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f_select.c
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1 /*
2  * Copyright (c) 2011 Stefano Sabatini
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 /**
22  * @file
23  * filter for selecting which frame passes in the filterchain
24  */
25 
26 #include "libavutil/avstring.h"
27 #include "libavutil/eval.h"
28 #include "libavutil/fifo.h"
29 #include "libavutil/internal.h"
30 #include "libavutil/opt.h"
31 #include "libavutil/pixelutils.h"
32 #include "avfilter.h"
33 #include "audio.h"
34 #include "formats.h"
35 #include "internal.h"
36 #include "video.h"
37 
38 static const char *const var_names[] = {
39  "TB", ///< timebase
40 
41  "pts", ///< original pts in the file of the frame
42  "start_pts", ///< first PTS in the stream, expressed in TB units
43  "prev_pts", ///< previous frame PTS
44  "prev_selected_pts", ///< previous selected frame PTS
45 
46  "t", ///< timestamp expressed in seconds
47  "start_t", ///< first PTS in the stream, expressed in seconds
48  "prev_t", ///< previous frame time
49  "prev_selected_t", ///< previously selected time
50 
51  "pict_type", ///< the type of picture in the movie
52  "I",
53  "P",
54  "B",
55  "S",
56  "SI",
57  "SP",
58  "BI",
59  "PICT_TYPE_I",
60  "PICT_TYPE_P",
61  "PICT_TYPE_B",
62  "PICT_TYPE_S",
63  "PICT_TYPE_SI",
64  "PICT_TYPE_SP",
65  "PICT_TYPE_BI",
66 
67  "interlace_type", ///< the frame interlace type
68  "PROGRESSIVE",
69  "TOPFIRST",
70  "BOTTOMFIRST",
71 
72  "consumed_samples_n",///< number of samples consumed by the filter (only audio)
73  "samples_n", ///< number of samples in the current frame (only audio)
74  "sample_rate", ///< sample rate (only audio)
75 
76  "n", ///< frame number (starting from zero)
77  "selected_n", ///< selected frame number (starting from zero)
78  "prev_selected_n", ///< number of the last selected frame
79 
80  "key", ///< tell if the frame is a key frame
81  "pos", ///< original position in the file of the frame
82 
83  "scene",
84 
85  NULL
86 };
87 
88 enum var_name {
90 
95 
100 
116 
121 
125 
129 
132 
134 
136 };
137 
138 typedef struct SelectContext {
139  const AVClass *class;
140  char *expr_str;
143  int do_scene_detect; ///< 1 if the expression requires scene detection variables, 0 otherwise
144  av_pixelutils_sad_fn sad; ///< Sum of the absolute difference function (scene detect only)
145  double prev_mafd; ///< previous MAFD (scene detect only)
146  AVFrame *prev_picref; ///< previous frame (scene detect only)
147  double select;
148  int select_out; ///< mark the selected output pad index
150 } SelectContext;
151 
152 #define OFFSET(x) offsetof(SelectContext, x)
153 #define DEFINE_OPTIONS(filt_name, FLAGS) \
154 static const AVOption filt_name##_options[] = { \
155  { "expr", "set an expression to use for selecting frames", OFFSET(expr_str), AV_OPT_TYPE_STRING, { .str = "1" }, .flags=FLAGS }, \
156  { "e", "set an expression to use for selecting frames", OFFSET(expr_str), AV_OPT_TYPE_STRING, { .str = "1" }, .flags=FLAGS }, \
157  { "outputs", "set the number of outputs", OFFSET(nb_outputs), AV_OPT_TYPE_INT, {.i64 = 1}, 1, INT_MAX, .flags=FLAGS }, \
