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/*
* Copyright (c) 2012 Clément Bœsch <ubitux@gmail.com>
*
* 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 "libavutil/opt.h"
#include "avfilter.h"
typedef struct {
const AVClass *class;
char *noise_str; ///< noise option string
double noise; ///< noise amplitude ratio
int duration; ///< minimum duration of silence until notification
int64_t nb_null_samples; ///< current number of continuous zero samples
double 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)
static const AVOption silencedetect_options[] = {
{ "n", "set noise tolerance", OFFSET(noise_str), AV_OPT_TYPE_STRING, {.str="-60dB"}, CHAR_MIN, CHAR_MAX },
{ "noise", "set noise tolerance", OFFSET(noise_str), AV_OPT_TYPE_STRING, {.str="-60dB"}, CHAR_MIN, CHAR_MAX },
{ "d", "set minimum duration in seconds", OFFSET(duration), AV_OPT_TYPE_INT, {.dbl=2}, 0, INT_MAX},
{ "duration", "set minimum duration in seconds", OFFSET(duration), AV_OPT_TYPE_INT, {.dbl=2}, 0, INT_MAX},
{ NULL },
};
static const char *silencedetect_get_name(void *ctx)
{
return "silencedetect";
}
static const AVClass silencedetect_class = {
.class_name = "SilenceDetectContext",
.item_name = silencedetect_get_name,
.option = silencedetect_options,
};
static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
{
int ret;
char *tail;
SilenceDetectContext *silence = ctx->priv;
silence->class = &silencedetect_class;
av_opt_set_defaults(silence);
if ((ret = av_set_options_string(silence, args, "=", ":")) < 0) {
av_log(ctx, AV_LOG_ERROR, "Error parsing options string: '%s'\n", args);
return ret;
}
silence->noise = strtod(silence->noise_str, &tail);
if (!strcmp(tail, "dB")) {
silence->noise = pow(10, silence->noise/20);
} else if (*tail) {
av_log(ctx, AV_LOG_ERROR, "Invalid value '%s' for noise parameter.\n",
silence->noise_str);
return AVERROR(EINVAL);
}
return 0;
}
static void filter_samples(AVFilterLink *inlink, AVFilterBufferRef *insamples)
{
int i;
SilenceDetectContext *silence = inlink->dst->priv;
const int nb_channels = av_get_channel_layout_nb_channels(inlink->channel_layout);
const int srate = inlink->sample_rate;
const int nb_samples = insamples->audio->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
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 * av_q2d(inlink->time_base) - silence->duration;
av_log(silence, AV_LOG_INFO,
"silence_start: %f\n", silence->start);
}
}
} else {
if (silence->start) {
double end = insamples->pts * av_q2d(inlink->time_base);
av_log(silence, AV_LOG_INFO,
"silence_end: %f | silence_duration: %f\n",
end, end - silence->start);
}
silence->nb_null_samples = silence->start = 0;
}
}
}
avfilter_filter_samples(inlink->dst->outputs[0], insamples);
}
static int query_formats(AVFilterContext *ctx)
{
AVFilterFormats *formats = NULL;
enum AVSampleFormat sample_fmts[] = {
AV_SAMPLE_FMT_DBL,
AV_SAMPLE_FMT_NONE
};
int packing_fmts[] = { AVFILTER_PACKED, -1 };
formats = avfilter_make_all_channel_layouts();
if (!formats)
return AVERROR(ENOMEM);
avfilter_set_common_channel_layouts(ctx, formats);
formats = avfilter_make_format_list(sample_fmts);
if (!formats)
return AVERROR(ENOMEM);
avfilter_set_common_sample_formats(ctx, formats);
formats = avfilter_make_format_list(packing_fmts);
if (!formats)
return AVERROR(ENOMEM);
avfilter_set_common_packing_formats(ctx, formats);
return 0;
}
AVFilter avfilter_af_silencedetect = {
.name = "silencedetect",
.description = NULL_IF_CONFIG_SMALL("Detect silence."),
.priv_size = sizeof(SilenceDetectContext),
.init = init,
.query_formats = query_formats,
.inputs = (const AVFilterPad[]) {
{ .name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.get_audio_buffer = avfilter_null_get_audio_buffer,
.filter_samples = filter_samples, },
{ .name = NULL }
},
.outputs = (const AVFilterPad[]) {
{ .name = "default",
.type = AVMEDIA_TYPE_AUDIO, },
{ .name = NULL }
},
};
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