path: root/libavfilter/af_tremolo.c (plain)
blob: 572e9e3b56082e474ec4480addeb19d512b1b2b3

1	/*
2	* Copyright (c) 2015 Kyle Swanson <k@ylo.ph>.
3	*
4	* This file is part of FFmpeg.
5	*
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.
10	*
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.
15	*
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
19	*/
20
21	#include "libavutil/opt.h"
22	#include "avfilter.h"
23	#include "internal.h"
24	#include "audio.h"
25
26	typedef struct TremoloContext {
27	const AVClass *class;
28	double freq;
29	double depth;
30	double *table;
31	int index;
32	} TremoloContext;
33
34	#define OFFSET(x) offsetof(TremoloContext, x)
35	#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
36
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 },
40	{ NULL }
41	};
42
43	AVFILTER_DEFINE_CLASS(tremolo);
44
45	static int filter_frame(AVFilterLink *inlink, AVFrame *in)
46	{
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;
53	AVFrame *out;
54	double *dst;
55	int n, c;
56
57	if (av_frame_is_writable(in)) {
58	out = in;
59	} else {
60	out = ff_get_audio_buffer(inlink, in->nb_samples);
61	if (!out) {
62	av_frame_free(&in);
63	return AVERROR(ENOMEM);
64	}
65	av_frame_copy_props(out, in);
66	}
67	dst = (double *)out->data[0];
68
69	for (n = 0; n < nb_samples; n++) {
70	for (c = 0; c < channels; c++)
71	dst[c] = src[c] * s->table[s->index];
72	dst += channels;
73	src += channels;
74	s->index++;
75	if (s->index >= inlink->sample_rate / s->freq)
76	s->index = 0;
77	}
78
79	if (in != out)
80	av_frame_free(&in);
81
82	return ff_filter_frame(outlink, out);
83	}
84
85	static int query_formats(AVFilterContext *ctx)
86	{
87	AVFilterFormats *formats;
88	AVFilterChannelLayouts *layouts;
89	static const enum AVSampleFormat sample_fmts[] = {
90	AV_SAMPLE_FMT_DBL,
91	AV_SAMPLE_FMT_NONE
92	};
93	int ret;
94
95	layouts = ff_all_channel_counts();
96	if (!layouts)
97	return AVERROR(ENOMEM);
98	ret = ff_set_common_channel_layouts(ctx, layouts);
99	if (ret < 0)
100	return ret;
101
102	formats = ff_make_format_list(sample_fmts);
103	if (!formats)
104	return AVERROR(ENOMEM);
105	ret = ff_set_common_formats(ctx, formats);
106	if (ret < 0)
107	return ret;
108
109	formats = ff_all_samplerates();
110	if (!formats)
111	return AVERROR(ENOMEM);
112	return ff_set_common_samplerates(ctx, formats);
113	}
114
115	static av_cold void uninit(AVFilterContext *ctx)
116	{
117	TremoloContext *s = ctx->priv;
118	av_freep(&s->table);
119	}
120
121	static int config_input(AVFilterLink *inlink)
122	{
123	AVFilterContext *ctx = inlink->dst;
124	TremoloContext *s = ctx->priv;
125	const double offset = 1. - s->depth / 2.;
126	int i;
127
128	s->table = av_malloc_array(inlink->sample_rate / s->freq, sizeof(*s->table));
129	if (!s->table)
130	return AVERROR(ENOMEM);
131
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;
136	}
137
138	s->index = 0;
139
140	return 0;
141	}
142
143	static const AVFilterPad avfilter_af_tremolo_inputs[] = {
144	{
145	.name = "default",
146	.type = AVMEDIA_TYPE_AUDIO,
147	.config_props = config_input,
148	.filter_frame = filter_frame,
149	},
150	{ NULL }
151	};
152
153	static const AVFilterPad avfilter_af_tremolo_outputs[] = {
154	{
155	.name = "default",
156	.type = AVMEDIA_TYPE_AUDIO,
157	},
158	{ NULL }
159	};
160
161	AVFilter ff_af_tremolo = {
162	.name = "tremolo",
163	.description = NULL_IF_CONFIG_SMALL("Apply tremolo effect."),
164	.priv_size = sizeof(TremoloContext),
165	.priv_class = &tremolo_class,
166	.uninit = uninit,
167	.query_formats = query_formats,
168	.inputs = avfilter_af_tremolo_inputs,
169	.outputs = avfilter_af_tremolo_outputs,
170	};
171