158  { "n", "set the number of outputs", OFFSET(nb_outputs), AV_OPT_TYPE_INT, {.i64 = 1}, 1, INT_MAX, .flags=FLAGS }, \
159  { NULL } \
160 }
161 
162 static int request_frame(AVFilterLink *outlink);
163 
164 static av_cold int init(AVFilterContext *ctx)
165 {
166  SelectContext *select = ctx->priv;
167  int i, ret;
168 
169  if ((ret = av_expr_parse(&select->expr, select->expr_str,
170  var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
171  av_log(ctx, AV_LOG_ERROR, "Error while parsing expression '%s'\n",
172  select->expr_str);
173  return ret;
174  }
175  select->do_scene_detect = !!strstr(select->expr_str, "scene");
176 
177  for (i = 0; i < select->nb_outputs; i++) {
178  AVFilterPad pad = { 0 };
179 
180  pad.name = av_asprintf("output%d", i);
181  if (!pad.name)
182  return AVERROR(ENOMEM);
183  pad.type = ctx->filter->inputs[0].type;
185  ff_insert_outpad(ctx, i, &pad);
186  }
187 
188  return 0;
189 }
190 
191 #define INTERLACE_TYPE_P 0
192 #define INTERLACE_TYPE_T 1
193 #define INTERLACE_TYPE_B 2
194 
195 static int config_input(AVFilterLink *inlink)
196 {
197  SelectContext *select = inlink->dst->priv;
198 
199  select->var_values[VAR_N] = 0.0;
200  select->var_values[VAR_SELECTED_N] = 0.0;
201 
202  select->var_values[VAR_TB] = av_q2d(inlink->time_base);
203 
204  select->var_values[VAR_PREV_PTS] = NAN;
207  select->var_values[VAR_PREV_T] = NAN;
208  select->var_values[VAR_START_PTS] = NAN;
209  select->var_values[VAR_START_T] = NAN;
210 
223 
227 
228  select->var_values[VAR_PICT_TYPE] = NAN;
229  select->var_values[VAR_INTERLACE_TYPE] = NAN;
230  select->var_values[VAR_SCENE] = NAN;
232  select->var_values[VAR_SAMPLES_N] = NAN;
233 
234  select->var_values[VAR_SAMPLE_RATE] =
235  inlink->type == AVMEDIA_TYPE_AUDIO ? inlink->sample_rate : NAN;
236 
237  if (select->do_scene_detect) {
238  select->sad = av_pixelutils_get_sad_fn(3, 3, 2, select); // 8x8 both sources aligned
239  if (!select->sad)
240  return AVERROR(EINVAL);
241  }
242  return 0;
243 }
244 
246 {
247  double ret = 0;
248  SelectContext *select = ctx->priv;
249  AVFrame *prev_picref = select->prev_picref;
250 
251  if (prev_picref &&
252  frame->height == prev_picref->height &&
253  frame->width == prev_picref->width) {
254  int x, y, nb_sad = 0;
255  int64_t sad = 0;
256  double mafd, diff;
257  uint8_t *p1 = frame->data[0];
258  uint8_t *p2 = prev_picref->data[0];
259  const int p1_linesize = frame->linesize[0];
260  const int p2_linesize = prev_picref->linesize[0];
261 
262  for (y = 0; y < frame->height - 7; y += 8) {
263  for (x = 0; x < frame->width*3 - 7; x += 8) {
264  sad += select->sad(p1 + x, p1_linesize, p2 + x, p2_linesize);
265  nb_sad += 8 * 8;
266  }
267  p1 += 8 * p1_linesize;
268  p2 += 8 * p2_linesize;
269  }
270  emms_c();
271  mafd = nb_sad ? (double)sad / nb_sad : 0;
272  diff = fabs(mafd - select->prev_mafd);
273  ret = av_clipf(FFMIN(mafd, diff) / 100., 0, 1);
274  select->prev_mafd = mafd;
275  av_frame_free(&prev_picref);
276  }
277  select->prev_picref = av_frame_clone(frame);
278  return ret;
279 }
280 
281 #define D2TS(d) (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))
282 #define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))
