2 * Copyright (c) 2015 Kyle Swanson <k@ylo.ph>.
4 * This file is part of FFmpeg.
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 #include "libavutil/opt.h"
26 typedef struct TremoloContext {
35 #define OFFSET(x) offsetof(TremoloContext, x)
36 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
38 static const AVOption tremolo_options[] = {
39 { "f", "set frequency in hertz", OFFSET(freq), AV_OPT_TYPE_DOUBLE, {.dbl = 5.0}, 0.1, 20000.0, FLAGS },
40 { "d", "set depth as percentage", OFFSET(depth), AV_OPT_TYPE_DOUBLE, {.dbl = 0.5}, 0.0, 1.0, FLAGS },
44 AVFILTER_DEFINE_CLASS(tremolo);
46 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
48 AVFilterContext *ctx = inlink->dst;
49 AVFilterLink *outlink = ctx->outputs[0];
50 TremoloContext *s = ctx->priv;
51 const double *src = (const double *)in->data[0];
52 const int channels = inlink->channels;
53 const int nb_samples = in->nb_samples;
58 if (av_frame_is_writable(in)) {
61 out = ff_get_audio_buffer(outlink, in->nb_samples);
64 return AVERROR(ENOMEM);
66 av_frame_copy_props(out, in);
68 dst = (double *)out->data[0];
70 for (n = 0; n < nb_samples; n++) {
71 for (c = 0; c < channels; c++)
72 dst[c] = src[c] * s->table[s->index];
76 if (s->index >= s->table_size)
83 return ff_filter_frame(outlink, out);
86 static int query_formats(AVFilterContext *ctx)
88 AVFilterFormats *formats;
89 AVFilterChannelLayouts *layouts;
90 static const enum AVSampleFormat sample_fmts[] = {
96 layouts = ff_all_channel_counts();
98 return AVERROR(ENOMEM);
99 ret = ff_set_common_channel_layouts(ctx, layouts);
103 formats = ff_make_format_list(sample_fmts);
105 return AVERROR(ENOMEM);
106 ret = ff_set_common_formats(ctx, formats);
110 formats = ff_all_samplerates();
112 return AVERROR(ENOMEM);
113 return ff_set_common_samplerates(ctx, formats);
116 static av_cold void uninit(AVFilterContext *ctx)
118 TremoloContext *s = ctx->priv;
122 static int config_input(AVFilterLink *inlink)
124 AVFilterContext *ctx = inlink->dst;
125 TremoloContext *s = ctx->priv;
126 const double offset = 1. - s->depth / 2.;
129 s->table_size = lrint(inlink->sample_rate / s->freq + 0.5);
130 s->table = av_malloc_array(s->table_size, sizeof(*s->table));
132 return AVERROR(ENOMEM);
134 for (i = 0; i < s->table_size; i++) {
135 double env = s->freq * i / inlink->sample_rate;
136 env = sin(2 * M_PI * fmod(env + 0.25, 1.0));
137 s->table[i] = env * (1 - fabs(offset)) + offset;
145 static const AVFilterPad avfilter_af_tremolo_inputs[] = {
148 .type = AVMEDIA_TYPE_AUDIO,
149 .config_props = config_input,
150 .filter_frame = filter_frame,
155 static const AVFilterPad avfilter_af_tremolo_outputs[] = {
158 .type = AVMEDIA_TYPE_AUDIO,
163 const AVFilter ff_af_tremolo = {
165 .description = NULL_IF_CONFIG_SMALL("Apply tremolo effect."),
166 .priv_size = sizeof(TremoloContext),
167 .priv_class = &tremolo_class,
169 .query_formats = query_formats,
170 .inputs = avfilter_af_tremolo_inputs,
171 .outputs = avfilter_af_tremolo_outputs,