FFmpeg
f_loop.c
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1 /*
2  * Copyright (c) 2016 Paul B Mahol
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
8  * License 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 GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "libavutil/audio_fifo.h"
22 #include "libavutil/avassert.h"
23 #include "libavutil/fifo.h"
24 #include "libavutil/internal.h"
25 #include "libavutil/opt.h"
26 #include "avfilter.h"
27 #include "audio.h"
28 #include "filters.h"
29 #include "formats.h"
30 #include "internal.h"
31 #include "video.h"
32 
33 typedef struct LoopContext {
34  const AVClass *class;
35 
39  int nb_frames;
41  int64_t start_pts;
42  int64_t duration;
43  int64_t current_sample;
44  int64_t nb_samples;
45  int64_t ignored_samples;
46 
47  int loop;
48  int eof;
49  int64_t size;
50  int64_t start;
51  int64_t pts;
52 } LoopContext;
53 
54 #define AFLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
55 #define VFLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
56 #define OFFSET(x) offsetof(LoopContext, x)
57 
59 {
60  LoopContext *s = ctx->priv;
61 
62  if (!s->size)
63  av_log(ctx, AV_LOG_WARNING, "Number of %s to loop is not set!\n",
64  ctx->input_pads[0].type == AVMEDIA_TYPE_VIDEO ? "frames" : "samples");
65 }
66 
67 #if CONFIG_ALOOP_FILTER
68 
69 static int aconfig_input(AVFilterLink *inlink)
70 {
71  AVFilterContext *ctx = inlink->dst;
72  LoopContext *s = ctx->priv;
73 
74  s->fifo = av_audio_fifo_alloc(inlink->format, inlink->channels, 8192);
75  s->left = av_audio_fifo_alloc(inlink->format, inlink->channels, 8192);
76  if (!s->fifo || !s->left)
77  return AVERROR(ENOMEM);
78 
79  check_size(ctx);
80 
81  return 0;
82 }
83 
84 static av_cold void auninit(AVFilterContext *ctx)
85 {
86  LoopContext *s = ctx->priv;
87 
90 }
91 
92 static int push_samples(AVFilterContext *ctx, int nb_samples)
93 {
94  AVFilterLink *outlink = ctx->outputs[0];
95  LoopContext *s = ctx->priv;
96  AVFrame *out;
97  int ret, i = 0;
98 
99  while (s->loop != 0 && i < nb_samples) {
100  out = ff_get_audio_buffer(outlink, FFMIN(nb_samples, s->nb_samples - s->current_sample));
101  if (!out)
102  return AVERROR(ENOMEM);
103  ret = av_audio_fifo_peek_at(s->fifo, (void **)out->extended_data, out->nb_samples, s->current_sample);
104  if (ret < 0) {
105  av_frame_free(&out);
106  return ret;
107  }
108  out->pts = s->pts;
109  out->nb_samples = ret;
110  s->pts += av_rescale_q(out->nb_samples, (AVRational){1, outlink->sample_rate}, outlink->time_base);
111  i += out->nb_samples;
112  s->current_sample += out->nb_samples;
113 
114  ret = ff_filter_frame(outlink, out);
115  if (ret < 0)
116  return ret;
117 
118  if (s->current_sample >= s->nb_samples) {
119  s->duration = s->pts;
120  s->current_sample = 0;
121 
122  if (s->loop > 0)
123  s->loop--;
124  }
125  }
126 
127  return ret;
128 }
129 
130 static int afilter_frame(AVFilterLink *inlink, AVFrame *frame)
131 {
132  AVFilterContext *ctx = inlink->dst;
133  AVFilterLink *outlink = ctx->outputs[0];
134  LoopContext *s = ctx->priv;
135  int ret = 0;
136 
137  if (s->ignored_samples + frame->nb_samples > s->start && s->size > 0 && s->loop != 0) {
138  if (s->nb_samples < s->size) {
139  int written = FFMIN(frame->nb_samples, s->size - s->nb_samples);
140  int drain = 0;
141 
142  ret = av_audio_fifo_write(s->fifo, (void **)frame->extended_data, written);
143  if (ret < 0)
144  return ret;
145  if (!s->nb_samples) {
146  drain = FFMAX(0, s->start - s->ignored_samples);
147  s->pts = frame->pts;