283 
285 {
286  SelectContext *select = ctx->priv;
287  AVFilterLink *inlink = ctx->inputs[0];
288  double res;
289 
290  if (isnan(select->var_values[VAR_START_PTS]))
291  select->var_values[VAR_START_PTS] = TS2D(frame->pts);
292  if (isnan(select->var_values[VAR_START_T]))
293  select->var_values[VAR_START_T] = TS2D(frame->pts) * av_q2d(inlink->time_base);
294 
295  select->var_values[VAR_N ] = inlink->frame_count;
296  select->var_values[VAR_PTS] = TS2D(frame->pts);
297  select->var_values[VAR_T ] = TS2D(frame->pts) * av_q2d(inlink->time_base);
298  select->var_values[VAR_POS] = av_frame_get_pkt_pos(frame) == -1 ? NAN : av_frame_get_pkt_pos(frame);
299  select->var_values[VAR_KEY] = frame->key_frame;
300 
301  switch (inlink->type) {
302  case AVMEDIA_TYPE_AUDIO:
303  select->var_values[VAR_SAMPLES_N] = frame->nb_samples;
304  break;
305 
306  case AVMEDIA_TYPE_VIDEO:
307  select->var_values[VAR_INTERLACE_TYPE] =
310  select->var_values[VAR_PICT_TYPE] = frame->pict_type;
311  if (select->do_scene_detect) {
312  char buf[32];
313  select->var_values[VAR_SCENE] = get_scene_score(ctx, frame);
314  // TODO: document metadata
315  snprintf(buf, sizeof(buf), "%f", select->var_values[VAR_SCENE]);
316  av_dict_set(avpriv_frame_get_metadatap(frame), "lavfi.scene_score", buf, 0);
317  }
318  break;
319  }
320 
321  select->select = res = av_expr_eval(select->expr, select->var_values, NULL);
322  av_log(inlink->dst, AV_LOG_DEBUG,
323  "n:%f pts:%f t:%f key:%d",
324  select->var_values[VAR_N],
325  select->var_values[VAR_PTS],
326  select->var_values[VAR_T],
327  frame->key_frame);
328 
329  switch (inlink->type) {
330  case AVMEDIA_TYPE_VIDEO:
331  av_log(inlink->dst, AV_LOG_DEBUG, " interlace_type:%c pict_type:%c scene:%f",
332  (!frame->interlaced_frame) ? 'P' :
333  frame->top_field_first ? 'T' : 'B',
335  select->var_values[VAR_SCENE]);
336  break;
337  case AVMEDIA_TYPE_AUDIO:
338  av_log(inlink->dst, AV_LOG_DEBUG, " samples_n:%d consumed_samples_n:%f",
339  frame->nb_samples,
341  break;
342  }
343 
344  if (res == 0) {
345  select->select_out = -1; /* drop */
346  } else if (isnan(res) || res < 0) {
347  select->select_out = 0; /* first output */
348  } else {
349  select->select_out = FFMIN(ceilf(res)-1, select->nb_outputs-1); /* other outputs */
350  }
351 
352  av_log(inlink->dst, AV_LOG_DEBUG, " -> select:%f select_out:%d\n", res, select->select_out);
353 
354  if (res) {
355  select->var_values[VAR_PREV_SELECTED_N] = select->var_values[VAR_N];
357  select->var_values[VAR_PREV_SELECTED_T] = select->var_values[VAR_T];
358  select->var_values[VAR_SELECTED_N] += 1.0;
359  if (inlink->type == AVMEDIA_TYPE_AUDIO)
360  select->var_values[VAR_CONSUMED_SAMPLES_N] += frame->nb_samples;
361  }
362 
363  select->var_values[VAR_PREV_PTS] = select->var_values[VAR_PTS];
364  select->var_values[VAR_PREV_T] = select->var_values[VAR_T];
365 }
366 
367 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
368 {
369  AVFilterContext *ctx = inlink->dst;
370  SelectContext *select = ctx->priv;
371 
372  select_frame(ctx, frame);
373  if (select->select)
374  return ff_filter_frame(ctx->outputs[select->select_out], frame);
375 
