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avfilter: add stereowiden filter
Signed-off-by: Paul B Mahol <onemda@gmail.com>
This commit is contained in:
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@ -6,6 +6,7 @@ version <next>:
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- extrastereo filter
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- ocr filter
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- alimiter filter
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- stereowiden filter
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version 2.8:
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@ -2394,6 +2394,33 @@ silenceremove=1:5:0.02
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@end example
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@end itemize
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@section stereowiden
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This filter enhance the stereo effect by suppressing signal common to both
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channels and by delaying the signal of left into right and vice versa,
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thereby widening the stereo effect.
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The filter accepts the following options:
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@table @option
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@item delay
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Time in milliseconds of the delay of left signal into right and vice versa.
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Default is 20 milliseconds.
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@item feedback
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Amount of gain in delayed signal into right and vice versa. Gives a delay
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effect of left signal in right output and vice versa which gives widening
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effect. Default is 0.3.
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@item crossfeed
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Cross feed of left into right with inverted phase. This helps in suppressing
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the mono. If the value is 1 it will cancel all the signal common to both
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channels. Default is 0.3.
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@item drymix
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Set level of input signal of original channel. Default is 0.8.
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@end table
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@section treble
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Boost or cut treble (upper) frequencies of the audio using a two-pole
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@ -80,6 +80,7 @@ OBJS-$(CONFIG_RESAMPLE_FILTER) += af_resample.o
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OBJS-$(CONFIG_SIDECHAINCOMPRESS_FILTER) += af_sidechaincompress.o
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OBJS-$(CONFIG_SILENCEDETECT_FILTER) += af_silencedetect.o
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OBJS-$(CONFIG_SILENCEREMOVE_FILTER) += af_silenceremove.o
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OBJS-$(CONFIG_STEREOWIDEN_FILTER) += af_stereowiden.o
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OBJS-$(CONFIG_TREBLE_FILTER) += af_biquads.o
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OBJS-$(CONFIG_VOLUME_FILTER) += af_volume.o
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OBJS-$(CONFIG_VOLUMEDETECT_FILTER) += af_volumedetect.o
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167
libavfilter/af_stereowiden.c
Normal file
167
libavfilter/af_stereowiden.c
Normal file
@ -0,0 +1,167 @@
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/*
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* Copyright (C) 2012 VLC authors and VideoLAN
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* Author : Sukrit Sangwan < sukritsangwan at gmail dot com >
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/channel_layout.h"
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#include "libavutil/opt.h"
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#include "avfilter.h"
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#include "audio.h"
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#include "formats.h"
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typedef struct StereoWidenContext {
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const AVClass *class;
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float delay;
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float feedback;
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float crossfeed;
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float drymix;
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float *buffer;
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float *write;
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int length;
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} StereoWidenContext;
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#define OFFSET(x) offsetof(StereoWidenContext, x)
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#define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
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static const AVOption stereowiden_options[] = {
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{ "delay", "set delay time", OFFSET(delay), AV_OPT_TYPE_FLOAT, {.dbl=20}, 1, 100, A },
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{ "feedback", "set feedback gain", OFFSET(feedback), AV_OPT_TYPE_FLOAT, {.dbl=.3}, 0, 0.9, A },
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{ "crossfeed", "set cross feed", OFFSET(crossfeed), AV_OPT_TYPE_FLOAT, {.dbl=.3}, 0, 0.8, A },
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{ "drymix", "set dry-mix", OFFSET(drymix), AV_OPT_TYPE_FLOAT, {.dbl=.8}, 0, 1.0, A },
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{ NULL }
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};
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AVFILTER_DEFINE_CLASS(stereowiden);
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static int query_formats(AVFilterContext *ctx)
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{
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AVFilterFormats *formats = NULL;
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AVFilterChannelLayouts *layout = NULL;
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ff_add_format(&formats, AV_SAMPLE_FMT_FLT);
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ff_set_common_formats(ctx, formats);
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ff_add_channel_layout(&layout, AV_CH_LAYOUT_STEREO);
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ff_set_common_channel_layouts(ctx, layout);
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formats = ff_all_samplerates();
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if (!formats)
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return AVERROR(ENOMEM);
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return ff_set_common_samplerates(ctx, formats);
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}
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static int config_input(AVFilterLink *inlink)
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{
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AVFilterContext *ctx = inlink->dst;