148  av_audio_fifo_drain(s->fifo, drain);
149  s->pts += av_rescale_q(s->start - s->ignored_samples, (AVRational){1, outlink->sample_rate}, outlink->time_base);
150  }
151  s->nb_samples += ret - drain;
152  drain = frame->nb_samples - written;
153  if (s->nb_samples == s->size && drain > 0) {
154  int ret2;
155 
156  ret2 = av_audio_fifo_write(s->left, (void **)frame->extended_data, frame->nb_samples);
157  if (ret2 < 0)
158  return ret2;
159  av_audio_fifo_drain(s->left, drain);
160  }
161  frame->nb_samples = ret;
162  s->pts += av_rescale_q(ret, (AVRational){1, outlink->sample_rate}, outlink->time_base);
163  ret = ff_filter_frame(outlink, frame);
164  } else {
165  int nb_samples = frame->nb_samples;
166 
167  av_frame_free(&frame);
168  ret = push_samples(ctx, nb_samples);
169  }
170  } else {
171  s->ignored_samples += frame->nb_samples;
172  frame->pts = s->pts;
173  s->pts += av_rescale_q(frame->nb_samples, (AVRational){1, outlink->sample_rate}, outlink->time_base);
174  ret = ff_filter_frame(outlink, frame);
175  }
176 
177  return ret;
178 }
179 
180 static int arequest_frame(AVFilterLink *outlink)
181 {
182  AVFilterContext *ctx = outlink->src;
183  LoopContext *s = ctx->priv;
184  int ret = 0;
185 
186  if ((!s->size) ||
187  (s->nb_samples < s->size) ||
188  (s->nb_samples >= s->size && s->loop == 0)) {
190 
191  if (s->loop == 0 && nb_samples > 0) {
192  AVFrame *out;
193 
194  out = ff_get_audio_buffer(outlink, nb_samples);
195  if (!out)
196  return AVERROR(ENOMEM);
197  av_audio_fifo_read(s->left, (void **)out->extended_data, nb_samples);
198  out->pts = s->pts;
199  s->pts += av_rescale_q(nb_samples, (AVRational){1, outlink->sample_rate}, outlink->time_base);
200  ret = ff_filter_frame(outlink, out);
201  if (ret < 0)
202  return ret;
203  }
204  ret = ff_request_frame(ctx->inputs[0]);
205  } else {
206  ret = push_samples(ctx, 1024);
207  }
208 
209  if (s->eof && s->nb_samples > 0 && s->loop != 0) {
210  ret = push_samples(ctx, 1024);
211  }
212 
213  return ret;
214 }
215 
216 static int aactivate(AVFilterContext *ctx)
217 {
218  AVFilterLink *inlink = ctx->inputs[0];
219  AVFilterLink *outlink = ctx->outputs[0];
220  LoopContext *s = ctx->priv;
221  AVFrame *frame = NULL;
222  int ret, status;
223  int64_t pts;
224 
225  FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink);
226 
227  if (!s->eof && (s->nb_samples < s->size || !s->loop || !s->size)) {
228  ret = ff_inlink_consume_frame(inlink, &frame);
229  if (ret < 0)
230  return ret;
231  if (ret > 0)
232  return afilter_frame(inlink, frame);
233  }
234 
235  if (!s->eof && ff_inlink_acknowledge_status(inlink, &status, &pts)) {
236  if (status == AVERROR_EOF) {
237  s->size = s->nb_samples;
238  s->eof = 1;
239  }
240  }
241 
242  if (s->eof && (!s->loop || !s->size)) {
244  return 0;
245  }
246 
247  if (!s->eof && (!s->size ||
248  (s->nb_samples < s->size) ||
249  (s->nb_samples >= s->size && s->loop == 0))) {
250  FF_FILTER_FORWARD_WANTED(outlink, inlink);
251  } else if (s->loop && s->nb_samples == s->size) {
252  return arequest_frame(outlink);
253  }
254 
255  return FFERROR_NOT_READY;
256 }
257 
258 static const AVOption aloop_options[] = {
259  { "loop", "number of loops", OFFSET(loop), AV_OPT_TYPE_INT, {.i64 = 0 }, -1, INT_MAX, AFLAGS },
260  { "size", "max number of samples to loop", OFFSET(size), AV_OPT_TYPE_INT64, {.i64 = 0 }, 0, INT32_MAX, AFLAGS },
261  { "start", "set the loop start sample", OFFSET(start), AV_OPT_TYPE_INT64, {.i64 = 0 }, 0, INT64_MAX, AFLAGS },
