FFmpeg
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  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 
49  int nb_samples, int64_t nb_samples_notify,
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 
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 }
79  int is_silence, int current_sample, int64_t nb_samples_notify,
81 {
82  int channel = current_sample % s->independent_channels;
83  if (is_silence) {
84  if (s->start[channel] == INT64_MIN) {
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 SILENCE_DETECT(dbl, double)
135 SILENCE_DETECT(flt, float)
137 SILENCE_DETECT(s16, int16_t)
138 
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;
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 
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 
199 {
202  static const enum AVSampleFormat sample_fmts[] = {
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 
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);
240  av_freep(&s->start);
241 }
242 
244  {
245  .name = "default",
246  .type = AVMEDIA_TYPE_AUDIO,
247  .config_props = config_input,
248  .filter_frame = filter_frame,
249  },
250  { NULL }
251 };
252 
254  {
255  .name = "default",
256  .type = AVMEDIA_TYPE_AUDIO,
257  },
258  { NULL }
259 };
260 
262  .name = "silencedetect",
263  .description = NULL_IF_CONFIG_SMALL("Detect silence."),
264  .priv_size = sizeof(SilenceDetectContext),
266  .uninit = uninit,
267  .inputs = silencedetect_inputs,
268  .outputs = silencedetect_outputs,
269  .priv_class = &silencedetect_class,
270 };
#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:550
This structure describes decoded (raw) audio or video data.
Definition: frame.h:295
AVOption.
Definition: opt.h:246
Main libavfilter public API header.
#define MAX_DURATION
int64_t frame_end
pts of the end of the current frame (used to compute duration of silence at EOS)
const char * key
#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:60
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:1093
#define av_cold
Definition: attributes.h:82
AVOptions.
timestamp utils, mostly useful for debugging/logging purposes
static const AVFilterPad silencedetect_inputs[]
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
GLsizei GLboolean const GLfloat * value
Definition: opengl_enc.c:108
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:388
#define OFFSET(x)
AVDictionary * metadata
metadata.
Definition: frame.h:581
signed 32 bits
Definition: samplefmt.h:62
#define av_log(a,...)
A filter pad used for either input or output.
Definition: internal.h:54
AVRational time_base
time_base
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:142
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:569
static const AVFilterPad silencedetect_outputs[]
static av_always_inline void update(SilenceDetectContext *s, AVFrame *insamples, int is_silence, int current_sample, int64_t nb_samples_notify, AVRational time_base)
#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:186
void * priv
private data for use by the filter
Definition: avfilter.h:353
int64_t duration
minimum duration of silence until notification
int64_t av_rescale(int64_t a, int64_t b, int64_t c)
Rescale a 64-bit integer with rounding to nearest.
Definition: mathematics.c:129
#define AV_TIME_BASE
Internal time base represented as integer.
Definition: avutil.h:254
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
#define s(width, name)
Definition: cbs_vp9.c:257
AVFilterChannelLayouts * ff_all_channel_layouts(void)
Construct an empty AVFilterChannelLayouts/AVFilterFormats struct – representing any channel layout (...
Definition: formats.c:400
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
A list of supported channel layouts.
Definition: formats.h:85
int channels
number of channels
void(* silencedetect)(struct SilenceDetectContext *s, AVFrame *insamples, int nb_samples, int64_t nb_samples_notify, AVRational time_base)
int independent_channels
number of entries in following arrays (always 1 in mono mode)
#define AV_LOG_INFO
Standard information.
Definition: log.h:187
int64_t * nb_null_samples
(array) current number of continuous zero samples
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several inputs
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:70
AVFILTER_DEFINE_CLASS(silencedetect)
int mono
mono mode : check each channel separately (default = check when ALL channels are silent) ...
Describe the class of an AVClass context structure.
Definition: log.h:67
Filter definition.
Definition: avfilter.h:144
Rational number (pair of numerator and denominator).
Definition: rational.h:58
static int query_formats(AVFilterContext *ctx)
const char * name
Filter name.
Definition: avfilter.h:148
#define snprintf
Definition: snprintf.h:34
AVFilterLink ** outputs
array of pointers to output links
Definition: avfilter.h:350
enum MovChannelLayoutTag * layouts
Definition: mov_chan.c:434
AVFilterFormats * ff_all_samplerates(void)
Definition: formats.c:394
The exact code depends on how similar the blocks are and how related they are to the and needs to apply these operations to the correct inlink or outlink if there are several Macros are available to factor that when no extra processing is inlink
signed 16 bits
Definition: samplefmt.h:61
channel
Use these values when setting the channel map with ebur128_set_channel().
Definition: ebur128.h:39
static const AVOption silencedetect_options[]
static av_cold void uninit(AVFilterContext *ctx)
A list of supported formats for one end of a filter link.
Definition: formats.h:64
An instance of a filter.
Definition: avfilter.h:338
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:701
#define av_freep(p)
#define av_always_inline
Definition: attributes.h:39
static void set_meta(AVFrame *insamples, int channel, const char *key, char *value)
#define av_malloc_array(a, b)
formats
Definition: signature.h:48
int nb_channels
int last_sample_rate
last sample rate to check for sample rate changes
internal API functions
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:361
int64_t * start
(array) if silence is detected, this value contains the time of the first zero sample (default/unset ...
int ff_set_common_samplerates(AVFilterContext *ctx, AVFilterFormats *samplerates)
Definition: formats.c:557
void * av_mallocz_array(size_t nmemb, size_t size)
Definition: mem.c:191