[FFmpeg-cvslog] avfilter: add audio crossfeed filter
Paul B Mahol
git at videolan.org
Wed May 17 21:22:23 EEST 2017
ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Sun May 14 18:30:12 2017 +0200| [deaab31d61fd3679491a5e81cd26432886815ddf] | committer: Paul B Mahol
avfilter: add audio crossfeed filter
Signed-off-by: Paul B Mahol <onemda at gmail.com>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=deaab31d61fd3679491a5e81cd26432886815ddf
---
Changelog | 1 +
doc/filters.texi | 29 ++++++++
libavfilter/Makefile | 1 +
libavfilter/af_crossfeed.c | 169 +++++++++++++++++++++++++++++++++++++++++++++
libavfilter/allfilters.c | 1 +
libavfilter/version.h | 4 +-
6 files changed, 203 insertions(+), 2 deletions(-)
diff --git a/Changelog b/Changelog
index 3504b7ff35..ff982e5db2 100644
--- a/Changelog
+++ b/Changelog
@@ -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
diff --git a/doc/filters.texi b/doc/filters.texi
index a7c6063969..69907d4f75 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -2251,6 +2251,35 @@ Set temperature degree in Celsius. This is the temperature of the environment.
Default is 20.
@end table
+ at 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:
+
+ at table @option
+ at 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.
+
+ at 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.
+
+ at item level_in
+Set input gain. Default is 0.9.
+
+ at item level_out
+Set output gain. Default is 1.
+ at end table
+
@section crystalizer
Simple algorithm to expand audio dynamic range.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index f177fdb42b..434a989244 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -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
diff --git a/libavfilter/af_crossfeed.c b/libavfilter/af_crossfeed.c
new file mode 100644
index 0000000000..d3def92fb3
--- /dev/null
+++ b/libavfilter/af_crossfeed.c
@@ -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,
+};
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index a8939b9094..2bcfce77be 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -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);
diff --git a/libavfilter/version.h b/libavfilter/version.h
index 853333d8f8..55cf5d0fc2 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -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, \
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