262  { NULL }
263 };
264 
265 AVFILTER_DEFINE_CLASS(aloop);
266 
267 static const AVFilterPad ainputs[] = {
268  {
269  .name = "default",
270  .type = AVMEDIA_TYPE_AUDIO,
271  .config_props = aconfig_input,
272  },
273  { NULL }
274 };
275 
276 static const AVFilterPad aoutputs[] = {
277  {
278  .name = "default",
279  .type = AVMEDIA_TYPE_AUDIO,
280  },
281  { NULL }
282 };
283 
285  .name = "aloop",
286  .description = NULL_IF_CONFIG_SMALL("Loop audio samples."),
287  .priv_size = sizeof(LoopContext),
288  .priv_class = &aloop_class,
289  .activate = aactivate,
290  .uninit = auninit,
291  .inputs = ainputs,
292  .outputs = aoutputs,
293 };
294 #endif /* CONFIG_ALOOP_FILTER */
295 
296 #if CONFIG_LOOP_FILTER
297 
298 static av_cold int init(AVFilterContext *ctx)
299 {
300  LoopContext *s = ctx->priv;
301 
302  s->frames = av_calloc(s->size, sizeof(*s->frames));
303  if (!s->frames)
304  return AVERROR(ENOMEM);
305 
306  check_size(ctx);
307 
308  return 0;
309 }
310 
311 static av_cold void uninit(AVFilterContext *ctx)
312 {
313  LoopContext *s = ctx->priv;
314  int i;
315 
316  for (i = 0; i < s->nb_frames; i++)
317  av_frame_free(&s->frames[i]);
318 
319  av_freep(&s->frames);
320  s->nb_frames = 0;
321 }
322 
323 static int push_frame(AVFilterContext *ctx)
324 {
325  AVFilterLink *outlink = ctx->outputs[0];
326  LoopContext *s = ctx->priv;
327  int64_t pts, duration;
328  int ret;
329 
331 
332  if (!out)
333  return AVERROR(ENOMEM);
334  out->pts += s->duration - s->start_pts;
335  if (out->pkt_duration)
336  duration = out->pkt_duration;
337  else
338  duration = av_rescale_q(1, av_inv_q(outlink->frame_rate), outlink->time_base);
339  pts = out->pts + duration;
340  ret = ff_filter_frame(outlink, out);
341  s->current_frame++;
342 
343  if (s->current_frame >= s->nb_frames) {
344  s->duration = pts;
345  s->current_frame = 0;
346 
347  if (s->loop > 0)
348  s->loop--;
349  }
350 
351  return ret;
352 }
353 
354 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
355 {
356  AVFilterContext *ctx = inlink->dst;
357  AVFilterLink *outlink = ctx->outputs[0];
358  LoopContext *s = ctx->priv;
359  int64_t duration;
360  int ret = 0;
361 
362  if (inlink->frame_count_out >= s->start && s->size > 0 && s->loop != 0) {
363  if (s->nb_frames < s->size) {
364  if (!s->nb_frames)
365  s->start_pts = frame->pts;
366  s->frames[s->nb_frames] = av_frame_clone(frame);
367  if (!s->frames[s->nb_frames]) {
368  av_frame_free(&frame);
369  return AVERROR(ENOMEM);
370  }
371  s->nb_frames++;
372  if (frame->pkt_duration)
373  duration = frame->pkt_duration;
374  else
375  duration = av_rescale_q(1, av_inv_q(outlink->frame_rate), outlink->time_base);
376  s->duration = frame->pts + duration;
377  ret = ff_filter_frame(outlink, frame);
378  } else {
379  av_frame_free(&frame);
380  ret = push_frame(ctx);
381  }
382  } else {
383  frame->pts += s->duration;
384  ret = ff_filter_frame(outlink, frame);
385  }
386 
387  return ret;
388 }
389 
390 static int activate(AVFilterContext *ctx)
391 {
392  AVFilterLink *inlink = ctx->inputs[0];
393  AVFilterLink *outlink = ctx->outputs[0];
394  LoopContext *s = ctx->priv;
395  AVFrame *frame = NULL;
396  int ret, status;
397  int64_t pts;
398 
399  FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink);
400 
401  if (!s->eof && (s->nb_frames < s->size || !s->loop || !s->size)) {
402  ret = ff_inlink_consume_frame(inlink, &frame);
403  if (ret < 0)
404  return ret;
405  if (ret > 0)
406  return filter_frame(inlink, frame);
407  }
408 
