FFmpeg
asrc_sine.c
Go to the documentation of this file.
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/mem.h"
27 #include "libavutil/opt.h"
28 #include "audio.h"
29 #include "avfilter.h"
30 #include "filters.h"
31 #include "formats.h"
32 #include "internal.h"
33 
34 typedef struct SineContext {
35  const AVClass *class;
36  double frequency;
37  double beep_factor;
41  int64_t duration;
42  int16_t *sin;
43  int64_t pts;
44  uint32_t phi; ///< current phase of the sine (2pi = 1<<32)
45  uint32_t dphi; ///< phase increment between two samples
46  unsigned beep_period;
47  unsigned beep_index;
48  unsigned beep_length;
49  uint32_t phi_beep; ///< current phase of the beep
50  uint32_t dphi_beep; ///< phase increment of the beep
51 } SineContext;
52 
53 #define CONTEXT SineContext
54 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
55 
56 #define OPT_GENERIC(name, field, def, min, max, descr, type, deffield, ...) \
57  { name, descr, offsetof(CONTEXT, field), AV_OPT_TYPE_ ## type, \
58  { .deffield = def }, min, max, FLAGS, __VA_ARGS__ }
59 
60 #define OPT_INT(name, field, def, min, max, descr, ...) \
61  OPT_GENERIC(name, field, def, min, max, descr, INT, i64, __VA_ARGS__)
62 
63 #define OPT_DBL(name, field, def, min, max, descr, ...) \
64  OPT_GENERIC(name, field, def, min, max, descr, DOUBLE, dbl, __VA_ARGS__)
65 
66 #define OPT_DUR(name, field, def, min, max, descr, ...) \
67  OPT_GENERIC(name, field, def, min, max, descr, DURATION, str, __VA_ARGS__)
68 
69 #define OPT_STR(name, field, def, min, max, descr, ...) \
70  OPT_GENERIC(name, field, def, min, max, descr, STRING, str, __VA_ARGS__)
71 
72 static const AVOption sine_options[] = {
73  OPT_DBL("frequency", frequency, 440, 0, DBL_MAX, "set the sine frequency",),
74  OPT_DBL("f", frequency, 440, 0, DBL_MAX, "set the sine frequency",),
75  OPT_DBL("beep_factor", beep_factor, 0, 0, DBL_MAX, "set the beep frequency factor",),
76  OPT_DBL("b", beep_factor, 0, 0, DBL_MAX, "set the beep frequency factor",),
77  OPT_INT("sample_rate", sample_rate, 44100, 1, INT_MAX, "set the sample rate",),
78  OPT_INT("r", sample_rate, 44100, 1, INT_MAX, "set the sample rate",),
79  OPT_DUR("duration", duration, 0, 0, INT64_MAX, "set the audio duration",),
80  OPT_DUR("d", duration, 0, 0, INT64_MAX, "set the audio duration",),
81  OPT_STR("samples_per_frame", samples_per_frame, "1024", 0, 0, "set the number of samples per frame",),
82  {NULL}
83 };
84 
86 
87 #define LOG_PERIOD 15
88 #define AMPLITUDE 4095
89 #define AMPLITUDE_SHIFT 3
90 
91 static void make_sin_table(int16_t *sin)
92 {
93  unsigned half_pi = 1 << (LOG_PERIOD - 2);
94  unsigned ampls = AMPLITUDE << AMPLITUDE_SHIFT;
95  uint64_t unit2 = (uint64_t)(ampls * ampls) << 32;
96  unsigned step, i, c, s, k, new_k, n2;
97 
98  /* Principle: if u = exp(i*a1) and v = exp(i*a2), then
99  exp(i*(a1+a2)/2) = (u+v) / length(u+v) */
100  sin[0] = 0;
101  sin[half_pi] = ampls;
102  for (step = half_pi; step > 1; step /= 2) {
103  /* k = (1 << 16) * amplitude / length(u+v)
104  In exact values, k is constant at a given step */
105  k = 0x10000;
106  for (i = 0; i < half_pi / 2; i += step) {
107  s = sin[i] + sin[i + step];
108  c = sin[half_pi - i] + sin[half_pi - i - step];
109  n2 = s * s + c * c;
110  /* Newton's method to solve n² * k² = unit² */
111  while (1) {
112  new_k = (k + unit2 / ((uint64_t)k * n2) + 1) >> 1;
113  if (k == new_k)
114  break;
115  k = new_k;
116  }
117  sin[i + step / 2] = (k * s + 0x7FFF) >> 16;
118  sin[half_pi - i - step / 2] = (k * c + 0x8000) >> 16;
119  }
120  }
121  /* Unshift amplitude */
122  for (i = 0; i <= half_pi; i++)
123  sin[i] = (sin[i] + (1 << (AMPLITUDE_SHIFT - 1))) >> AMPLITUDE_SHIFT;
124  /* Use symmetries to fill the other three quarters */
