/* * 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 } }, };