1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
|
/*
* Copyright (c) 2013 Nicolas George
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <float.h>
#include "libavutil/avassert.h"
#include "libavutil/channel_layout.h"
#include "libavutil/opt.h"
#include "audio.h"
#include "avfilter.h"
#include "internal.h"
typedef struct {
const AVClass *class;
double frequency;
double beep_factor;
int samples_per_frame;
int sample_rate;
int64_t duration;
int16_t *sin;
int64_t pts;
uint32_t phi; ///< current phase of the sine (2pi = 1<<32)
uint32_t dphi; ///< phase increment between two samples
unsigned beep_period;
unsigned beep_index;
unsigned beep_length;
uint32_t phi_beep; ///< current phase of the beep
uint32_t dphi_beep; ///< phase increment of the beep
} SineContext;
#define CONTEXT SineContext
#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
#define OPT_GENERIC(name, field, def, min, max, descr, type, deffield, ...) \
{ name, descr, offsetof(CONTEXT, field), AV_OPT_TYPE_ ## type, \
{ .deffield = def }, min, max, FLAGS, __VA_ARGS__ }
#define OPT_INT(name, field, def, min, max, descr, ...) \
OPT_GENERIC(name, field, def, min, max, descr, INT, i64, __VA_ARGS__)
#define OPT_DBL(name, field, def, min, max, descr, ...) \
OPT_GENERIC(name, field, def, min, max, descr, DOUBLE, dbl, __VA_ARGS__)
#define OPT_DUR(name, field, def, min, max, descr, ...) \
OPT_GENERIC(name, field, def, min, max, descr, DURATION, str, __VA_ARGS__)
static const AVOption sine_options[] = {
OPT_DBL("frequency", frequency, 440, 0, DBL_MAX, "set the sine frequency"),
OPT_DBL("f", frequency, 440, 0, DBL_MAX, "set the sine frequency"),
OPT_DBL("beep_factor", beep_factor, 0, 0, DBL_MAX, "set the beep fequency factor"),
OPT_DBL("b", beep_factor, 0, 0, DBL_MAX, "set the beep fequency factor"),
OPT_INT("sample_rate", sample_rate, 44100, 1, INT_MAX, "set the sample rate"),
OPT_INT("r", sample_rate, 44100, 1, INT_MAX, "set the sample rate"),
OPT_DUR("duration", duration, 0, 0, INT64_MAX, "set the audio duration"),
OPT_DUR("d", duration, 0, 0, INT64_MAX, "set the audio duration"),
OPT_INT("samples_per_frame", samples_per_frame, 1024, 0, INT_MAX, "set the number of samples per frame"),
{NULL},
};
AVFILTER_DEFINE_CLASS(sine);
#define LOG_PERIOD 15
#define AMPLITUDE 4095
#define AMPLITUDE_SHIFT 3
static void make_sin_table(int16_t *sin)
{
unsigned half_pi = 1 << (LOG_PERIOD - 2);
unsigned ampls = AMPLITUDE << AMPLITUDE_SHIFT;
uint64_t unit2 = (uint64_t)(ampls * ampls) << 32;
unsigned step, i, c, s, k, new_k, n2;
/* Principle: if u = exp(i*a1) and v = exp(i*a2), then
exp(i*(a1+a2)/2) = (u+v) / length(u+v) */
sin[0] = 0;
sin[half_pi] = ampls;
for (step = half_pi; step > 1; step /= 2) {
/* k = (1 << 16) * amplitude / length(u+v)
In exact values, k is constant at a given step */
k = 0x10000;
for (i = 0; i < half_pi / 2; i += step) {
s = sin[i] + sin[i + step];
c = sin[half_pi - i] + sin[half_pi - i - step];
n2 = s * s + c * c;
/* Newton's method to solve n² * k² = unit² */
while (1) {
new_k = (k + unit2 / ((uint64_t)k * n2) + 1) >> 1;
