diff options
Diffstat (limited to 'libavfilter/af_silencedetect.c')
| -rw-r--r-- | libavfilter/af_silencedetect.c | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/libavfilter/af_silencedetect.c b/libavfilter/af_silencedetect.c new file mode 100644 index 0000000000..2ea5d7f5bc --- /dev/null +++ b/libavfilter/af_silencedetect.c @@ -0,0 +1,171 @@ +/* + * 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/audioconvert.h" +#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; + 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) +#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_AUDIO_PARAM +static const AVOption silencedetect_options[] = { + { "n", "set noise tolerance", OFFSET(noise_str), AV_OPT_TYPE_STRING, {.str="-60dB"}, CHAR_MIN, CHAR_MAX, FLAGS }, + { "noise", "set noise tolerance", OFFSET(noise_str), AV_OPT_TYPE_STRING, {.str="-60dB"}, CHAR_MIN, CHAR_MAX, FLAGS }, + { "d", "set minimum duration in seconds", OFFSET(duration), AV_OPT_TYPE_INT, {.i64=2}, 0, INT_MAX, FLAGS }, + { "duration", "set minimum duration in seconds", OFFSET(duration), AV_OPT_TYPE_INT, {.i64=2}, 0, INT_MAX, FLAGS }, + { NULL }, +}; + +AVFILTER_DEFINE_CLASS(silencedetect); + +static av_cold int init(AVFilterContext *ctx, const char *args) +{ + 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) + 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); + } + av_opt_free(silence); + + return 0; +} + +static int 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; + } + } + } + + return 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 = 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; +} + +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 } + }, + .priv_class = &silencedetect_class, +}; |