@@ -12,6 +12,7 @@ version <next>:

 - afir audio filter

 - scale_cuda CUDA based video scale filter

 - librsvg support for svg rasterization

+- crossfeed audio filter

 version 3.3:

 - CrystalHD decoder moved to new decode API

@@ -2251,6 +2251,35 @@ Set temperature degree in Celsius. This is the temperature of the environment.

 Default is 20.

 @end table

+@section crossfeed

+Apply headphone crossfeed filter.

+

+Crossfeed is the process of blending the left and right channels of stereo

+audio recording.

+It is mainly used to reduce extreme stereo separation of low frequencies.

+

+The intent is to produce more speaker like sound to the listener.

+

+The filter accepts the following options:

+

+@table @option

+@item strength

+Set strength of crossfeed. Default is 0.2. Allowed range is from 0 to 1.

+This sets gain of low shelf filter for side part of stereo image.

+Default is -6dB. Max allowed is -30db when strength is set to 1.

+

+@item range

+Set soundstage wideness. Default is 0.5. Allowed range is from 0 to 1.

+This sets cut off frequency of low shelf filter. Default is cut off near

+1550 Hz. With range set to 1 cut off frequency is set to 2100 Hz.

+

+@item level_in

+Set input gain. Default is 0.9.

+

+@item level_out

+Set output gain. Default is 1.

+@end table

+

 @section crystalizer

 Simple algorithm to expand audio dynamic range.

@@ -81,6 +81,7 @@ OBJS-$(CONFIG_CHANNELSPLIT_FILTER)           += af_channelsplit.o

 OBJS-$(CONFIG_CHORUS_FILTER)                 += af_chorus.o generate_wave_table.o

 OBJS-$(CONFIG_COMPAND_FILTER)                += af_compand.o

 OBJS-$(CONFIG_COMPENSATIONDELAY_FILTER)      += af_compensationdelay.o

+OBJS-$(CONFIG_CROSSFEED_FILTER)              += af_crossfeed.o

 OBJS-$(CONFIG_CRYSTALIZER_FILTER)            += af_crystalizer.o

 OBJS-$(CONFIG_DCSHIFT_FILTER)                += af_dcshift.o

 OBJS-$(CONFIG_DYNAUDNORM_FILTER)             += af_dynaudnorm.o

new file mode 100644

@@ -0,0 +1,169 @@

+/*

+ * 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

+ */

+

+#include "libavutil/channel_layout.h"

+#include "libavutil/opt.h"

+#include "avfilter.h"

+#include "audio.h"

+#include "formats.h"

+

+typedef struct CrossfeedContext {

+    const AVClass *class;

+

+    double range;

+    double strength;

+    double level_in;

+    double level_out;

+

+    double a0, a1, a2;

+    double b0, b1, b2;

+

+    double i1, i2;

+    double o1, o2;

+} CrossfeedContext;

+

+static int query_formats(AVFilterContext *ctx)

+{

+    AVFilterFormats *formats = NULL;

+    AVFilterChannelLayouts *layout = NULL;

+    int ret;

+

+    if ((ret = ff_add_format                 (&formats, AV_SAMPLE_FMT_DBL  )) < 0 ||

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

+        (ret = ff_add_channel_layout         (&layout , AV_CH_LAYOUT_STEREO)) < 0 ||

+        (ret = ff_set_common_channel_layouts (ctx     , layout             )) < 0 ||

+        (ret = ff_set_common_samplerates     (ctx     , ff_all_samplerates())) < 0)

+        return ret;

+

+    return 0;

+}

+

+static int config_input(AVFilterLink *inlink)

+{

+    AVFilterContext *ctx = inlink->dst;

+    CrossfeedContext *s = ctx->priv;

+    double A = exp(s->strength * -30 / 40 * log(10.));

+    double w0 = 2 * M_PI * (1. - s->range) * 2100 / inlink->sample_rate;

+    double alpha;

+

+    alpha = sin(w0) / 2 * sqrt(2 * (1 / 0.5 - 1) + 2);

+

+    s->a0 =          (A + 1) + (A - 1) * cos(w0) + 2 * sqrt(A) * alpha;

+    s->a1 =    -2 * ((A - 1) + (A + 1) * cos(w0));

+    s->a2 =          (A + 1) + (A - 1) * cos(w0) - 2 * sqrt(A) * alpha;

+    s->b0 =     A * ((A + 1) - (A - 1) * cos(w0) + 2 * sqrt(A) * alpha);

+    s->b1 = 2 * A * ((A - 1) - (A + 1) * cos(w0));

+    s->b2 =     A * ((A + 1) - (A - 1) * cos(w0) - 2 * sqrt(A) * alpha);

