@@ -38,6 +38,7 @@ version <next>:

 - acompressor filter

 - support encoding 16-bit RLE SGI images

 - apulsator filter

+- sidechaingate audio filter

 version 2.8:

@@ -2597,6 +2597,67 @@ ffmpeg -i main.flac -i sidechain.flac -filter_complex "[1:a]asplit=2[sc][mix];[0

 @end example

 @end itemize

+@section sidechaingate

+

+A sidechain gate acts like a normal (wideband) gate but has the ability to

+filter the detected signal before sending it to the gain reduction stage.

+Normally a gate uses the full range signal to detect a level above the

+threshold.

+For example: If you cut all lower frequencies from your sidechain signal

+the gate will decrease the volume of your track only if not enough highs

+appear. With this technique you are able to reduce the resonation of a

+natural drum or remove "rumbling" of muted strokes from a heavily distorted

+guitar.

+It needs two input streams and returns one output stream.

+First input stream will be processed depending on second stream signal.

+

+The filter accepts the following options:

+

+@table @option

+@item level_in

+Set input level before filtering.

+Default is 1. Allowed range is from 0.015625 to 64.

+

+@item range

+Set the level of gain reduction when the signal is below the threshold.

+Default is 0.06125. Allowed range is from 0 to 1.

+

+@item threshold

+If a signal rises above this level the gain reduction is released.

+Default is 0.125. Allowed range is from 0 to 1.

+

+@item ratio

+Set a ratio about which the signal is reduced.

+Default is 2. Allowed range is from 1 to 9000.

+

+@item attack

+Amount of milliseconds the signal has to rise above the threshold before gain

+reduction stops.

+Default is 20 milliseconds. Allowed range is from 0.01 to 9000.

+

+@item release

+Amount of milliseconds the signal has to fall below the threshold before the

+reduction is increased again. Default is 250 milliseconds.

+Allowed range is from 0.01 to 9000.

+

+@item makeup

+Set amount of amplification of signal after processing.

+Default is 1. Allowed range is from 1 to 64.

+

+@item knee

+Curve the sharp knee around the threshold to enter gain reduction more softly.

+Default is 2.828427125. Allowed range is from 1 to 8.

+

+@item detection

+Choose if exact signal should be taken for detection or an RMS like one.

+Default is peak. Can be peak or rms.

+

+@item link

+Choose if the average level between all channels or the louder channel affects

+the reduction.

+Default is average. Can be average or maximum.

+@end table

+

 @section silencedetect

 Detect silence in an audio stream.

@@ -83,6 +83,7 @@ OBJS-$(CONFIG_REPLAYGAIN_FILTER)             += af_replaygain.o

 OBJS-$(CONFIG_RESAMPLE_FILTER)               += af_resample.o

 OBJS-$(CONFIG_RUBBERBAND_FILTER)             += af_rubberband.o

 OBJS-$(CONFIG_SIDECHAINCOMPRESS_FILTER)      += af_sidechaincompress.o

+OBJS-$(CONFIG_SIDECHAINGATE_FILTER)          += af_agate.o

 OBJS-$(CONFIG_SILENCEDETECT_FILTER)          += af_silencedetect.o

 OBJS-$(CONFIG_SILENCEREMOVE_FILTER)          += af_silenceremove.o

 OBJS-$(CONFIG_STEREOTOOLS_FILTER)            += af_stereotools.o

@@ -18,6 +18,12 @@

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  */

+/**

+ * @file

+ * Audio (Sidechain) Gate filter

+ */

+

+#include "libavutil/avassert.h"

 #include "libavutil/channel_layout.h"

 #include "libavutil/opt.h"

 #include "avfilter.h"

@@ -46,12 +52,14 @@ typedef struct AudioGateContext {

     double lin_slope;

     double attack_coeff;

     double release_coeff;

+

+    AVFrame *input_frame[2];

 } AudioGateContext;

 #define OFFSET(x) offsetof(AudioGateContext, x)

 #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM

-static const AVOption agate_options[] = {

+static const AVOption options[] = {

     { "level_in",  "set input level",        OFFSET(level_in),  AV_OPT_TYPE_DOUBLE, {.dbl=1},           0.015625,   64, A },