376  av_frame_free(&frame);
377  return 0;
378 }
379 
380 static int request_frame(AVFilterLink *outlink)
381 {
382  AVFilterContext *ctx = outlink->src;
383  SelectContext *select = ctx->priv;
384  AVFilterLink *inlink = outlink->src->inputs[0];
385  int out_no = FF_OUTLINK_IDX(outlink);
386 
387  do {
388  int ret = ff_request_frame(inlink);
389  if (ret < 0)
390  return ret;
391  } while (select->select_out != out_no);
392 
393  return 0;
394 }
395 
396 static av_cold void uninit(AVFilterContext *ctx)
397 {
398  SelectContext *select = ctx->priv;
399  int i;
400 
401  av_expr_free(select->expr);
402  select->expr = NULL;
403 
404  for (i = 0; i < ctx->nb_outputs; i++)
405  av_freep(&ctx->output_pads[i].name);
406 
407  if (select->do_scene_detect) {
408  av_frame_free(&select->prev_picref);
409  }
410 }
411 
413 {
414  SelectContext *select = ctx->priv;
415 
416  if (!select->do_scene_detect) {
417  return ff_default_query_formats(ctx);
418  } else {
419  int ret;
420  static const enum AVPixelFormat pix_fmts[] = {
423  };
424  AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
425 
426  if (!fmts_list)
427  return AVERROR(ENOMEM);
428  ret = ff_set_common_formats(ctx, fmts_list);
429  if (ret < 0)
430  return ret;
431  }
432  return 0;
433 }
434 
435 #if CONFIG_ASELECT_FILTER
436 
438 AVFILTER_DEFINE_CLASS(aselect);
439 
440 static av_cold int aselect_init(AVFilterContext *ctx)
441 {
442  SelectContext *select = ctx->priv;
443  int ret;
444 
445  if ((ret = init(ctx)) < 0)
446  return ret;
447 
448  if (select->do_scene_detect) {
449  av_log(ctx, AV_LOG_ERROR, "Scene detection is ignored in aselect filter\n");
450  return AVERROR(EINVAL);
451  }
452 
453  return 0;
454 }
455 
456 static const AVFilterPad avfilter_af_aselect_inputs[] = {
457  {
458  .name = "default",
459  .type = AVMEDIA_TYPE_AUDIO,
460  .config_props = config_input,
461  .filter_frame = filter_frame,
462  },
463  { NULL }
464 };
465 
466 AVFilter ff_af_aselect = {
467  .name = "aselect",
468  .description = NULL_IF_CONFIG_SMALL("Select audio frames to pass in output."),
469  .init = aselect_init,
470  .uninit = uninit,
471  .priv_size = sizeof(SelectContext),
472  .inputs = avfilter_af_aselect_inputs,
473  .priv_class = &aselect_class,
475 };
476 #endif /* CONFIG_ASELECT_FILTER */
477 
478 #if CONFIG_SELECT_FILTER
479 
481 AVFILTER_DEFINE_CLASS(select);
482 
483 static av_cold int select_init(AVFilterContext *ctx)
484 {
485  int ret;
486 
487  if ((ret = init(ctx)) < 0)
488  return ret;
489 
490  return 0;
491 }
492 
493 static const AVFilterPad avfilter_vf_select_inputs[] = {
494  {
495  .name = "default",
496  .type = AVMEDIA_TYPE_VIDEO,
497  .config_props = config_input,
498  .filter_frame = filter_frame,
499  },
500  { NULL }
501 };
502 
503 AVFilter ff_vf_select = {
504  .name = "select",
505  .description = NULL_IF_CONFIG_SMALL("Select video frames to pass in output."),
506  .init = select_init,
507  .uninit = uninit,
508  .query_formats = query_formats,
509  .priv_size = sizeof(SelectContext),
510  .priv_class = &select_class,
511  .inputs = avfilter_vf_select_inputs,
513 };
514 #endif /* CONFIG_SELECT_FILTER */
#define NULL
Definition: coverity.c:32
BI type.