+

+    s->a1 /= s->a0;

+    s->a2 /= s->a0;

+    s->b0 /= s->a0;

+    s->b1 /= s->a0;

+    s->b2 /= s->a0;

+

+    return 0;

+}

+

+static int filter_frame(AVFilterLink *inlink, AVFrame *in)

+{

+    AVFilterContext *ctx = inlink->dst;

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

+    CrossfeedContext *s = ctx->priv;

+    const double *src = (const double *)in->data[0];

+    const double level_in = s->level_in;

+    const double level_out = s->level_out;

+    const double b0 = s->b0;

+    const double b1 = s->b1;

+    const double b2 = s->b2;

+    const double a1 = s->a1;

+    const double a2 = s->a2;

+    AVFrame *out;

+    double *dst;

+    int n;

+

+    if (av_frame_is_writable(in)) {

+        out = in;

+    } else {

+        out = ff_get_audio_buffer(inlink, in->nb_samples);

+        if (!out) {

+            av_frame_free(&in);

+            return AVERROR(ENOMEM);

+        }

+        av_frame_copy_props(out, in);

+    }

+    dst = (double *)out->data[0];

+

+    for (n = 0; n < out->nb_samples; n++, src += 2, dst += 2) {

+        double mid = (src[0] + src[1]) * level_in * .5;

+        double side = (src[0] - src[1]) * level_in * .5;

+        double oside = side * b0 + s->i1 * b1 + s->i2 * b2 - s->o1 * a1 - s->o2 * a2;

+

+        s->i2 = s->i1;

+        s->i1 = side;

+        s->o2 = s->o1;

+        s->o1 = oside;

+

+        dst[0] = (mid + oside) * level_out;

+        dst[1] = (mid - oside) * level_out;

+    }

+

+    if (out != in)

+        av_frame_free(&in);

+    return ff_filter_frame(outlink, out);

+}

+

+#define OFFSET(x) offsetof(CrossfeedContext, x)

+#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM

+

+static const AVOption crossfeed_options[] = {

+    { "strength",  "set crossfeed strength",  OFFSET(strength),  AV_OPT_TYPE_DOUBLE, {.dbl=.2}, 0, 1, FLAGS },

+    { "range",     "set soundstage wideness", OFFSET(range),     AV_OPT_TYPE_DOUBLE, {.dbl=.5}, 0, 1, FLAGS },

+    { "level_in",  "set level in",            OFFSET(level_in),  AV_OPT_TYPE_DOUBLE, {.dbl=.9}, 0, 1, FLAGS },

+    { "level_out", "set level out",           OFFSET(level_out), AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0, 1, FLAGS },

+    { NULL }

+};

+

+AVFILTER_DEFINE_CLASS(crossfeed);

+

+static const AVFilterPad inputs[] = {

+    {

+        .name         = "default",

+        .type         = AVMEDIA_TYPE_AUDIO,

+        .filter_frame = filter_frame,

+        .config_props = config_input,

+    },

+    { NULL }

+};

+

+static const AVFilterPad outputs[] = {

+    {

+        .name = "default",

+        .type = AVMEDIA_TYPE_AUDIO,

+    },

+    { NULL }

+};

+

+AVFilter ff_af_crossfeed = {

+    .name           = "crossfeed",

+    .description    = NULL_IF_CONFIG_SMALL("Apply headphone crossfeed filter."),

+    .query_formats  = query_formats,

+    .priv_size      = sizeof(CrossfeedContext),

+    .priv_class     = &crossfeed_class,

+    .inputs         = inputs,

+    .outputs        = outputs,

+};

@@ -94,6 +94,7 @@ static void register_all(void)

     REGISTER_FILTER(CHORUS,         chorus,         af);

     REGISTER_FILTER(COMPAND,        compand,        af);

     REGISTER_FILTER(COMPENSATIONDELAY, compensationdelay, af);

+    REGISTER_FILTER(CROSSFEED,      crossfeed,      af);

     REGISTER_FILTER(CRYSTALIZER,    crystalizer,    af);

     REGISTER_FILTER(DCSHIFT,        dcshift,        af);

     REGISTER_FILTER(DYNAUDNORM,     dynaudnorm,     af);

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

 #include "libavutil/version.h"

 #define LIBAVFILTER_VERSION_MAJOR   6

-#define LIBAVFILTER_VERSION_MINOR  89

-#define LIBAVFILTER_VERSION_MICRO 101

+#define LIBAVFILTER_VERSION_MINOR  90

+#define LIBAVFILTER_VERSION_MICRO 100

 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

                                                LIBAVFILTER_VERSION_MINOR, \