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 "filters.h"
30 #include "internal.h"
31 
32 typedef struct SineContext {
33  const AVClass *class;
34  double frequency;
35  double beep_factor;
39  int64_t duration;
40  int16_t *sin;
41  int64_t pts;
42  uint32_t phi; ///< current phase of the sine (2pi = 1<<32)
43  uint32_t dphi; ///< phase increment between two samples
44  unsigned beep_period;
45  unsigned beep_index;
46  unsigned beep_length;
47  uint32_t phi_beep; ///< current phase of the beep
48  uint32_t dphi_beep; ///< phase increment of the beep
49 } SineContext;
50 
51 #define CONTEXT SineContext
52 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
53 
54 #define OPT_GENERIC(name, field, def, min, max, descr, type, deffield, ...) \
55  { name, descr, offsetof(CONTEXT, field), AV_OPT_TYPE_ ## type, \
56  { .deffield = def }, min, max, FLAGS, __VA_ARGS__ }
57 
58 #define OPT_INT(name, field, def, min, max, descr, ...) \
59  OPT_GENERIC(name, field, def, min, max, descr, INT, i64, __VA_ARGS__)
60 
61 #define OPT_DBL(name, field, def, min, max, descr, ...) \
62  OPT_GENERIC(name, field, def, min, max, descr, DOUBLE, dbl, __VA_ARGS__)
63 
64 #define OPT_DUR(name, field, def, min, max, descr, ...) \
65  OPT_GENERIC(name, field, def, min, max, descr, DURATION, str, __VA_ARGS__)
66 
67 #define OPT_STR(name, field, def, min, max, descr, ...) \
68  OPT_GENERIC(name, field, def, min, max, descr, STRING, str, __VA_ARGS__)
69 
70 static const AVOption sine_options[] = {
71  OPT_DBL("frequency", frequency, 440, 0, DBL_MAX, "set the sine frequency",),
72  OPT_DBL("f", frequency, 440, 0, DBL_MAX, "set the sine frequency",),
73  OPT_DBL("beep_factor", beep_factor, 0, 0, DBL_MAX, "set the beep frequency factor",),
74  OPT_DBL("b", beep_factor, 0, 0, DBL_MAX, "set the beep frequency factor",),
75  OPT_INT("sample_rate", sample_rate, 44100, 1, INT_MAX, "set the sample rate",),
76  OPT_INT("r", sample_rate, 44100, 1, INT_MAX, "set the sample rate",),
77  OPT_DUR("duration", duration, 0, 0, INT64_MAX, "set the audio duration",),
78  OPT_DUR("d", duration, 0, 0, INT64_MAX, "set the audio duration",),
79  OPT_STR("samples_per_frame", samples_per_frame, "1024", 0, 0, "set the number of samples per frame",),
80  {NULL}
81 };
82 
84 
85 #define LOG_PERIOD 15
86 #define AMPLITUDE 4095
87 #define AMPLITUDE_SHIFT 3
88 
89 static void make_sin_table(int16_t *sin)
90 {
91  unsigned half_pi = 1 << (LOG_PERIOD - 2);
92  unsigned ampls = AMPLITUDE << AMPLITUDE_SHIFT;
93  uint64_t unit2 = (uint64_t)(ampls * ampls) << 32;
94  unsigned step, i, c, s, k, new_k, n2;
95 
96  /* Principle: if u = exp(i*a1) and v = exp(i*a2), then
97  exp(i*(a1+a2)/2) = (u+v) / length(u+v) */
98  sin[0] = 0;
99  sin[half_pi] = ampls;
100  for (step = half_pi; step > 1; step /= 2) {
101  /* k = (1 << 16) * amplitude / length(u+v)
102  In exact values, k is constant at a given step */
103  k = 0x10000;
104  for (i = 0; i < half_pi / 2; i += step) {
105  s = sin[i] + sin[i + step];
106  c = sin[half_pi - i] + sin[half_pi - i - step];
107  n2 = s * s + c * c;
108  /* Newton's method to solve n² * k² = unit² */
109  while (1) {
110  new_k = (k + unit2 / ((uint64_t)k * n2) + 1) >> 1;
111  if (k == new_k)
112  break;
113  k = new_k;
114  }
115  sin[i + step / 2] = (k * s + 0x7FFF) >> 16;
116  sin[half_pi - i - step / 2] = (k * c + 0x8000) >> 16;
117  }
118  }
119  /* Unshift amplitude */
120  for (i = 0; i <= half_pi; i++)
121  sin[i] = (sin[i] + (1 << (AMPLITUDE_SHIFT - 1))) >> AMPLITUDE_SHIFT;
122  /* Use symmetries to fill the other three quarters */
123  for (i = 0; i < half_pi; i++)
124  sin[half_pi * 2 - i] = sin[i];
125  for (i = 0; i < 2 * half_pi; i++)
126  sin[i + 2 * half_pi] = -sin[i];
127 }
128 
129 static const char *const var_names[] = {
130  "n",
131  "pts",
132  "t",
133  "TB",
134  NULL
135 };
136 
137 enum {
143 };
144 
146 {
147  int ret;
148  SineContext *sine = ctx->priv;
149 
150  if (!(sine->sin = av_malloc(sizeof(*sine->sin) << LOG_PERIOD)))
151  return AVERROR(ENOMEM);