409  if (!s->eof && ff_inlink_acknowledge_status(inlink, &status, &pts)) {
410  if (status == AVERROR_EOF) {
411  s->size = s->nb_frames;
412  s->eof = 1;
413  }
414  }
415 
416  if (s->eof && (!s->loop || !s->size)) {
418  return 0;
419  }
420 
421  if (!s->eof && (!s->size ||
422  (s->nb_frames < s->size) ||
423  (s->nb_frames >= s->size && s->loop == 0))) {
424  FF_FILTER_FORWARD_WANTED(outlink, inlink);
425  } else if (s->loop && s->nb_frames == s->size) {
426  return push_frame(ctx);
427  }
428 
429  return FFERROR_NOT_READY;
430 }
431 
432 static const AVOption loop_options[] = {
433  { "loop", "number of loops", OFFSET(loop), AV_OPT_TYPE_INT, {.i64 = 0 }, -1, INT_MAX, VFLAGS },
434  { "size", "max number of frames to loop", OFFSET(size), AV_OPT_TYPE_INT64, {.i64 = 0 }, 0, INT16_MAX, VFLAGS },
435  { "start", "set the loop start frame", OFFSET(start), AV_OPT_TYPE_INT64, {.i64 = 0 }, 0, INT64_MAX, VFLAGS },
436  { NULL }
437 };
438 
440 
441 static const AVFilterPad inputs[] = {
442  {
443  .name = "default",
444  .type = AVMEDIA_TYPE_VIDEO,
445  },
446  { NULL }
447 };
448 
449 static const AVFilterPad outputs[] = {
450  {
451  .name = "default",
452  .type = AVMEDIA_TYPE_VIDEO,
453  },
454  { NULL }
455 };
456 
458  .name = "loop",
459  .description = NULL_IF_CONFIG_SMALL("Loop video frames."),
460  .priv_size = sizeof(LoopContext),
461  .priv_class = &loop_class,
462  .init = init,
463  .uninit = uninit,
464  .activate = activate,
465  .inputs = inputs,
466  .outputs = outputs,
467 };
468 #endif /* CONFIG_LOOP_FILTER */
int ff_inlink_consume_frame(AVFilterLink *link, AVFrame **rframe)
Take a frame from the link&#39;s FIFO and update the link&#39;s stats.
Definition: avfilter.c:1494
#define NULL
Definition: coverity.c:32
static int push_samples(ATempoContext *atempo, AVFilterLink *outlink, int n_out)
Definition: af_atempo.c:1051
static void check_size(AVFilterContext *ctx)
Definition: f_loop.c:58
AVAudioFifo * av_audio_fifo_alloc(enum AVSampleFormat sample_fmt, int channels, int nb_samples)
Allocate an AVAudioFifo.
Definition: audio_fifo.c:59
int av_audio_fifo_read(AVAudioFifo *af, void **data, int nb_samples)
Read data from an AVAudioFifo.
Definition: audio_fifo.c:181
This structure describes decoded (raw) audio or video data.
Definition: frame.h:295
AVOption.
Definition: opt.h:246
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
Main libavfilter public API header.
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
void av_audio_fifo_free(AVAudioFifo *af)
Free an AVAudioFifo.
Definition: audio_fifo.c:45
int64_t pts
Definition: f_loop.c:51
enum AVMediaType type
AVFilterPad type.
Definition: internal.h:65
int loop
Definition: f_loop.c:47
return FFERROR_NOT_READY
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
AVFrame ** frames
Definition: f_loop.c:38
void * av_calloc(size_t nmemb, size_t size)
Non-inlined equivalent of av_mallocz_array().
Definition: mem.c:244
const char * name
Pad name.
Definition: internal.h:60
AVFilterLink ** inputs
array of pointers to input links
Definition: avfilter.h:346
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
static av_cold int uninit(AVCodecContext *avctx)
Definition: crystalhd.c:279
AVOptions.
filter_frame For filters that do not use the activate() callback
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:388
int eof
Definition: f_loop.c:48
int current_frame
Definition: f_loop.c:40
static int push_frame(AVFilterContext *ctx, unsigned in_no, AVFrame *buf)
Definition: avf_concat.c:174
#define AVERROR_EOF
End of file.