125  for (i = 0; i < half_pi; i++)
126  sin[half_pi * 2 - i] = sin[i];
127  for (i = 0; i < 2 * half_pi; i++)
128  sin[i + 2 * half_pi] = -sin[i];
129 }
130 
131 static const char *const var_names[] = {
132  "n",
133  "pts",
134  "t",
135  "TB",
136  NULL
137 };
138 
139 enum {
145 };
146 
148 {
149  int ret;
150  SineContext *sine = ctx->priv;
151 
152  if (!(sine->sin = av_malloc(sizeof(*sine->sin) << LOG_PERIOD)))
153  return AVERROR(ENOMEM);
154  sine->dphi = ldexp(sine->frequency, 32) / sine->sample_rate + 0.5;
155  make_sin_table(sine->sin);
156 
157  if (sine->beep_factor) {
158  sine->beep_period = sine->sample_rate;
159  sine->beep_length = sine->beep_period / 25;
160  sine->dphi_beep = ldexp(sine->beep_factor * sine->frequency, 32) /
161  sine->sample_rate + 0.5;
162  }
163 
166  NULL, NULL, NULL, NULL, 0, sine);
167  if (ret < 0)
168  return ret;
169 
170  return 0;
171 }
172 
174 {
175  SineContext *sine = ctx->priv;
176 
179  av_freep(&sine->sin);
180 }
181 
183 {
184  SineContext *sine = ctx->priv;
185  static const AVChannelLayout chlayouts[] = { AV_CHANNEL_LAYOUT_MONO, { 0 } };
186  int sample_rates[] = { sine->sample_rate, -1 };
187  static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16,
190  if (ret < 0)
191  return ret;
192 
194  if (ret < 0)
195  return ret;
196 
198 }
199 
200 static av_cold int config_props(AVFilterLink *outlink)
201 {
202  SineContext *sine = outlink->src->priv;
203  sine->duration = av_rescale(sine->duration, sine->sample_rate, AV_TIME_BASE);
204  return 0;
205 }
206 
208 {
209  AVFilterLink *outlink = ctx->outputs[0];
210  SineContext *sine = ctx->priv;
211  AVFrame *frame;
212  double values[VAR_VARS_NB] = {
213  [VAR_N] = outlink->frame_count_in,
214  [VAR_PTS] = sine->pts,
215  [VAR_T] = sine->pts * av_q2d(outlink->time_base),
216  [VAR_TB] = av_q2d(outlink->time_base),
217  };
218  int i, nb_samples = lrint(av_expr_eval(sine->samples_per_frame_expr, values, sine));
219  int16_t *samples;
220 
221  if (!ff_outlink_frame_wanted(outlink))
222  return FFERROR_NOT_READY;
223  if (nb_samples <= 0) {
224  av_log(sine, AV_LOG_WARNING, "nb samples expression evaluated to %d, "
225  "defaulting to 1024\n", nb_samples);
226  nb_samples = 1024;
227  }
228 
229  if (sine->duration) {
230  nb_samples = FFMIN(nb_samples, sine->duration - sine->pts);
231  av_assert1(nb_samples >= 0);
232  if (!nb_samples) {
233  ff_outlink_set_status(outlink, AVERROR_EOF, sine->pts);
234  return 0;
235  }
236  }
237  if (!(frame = ff_get_audio_buffer(outlink, nb_samples)))
238  return AVERROR(ENOMEM);
239  samples = (int16_t *)frame->data[0];
240 
241  for (i = 0; i < nb_samples; i++) {
242  samples[i] = sine->sin[sine->phi >> (32 - LOG_PERIOD)];
243  sine->phi += sine->dphi;
244  if (sine->beep_index < sine->beep_length) {
245  samples[i] += sine->sin[sine->phi_beep >> (32 - LOG_PERIOD)] * 2;
246  sine->phi_beep += sine->dphi_beep;
247  }
248  if (++sine->beep_index == sine->beep_period)
249  sine->beep_index = 0;
250  }
251 
252  frame->pts = sine->pts;
253  sine->pts += nb_samples;
254  return ff_filter_frame(outlink, frame);
255 }
256 
257 static const AVFilterPad sine_outputs[] = {
258  {
259  .name = "default",
260  .type = AVMEDIA_TYPE_AUDIO,
261  .config_props = config_props,
262  },
263 };
264 
266  .name = "sine",
267  .description = NULL_IF_CONFIG_SMALL("Generate sine wave audio signal."),
268  .init = init,
269  .uninit = uninit,
270  .activate = activate,
271  .priv_size = sizeof(SineContext),
272  .inputs = NULL,
275  .priv_class = &sine_class,
276 };
ff_get_audio_buffer
AVFrame * ff_get_audio_buffer(AVFilterLink *link, int nb_samples)
Request an audio samples buffer with a specific set of permissions.
