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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 };
#define NULL
Definition: coverity.c:32
int ff_set_common_channel_layouts(AVFilterContext *ctx, AVFilterChannelLayouts *layouts)
A helper for query_formats() which sets all links to the same list of channel layouts/sample rates...
Definition: formats.c:549
const char * s
Definition: avisynth_c.h:631
This structure describes decoded (raw) audio or video data.
Definition: frame.h:184
static int noise(AVBSFContext *ctx, AVPacket *out)
Definition: noise_bsf.c:37
AVOption.
Definition: opt.h:245
Main libavfilter public API header.
static enum AVSampleFormat formats[]
#define SILENCE_DETECT(name, type)
AVFilter ff_af_silencedetect
AVFilterFormats * ff_make_format_list(const int *fmts)
Create a list of supported formats.
Definition: formats.c:283
const char * name
Pad name.
Definition: internal.h:59
static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1180
AVOptions.
timestamp utils, mostly useful for debugging/logging purposes
static const AVFilterPad silencedetect_inputs[]
double duration
minimum duration of silence until notification
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:268
#define OFFSET(x)
int64_t duration
Definition: movenc.c:63
static double av_q2d(AVRational a)
Convert rational to double.
Definition: rational.h:80
AVDictionaryEntry * av_dict_get(const AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags)
Get a dictionary entry with matching key.
Definition: dict.c:39
AVDictionary * metadata
metadata.
Definition: frame.h:465
signed 32 bits
Definition: samplefmt.h:62
#define av_log(a,...)
A filter pad used for either input or output.
Definition: internal.h:53
static char * get_metadata_val(AVFrame *insamples, const char *key)
int ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats)
A helper for query_formats() which sets all links to the same list of formats.
Definition: formats.c:568
static const AVFilterPad silencedetect_outputs[]
#define AVERROR(e)
Definition: error.h:43
#define FLAGS
#define av_ts2timestr(ts, tb)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: timestamp.h:76
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:176
void * priv
private data for use by the filter
Definition: avfilter.h:320
int64_t start
if silence is detected, this value contains the time of the first zero sample
static av_always_inline void update(SilenceDetectContext *s, AVFrame *insamples, int is_silence, int64_t nb_samples_notify, AVRational time_base)
double noise
noise amplitude ratio
typedef void(APIENTRY *FF_PFNGLACTIVETEXTUREPROC)(GLenum texture)
static int config_input(AVFilterLink *inlink)
int32_t
AVFormatContext * ctx
Definition: movenc.c:48
static const AVFilterPad outputs[]
Definition: af_afftfilt.c:386
AVFilterChannelLayouts * ff_all_channel_layouts(void)
Construct an empty AVFilterChannelLayouts/AVFilterFormats struct – representing any channel layout (w...
Definition: formats.c:401
A list of supported channel layouts.
Definition: formats.h:85
#define AV_LOG_INFO
Standard information.
Definition: log.h:187
static const AVFilterPad inputs[]
Definition: af_afftfilt.c:376
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
Definition: dict.c:69
AVFILTER_DEFINE_CLASS(silencedetect)
Describe the class of an AVClass context structure.
Definition: log.h:67
Filter definition.
Definition: avfilter.h:142
rational number numerator/denominator
Definition: rational.h:43
static int query_formats(AVFilterContext *ctx)
const char * name
Filter name.
Definition: avfilter.h:146
AVFilterLink ** outputs
array of pointers to output links
Definition: avfilter.h:317
enum MovChannelLayoutTag * layouts
Definition: mov_chan.c:434
AVFilterFormats * ff_all_samplerates(void)
Definition: formats.c:395
void(* silencedetect)(struct SilenceDetectContext *s, AVFrame *insamples, int nb_samples, int64_t nb_samples_notify, AVRational time_base)
signed 16 bits
Definition: samplefmt.h:61
int64_t nb_null_samples
current number of continuous zero samples
static const AVOption silencedetect_options[]
char * value
Definition: dict.h:87
A list of supported formats for one end of a filter link.
Definition: formats.h:64
An instance of a filter.
Definition: avfilter.h:305
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:701
#define av_always_inline
Definition: attributes.h:39
int nb_channels
int last_sample_rate
last sample rate to check for sample rate changes
internal API functions
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:241
int ff_set_common_samplerates(AVFilterContext *ctx, AVFilterFormats *samplerates)
Definition: formats.c:556