152  sine->dphi = ldexp(sine->frequency, 32) / sine->sample_rate + 0.5;
153  make_sin_table(sine->sin);
154 
155  if (sine->beep_factor) {
156  sine->beep_period = sine->sample_rate;
157  sine->beep_length = sine->beep_period / 25;
158  sine->dphi_beep = ldexp(sine->beep_factor * sine->frequency, 32) /
159  sine->sample_rate + 0.5;
160  }
161 
164  NULL, NULL, NULL, NULL, 0, sine);
165  if (ret < 0)
166  return ret;
167 
168  return 0;
169 }
170 
172 {
173  SineContext *sine = ctx->priv;
174 
177  av_freep(&sine->sin);
178 }
179 
181 {
182  SineContext *sine = ctx->priv;
183  static const int64_t chlayouts[] = { AV_CH_LAYOUT_MONO, -1 };
184  int sample_rates[] = { sine->sample_rate, -1 };
185  static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16,
188  if (ret < 0)
189  return ret;
190 
192  if (ret < 0)
193  return ret;
194 
196 }
197 
198 static av_cold int config_props(AVFilterLink *outlink)
199 {
200  SineContext *sine = outlink->src->priv;
201  sine->duration = av_rescale(sine->duration, sine->sample_rate, AV_TIME_BASE);
202  return 0;
203 }
204 
206 {
207  AVFilterLink *outlink = ctx->outputs[0];
208  SineContext *sine = ctx->priv;
209  AVFrame *frame;
210  double values[VAR_VARS_NB] = {
211  [VAR_N] = outlink->frame_count_in,
212  [VAR_PTS] = sine->pts,
213  [VAR_T] = sine->pts * av_q2d(outlink->time_base),
214  [VAR_TB] = av_q2d(outlink->time_base),
215  };
216  int i, nb_samples = lrint(av_expr_eval(sine->samples_per_frame_expr, values, sine));
217  int16_t *samples;
218 
219  if (!ff_outlink_frame_wanted(outlink))
220  return FFERROR_NOT_READY;
221  if (nb_samples <= 0) {
222  av_log(sine, AV_LOG_WARNING, "nb samples expression evaluated to %d, "
223  "defaulting to 1024\n", nb_samples);
224  nb_samples = 1024;
225  }
226 
227  if (sine->duration) {
228  nb_samples = FFMIN(nb_samples, sine->duration - sine->pts);
229  av_assert1(nb_samples >= 0);
230  if (!nb_samples) {
231  ff_outlink_set_status(outlink, AVERROR_EOF, sine->pts);
232  return 0;
233  }
234  }
235  if (!(frame = ff_get_audio_buffer(outlink, nb_samples)))
236  return AVERROR(ENOMEM);
237  samples = (int16_t *)frame->data[0];
238 
239  for (i = 0; i < nb_samples; i++) {
240  samples[i] = sine->sin[sine->phi >> (32 - LOG_PERIOD)];
241  sine->phi += sine->dphi;
242  if (sine->beep_index < sine->beep_length) {
243  samples[i] += sine->sin[sine->phi_beep >> (32 - LOG_PERIOD)] * 2;
244  sine->phi_beep += sine->dphi_beep;
245  }
246  if (++sine->beep_index == sine->beep_period)
247  sine->beep_index = 0;
248  }
249 
250  frame->pts = sine->pts;
251  sine->pts += nb_samples;
252  return ff_filter_frame(outlink, frame);
253 }
254 
255 static const AVFilterPad sine_outputs[] = {
256  {
257  .name = "default",
258  .type = AVMEDIA_TYPE_AUDIO,
259  .config_props = config_props,
260  },
261 };
262 
264  .name = "sine",
265  .description = NULL_IF_CONFIG_SMALL("Generate sine wave audio signal."),
266  .init = init,
267  .uninit = uninit,
268  .activate = activate,
269  .priv_size = sizeof(SineContext),
270  .inputs = NULL,
273  .priv_class = &sine_class,
274 };
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:88
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:39
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:70
VAR_PTS
@ VAR_PTS
Definition: asrc_sine.c:139
ff_filter_frame
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1018
sample_fmts
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:948
SineContext::frequency
double frequency
Definition: asrc_sine.c:34
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:57
VAR_N
@ VAR_N
Definition: asrc_sine.c:138
FFERROR_NOT_READY
return FFERROR_NOT_READY
Definition: filter_design.txt:204
AV_CH_LAYOUT_MONO
#define AV_CH_LAYOUT_MONO
Definition: channel_layout.h:90
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:683
VAR_VARS_NB
@ VAR_VARS_NB
Definition: asrc_sine.c:142
AVFILTER_DEFINE_CLASS
AVFILTER_DEFINE_CLASS(sine)
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:303
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:198
AVOption
AVOption.