Definition: avutil.h:272
This structure describes decoded (raw) audio or video data.
Definition: frame.h:171
static av_cold void uninit(AVFilterContext *ctx)
Definition: f_select.c:396
Main libavfilter public API header.
packed RGB 8:8:8, 24bpp, RGBRGB...
Definition: pixfmt.h:65
#define AV_OPT_FLAG_AUDIO_PARAM
Definition: opt.h:290
#define INTERLACE_TYPE_P
Definition: f_select.c:191
enum AVMediaType type
AVFilterPad type.
Definition: internal.h:74
#define FF_OUTLINK_IDX(link)
Definition: internal.h:349
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:653
AVFilterFormats * ff_make_format_list(const int *fmts)
Create a list of supported formats.
Definition: formats.c:283
Switching Intra.
Definition: avutil.h:270
const char * name
Pad name.
Definition: internal.h:69
AVFilterLink ** inputs
array of pointers to input links
Definition: avfilter.h:641
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1158
AVFilterPad * output_pads
array of output pads
Definition: avfilter.h:647
uint8_t
#define av_cold
Definition: attributes.h:74
int(* request_frame)(AVFilterLink *link)
Frame request callback.
Definition: internal.h:122
AVOptions.
static void select_frame(AVFilterContext *ctx, AVFrame *frame)
Definition: f_select.c:284
static av_always_inline av_const int isnan(float x)
Definition: libm.h:96
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:257
Definition: eval.c:144
int nb_outputs
Definition: f_select.c:149
#define INTERLACE_TYPE_T
Definition: f_select.c:192
static AVFrame * frame
char * expr_str
Definition: f_select.c:140
static double av_q2d(AVRational a)
Convert rational to double.
Definition: rational.h:80
char av_get_picture_type_char(enum AVPictureType pict_type)
Return a single letter to describe the given picture type pict_type.
Definition: utils.c:91
int interlaced_frame
The content of the picture is interlaced.
Definition: frame.h:367
#define AVFILTER_FLAG_DYNAMIC_OUTPUTS
The number of the filter outputs is not determined just by AVFilter.outputs.
Definition: avfilter.h:437
#define av_log(a,...)
A filter pad used for either input or output.
Definition: internal.h:63
static int query_formats(AVFilterContext *ctx)
Definition: f_select.c:412
int width
width and height of the video frame
Definition: frame.h:220
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
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:542
#define AV_OPT_FLAG_FILTERING_PARAM
a generic parameter which can be set by the user for filtering
Definition: opt.h:302
double var_values[VAR_VARS_NB]
Definition: f_select.c:142
#define AVERROR(e)
Definition: error.h:43
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:148
unsigned nb_outputs
number of output pads
Definition: avfilter.h:652
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:175
void * priv
private data for use by the filter
Definition: avfilter.h:654
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:197
int(* av_pixelutils_sad_fn)(const uint8_t *src1, ptrdiff_t stride1, const uint8_t *src2, ptrdiff_t stride2)
Sum of abs(src1[x] - src2[x])
Definition: pixelutils.h:29
int select_out
mark the selected output pad index
Definition: f_select.c:148
char * av_asprintf(const char *fmt,...)
Definition: avstring.c:113
var_name
Definition: aeval.c:46
static int config_input(AVFilterLink *inlink)
Definition: f_select.c:195
common internal API header
enum AVPictureType pict_type
Picture type of the frame.
Definition: frame.h:242
#define FFMIN(a, b)
Definition: common.h:66
float y
av_pixelutils_sad_fn sad
Sum of the absolute difference function (scene detect only)
Definition: f_select.c:144
packed RGB 8:8:8, 24bpp, BGRBGR...
