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path: root/libavfilter/asrc_sine.c (plain)
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1/*
2 * Copyright (c) 2013 Nicolas George
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 License
8 * 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
14 * GNU Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public License
17 * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
18 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21#include <float.h>
22
23#include "libavutil/avassert.h"
24#include "libavutil/channel_layout.h"
25#include "libavutil/eval.h"
26#include "libavutil/opt.h"
27#include "audio.h"
28#include "avfilter.h"
29#include "internal.h"
30
31typedef struct {
32 const AVClass *class;
33 double frequency;
34 double beep_factor;
35 char *samples_per_frame;
36 AVExpr *samples_per_frame_expr;
37 int sample_rate;
38 int64_t duration;
39 int16_t *sin;
40 int64_t pts;
41 uint32_t phi; ///< current phase of the sine (2pi = 1<<32)
42 uint32_t dphi; ///< phase increment between two samples
43 unsigned beep_period;
44 unsigned beep_index;
45 unsigned beep_length;
46 uint32_t phi_beep; ///< current phase of the beep
47 uint32_t dphi_beep; ///< phase increment of the beep
48} SineContext;
49
50#define CONTEXT SineContext
51#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
52
53#define OPT_GENERIC(name, field, def, min, max, descr, type, deffield, ...) \
54 { name, descr, offsetof(CONTEXT, field), AV_OPT_TYPE_ ## type, \
55 { .deffield = def }, min, max, FLAGS, __VA_ARGS__ }
56
57#define OPT_INT(name, field, def, min, max, descr, ...) \
58 OPT_GENERIC(name, field, def, min, max, descr, INT, i64, __VA_ARGS__)
59
60#define OPT_DBL(name, field, def, min, max, descr, ...) \
61 OPT_GENERIC(name, field, def, min, max, descr, DOUBLE, dbl, __VA_ARGS__)
62
63#define OPT_DUR(name, field, def, min, max, descr, ...) \
64 OPT_GENERIC(name, field, def, min, max, descr, DURATION, str, __VA_ARGS__)
65
66#define OPT_STR(name, field, def, min, max, descr, ...) \
67 OPT_GENERIC(name, field, def, min, max, descr, STRING, str, __VA_ARGS__)
68
69static const AVOption sine_options[] = {
70 OPT_DBL("frequency", frequency, 440, 0, DBL_MAX, "set the sine frequency",),
71 OPT_DBL("f", frequency, 440, 0, DBL_MAX, "set the sine frequency",),
72 OPT_DBL("beep_factor", beep_factor, 0, 0, DBL_MAX, "set the beep frequency factor",),
73 OPT_DBL("b", beep_factor, 0, 0, DBL_MAX, "set the beep frequency factor",),
74 OPT_INT("sample_rate", sample_rate, 44100, 1, INT_MAX, "set the sample rate",),
75 OPT_INT("r", sample_rate, 44100, 1, INT_MAX, "set the sample rate",),
76 OPT_DUR("duration", duration, 0, 0, INT64_MAX, "set the audio duration",),
77 OPT_DUR("d", duration, 0, 0, INT64_MAX, "set the audio duration",),
78 OPT_STR("samples_per_frame", samples_per_frame, "1024", 0, 0, "set the number of samples per frame",),
79 {NULL}
80};
81
82AVFILTER_DEFINE_CLASS(sine);
83
84#define LOG_PERIOD 15
85#define AMPLITUDE 4095
86#define AMPLITUDE_SHIFT 3
87
88static void make_sin_table(int16_t *sin)
89{
90 unsigned half_pi = 1 << (LOG_PERIOD - 2);
91 unsigned ampls = AMPLITUDE << AMPLITUDE_SHIFT;
92 uint64_t unit2 = (uint64_t)(ampls * ampls) << 32;
93 unsigned step, i, c, s, k, new_k, n2;
94
95 /* Principle: if u = exp(i*a1) and v = exp(i*a2), then
96 exp(i*(a1+a2)/2) = (u+v) / length(u+v) */
97 sin[0] = 0;
98 sin[half_pi] = ampls;
99 for (step = half_pi; step > 1; step /= 2) {
100 /* k = (1 << 16) * amplitude / length(u+v)
101 In exact values, k is constant at a given step */
102 k = 0x10000;
103 for (i = 0; i < half_pi / 2; i += step) {
104 s = sin[i] + sin[i + step];
105 c = sin[half_pi - i] + sin[half_pi - i - step];
106 n2 = s * s + c * c;
107 /* Newton's method to solve n² * k² = unit² */
108 while (1) {
109 new_k = (k + unit2 / ((uint64_t)k * n2) + 1) >> 1;
110 if (k == new_k)
111 break;
112 k = new_k;
113 }
114 sin[i + step / 2] = (k * s + 0x7FFF) >> 16;
115 sin[half_pi - i - step / 2] = (k * c + 0x8000) >> 16;
116 }
117 }
118 /* Unshift amplitude */
119 for (i = 0; i <= half_pi; i++)
120 sin[i] = (sin[i] + (1 << (AMPLITUDE_SHIFT - 1))) >> AMPLITUDE_SHIFT;
121 /* Use symmetries to fill the other three quarters */
122 for (i = 0; i < half_pi; i++)
123 sin[half_pi * 2 - i] = sin[i];
124 for (i = 0; i < 2 * half_pi; i++)