Definition: opt.h:247
FILTER_QUERY_FUNC
#define FILTER_QUERY_FUNC(func)
Definition: internal.h:168
float.h
VAR_TB
@ VAR_TB
Definition: asrc_sine.c:141
AVFilter::name
const char * name
Filter name.
Definition: avfilter.h:153
make_sin_table
static void make_sin_table(int16_t *sin)
Definition: asrc_sine.c:89
sample_rate
sample_rate
Definition: ffmpeg_filter.c:156
activate
static int activate(AVFilterContext *ctx)
Definition: asrc_sine.c:205
ff_set_common_channel_layouts_from_list
int ff_set_common_channel_layouts_from_list(AVFilterContext *ctx, const int64_t *fmts)
Equivalent to ff_set_common_channel_layouts(ctx, ff_make_format64_list(fmts))
Definition: formats.c:665
av_malloc
#define av_malloc(s)
Definition: tableprint_vlc.h:31
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:685
uninit
static av_cold void uninit(AVFilterContext *ctx)
Definition: asrc_sine.c:171
AVFilterContext::priv
void * priv
private data for use by the filter
Definition: avfilter.h:401
OPT_DBL
#define OPT_DBL(name, field, def, min, max, descr,...)
Definition: asrc_sine.c:61
av_expr_free
void av_expr_free(AVExpr *e)
Free a parsed expression previously created with av_expr_parse().
Definition: eval.c:336
AVFilterPad
A filter pad used for either input or output.
Definition: internal.h:50
avassert.h
lrint
#define lrint
Definition: tablegen.h:53
av_cold
#define av_cold
Definition: attributes.h:90
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
duration
int64_t duration
Definition: movenc.c:64
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:257
AMPLITUDE_SHIFT
#define AMPLITUDE_SHIFT
Definition: asrc_sine.c:87
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:705
filters.h
ctx
AVFormatContext * ctx
Definition: movenc.c:48
av_expr_eval
double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
Evaluate a previously parsed expression.
Definition: eval.c:766
AVExpr
Definition: eval.c:157
var_names
static const char *const var_names[]
Definition: asrc_sine.c:129
OPT_DUR
#define OPT_DUR(name, field, def, min, max, descr,...)
Definition: asrc_sine.c:64
SineContext::beep_index
unsigned beep_index
Definition: asrc_sine.c:45
SineContext::samples_per_frame_expr
AVExpr * samples_per_frame_expr
Definition: asrc_sine.c:37
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:66
LOG_PERIOD
#define LOG_PERIOD
Definition: asrc_sine.c:85
NULL
#define NULL
Definition: coverity.c:32
SineContext::sample_rate
int sample_rate
Definition: asrc_sine.c:38
SineContext::pts
int64_t pts
Definition: asrc_sine.c:41
SineContext::dphi_beep
uint32_t dphi_beep
phase increment of the beep
Definition: asrc_sine.c:48
SineContext
Definition: asrc_sine.c:32
VAR_T
@ VAR_T
Definition: asrc_sine.c:140
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
for
for(j=16;j >0;--j)
Definition: h264pred_template.c:469
SineContext::beep_factor
double beep_factor
Definition: asrc_sine.c:35
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:117
OPT_STR
#define OPT_STR(name, field, def, min, max, descr,...)
Definition: asrc_sine.c:67
AV_SAMPLE_FMT_NONE
@ AV_SAMPLE_FMT_NONE
Definition: samplefmt.h:59
sine_outputs
static const AVFilterPad sine_outputs[]
Definition: asrc_sine.c:255
OPT_INT
#define OPT_INT(name, field, def, min, max, descr,...)
Definition: asrc_sine.c:58
sample_rates
sample_rates
Definition: ffmpeg_filter.c:156
internal.h
SineContext::sin
int16_t * sin
Definition: asrc_sine.c:40
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:271
SineContext::phi
uint32_t phi
current phase of the sine (2pi = 1<<32)
Definition: asrc_sine.c:42
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:53
AVSampleFormat
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
AV_SAMPLE_FMT_S16
@ AV_SAMPLE_FMT_S16
signed 16 bits
Definition: samplefmt.h:61
AVFilterPad::name
const char * name
Pad name.
Definition: internal.h:56
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:128
init
static av_cold int init(AVFilterContext *ctx)
Definition: asrc_sine.c:145
AVFilter
Filter definition.
Definition: avfilter.h:149
SineContext::beep_length
unsigned beep_length
Definition: asrc_sine.c:46
SineContext::beep_period
unsigned beep_period
Definition: asrc_sine.c:44
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
channel_layout.h
avfilter.h
SineContext::dphi
uint32_t dphi
phase increment between two samples
Definition: asrc_sine.c:43
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:386
ff_asrc_sine
const AVFilter ff_asrc_sine
Definition: asrc_sine.c:263
audio.h
FILTER_OUTPUTS
#define FILTER_OUTPUTS(array)
Definition: internal.h:192
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
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:47
AMPLITUDE
#define AMPLITUDE
Definition: asrc_sine.c:86
query_formats
static av_cold int query_formats(AVFilterContext *ctx)
Definition: asrc_sine.c:180
SineContext::samples_per_frame
char * samples_per_frame
Definition: asrc_sine.c:36