     { "range",     "set max gain reduction", OFFSET(range),     AV_OPT_TYPE_DOUBLE, {.dbl=0.06125},     0, 1, A },

     { "threshold", "set threshold",          OFFSET(threshold), AV_OPT_TYPE_DOUBLE, {.dbl=0.125},       0, 1, A },

@@ -69,6 +77,7 @@ static const AVOption agate_options[] = {

     { NULL }

 };

+#define agate_options options

 AVFILTER_DEFINE_CLASS(agate);

 static int query_formats(AVFilterContext *ctx)

@@ -97,7 +106,7 @@ static int query_formats(AVFilterContext *ctx)

     return ff_set_common_samplerates(ctx, formats);

 }

-static int config_input(AVFilterLink *inlink)

+static int agate_config_input(AVFilterLink *inlink)

 {

     AVFilterContext *ctx = inlink->dst;

     AudioGateContext *s = ctx->priv;

@@ -221,7 +230,7 @@ static const AVFilterPad inputs[] = {

         .name         = "default",

         .type         = AVMEDIA_TYPE_AUDIO,

         .filter_frame = filter_frame,

-        .config_props = config_input,

+        .config_props = agate_config_input,

     },

     { NULL }

 };

@@ -243,3 +252,158 @@ AVFilter ff_af_agate = {

     .inputs         = inputs,

     .outputs        = outputs,

 };

+

+#if CONFIG_SIDECHAINGATE_FILTER

+

+#define sidechaingate_options options

+AVFILTER_DEFINE_CLASS(sidechaingate);

+

+static int scfilter_frame(AVFilterLink *link, AVFrame *in)

+{

+    AVFilterContext *ctx = link->dst;

+    AudioGateContext *s = ctx->priv;

+    AVFilterLink *outlink = ctx->outputs[0];

+    const double *scsrc;

+    double *sample;

+    int nb_samples;

+    int ret, i;

+

+    for (i = 0; i < 2; i++)

+        if (link == ctx->inputs[i])

+            break;

+    av_assert0(i < 2 && !s->input_frame[i]);

+    s->input_frame[i] = in;

+

+    if (!s->input_frame[0] || !s->input_frame[1])

+        return 0;

+

+    nb_samples = FFMIN(s->input_frame[0]->nb_samples,

+                       s->input_frame[1]->nb_samples);

+

+    sample = (double *)s->input_frame[0]->data[0];

+    scsrc = (const double *)s->input_frame[1]->data[0];

+

+    gate(s, sample, sample, scsrc, nb_samples,

+         ctx->inputs[0], ctx->inputs[1]);

+    ret = ff_filter_frame(outlink, s->input_frame[0]);

+

+    s->input_frame[0] = NULL;

+    av_frame_free(&s->input_frame[1]);

+

+    return ret;

+}

+

+static int screquest_frame(AVFilterLink *outlink)

+{

+    AVFilterContext *ctx = outlink->src;

+    AudioGateContext *s = ctx->priv;

+    int i, ret;

+

+    /* get a frame on each input */

+    for (i = 0; i < 2; i++) {

+        AVFilterLink *inlink = ctx->inputs[i];

+        if (!s->input_frame[i] &&

+            (ret = ff_request_frame(inlink)) < 0)

+            return ret;

+

+        /* request the same number of samples on all inputs */

+        if (i == 0)

+            ctx->inputs[1]->request_samples = s->input_frame[0]->nb_samples;

+    }

+

+    return 0;

+}

+

+static int scquery_formats(AVFilterContext *ctx)

+{

+    AVFilterFormats *formats;

+    AVFilterChannelLayouts *layouts = NULL;

+    static const enum AVSampleFormat sample_fmts[] = {

+        AV_SAMPLE_FMT_DBL,

+        AV_SAMPLE_FMT_NONE

+    };

+    int ret, i;

+

+    if (!ctx->inputs[0]->in_channel_layouts ||

+        !ctx->inputs[0]->in_channel_layouts->nb_channel_layouts) {

+        av_log(ctx, AV_LOG_WARNING,

+               "No channel layout for input 1\n");

