FFmpeg
asrc_sine.c
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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"
25 #include "libavutil/eval.h"
26 #include "libavutil/opt.h"
27 #include "audio.h"
28 #include "avfilter.h"
29 #include "internal.h"
30 
31 typedef struct SineContext {
32  const AVClass *class;
33  double frequency;
34  double beep_factor;
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 
69 static 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 
83 
84 #define LOG_PERIOD 15
85 #define AMPLITUDE 4095
86 #define AMPLITUDE_SHIFT 3
87 
88 static 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 
128 static const char *const var_names[] = {
129  "n",
130  "pts",
131  "t",
132  "TB",
133  NULL
134 };
135 
136 enum {
142 };
143 
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 
163  NULL, NULL, NULL, NULL, 0, sine);
164  if (ret < 0)
165  return ret;
166 
167  return 0;
168 }
169 
171 {
172  SineContext *sine = ctx->priv;
173 
176  av_freep(&sine->sin);
177 }
178 
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,
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 
210 static 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 
217 static 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 
262 static 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 
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 };
#define NULL
Definition: coverity.c:32
int ff_set_common_channel_layouts(AVFilterContext *ctx, AVFilterChannelLayouts *layouts)
A helper for query_formats() which sets all links to the same list of channel layouts/sample rates...
Definition: formats.c:550
AVFilter ff_asrc_sine
Definition: asrc_sine.c:272
This structure describes decoded (raw) audio or video data.
Definition: frame.h:295
AVOption.
Definition: opt.h:246
#define OPT_INT(name, field, def, min, max, descr,...)
Definition: asrc_sine.c:57
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
Main libavfilter public API header.
uint32_t dphi_beep
phase increment of the beep
Definition: asrc_sine.c:47
static const AVOption sine_options[]
Definition: asrc_sine.c:69
#define AMPLITUDE
Definition: asrc_sine.c:85
uint32_t phi_beep
current phase of the beep
Definition: asrc_sine.c:46
int av_expr_parse(AVExpr **expr, const char *s, const char *const *const_names, const char *const *func1_names, double(*const *funcs1)(void *, double), const char *const *func2_names, double(*const *funcs2)(void *, double, double), int log_offset, void *log_ctx)
Parse an expression.
Definition: eval.c:683
AVFilterFormats * ff_make_format_list(const int *fmts)
Create a list of supported formats.
Definition: formats.c:283
const char * name
Pad name.
Definition: internal.h:60
AVFILTER_DEFINE_CLASS(sine)
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1093
#define av_cold
Definition: attributes.h:82
#define av_malloc(s)
AVOptions.
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:388
Definition: eval.c:157
static double av_q2d(AVRational a)
Convert an AVRational to a double.
Definition: rational.h:104
#define AVERROR_EOF
End of file.
Definition: error.h:55
static av_cold int init(AVFilterContext *ctx)
Definition: asrc_sine.c:144
#define av_log(a,...)
char * samples_per_frame
Definition: asrc_sine.c:35
#define LOG_PERIOD
Definition: asrc_sine.c:84
A filter pad used for either input or output.
Definition: internal.h:54
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
int ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats)
A helper for query_formats() which sets all links to the same list of formats.
Definition: formats.c:569
AVFrame * ff_get_audio_buffer(AVFilterLink *link, int nb_samples)
Request an audio samples buffer with a specific set of permissions.
Definition: audio.c:86
int sample_rate
Definition: asrc_sine.c:37
AVExpr * samples_per_frame_expr
Definition: asrc_sine.c:36
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
void * priv
private data for use by the filter
Definition: avfilter.h:353
double frequency
Definition: asrc_sine.c:33
simple assert() macros that are a bit more flexible than ISO C assert().
unsigned beep_length
Definition: asrc_sine.c:45
audio channel layout utility functions
#define av_assert1(cond)
assert() equivalent, that does not lie in speed critical code.
Definition: avassert.h:53
int64_t av_rescale(int64_t a, int64_t b, int64_t c)
Rescale a 64-bit integer with rounding to nearest.
Definition: mathematics.c:129
int64_t pts
Definition: asrc_sine.c:40
#define AV_TIME_BASE
Internal time base represented as integer.
Definition: avutil.h:254
#define FFMIN(a, b)
Definition: common.h:96
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return values
AVFormatContext * ctx
Definition: movenc.c:48
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
#define s(width, name)
Definition: cbs_vp9.c:257
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
A list of supported channel layouts.
Definition: formats.h:85
double beep_factor
Definition: asrc_sine.c:34
static int request_frame(AVFilterLink *outlink)
Definition: asrc_sine.c:217
static const AVFilterPad sine_outputs[]
Definition: asrc_sine.c:262
AVFilterChannelLayouts * avfilter_make_format64_list(const int64_t *fmts)
Definition: formats.c:303
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
void av_expr_free(AVExpr *e)
Free a parsed expression previously created with av_expr_parse().
Definition: eval.c:336
#define OPT_DBL(name, field, def, min, max, descr,...)
Definition: asrc_sine.c:60
static const char *const var_names[]
Definition: asrc_sine.c:128
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several inputs
Describe the class of an AVClass context structure.
Definition: log.h:67
Filter definition.
Definition: avfilter.h:144
const char * name
Filter name.
Definition: avfilter.h:148
static void make_sin_table(int16_t *sin)
Definition: asrc_sine.c:88
enum MovChannelLayoutTag * layouts
Definition: mov_chan.c:434
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:309
static av_cold void uninit(AVFilterContext *ctx)
Definition: asrc_sine.c:170
sample_rates
unsigned beep_period
Definition: asrc_sine.c:43
int64_t duration
Definition: asrc_sine.c:38
signed 16 bits
Definition: samplefmt.h:61
#define AMPLITUDE_SHIFT
Definition: asrc_sine.c:86
static av_cold int config_props(AVFilterLink *outlink)
Definition: asrc_sine.c:210
double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
Evaluate a previously parsed expression.
Definition: eval.c:738
uint32_t phi
current phase of the sine (2pi = 1<<32)
Definition: asrc_sine.c:41
A list of supported formats for one end of a filter link.
Definition: formats.h:64
uint32_t dphi
phase increment between two samples
Definition: asrc_sine.c:42
#define lrint
Definition: tablegen.h:53
static av_cold int query_formats(AVFilterContext *ctx)
Definition: asrc_sine.c:179
int16_t * sin
Definition: asrc_sine.c:39
An instance of a filter.
Definition: avfilter.h:338
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:701
unsigned beep_index
Definition: asrc_sine.c:44
Filter the word “frame” indicates either a video frame or a group of audio samples
#define av_freep(p)
formats
Definition: signature.h:48
#define OPT_STR(name, field, def, min, max, descr,...)
Definition: asrc_sine.c:66
internal API functions
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
#define AV_CH_LAYOUT_MONO
for(j=16;j >0;--j)
int ff_set_common_samplerates(AVFilterContext *ctx, AVFilterFormats *samplerates)
Definition: formats.c:557
trying all byte sequences megabyte in length and selecting the best looking sequence will yield cases to try But a word about which is also called distortion Distortion can be quantified by almost any quality measurement one chooses the sum of squared differences is used but more complex methods that consider psychovisual effects can be used as well It makes no difference in this discussion First step
simple arithmetic expression evaluator
#define OPT_DUR(name, field, def, min, max, descr,...)
Definition: asrc_sine.c:63