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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     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