125 sin[i + 2 * half_pi] = -sin[i];
126}
127
128static const char *const var_names[] = {
129 "n",
130 "pts",
131 "t",
132 "TB",
133 NULL
134};
135
136enum {
137 VAR_N,
138 VAR_PTS,
139 VAR_T,
140 VAR_TB,
141 VAR_VARS_NB
142};
143
144static av_cold int init(AVFilterContext *ctx)
145{
146 int ret;
147 SineContext *sine = ctx->priv;
148
149 if (!(sine->sin = av_malloc(sizeof(*sine->sin) << LOG_PERIOD)))
150 return AVERROR(ENOMEM);
151 sine->dphi = ldexp(sine->frequency, 32) / sine->sample_rate + 0.5;
152 make_sin_table(sine->sin);
153
154 if (sine->beep_factor) {
155 sine->beep_period = sine->sample_rate;
156 sine->beep_length = sine->beep_period / 25;
157 sine->dphi_beep = ldexp(sine->beep_factor * sine->frequency, 32) /
158 sine->sample_rate + 0.5;
159 }
160
161 ret = av_expr_parse(&sine->samples_per_frame_expr,
162 sine->samples_per_frame, var_names,
163 NULL, NULL, NULL, NULL, 0, sine);
164 if (ret < 0)
165 return ret;
166
167 return 0;
168}
169
170static av_cold void uninit(AVFilterContext *ctx)
171{
172 SineContext *sine = ctx->priv;
173
174 av_expr_free(sine->samples_per_frame_expr);
175 sine->samples_per_frame_expr = NULL;
176 av_freep(&sine->sin);
177}
178
179static av_cold int query_formats(AVFilterContext *ctx)
180{
181 SineContext *sine = ctx->priv;
182 static const int64_t chlayouts[] = { AV_CH_LAYOUT_MONO, -1 };
183 int sample_rates[] = { sine->sample_rate, -1 };
184 static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16,
185 AV_SAMPLE_FMT_NONE };
186 AVFilterFormats *formats;
187 AVFilterChannelLayouts *layouts;
188 int ret;
189
190 formats = ff_make_format_list(sample_fmts);
191 if (!formats)
192 return AVERROR(ENOMEM);
193 ret = ff_set_common_formats (ctx, formats);
194 if (ret < 0)
195 return ret;
196
197 layouts = avfilter_make_format64_list(chlayouts);
198 if (!layouts)
199 return AVERROR(ENOMEM);
200 ret = ff_set_common_channel_layouts(ctx, layouts);
201 if (ret < 0)
202 return ret;
203
204 formats = ff_make_format_list(sample_rates);
205 if (!formats)
206 return AVERROR(ENOMEM);
207 return ff_set_common_samplerates(ctx, formats);
208}
209
210static av_cold int config_props(AVFilterLink *outlink)
211{
212 SineContext *sine = outlink->src->priv;
213 sine->duration = av_rescale(sine->duration, sine->sample_rate, AV_TIME_BASE);
214 return 0;
215}
216
217static int request_frame(AVFilterLink *outlink)
218{
219 SineContext *sine = outlink->src->priv;
220 AVFrame *frame;
221 double values[VAR_VARS_NB] = {
222 [VAR_N] = outlink->frame_count_in,
223 [VAR_PTS] = sine->pts,
224 [VAR_T] = sine->pts * av_q2d(outlink->time_base),
225 [VAR_TB] = av_q2d(outlink->time_base),
226 };
227 int i, nb_samples = lrint(av_expr_eval(sine->samples_per_frame_expr, values, sine));
228 int16_t *samples;
229
230 if (nb_samples <= 0) {
231 av_log(sine, AV_LOG_WARNING, "nb samples expression evaluated to %d, "
232 "defaulting to 1024\n", nb_samples);
233 nb_samples = 1024;
234 }
235
236 if (sine->duration) {
237 nb_samples = FFMIN(nb_samples, sine->duration - sine->pts);
238 av_assert1(nb_samples >= 0);
239 if (!nb_samples)
240 return AVERROR_EOF;
241 }
242 if (!(frame = ff_get_audio_buffer(outlink, nb_samples)))
243 return AVERROR(ENOMEM);
244 samples = (int16_t *)frame->data[0];
245
246 for (i = 0; i < nb_samples; i++) {
247 samples[i] = sine->sin[sine->phi >> (32 - LOG_PERIOD)];
248 sine->phi += sine->dphi;
249 if (sine->beep_index < sine->beep_length) {
250 samples[i] += sine->sin[sine->phi_beep >> (32 - LOG_PERIOD)] << 1;
251 sine->phi_beep += sine->dphi_beep;
252 }
253 if (++sine->beep_index == sine->beep_period)
254 sine->beep_index = 0;
255 }
256
257 frame->pts = sine->pts;
258 sine->pts += nb_samples;
259 return ff_filter_frame(outlink, frame);
260}
261
262static const AVFilterPad sine_outputs[] = {
263 {
264 .name = "default",
265 .type = AVMEDIA_TYPE_AUDIO,
266 .request_frame = request_frame,
267 .config_props = config_props,
268 },
269 { NULL }
270};
271
272AVFilter ff_asrc_sine = {
273 .name = "sine",
274 .description = NULL_IF_CONFIG_SMALL("Generate sine wave audio signal."),
275 .query_formats = query_formats,
276 .init = init,
277 .uninit = uninit,
278 .priv_size = sizeof(SineContext),
279 .inputs = NULL,
280 .outputs = sine_outputs,
281 .priv_class = &sine_class,
282};
283
generated by cgit at 2024-05-17 04:59:51 (GMT)