[FFmpeg-cvslog] avfilter: add extrastereo filter
Paul B Mahol
git at videolan.org
Tue Sep 8 12:51:55 CEST 2015
ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Sat Sep 5 03:55:47 2015 +0000| [b31041adc32f9bb26a400903f13c2220fa6e08f5] | committer: Paul B Mahol
avfilter: add extrastereo filter
Signed-off-by: Paul B Mahol <onemda at gmail.com>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b31041adc32f9bb26a400903f13c2220fa6e08f5
---
Changelog | 1 +
doc/filters.texi | 17 ++++++
libavfilter/Makefile | 1 +
libavfilter/af_extrastereo.c | 128 ++++++++++++++++++++++++++++++++++++++++++
libavfilter/allfilters.c | 1 +
libavfilter/version.h | 2 +-
6 files changed, 149 insertions(+), 1 deletion(-)
diff --git a/Changelog b/Changelog
index 7e929e9..d538c42 100644
--- a/Changelog
+++ b/Changelog
@@ -3,6 +3,7 @@ releases are sorted from youngest to oldest.
version <next>:
- DXV decoding
+- extrastereo filter
version 2.8:
diff --git a/doc/filters.texi b/doc/filters.texi
index 4d69cd4..37e6454 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -1817,6 +1817,23 @@ equalizer=f=1000:width_type=q:width=1:g=2,equalizer=f=100:width_type=q:width=2:g
@end example
@end itemize
+ at section extrastereo
+
+Linearly increases the difference between left and right channels which
+adds some sort of "live" effect to playback.
+
+The filter accepts the following option:
+
+ at table @option
+ at item m
+Sets the difference coefficient (default: 2.5). 0.0 means mono sound
+(average of both channels), with 1.0 sound will be unchanged, with
+-1.0 left and right channels will be swapped.
+
+ at item c
+Enable clipping. By default is enabled.
+ at end table
+
@section flanger
Apply a flanging effect to the audio.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index a8b3a4d..11a8646 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -67,6 +67,7 @@ OBJS-$(CONFIG_DYNAUDNORM_FILTER) += af_dynaudnorm.o
OBJS-$(CONFIG_EARWAX_FILTER) += af_earwax.o
OBJS-$(CONFIG_EBUR128_FILTER) += f_ebur128.o
OBJS-$(CONFIG_EQUALIZER_FILTER) += af_biquads.o
+OBJS-$(CONFIG_EXTRASTEREO_FILTER) += af_extrastereo.o
OBJS-$(CONFIG_FLANGER_FILTER) += af_flanger.o generate_wave_table.o
OBJS-$(CONFIG_HIGHPASS_FILTER) += af_biquads.o
OBJS-$(CONFIG_JOIN_FILTER) += af_join.o
diff --git a/libavfilter/af_extrastereo.c b/libavfilter/af_extrastereo.c
new file mode 100644
index 0000000..4877244
--- /dev/null
+++ b/libavfilter/af_extrastereo.c
@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2015 The FFmpeg Project
+ *
+ * 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 ExtraStereoContext {
+ const AVClass *class;
+ float mult;
+ int clip;
+} ExtraStereoContext;
+
+#define OFFSET(x) offsetof(ExtraStereoContext, x)
+#define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption extrastereo_options[] = {
+ { "m", "set the difference coefficient", OFFSET(mult), AV_OPT_TYPE_FLOAT, {.dbl=2.5}, -10, 10, A },
+ { "c", "enable clipping", OFFSET(clip), AV_OPT_TYPE_INT, {.i64=1}, 0, 1, A },
+ { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(extrastereo);
+
+static int query_formats(AVFilterContext *ctx)
+{
+ AVFilterFormats *formats = NULL;
+ AVFilterChannelLayouts *layout = NULL;
+
+ ff_add_format(&formats, AV_SAMPLE_FMT_FLT);
+ ff_set_common_formats(ctx, formats);
+ ff_add_channel_layout(&layout, AV_CH_LAYOUT_STEREO);
+ ff_set_common_channel_layouts(ctx, layout);
+
+ formats = ff_all_samplerates();
+ if (!formats)
+ return AVERROR(ENOMEM);
+ return ff_set_common_samplerates(ctx, formats);
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+ AVFilterContext *ctx = inlink->dst;
+ AVFilterLink *outlink = ctx->outputs[0];
+ ExtraStereoContext *s = ctx->priv;
+ const float *src = (const float *)in->data[0];
+ const float mult = s->mult;
+ AVFrame *out = NULL;
+ float *dst;
+ int n;
+
+ if (av_frame_is_writable(in)) {
+ out = in;
+ } else {
+ AVFrame *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 = (float *)out->data[0];
+
+ for (n = 0; n < in->nb_samples; n++) {
+ float average, left, right;
+
+ left = src[n * 2 ];
+ right = src[n * 2 + 1];
+ average = (left + right) / 2.;
+ left = average + mult * (left - average);
+ right = average + mult * (right - average);
+
+ if (s->clip) {
+ dst[n * 2 ] = av_clipf(left, -1, 1);
+ dst[n * 2 + 1] = av_clipf(right, -1, 1);
+ }
+ }
+
+ if (out != in)
+ av_frame_free(&in);
+ return ff_filter_frame(outlink, out);
+}
+
+static const AVFilterPad inputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_AUDIO,
+ .filter_frame = filter_frame,
+ },
+ { NULL }
+};
+
+static const AVFilterPad outputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_AUDIO,
+ },
+ { NULL }
+};
+
+AVFilter ff_af_extrastereo = {
+ .name = "extrastereo",
+ .description = NULL_IF_CONFIG_SMALL("Increase difference between stereo audio channels."),
+ .query_formats = query_formats,
+ .priv_size = sizeof(ExtraStereoContext),
+ .priv_class = &extrastereo_class,
+ .inputs = inputs,
+ .outputs = outputs,
+};
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 427585f..9df2d53 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -89,6 +89,7 @@ void avfilter_register_all(void)
REGISTER_FILTER(EARWAX, earwax, af);
REGISTER_FILTER(EBUR128, ebur128, af);
REGISTER_FILTER(EQUALIZER, equalizer, af);
+ REGISTER_FILTER(EXTRASTEREO, extrastereo, af);
REGISTER_FILTER(FLANGER, flanger, af);
REGISTER_FILTER(HIGHPASS, highpass, af);
REGISTER_FILTER(JOIN, join, af);
diff --git a/libavfilter/version.h b/libavfilter/version.h
index 5ef78dc..87a5836 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -30,7 +30,7 @@
#include "libavutil/version.h"
#define LIBAVFILTER_VERSION_MAJOR 6
-#define LIBAVFILTER_VERSION_MINOR 0
+#define LIBAVFILTER_VERSION_MINOR 1
#define LIBAVFILTER_VERSION_MICRO 100
#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
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