Definition: audio.c:97
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:186
SineContext::duration
int64_t duration
Definition: asrc_sine.c:41
AVERROR
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
opt.h
sine_options
static const AVOption sine_options[]
Definition: asrc_sine.c:72
ff_filter_frame
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1015
sample_fmts
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:948
SineContext::frequency
double frequency
Definition: asrc_sine.c:36
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:57
FFERROR_NOT_READY
return FFERROR_NOT_READY
Definition: filter_design.txt:204
ff_set_common_samplerates_from_list
int ff_set_common_samplerates_from_list(AVFilterContext *ctx, const int *samplerates)
Equivalent to ff_set_common_samplerates(ctx, ff_make_format_list(samplerates))
Definition: formats.c:816
AVFILTER_DEFINE_CLASS
AVFILTER_DEFINE_CLASS(sine)
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:375
step
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
Definition: rate_distortion.txt:58
config_props
static av_cold int config_props(AVFilterLink *outlink)
Definition: asrc_sine.c:200
AVOption
AVOption.
Definition: opt.h:346
FILTER_QUERY_FUNC
#define FILTER_QUERY_FUNC(func)
Definition: internal.h:159
float.h
AVFilter::name
const char * name
Filter name.
Definition: avfilter.h:170
make_sin_table
static void make_sin_table(int16_t *sin)
Definition: asrc_sine.c:91
VAR_T
@ VAR_T
Definition: asrc_sine.c:142
sample_rate
sample_rate
Definition: ffmpeg_filter.c:424
activate
static int activate(AVFilterContext *ctx)
Definition: asrc_sine.c:207
av_malloc
#define av_malloc(s)
Definition: tableprint_vlc.h:30
formats.h
av_expr_parse
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:710
uninit
static av_cold void uninit(AVFilterContext *ctx)
Definition: asrc_sine.c:173
AVFilterContext::priv
void * priv
private data for use by the filter
Definition: avfilter.h:422
OPT_DBL
#define OPT_DBL(name, field, def, min, max, descr,...)
Definition: asrc_sine.c:63
av_expr_free
void av_expr_free(AVExpr *e)
Free a parsed expression previously created with av_expr_parse().
Definition: eval.c:358
AVFilterPad
A filter pad used for either input or output.
Definition: internal.h:33
avassert.h
lrint
#define lrint
Definition: tablegen.h:53
av_cold
#define av_cold
Definition: attributes.h:90
duration
int64_t duration
Definition: movenc.c:65
ff_outlink_set_status
static void ff_outlink_set_status(AVFilterLink *link, int status, int64_t pts)
Set the status field of a link from the source filter.
Definition: filters.h:189
s
#define s(width, name)
Definition: cbs_vp9.c:198
AMPLITUDE_SHIFT
#define AMPLITUDE_SHIFT
Definition: asrc_sine.c:89
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
av_q2d
static double av_q2d(AVRational a)
Convert an AVRational to a double.
Definition: rational.h:104
ff_set_common_formats_from_list
int ff_set_common_formats_from_list(AVFilterContext *ctx, const int *fmts)
Equivalent to ff_set_common_formats(ctx, ff_make_format_list(fmts))
Definition: formats.c:874
filters.h
ctx
AVFormatContext * ctx
Definition: movenc.c:49
av_expr_eval
double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
Evaluate a previously parsed expression.
Definition: eval.c:792
AVExpr
Definition: eval.c:158
var_names
static const char *const var_names[]
Definition: asrc_sine.c:131
ff_set_common_channel_layouts_from_list
int ff_set_common_channel_layouts_from_list(AVFilterContext *ctx, const AVChannelLayout *fmts)
Equivalent to ff_set_common_channel_layouts(ctx, ff_make_channel_layout_list(fmts))
Definition: formats.c:798
OPT_DUR
#define OPT_DUR(name, field, def, min, max, descr,...)
