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/*
* Copyright (c) 2012 Clément Bœsch <u pkh me>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* Audio silence detector
*/
#include <float.h> /* DBL_MAX */
#include "libavutil/opt.h"
#include "libavutil/timestamp.h"
#include "audio.h"
#include "formats.h"
#include "avfilter.h"
#include "internal.h"
typedef struct {
const AVClass *class;
double noise; ///< noise amplitude ratio
double duration; ///< minimum duration of silence until notification
int64_t nb_null_samples; ///< current number of continuous zero samples
int64_t start; ///< if silence is detected, this value contains the time of the first zero sample
int last_sample_rate; ///< last sample rate to check for sample rate changes
} SilenceDetectContext;
#define OFFSET(x) offsetof(SilenceDetectContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_AUDIO_PARAM
static const AVOption silencedetect_options[] = {
{ "n", "set noise tolerance", OFFSET(noise), AV_OPT_TYPE_DOUBLE, {.dbl=0.001}, 0, DBL_MAX, FLAGS },
{ "noise", "set noise tolerance", OFFSET(noise), AV_OPT_TYPE_DOUBLE, {.dbl=0.001}, 0, DBL_MAX, FLAGS },
{ "d", "set minimum duration in seconds", OFFSET(duration), AV_OPT_TYPE_DOUBLE, {.dbl=2.}, 0, 24*60*60, FLAGS },
{ "duration", "set minimum duration in seconds", OFFSET(duration), AV_OPT_TYPE_DOUBLE, {.dbl=2.}, 0, 24*60*60, FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(silencedetect);
static char *get_metadata_val(AVFrame *insamples, const char *key)
{
AVDictionaryEntry *e = av_dict_get(insamples->metadata, key, NULL, 0);
return e && e->value ? e->value : NULL;
}
static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
{
int i;
SilenceDetectContext *silence = inlink->dst->priv;
const int nb_channels = inlink->channels;
const int srate = inlink->sample_rate;
const int nb_samples = insamples->nb_samples * nb_channels;
const int64_t nb_samples_notify = srate * silence->duration * nb_channels;
// scale number of null samples to the new sample rate
if (silence->last_sample_rate && silence->last_sample_rate != srate)
silence->nb_null_samples =
srate * silence->nb_null_samples / silence->last_sample_rate;
silence->last_sample_rate = srate;
// TODO: support more sample formats
// TODO: document metadata
if (insamples->format == AV_SAMPLE_FMT_DBL) {
double *p = (double *)insamples->data[0];
for (i = 0; i < nb_samples; i++, p++) {
if (*p < silence->noise && *p > -silence->noise) {
if (!silence->start) {
silence->nb_null_samples++;
if (silence->nb_null_samples >= nb_samples_notify) {
silence->start = insamples->pts - (int64_t)(silence->duration / av_q2d(inlink->time_base) + .5);
av_dict_set(&insamples->metadata, "lavfi.silence_start",
av_ts2timestr(silence->start, &inlink->time_base), 0);
av_log(silence, AV_LOG_INFO, "silence_start: %s\n",
get_metadata_val(insamples, "lavfi.silence_start"));
}
}
} else {
if (silence->start) {
av_dict_set(&insamples->metadata, "lavfi.silence_end",
av_ts2timestr(insamples->pts, &inlink->time_base), 0);
av_dict_set(&insamples->metadata, "lavfi.silence_duration",
av_ts2timestr(insamples->pts - silence->start, &inlink->time_base), 0);
av_log(silence, AV_LOG_INFO,
"silence_end: %s | silence_duration: %s\n",
get_metadata_val(insamples, "lavfi.silence_end"),
get_metadata_val(insamples, "lavfi.silence_duration"));
}
silence->nb_null_samples = silence->start = 0;
}
}
}
return ff_filter_frame(inlink->dst->outputs[0], insamples);
}
static int query_formats(AVFilterContext *ctx)
{
AVFilterFormats *formats = NULL;
AVFilterChannelLayouts *layouts = NULL;
static const enum AVSampleFormat sample_fmts[] = {
AV_SAMPLE_FMT_DBL,
AV_SAMPLE_FMT_NONE
};
layouts = ff_all_channel_layouts();
if (!layouts)
return AVERROR(ENOMEM);
ff_set_common_channel_layouts(ctx, layouts);
formats = ff_make_format_list(sample_fmts);
if (!formats)
return AVERROR(ENOMEM);
ff_set_common_formats(ctx, formats);
formats = ff_all_samplerates();
if (!formats)
return AVERROR(ENOMEM);
ff_set_common_samplerates(ctx, formats);
return 0;
}
static const AVFilterPad silencedetect_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.filter_frame = filter_frame,
},
{ NULL }
};
static const AVFilterPad silencedetect_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
},
{ NULL }
};
AVFilter avfilter_af_silencedetect = {
.name = "silencedetect",
.description = NULL_IF_CONFIG_SMALL("Detect silence."),
.priv_size = sizeof(SilenceDetectContext),
.query_formats = query_formats,
.inputs = silencedetect_inputs,
.outputs = silencedetect_outputs,
.priv_class = &silencedetect_class,
};
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