@@ -20,6 +20,7 @@ version next:

 - v308 Quicktime Uncompressed 4:4:4 encoder and decoder

 - yuv4 libquicktime packed 4:2:0 encoder and decoder

 - ffprobe -show_frames option

+- silencedetect audio filter

 version 0.9:

@@ -358,6 +358,36 @@ Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system

 that should be preferred (see "-ac" option) unless you have very specific

 needs.

+@section silencedetect

+

+Detect silence in an audio stream.

+

+This filter logs a message when it detects that the input audio volume is less

+or equal to a noise tolerance value for a duration greater or equal to the

+minimum detected noise duration.

+

+The printed times and duration are expressed in seconds.

+

+@table @option

+@item duration, d

+Set silence duration until notification (default is 2 seconds).

+

+@item noise, n

+Set noise tolerance. Can be specified in dB (in case "dB" is appended to the

+specified value) or amplitude ratio. Default is -60dB, or 0.001.

+@end table

+

+Detect 5 seconds of silence with -50dB noise tolerance:

+@example

+silencedetect=n=-50dB:d=5

+@end example

+

+Complete example with @command{ffmpeg} to detect silence with 0.0001 noise

+tolerance in @file{silence.mp3}:

+@example

+ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -

+@end example

+

 @section volume

 Adjust the input audio volume.

@@ -34,6 +34,7 @@ OBJS-$(CONFIG_ASPLIT_FILTER)                 += af_asplit.o

 OBJS-$(CONFIG_ASTREAMSYNC_FILTER)            += af_astreamsync.o

 OBJS-$(CONFIG_EARWAX_FILTER)                 += af_earwax.o

 OBJS-$(CONFIG_PAN_FILTER)                    += af_pan.o

+OBJS-$(CONFIG_SILENCEDETECT_FILTER)          += af_silencedetect.o

 OBJS-$(CONFIG_VOLUME_FILTER)                 += af_volume.o

 OBJS-$(CONFIG_ABUFFER_FILTER)                += asrc_abuffer.o

new file mode 100644

@@ -0,0 +1,175 @@

+/*

+ * 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 }

+    },

+};

@@ -44,6 +44,7 @@ void avfilter_register_all(void)

     REGISTER_FILTER (ASTREAMSYNC, astreamsync, af);

     REGISTER_FILTER (EARWAX,      earwax,      af);

     REGISTER_FILTER (PAN,         pan,         af);

+    REGISTER_FILTER (SILENCEDETECT, silencedetect, af);

     REGISTER_FILTER (VOLUME,      volume,      af);

     REGISTER_FILTER (ABUFFER,     abuffer,     asrc);

@@ -30,8 +30,8 @@

 #include "libavcodec/avcodec.h"

 #define LIBAVFILTER_VERSION_MAJOR  2

-#define LIBAVFILTER_VERSION_MINOR 57

-#define LIBAVFILTER_VERSION_MICRO 101

+#define LIBAVFILTER_VERSION_MINOR 58

+#define LIBAVFILTER_VERSION_MICRO 100

 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

                                                LIBAVFILTER_VERSION_MINOR, \