Definition: asrc_sine.c:66
SineContext::beep_index
unsigned beep_index
Definition: asrc_sine.c:47
SineContext::samples_per_frame_expr
AVExpr * samples_per_frame_expr
Definition: asrc_sine.c:39
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:66
LOG_PERIOD
#define LOG_PERIOD
Definition: asrc_sine.c:87
NULL
#define NULL
Definition: coverity.c:32
SineContext::sample_rate
int sample_rate
Definition: asrc_sine.c:40
SineContext::pts
int64_t pts
Definition: asrc_sine.c:43
VAR_PTS
@ VAR_PTS
Definition: asrc_sine.c:141
inputs
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
Definition: filter_design.txt:243
SineContext::dphi_beep
uint32_t dphi_beep
phase increment of the beep
Definition: asrc_sine.c:50
SineContext
Definition: asrc_sine.c:34
c
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
SineContext::beep_factor
double beep_factor
Definition: asrc_sine.c:37
eval.h
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:94
AVChannelLayout
An AVChannelLayout holds information about the channel layout of audio data.
Definition: channel_layout.h:303
OPT_STR
#define OPT_STR(name, field, def, min, max, descr,...)
Definition: asrc_sine.c:69
for
for(k=2;k<=8;++k)
Definition: h264pred_template.c:425
AV_SAMPLE_FMT_NONE
@ AV_SAMPLE_FMT_NONE
Definition: samplefmt.h:56
sine_outputs
static const AVFilterPad sine_outputs[]
Definition: asrc_sine.c:257
OPT_INT
#define OPT_INT(name, field, def, min, max, descr,...)
Definition: asrc_sine.c:60
sample_rates
sample_rates
Definition: ffmpeg_filter.c:424
internal.h
SineContext::sin
int16_t * sin
Definition: asrc_sine.c:42
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
SineContext::phi
uint32_t phi
current phase of the sine (2pi = 1<<32)
Definition: asrc_sine.c:44
AV_TIME_BASE
#define AV_TIME_BASE
Internal time base represented as integer.
Definition: avutil.h:254
av_assert1
#define av_assert1(cond)
assert() equivalent, that does not lie in speed critical code.
Definition: avassert.h:56
AVSampleFormat
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:55
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
AV_SAMPLE_FMT_S16
@ AV_SAMPLE_FMT_S16
signed 16 bits
Definition: samplefmt.h:58
AVFilterPad::name
const char * name
Pad name.
Definition: internal.h:39
av_rescale
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
init
static av_cold int init(AVFilterContext *ctx)
Definition: asrc_sine.c:147
AVFilter
Filter definition.
Definition: avfilter.h:166
SineContext::beep_length
unsigned beep_length
Definition: asrc_sine.c:48
SineContext::beep_period
unsigned beep_period
Definition: asrc_sine.c:46
ret
ret
Definition: filter_design.txt:187
frame
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
Definition: filter_design.txt:264
VAR_TB
@ VAR_TB
Definition: asrc_sine.c:143
VAR_VARS_NB
@ VAR_VARS_NB
Definition: asrc_sine.c:144
channel_layout.h
avfilter.h
SineContext::dphi
uint32_t dphi
phase increment between two samples
Definition: asrc_sine.c:45
values
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
Definition: filter_design.txt:263
samples
Filter the word “frame” indicates either a video frame or a group of audio samples
Definition: filter_design.txt:8
AVFilterContext
An instance of a filter.
Definition: avfilter.h:407
VAR_N
@ VAR_N
Definition: asrc_sine.c:140
ff_asrc_sine
const AVFilter ff_asrc_sine
Definition: asrc_sine.c:265
mem.h
audio.h
AV_CHANNEL_LAYOUT_MONO
#define AV_CHANNEL_LAYOUT_MONO
Definition: channel_layout.h:378
FILTER_OUTPUTS
#define FILTER_OUTPUTS(array)
Definition: internal.h:183
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
ff_outlink_frame_wanted
the definition of that something depends on the semantic of the filter The callback must examine the status of the filter s links and proceed accordingly The status of output links is stored in the status_in and status_out fields and tested by the ff_outlink_frame_wanted() function. If this function returns true
SineContext::phi_beep
uint32_t phi_beep
current phase of the beep
Definition: asrc_sine.c:49
AMPLITUDE
#define AMPLITUDE
Definition: asrc_sine.c:88
query_formats
static av_cold int query_formats(AVFilterContext *ctx)
Definition: asrc_sine.c:182
SineContext::samples_per_frame
char * samples_per_frame
Definition: asrc_sine.c:38