| /* |
| * 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 } |
| }, |
| }; |