[FFmpeg-devel] =?y?q?=5BPATCH=5D=20lavfi=3A=20add=20earwax=20audio=20filter=2C=20ported=20from=20Sox?=
Stefano Sabatini
stefasab at gmail.com
Tue Nov 1 01:51:32 CET 2011
From: Mina Nagy Zaki <mnzaki at gmail.com>
Signed-off-by: Stefano Sabatini <stefasab at gmail.com>
---
doc/filters.texi | 10 +++
libavfilter/Makefile | 1 +
libavfilter/af_earwax.c | 159 ++++++++++++++++++++++++++++++++++++++++++++++
libavfilter/allfilters.c | 1 +
4 files changed, 171 insertions(+), 0 deletions(-)
create mode 100644 libavfilter/af_earwax.c
diff --git a/doc/filters.texi b/doc/filters.texi
index f282b18..7085ae1 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -224,6 +224,16 @@ expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3} @var{c4} @var{c5}
@var{c6} @var{c7}]"
@end table
+ at section earwax
+
+Make audio easier to listen to on headphones. Adds `cues' to 44.1kHz
+stereo (i.e. audio CD format) audio so that when listened to on
+headphones the stereo image is moved from inside your head (standard
+for headphones) to outside and in front of the listener (standard for
+speakers).
+
+Ported from SoX.
+
@section ladspa
Apply a LADSPA effect.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 040d565..583dd6d 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -28,6 +28,7 @@ OBJS-$(CONFIG_AFORMAT_FILTER) += af_aformat.o
OBJS-$(CONFIG_ANULL_FILTER) += af_anull.o
OBJS-$(CONFIG_ARESAMPLE_FILTER) += af_aresample.o
OBJS-$(CONFIG_ASHOWINFO_FILTER) += af_ashowinfo.o
+OBJS-$(CONFIG_EARWAX_FILTER) += af_earwax.o
OBJS-$(CONFIG_LADSPA_FILTER) += af_ladspa.o
OBJS-$(CONFIG_SOX_FILTER) += af_sox.o
diff --git a/libavfilter/af_earwax.c b/libavfilter/af_earwax.c
new file mode 100644
index 0000000..21099e2
--- /dev/null
+++ b/libavfilter/af_earwax.c
@@ -0,0 +1,159 @@
+/*
+ * Copyright (c) 2011 Mina Nagy Zaki
+ * Copyright (c) 2000 Edward Beingessner And Sundry Contributors.
+ * This source code is freely redistributable and may be used for any purpose.
+ * This copyright notice must be maintained. Edward Beingessner And Sundry
+ * Contributors are not responsible for the consequences of using this
+ * software.
+ *
+ * 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
+ * Stereo Widening Effect. Adds audio cues to move stereo image in
+ * front of the listener. Adapted from the libsox earwax effect.
+ */
+
+#include "libavutil/audioconvert.h"
+#include "avfilter.h"
+
+#define NUMTAPS 64
+
+static const int8_t filt[NUMTAPS] = {
+/* 30° 330° */
+ 4, -6, /* 32 tap stereo FIR filter. */
+ 4, -11, /* One side filters as if the */
+ -1, -5, /* signal was from 30 degrees */
+ 3, 3, /* from the ear, the other as */
+ -2, 5, /* if 330 degrees. */
+ -5, 0,
+ 9, 1,
+ 6, 3, /* Input */
+ -4, -1, /* Left Right */
+ -5, -3, /* __________ __________ */
+ -2, -5, /* | | | | */
+ -7, 1, /* .---| Hh,0(f) | | Hh,0(f) |---. */
+ 6, -7, /* / |__________| |__________| \ */
+ 30, -29, /* / \ / \ */
+ 12, -3, /* / X \ */
+ -11, 4, /* / / \ \ */
+ -3, 7, /* ____V_____ __________V V__________ _____V____ */
+ -20, 23, /* | | | | | | | | */
+ 2, 0, /* | Hh,30(f) | | Hh,330(f)| | Hh,330(f)| | Hh,30(f) | */
+ 1, -6, /* |__________| |__________| |__________| |__________| */
+ -14, -5, /* \ ___ / \ ___ / */
