libavfilter/af_silencedetect.c

   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/mem.h"
  29 #include "libavutil/opt.h"
  30 #include "libavutil/timestamp.h"
  31 #include "audio.h"
  32 #include "avfilter.h"
  33 #include "filters.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
  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 }
  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
 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
 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
 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 const FFFilter ff_af_silencedetect = {
 257     .p.name        = "silencedetect",
 258     .p.description = NULL_IF_CONFIG_SMALL("Detect silence."),
 259     .p.priv_class  = &silencedetect_class,
 260     .p.flags       = AVFILTER_FLAG_METADATA_ONLY,
 261     .priv_size     = sizeof(SilenceDetectContext),
 262     .uninit        = uninit,
 263     FILTER_INPUTS(silencedetect_inputs),
 264     FILTER_OUTPUTS(ff_audio_default_filterpad),
 265     FILTER_SAMPLEFMTS(AV_SAMPLE_FMT_DBL, AV_SAMPLE_FMT_DBLP,
 266                       AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_FLTP,
 267                       AV_SAMPLE_FMT_S32, AV_SAMPLE_FMT_S32P,
 268                       AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_S16P),
 269 };