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StereoWidenContext *s = ctx->priv;
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s->length = 2 * s->delay * inlink->sample_rate / 1000;
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s->buffer = av_calloc(s->length, sizeof(s->buffer));
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if (!s->buffer)
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return AVERROR(ENOMEM);
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s->write = s->buffer;
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return 0;
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}
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static int filter_frame(AVFilterLink *inlink, AVFrame *in)
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{
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AVFilterContext *ctx = inlink->dst;
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AVFilterLink *outlink = ctx->outputs[0];
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StereoWidenContext *s = ctx->priv;
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const float *src = (const float *)in->data[0];
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const float drymix = s->drymix;
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const float crossfeed = s->crossfeed;
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const float feedback = s->feedback;
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AVFrame *out = NULL;
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float *dst;
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int n;
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if (av_frame_is_writable(in)) {
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out = in;
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} else {
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AVFrame *out = ff_get_audio_buffer(inlink, in->nb_samples);
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if (!out) {
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av_frame_free(&in);
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return AVERROR(ENOMEM);
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}
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av_frame_copy_props(out, in);
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}
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dst = (float *)out->data[0];
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for (n = 0; n < in->nb_samples; n++, src += 2, dst += 2) {
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const float left = src[0], right = src[1];
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float *read = s->write + 2;
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if (read > s->buffer + s->length)
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read = s->buffer;
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dst[0] = drymix * left - crossfeed * right - feedback * read[1];
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dst[1] = drymix * right - crossfeed * left - feedback * read[0];
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s->write[0] = left;
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s->write[1] = right;
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if (s->write == s->buffer + s->length)
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s->write = s->buffer;
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else
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s->write += 2;
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}
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if (out != in)
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av_frame_free(&in);
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return ff_filter_frame(outlink, out);
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}
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static av_cold void uninit(AVFilterContext *ctx)
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{
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StereoWidenContext *s = ctx->priv;
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av_freep(&s->buffer);
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}
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static const AVFilterPad inputs[] = {
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{
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.name = "default",
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.type = AVMEDIA_TYPE_AUDIO,
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.filter_frame = filter_frame,
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.config_props = config_input,
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},
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{ NULL }
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};
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static const AVFilterPad outputs[] = {
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{
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.name = "default",
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.type = AVMEDIA_TYPE_AUDIO,
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},
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{ NULL }
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};
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AVFilter ff_af_stereowiden = {
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.name = "stereowiden",
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.description = NULL_IF_CONFIG_SMALL("Apply stereo widening effect."),
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.query_formats = query_formats,
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.priv_size = sizeof(StereoWidenContext),
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.priv_class = &stereowiden_class,
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.uninit = uninit,
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.inputs = inputs,
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.outputs = outputs,
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};
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@ -102,6 +102,7 @@ void avfilter_register_all(void)
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REGISTER_FILTER(SIDECHAINCOMPRESS, sidechaincompress, af);
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REGISTER_FILTER(SILENCEDETECT, silencedetect, af);
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REGISTER_FILTER(SILENCEREMOVE, silenceremove, af);
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REGISTER_FILTER(STEREOWIDEN, stereowiden, af);
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REGISTER_FILTER(TREBLE, treble, af);
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REGISTER_FILTER(VOLUME, volume, af);
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REGISTER_FILTER(VOLUMEDETECT, volumedetect, af);
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@ -30,7 +30,7 @@
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#include "libavutil/version.h"
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#define LIBAVFILTER_VERSION_MAJOR 6
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#define LIBAVFILTER_VERSION_MINOR 3
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#define LIBAVFILTER_VERSION_MINOR 4
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#define LIBAVFILTER_VERSION_MICRO 100
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#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
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