if (k == new_k)
break;
k = new_k;
}
sin[i + step / 2] = (k * s + 0x7FFF) >> 16;
sin[half_pi - i - step / 2] = (k * c + 0x8000) >> 16;
}
}
/* Unshift amplitude */
for (i = 0; i <= half_pi; i++)
sin[i] = (sin[i] + (1 << (AMPLITUDE_SHIFT - 1))) >> AMPLITUDE_SHIFT;
/* Use symmetries to fill the other three quarters */
for (i = 0; i < half_pi; i++)
sin[half_pi * 2 - i] = sin[i];
for (i = 0; i < 2 * half_pi; i++)
sin[i + 2 * half_pi] = -sin[i];
}
static av_cold int init(AVFilterContext *ctx)
{
SineContext *sine = ctx->priv;
if (!(sine->sin = av_malloc(sizeof(*sine->sin) << LOG_PERIOD)))
return AVERROR(ENOMEM);
sine->dphi = ldexp(sine->frequency, 32) / sine->sample_rate + 0.5;
make_sin_table(sine->sin);
if (sine->beep_factor) {
sine->beep_period = sine->sample_rate;
sine->beep_length = sine->beep_period / 25;
sine->dphi_beep = ldexp(sine->beep_factor * sine->frequency, 32) /
sine->sample_rate + 0.5;
}
return 0;
}
static av_cold void uninit(AVFilterContext *ctx)
{
SineContext *sine = ctx->priv;
av_freep(&sine->sin);
}
static av_cold int query_formats(AVFilterContext *ctx)
{
SineContext *sine = ctx->priv;
static const int64_t chlayouts[] = { AV_CH_LAYOUT_MONO, -1 };
int sample_rates[] = { sine->sample_rate, -1 };
static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16,
AV_SAMPLE_FMT_NONE };
ff_set_common_formats (ctx, ff_make_format_list(sample_fmts));
ff_set_common_channel_layouts(ctx, avfilter_make_format64_list(chlayouts));
ff_set_common_samplerates(ctx, ff_make_format_list(sample_rates));
return 0;
}
static av_cold int config_props(AVFilterLink *outlink)
{
SineContext *sine = outlink->src->priv;
sine->duration = av_rescale(sine->duration, sine->sample_rate, AV_TIME_BASE);
return 0;
}
static int request_frame(AVFilterLink *outlink)
{
SineContext *sine = outlink->src->priv;
AVFrame *frame;
int i, nb_samples = sine->samples_per_frame;
int16_t *samples;
if (sine->duration) {
nb_samples = FFMIN(nb_samples, sine->duration - sine->pts);
av_assert1(nb_samples >= 0);
if (!nb_samples)
return AVERROR_EOF;
}
if (!(frame = ff_get_audio_buffer(outlink, nb_samples)))
return AVERROR(ENOMEM);
samples = (int16_t *)frame->data[0];
for (i = 0; i < nb_samples; i++) {
samples[i] = sine->sin[sine->phi >> (32 - LOG_PERIOD)];
sine->phi += sine->dphi;
if (sine->beep_index < sine->beep_length) {
samples[i] += sine->sin[sine->phi_beep >> (32 - LOG_PERIOD)] << 1;
sine->phi_beep += sine->dphi_beep;
}
if (++sine->beep_index == sine->beep_period)
sine->beep_index = 0;
}
frame->pts = sine->pts;
sine->pts += nb_samples;
return ff_filter_frame(outlink, frame);
}
static const AVFilterPad sine_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.request_frame = request_frame,
.config_props = config_props,
},
{ NULL }
};
AVFilter avfilter_asrc_sine = {
.name = "sine",
.description = NULL_IF_CONFIG_SMALL("Generate sine wave audio signal."),
.query_formats = query_formats,
.init = init,
.uninit = uninit,
.priv_size = sizeof(SineContext),
.inputs = NULL,
.outputs = sine_outputs,
.priv_class = &sine_class,
};
|