Definition: error.h:55
ptrdiff_t size
Definition: opengl_enc.c:100
#define av_log(a,...)
#define FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink)
Forward the status on an output link to an input link.
Definition: filters.h:199
int64_t current_sample
Definition: f_loop.c:43
A filter pad used for either input or output.
Definition: internal.h:54
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:142
int ff_inlink_acknowledge_status(AVFilterLink *link, int *rstatus, int64_t *rpts)
Test and acknowledge the change of status on the link.
Definition: avfilter.c:1449
AVFilterPad * input_pads
array of input pads
Definition: avfilter.h:345
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
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
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:202
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
int64_t start
Definition: f_loop.c:50
void * priv
private data for use by the filter
Definition: avfilter.h:353
int nb_frames
Definition: f_loop.c:39
simple assert() macros that are a bit more flexible than ISO C assert().
#define FFMAX(a, b)
Definition: common.h:94
Context for an Audio FIFO Buffer.
Definition: audio_fifo.c:34
common internal API header
int av_audio_fifo_size(AVAudioFifo *af)
Get the current number of samples in the AVAudioFifo available for reading.
Definition: audio_fifo.c:228
#define FFMIN(a, b)
Definition: common.h:96
int64_t duration
Definition: f_loop.c:42
int64_t start_pts
Definition: f_loop.c:41
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
#define AFLAGS
Definition: f_loop.c:54
int64_t size
Definition: f_loop.c:49
AVFrame * av_frame_clone(const AVFrame *src)
Create a new frame that references the same data as src.
Definition: frame.c:540
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
int64_t pkt_duration
duration of the corresponding packet, expressed in AVStream->time_base units, 0 if unknown...
Definition: frame.h:574
a very simple circular buffer FIFO implementation
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
AVAudioFifo * left
Definition: f_loop.c:37
Describe the class of an AVClass context structure.
Definition: log.h:67
Filter definition.
Definition: avfilter.h:144
Rational number (pair of numerator and denominator).
Definition: rational.h:58
they must not be accessed directly The fifo field contains the frames that are queued in the input for processing by the filter The status_in and status_out fields contains the queued status(EOF or error) of the link
const char * name
Filter name.
Definition: avfilter.h:148
AVFilterLink ** outputs
array of pointers to output links
Definition: avfilter.h:350
int64_t nb_samples
Definition: f_loop.c:44
static int filter_frame(DBEContext *s, AVFrame *frame)
Definition: dolby_e.c:565
int av_audio_fifo_write(AVAudioFifo *af, void **data, int nb_samples)
Write data to an AVAudioFifo.
Definition: audio_fifo.c:112
int64_t ignored_samples
Definition: f_loop.c:45
The exact code depends on how similar the blocks are and how related they are to the and needs to apply these operations to the correct inlink or outlink if there are several Macros are available to factor that when no extra processing is inlink
int av_audio_fifo_drain(AVAudioFifo *af, int nb_samples)
Drain data from an AVAudioFifo.
Definition: audio_fifo.c:201
static av_always_inline AVRational av_inv_q(AVRational q)
Invert a rational.
Definition: rational.h:159
AVFilter ff_vf_loop
FF_FILTER_FORWARD_WANTED(outlink, inlink)
Audio FIFO Buffer.
#define AVFILTER_DEFINE_CLASS(fname)
Definition: internal.h:334
#define OFFSET(x)
Definition: f_loop.c:56
AVAudioFifo * fifo
Definition: f_loop.c:36
An instance of a filter.
Definition: avfilter.h:338
#define VFLAGS
Definition: f_loop.c:55
FILE * out
Definition: movenc.c:54
AVFilter ff_af_aloop
#define av_freep(p)
int ff_request_frame(AVFilterLink *link)
Request an input frame from the filter at the other end of the link.
Definition: avfilter.c:407
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
uint8_t ** extended_data
pointers to the data planes/channels.
Definition: frame.h:342
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:361
int av_audio_fifo_peek_at(AVAudioFifo *af, void **data, int nb_samples, int offset)
Peek data from an AVAudioFifo.
Definition: audio_fifo.c:157