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/*
* Copyright (C) 2012 VLC authors and VideoLAN
* Author : Sukrit Sangwan < sukritsangwan at gmail dot com >
*
* 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 StereoWidenContext {
const AVClass *class;
float delay;
float feedback;
float crossfeed;
float drymix;
float *buffer;
float *write;
int length;
} StereoWidenContext;
#define OFFSET(x) offsetof(StereoWidenContext, x)
#define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
static const AVOption stereowiden_options[] = {
{ "delay", "set delay time", OFFSET(delay), AV_OPT_TYPE_FLOAT, {.dbl=20}, 1, 100, A },
{ "feedback", "set feedback gain", OFFSET(feedback), AV_OPT_TYPE_FLOAT, {.dbl=.3}, 0, 0.9, A },
{ "crossfeed", "set cross feed", OFFSET(crossfeed), AV_OPT_TYPE_FLOAT, {.dbl=.3}, 0, 0.8, A },
{ "drymix", "set dry-mix", OFFSET(drymix), AV_OPT_TYPE_FLOAT, {.dbl=.8}, 0, 1.0, A },
{ NULL }
};
AVFILTER_DEFINE_CLASS(stereowiden);
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 config_input(AVFilterLink *inlink)
{
AVFilterContext *ctx = inlink->dst;
StereoWidenContext *s = ctx->priv;
s->length = 2 * s->delay * inlink->sample_rate / 1000;
s->buffer = av_calloc(s->length, sizeof(*s->buffer));
if (!s->buffer)
return AVERROR(ENOMEM);
s->write = s->buffer;
return 0;
}
static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
AVFilterContext *ctx = inlink->dst;
AVFilterLink *outlink = ctx->outputs[0];
StereoWidenContext *s = ctx->priv;
const float *src = (const float *)in->data[0];
const float drymix = s->drymix;
const float crossfeed = s->crossfeed;
const float feedback = s->feedback;
AVFrame *out;
float *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 = (float *)out->data[0];
for (n = 0; n < in->nb_samples; n++, src += 2, dst += 2) {
const float left = src[0], right = src[1];
float *read = s->write + 2;
if (read > s->buffer + s->length)
read = s->buffer;
dst[0] = drymix * left - crossfeed * right - feedback * read[1];
dst[1] = drymix * right - crossfeed * left - feedback * read[0];
s->write[0] = left;
s->write[1] = right;
if (s->write == s->buffer + s->length)
s->write = s->buffer;
else
s->write += 2;
}
if (out != in)
av_frame_free(&in);
return ff_filter_frame(outlink, out);
}
static av_cold void uninit(AVFilterContext *ctx)
{
StereoWidenContext *s = ctx->priv;
av_freep(&s->buffer);
}
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_stereowiden = {
.name = "stereowiden",
.description = NULL_IF_CONFIG_SMALL("Apply stereo widening effect."),
.query_formats = query_formats,
.priv_size = sizeof(StereoWidenContext),
.priv_class = &stereowiden_class,
.uninit = uninit,
.inputs = inputs,
.outputs = outputs,
};
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