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/*
* Copyright (c) 2015 Kyle Swanson <k@ylo.ph>.
*
* 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/opt.h"
#include "avfilter.h"
#include "internal.h"
#include "audio.h"
typedef struct TremoloContext {
const AVClass *class;
double freq;
double depth;
double *table;
int table_size;
int index;
} TremoloContext;
#define OFFSET(x) offsetof(TremoloContext, x)
#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
static const AVOption tremolo_options[] = {
{ "f", "set frequency in hertz", OFFSET(freq), AV_OPT_TYPE_DOUBLE, {.dbl = 5.0}, 0.1, 20000.0, FLAGS },
{ "d", "set depth as percentage", OFFSET(depth), AV_OPT_TYPE_DOUBLE, {.dbl = 0.5}, 0.0, 1.0, FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(tremolo);
static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
AVFilterContext *ctx = inlink->dst;
AVFilterLink *outlink = ctx->outputs[0];
TremoloContext *s = ctx->priv;
const double *src = (const double *)in->data[0];
const int channels = inlink->ch_layout.nb_channels;
const int nb_samples = in->nb_samples;
AVFrame *out;
double *dst;
int n, c;
if (av_frame_is_writable(in)) {
out = in;
} else {
out = ff_get_audio_buffer(outlink, 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 < nb_samples; n++) {
for (c = 0; c < channels; c++)
dst[c] = src[c] * s->table[s->index];
dst += channels;
src += channels;
s->index++;
if (s->index >= s->table_size)
s->index = 0;
}
if (in != out)
av_frame_free(&in);
return ff_filter_frame(outlink, out);
}
static av_cold void uninit(AVFilterContext *ctx)
{
TremoloContext *s = ctx->priv;
av_freep(&s->table);
}
static int config_input(AVFilterLink *inlink)
{
AVFilterContext *ctx = inlink->dst;
TremoloContext *s = ctx->priv;
const double offset = 1. - s->depth / 2.;
int i;
s->table_size = lrint(inlink->sample_rate / s->freq + 0.5);
s->table = av_malloc_array(s->table_size, sizeof(*s->table));
if (!s->table)
return AVERROR(ENOMEM);
for (i = 0; i < s->table_size; i++) {
double env = s->freq * i / inlink->sample_rate;
env = sin(2 * M_PI * fmod(env + 0.25, 1.0));
s->table[i] = env * (1 - fabs(offset)) + offset;
}
s->index = 0;
return 0;
}
static const AVFilterPad avfilter_af_tremolo_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.config_props = config_input,
.filter_frame = filter_frame,
},
};
const AVFilter ff_af_tremolo = {
.name = "tremolo",
.description = NULL_IF_CONFIG_SMALL("Apply tremolo effect."),
.priv_size = sizeof(TremoloContext),
.priv_class = &tremolo_class,
.uninit = uninit,
FILTER_INPUTS(avfilter_af_tremolo_inputs),
FILTER_OUTPUTS(ff_audio_default_filterpad),
FILTER_SINGLE_SAMPLEFMT(AV_SAMPLE_FMT_DBL),
.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
};
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