2015-09-21 17:16:43 +02:00
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/*
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* Copyright (c) 2015 Kyle Swanson <k@ylo.ph>.
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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/opt.h"
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#include "avfilter.h"
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#include "internal.h"
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#include "audio.h"
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typedef struct TremoloContext {
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const AVClass *class;
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double freq;
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double depth;
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2015-09-23 23:03:35 +02:00
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double *table;
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2019-10-19 19:34:47 +02:00
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int table_size;
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2015-09-23 23:03:35 +02:00
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int index;
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2015-09-21 17:16:43 +02:00
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} TremoloContext;
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#define OFFSET(x) offsetof(TremoloContext, x)
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#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
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static const AVOption tremolo_options[] = {
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{ "f", "set frequency in hertz", OFFSET(freq), AV_OPT_TYPE_DOUBLE, {.dbl = 5.0}, 0.1, 20000.0, FLAGS },
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{ "d", "set depth as percentage", OFFSET(depth), AV_OPT_TYPE_DOUBLE, {.dbl = 0.5}, 0.0, 1.0, FLAGS },
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{ NULL }
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};
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AVFILTER_DEFINE_CLASS(tremolo);
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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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2015-09-23 23:03:35 +02:00
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TremoloContext *s = ctx->priv;
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2015-09-21 17:16:43 +02:00
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const double *src = (const double *)in->data[0];
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const int channels = inlink->channels;
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const int nb_samples = in->nb_samples;
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AVFrame *out;
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double *dst;
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int n, c;
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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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2018-01-03 22:47:40 +01:00
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out = ff_get_audio_buffer(outlink, in->nb_samples);
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2015-09-21 17:16:43 +02:00
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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 = (double *)out->data[0];
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for (n = 0; n < nb_samples; n++) {
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for (c = 0; c < channels; c++)
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2015-09-23 23:03:35 +02:00
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dst[c] = src[c] * s->table[s->index];
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2015-09-21 17:16:43 +02:00
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dst += channels;
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src += channels;
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2015-09-23 23:03:35 +02:00
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s->index++;
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2019-10-19 19:34:47 +02:00
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if (s->index >= s->table_size)
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2015-09-23 23:03:35 +02:00
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s->index = 0;
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2015-09-21 17:16:43 +02:00
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}
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if (in != out)
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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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TremoloContext *s = ctx->priv;
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2015-09-23 23:03:35 +02:00
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av_freep(&s->table);
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2015-09-21 17:16:43 +02:00
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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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TremoloContext *s = ctx->priv;
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2015-09-23 23:03:35 +02:00
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const double offset = 1. - s->depth / 2.;
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int i;
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2015-09-21 17:16:43 +02:00
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2020-12-25 14:01:52 +01:00
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s->table_size = lrint(inlink->sample_rate / s->freq + 0.5);
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2019-10-19 19:34:47 +02:00
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s->table = av_malloc_array(s->table_size, sizeof(*s->table));
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2015-09-23 23:03:35 +02:00
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if (!s->table)
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2015-09-21 17:16:43 +02:00
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return AVERROR(ENOMEM);
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2019-10-19 19:34:47 +02:00
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for (i = 0; i < s->table_size; i++) {
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2015-09-23 23:03:35 +02:00
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double env = s->freq * i / inlink->sample_rate;
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env = sin(2 * M_PI * fmod(env + 0.25, 1.0));
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s->table[i] = env * (1 - fabs(offset)) + offset;
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}
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s->index = 0;
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2015-09-21 17:16:43 +02:00
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return 0;
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}
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static const AVFilterPad avfilter_af_tremolo_inputs[] = {
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{
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.name = "default",
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.type = AVMEDIA_TYPE_AUDIO,
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.config_props = config_input,
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.filter_frame = filter_frame,
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},
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};
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static const AVFilterPad avfilter_af_tremolo_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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};
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2021-04-19 18:33:56 +02:00
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const AVFilter ff_af_tremolo = {
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2015-09-21 17:16:43 +02:00
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.name = "tremolo",
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.description = NULL_IF_CONFIG_SMALL("Apply tremolo effect."),
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.priv_size = sizeof(TremoloContext),
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.priv_class = &tremolo_class,
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.uninit = uninit,
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2021-08-12 13:05:31 +02:00
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FILTER_INPUTS(avfilter_af_tremolo_inputs),
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FILTER_OUTPUTS(avfilter_af_tremolo_outputs),
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2021-09-27 13:10:11 +02:00
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FILTER_SINGLE_SAMPLEFMT(AV_SAMPLE_FMT_DBL),
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2015-09-21 17:16:43 +02:00
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};
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