Definition: pixfmt.h:66
AVFrame * av_frame_clone(const AVFrame *src)
Create a new frame that references the same data as src.
Definition: frame.c:451
static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
Definition: f_select.c:367
const AVFilterPad * inputs
List of inputs, terminated by a zeroed element.
Definition: avfilter.h:490
int ff_default_query_formats(AVFilterContext *ctx)
Definition: formats.c:571
AVDictionary ** avpriv_frame_get_metadatap(AVFrame *frame)
Definition: frame.c:47
void av_expr_free(AVExpr *e)
Free a parsed expression previously created with av_expr_parse().
Definition: eval.c:313
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:199
#define AV_OPT_FLAG_VIDEO_PARAM
Definition: opt.h:291
static double get_scene_score(AVFilterContext *ctx, AVFrame *frame)
Definition: f_select.c:245
a very simple circular buffer FIFO implementation
void * buf
Definition: avisynth_c.h:553
double prev_mafd
previous MAFD (scene detect only)
Definition: f_select.c:145
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
Definition: dict.c:69
av_pixelutils_sad_fn av_pixelutils_get_sad_fn(int w_bits, int h_bits, int aligned, void *log_ctx)
Get a potentially optimized pointer to a Sum-of-absolute-differences function (see the av_pixelutils_...
Definition: pixelutils.c:64
Definition: f_select.c:96
Switching Predicted.
Definition: avutil.h:271
Describe the class of an AVClass context structure.
Definition: log.h:67
Filter definition.
Definition: avfilter.h:470
static const AVFilterPad inputs[]
Definition: af_ashowinfo.c:239
#define TS2D(ts)
Definition: f_select.c:282
const char * name
Filter name.
Definition: avfilter.h:474
#define snprintf
Definition: snprintf.h:34
AVFilterLink ** outputs
array of pointers to output links
Definition: avfilter.h:648
static enum AVPixelFormat pix_fmts[]
Definition: libkvazaar.c:209
static int request_frame(AVFilterLink *outlink)
Definition: f_select.c:380
static int flags
Definition: cpu.c:47
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:182
int do_scene_detect
1 if the expression requires scene detection variables, 0 otherwise
Definition: f_select.c:143
AVFrame * prev_picref
previous frame (scene detect only)
Definition: f_select.c:146
#define DEFINE_OPTIONS(filt_name, FLAGS)
Definition: f_select.c:153
static av_cold int init(AVFilterContext *ctx)
Definition: f_select.c:164
Bi-dir predicted.
Definition: avutil.h:268
static av_always_inline int diff(const uint32_t a, const uint32_t b)
int top_field_first
If the content is interlaced, is top field displayed first.
Definition: frame.h:372
#define NAN
Definition: math.h:28
double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
Evaluate a previously parsed expression.
Definition: eval.c:708
int64_t av_frame_get_pkt_pos(const AVFrame *frame)
#define AVFILTER_DEFINE_CLASS(fname)
Definition: internal.h:334
AVExpr * expr
Definition: f_select.c:141
int key_frame
1 -> keyframe, 0-> not
Definition: frame.h:237
A list of supported formats for one end of a filter link.
Definition: formats.h:64
An instance of a filter.
Definition: avfilter.h:633
static const char *const var_names[]
Definition: f_select.c:38
int height
Definition: frame.h:220
#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:343
#define INTERLACE_TYPE_B
Definition: f_select.c:193
internal API functions
static int ff_insert_outpad(AVFilterContext *f, unsigned index, AVFilterPad *p)
Insert a new output pad for the filter.
Definition: internal.h:285
AVPixelFormat
Pixel format.
Definition: pixfmt.h:61
double select
Definition: f_select.c:147
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:225
const AVFilter * filter
the AVFilter of which this is an instance
Definition: avfilter.h:636
Predicted.
Definition: avutil.h:267
simple arithmetic expression evaluator