+ 15, -18, /* \ / \ / _____ \ / \ / */
+ 6, 7, /* `->| + |<--' / \ `-->| + |<-' */
+ 15, -10, /* \___/ _/ \_ \___/ */
+ -14, 22, /* \ / \ / \ / */
+ -7, -2, /* `--->| | | |<---' */
+ -4, 9, /* \_/ \_/ */
+ 6, -12, /* */
+ 6, -6, /* Headphones */
+ 0, -11,
+ 0, -5,
+ 4, 0};
+
+typedef struct {
+ int16_t taps[NUMTAPS * 2];
+} EarwaxContext;
+
+static int query_formats(AVFilterContext *ctx)
+{
+ AVFilterFormats *formats = NULL;
+ avfilter_add_format(&formats, AV_SAMPLE_FMT_S16);
+ avfilter_set_common_sample_formats(ctx, formats);
+ formats = NULL;
+ avfilter_add_format(&formats, AV_CH_LAYOUT_STEREO);
+ avfilter_set_common_channel_layouts(ctx, formats);
+ formats = NULL;
+ avfilter_add_format(&formats, AVFILTER_PACKED);
+ avfilter_set_common_packing_formats(ctx, formats);
+
+ return 0;
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+ if (inlink->sample_rate != 44100) {
+ av_log(inlink->dst, AV_LOG_ERROR,
+ "The earwax filter only works for 44.1kHz audio. Insert "
+ "a resample filter before this\n");
+ return AVERROR(EINVAL);
+ }
+ return 0;
+}
+
+//FIXME: replace with DSPContext.scalarproduct_int16
+static inline int16_t *scalarproduct(int16_t *in, int16_t *endin, int16_t *out)
+{
+ int32_t sample;
+ int16_t j;
+
+ while (in < endin) {
+ sample = 0;
+ for (j = 0; j < NUMTAPS; j++)
+ sample += in[j] * filt[j];
+ *out = sample >> 6;
+ out++; in++;
+ }
+
+ return out;
+}
+
+static void filter_samples(AVFilterLink *inlink, AVFilterBufferRef *insamples)
+{
+ int16_t *taps, *endin, *in, *out;
+ AVFilterBufferRef *outref =
+ avfilter_get_audio_buffer(inlink, AV_PERM_WRITE,
+ insamples->audio->nb_samples);
+ taps = ((EarwaxContext*)inlink->dst->priv)->taps;
+ out = (int16_t *)outref->data[0];
+ in = (int16_t *)insamples->data[0];
+
+ // copy part of new input and process with saved input
+ memcpy(taps+NUMTAPS, in, NUMTAPS * sizeof(*taps));
+ out = scalarproduct(taps, taps + NUMTAPS, out);
+
+ // process current input
+ endin = in + insamples->audio->nb_samples * 2 - NUMTAPS;
+ out = scalarproduct(in, endin, out);
+
+ // save part of input for next round
+ memcpy(taps, endin, NUMTAPS * sizeof(*taps));
+
+ avfilter_filter_samples(inlink->dst->outputs[0], outref);
+ avfilter_unref_buffer(insamples);
+}
+
+AVFilter avfilter_af_earwax = {
+ .name = "earwax",
+ .description = NULL_IF_CONFIG_SMALL("Widen the stereo image."),
+ .query_formats = query_formats,
+ .priv_size = sizeof(EarwaxContext),
+ .inputs = (AVFilterPad[]) {{ .name = "default",
+ .type = AVMEDIA_TYPE_AUDIO,
+ .filter_samples = filter_samples,
+ .config_props = config_input,
+ .min_perms = AV_PERM_READ, },
+ { .name = NULL}},
+
+ .outputs = (AVFilterPad[]) {{ .name = "default",
+ .type = AVMEDIA_TYPE_AUDIO, },
+ { .name = NULL}},
+};
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index a7468c0..185114c 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -39,6 +39,7 @@ void avfilter_register_all(void)
REGISTER_FILTER (ANULL, anull, af);
REGISTER_FILTER (ARESAMPLE, aresample, af);
REGISTER_FILTER (ASHOWINFO, ashowinfo, af);
+ REGISTER_FILTER (EARWAX, earwax, af);
REGISTER_FILTER (LADSPA, ladspa, af);
REGISTER_FILTER (SOX, sox, af);
--
1.7.4.1
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