+            return AVERROR(EAGAIN);

+    }

+

+    if ((ret = ff_add_channel_layout(&layouts, ctx->inputs[0]->in_channel_layouts->channel_layouts[0])) < 0 ||

+        (ret = ff_channel_layouts_ref(layouts, &ctx->outputs[0]->in_channel_layouts)) < 0)

+        return ret;

+

+    for (i = 0; i < 2; i++) {

+        layouts = ff_all_channel_counts();

+        if ((ret = ff_channel_layouts_ref(layouts, &ctx->inputs[i]->out_channel_layouts)) < 0)

+            return ret;

+    }

+

+    formats = ff_make_format_list(sample_fmts);

+    if ((ret = ff_set_common_formats(ctx, formats)) < 0)

+        return ret;

+

+    formats = ff_all_samplerates();

+    return ff_set_common_samplerates(ctx, formats);

+}

+

+static int scconfig_output(AVFilterLink *outlink)

+{

+    AVFilterContext *ctx = outlink->src;

+

+    if (ctx->inputs[0]->sample_rate != ctx->inputs[1]->sample_rate) {

+        av_log(ctx, AV_LOG_ERROR,

+               "Inputs must have the same sample rate "

+               "%d for in0 vs %d for in1\n",

+               ctx->inputs[0]->sample_rate, ctx->inputs[1]->sample_rate);

+        return AVERROR(EINVAL);

+    }

+

+    outlink->sample_rate = ctx->inputs[0]->sample_rate;

+    outlink->time_base   = ctx->inputs[0]->time_base;

+    outlink->channel_layout = ctx->inputs[0]->channel_layout;

+    outlink->channels = ctx->inputs[0]->channels;

+

+    agate_config_input(ctx->inputs[0]);

+

+    return 0;

+}

+

+static const AVFilterPad sidechaingate_inputs[] = {

+    {

+        .name           = "main",

+        .type           = AVMEDIA_TYPE_AUDIO,

+        .filter_frame   = scfilter_frame,

+        .needs_writable = 1,

+        .needs_fifo     = 1,

+    },{

+        .name           = "sidechain",

+        .type           = AVMEDIA_TYPE_AUDIO,

+        .filter_frame   = scfilter_frame,

+        .needs_fifo     = 1,

+    },

+    { NULL }

+};

+

+static const AVFilterPad sidechaingate_outputs[] = {

+    {

+        .name          = "default",

+        .type          = AVMEDIA_TYPE_AUDIO,

+        .config_props  = scconfig_output,

+        .request_frame = screquest_frame,

+    },

+    { NULL }

+};

+

+AVFilter ff_af_sidechaingate = {

+    .name           = "sidechaingate",

+    .description    = NULL_IF_CONFIG_SMALL("Audio sidechain gate."),

+    .priv_size      = sizeof(AudioGateContext),

+    .priv_class     = &sidechaingate_class,

+    .query_formats  = scquery_formats,

+    .inputs         = sidechaingate_inputs,

+    .outputs        = sidechaingate_outputs,

+};

+#endif  /* CONFIG_SIDECHAINGATE_FILTER */

@@ -105,6 +105,7 @@ void avfilter_register_all(void)

     REGISTER_FILTER(RESAMPLE,       resample,       af);

     REGISTER_FILTER(RUBBERBAND,     rubberband,     af);

     REGISTER_FILTER(SIDECHAINCOMPRESS, sidechaincompress, af);

+    REGISTER_FILTER(SIDECHAINGATE,  sidechaingate,  af);

     REGISTER_FILTER(SILENCEDETECT,  silencedetect,  af);

     REGISTER_FILTER(SILENCEREMOVE,  silenceremove,  af);

     REGISTER_FILTER(STEREOTOOLS,    stereotools,    af);

@@ -30,7 +30,7 @@

 #include "libavutil/version.h"

 #define LIBAVFILTER_VERSION_MAJOR   6

-#define LIBAVFILTER_VERSION_MINOR  18

+#define LIBAVFILTER_VERSION_MINOR  19

 #define LIBAVFILTER_VERSION_MICRO 100

 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \