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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  static const enum AVPixelFormat pix_fmts[] = {
422  };
424  }
425  return 0;
426 }
427 
428 #if CONFIG_ASELECT_FILTER
429 
431 AVFILTER_DEFINE_CLASS(aselect);
432 
433 static av_cold int aselect_init(AVFilterContext *ctx)
434 {
435  SelectContext *select = ctx->priv;
436  int ret;
437 
438  if ((ret = init(ctx)) < 0)
439  return ret;
440 
441  if (select->do_scene_detect) {
442  av_log(ctx, AV_LOG_ERROR, "Scene detection is ignored in aselect filter\n");
443  return AVERROR(EINVAL);
444  }
445 
446  return 0;
447 }
448 
449 static const AVFilterPad avfilter_af_aselect_inputs[] = {
450  {
451  .name = "default",
452  .type = AVMEDIA_TYPE_AUDIO,
453  .config_props = config_input,
454  .filter_frame = filter_frame,
455  },
456  { NULL }
457 };
458 
459 AVFilter ff_af_aselect = {
460  .name = "aselect",
461  .description = NULL_IF_CONFIG_SMALL("Select audio frames to pass in output."),
462  .init = aselect_init,
463  .uninit = uninit,
464  .priv_size = sizeof(SelectContext),
465  .inputs = avfilter_af_aselect_inputs,
466  .priv_class = &aselect_class,
468 };
469 #endif /* CONFIG_ASELECT_FILTER */
470 
471 #if CONFIG_SELECT_FILTER
472 
474 AVFILTER_DEFINE_CLASS(select);
475 
476 static av_cold int select_init(AVFilterContext *ctx)
477 {
478  int ret;
479 
480  if ((ret = init(ctx)) < 0)
481  return ret;
482 
483  return 0;
484 }
485 
486 static const AVFilterPad avfilter_vf_select_inputs[] = {
487  {
488  .name = "default",
489  .type = AVMEDIA_TYPE_VIDEO,
490  .config_props = config_input,
491  .filter_frame = filter_frame,
492  },
493  { NULL }
494 };
495 
496 AVFilter ff_vf_select = {
497  .name = "select",
498  .description = NULL_IF_CONFIG_SMALL("Select video frames to pass in output."),
499  .init = select_init,
500  .uninit = uninit,
501  .query_formats = query_formats,
502  .priv_size = sizeof(SelectContext),
503  .priv_class = &select_class,
504  .inputs = avfilter_vf_select_inputs,
506 };
507 #endif /* CONFIG_SELECT_FILTER */