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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 "libavutil/timestamp.h"
- #include "audio.h"
- #include "formats.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
- 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)
- 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 - silence->duration / av_q2d(inlink->time_base);
- av_log(silence, AV_LOG_INFO,
- "silence_start: %s\n", av_ts2timestr(silence->start, &inlink->time_base));
- }
- }
- } else {
- if (silence->start)
- av_log(silence, AV_LOG_INFO,
- "silence_end: %s | silence_duration: %s\n",
- av_ts2timestr(insamples->pts, &inlink->time_base),
- av_ts2timestr(insamples->pts - silence->start, &inlink->time_base));
- silence->nb_null_samples = silence->start = 0;
- }
- }
- }
- ff_filter_samples(inlink->dst->outputs[0], insamples);
- }
- static int query_formats(AVFilterContext *ctx)
- {
- AVFilterFormats *formats = NULL;
- AVFilterChannelLayouts *layouts = NULL;
- 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 = avfilter_make_format_list(sample_fmts);
- if (!formats)
- return AVERROR(ENOMEM);
- avfilter_set_common_sample_formats(ctx, formats);
- formats = ff_all_samplerates();
- if (!formats)
- return AVERROR(ENOMEM);
- ff_set_common_samplerates(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 = ff_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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