels; c++)
241 if (s->start[c] > INT64_MIN)
242 update(s, NULL, 0, c, 0, s->time_base);
243 av_freep(&s->nb_null_samples);
244 av_freep(&s->start);
245 }
246
247 static const AVFilterPad silencedetect_inputs[] = {
248 {
249 .name = "default",
250 .type = AVMEDIA_TYPE_AUDIO,
251 .config_props = config_input,
252 .filter_frame = filter_frame,
253 },
254 };
255
256 static const AVFilterPad silencedetect_outputs[] = {
257 {
258 .name = "default",
259 .type = AVMEDIA_TYPE_AUDIO,
260 },
261 };
262
263 const AVFilter ff_af_silencedetect = {
264 .name = "silencedetect",
265 .description = NULL_IF_CONFIG_SMALL("Detect silence."),
266 .priv_size = sizeof(SilenceDetectContext),
267 .uninit = uninit,
268 FILTER_INPUTS(silencedetect_inputs),
269 FILTER_OUTPUTS(silencedetect_outputs),
270 FILTER_SAMPLEFMTS(AV_SAMPLE_FMT_DBL, AV_SAMPLE_FMT_DBLP,
271 AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_FLTP,
272 AV_SAMPLE_FMT_S32, AV_SAMPLE_FMT_S32P,
273 AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_S16P),
274 .priv_class = &silencedetect_class,
275 .flags = AVFILTER_FLAG_METADATA_ONLY,
276 };
277