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 {
34 #define OFFSET(x) offsetof(TremoloContext, x)
35 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
37 static const AVOption tremolo_options[] = {
38 { "f", "set frequency in hertz", OFFSET(freq), AV_OPT_TYPE_DOUBLE, {.dbl = 5.0}, 0.1, 20000.0, FLAGS },
39 { "d", "set depth as percentage", OFFSET(depth), AV_OPT_TYPE_DOUBLE, {.dbl = 0.5}, 0.0, 1.0, FLAGS },
43 AVFILTER_DEFINE_CLASS(tremolo);
45 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
47 AVFilterContext *ctx = inlink->dst;
48 AVFilterLink *outlink = ctx->outputs[0];
49 TremoloContext *s = ctx->priv;
50 const double *src = (const double *)in->data[0];
51 const int channels = inlink->channels;
52 const int nb_samples = in->nb_samples;
57 if (av_frame_is_writable(in)) {
60 out = ff_get_audio_buffer(outlink, in->nb_samples);
63 return AVERROR(ENOMEM);
65 av_frame_copy_props(out, in);
67 dst = (double *)out->data[0];
69 for (n = 0; n < nb_samples; n++) {
70 for (c = 0; c < channels; c++)
71 dst[c] = src[c] * s->table[s->index];
75 if (s->index >= inlink->sample_rate / s->freq)
82 return ff_filter_frame(outlink, out);
85 static int query_formats(AVFilterContext *ctx)
87 AVFilterFormats *formats;
88 AVFilterChannelLayouts *layouts;
89 static const enum AVSampleFormat sample_fmts[] = {
95 layouts = ff_all_channel_counts();
97 return AVERROR(ENOMEM);
98 ret = ff_set_common_channel_layouts(ctx, layouts);
102 formats = ff_make_format_list(sample_fmts);
104 return AVERROR(ENOMEM);
105 ret = ff_set_common_formats(ctx, formats);
109 formats = ff_all_samplerates();
111 return AVERROR(ENOMEM);
112 return ff_set_common_samplerates(ctx, formats);
115 static av_cold void uninit(AVFilterContext *ctx)
117 TremoloContext *s = ctx->priv;
121 static int config_input(AVFilterLink *inlink)
123 AVFilterContext *ctx = inlink->dst;
124 TremoloContext *s = ctx->priv;
125 const double offset = 1. - s->depth / 2.;
128 s->table = av_malloc_array(inlink->sample_rate / s->freq, sizeof(*s->table));
130 return AVERROR(ENOMEM);
132 for (i = 0; i < inlink->sample_rate / s->freq; i++) {
133 double env = s->freq * i / inlink->sample_rate;
134 env = sin(2 * M_PI * fmod(env + 0.25, 1.0));
135 s->table[i] = env * (1 - fabs(offset)) + offset;
143 static const AVFilterPad avfilter_af_tremolo_inputs[] = {
146 .type = AVMEDIA_TYPE_AUDIO,
147 .config_props = config_input,
148 .filter_frame = filter_frame,
153 static const AVFilterPad avfilter_af_tremolo_outputs[] = {
156 .type = AVMEDIA_TYPE_AUDIO,
161 AVFilter ff_af_tremolo = {
163 .description = NULL_IF_CONFIG_SMALL("Apply tremolo effect."),
164 .priv_size = sizeof(TremoloContext),
165 .priv_class = &tremolo_class,
167 .query_formats = query_formats,
168 .inputs = avfilter_af_tremolo_inputs,
169 .outputs = avfilter_af_tremolo_outputs,