FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
graphparser.c
Go to the documentation of this file.
1 /*
2  * filter graph parser
3  * Copyright (c) 2008 Vitor Sessak
4  * Copyright (c) 2007 Bobby Bingham
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include <string.h>
24 #include <stdio.h>
25 
26 #include "libavutil/avstring.h"
27 #include "libavutil/mem.h"
28 #include "avfilter.h"
29 
30 #define WHITESPACES " \n\t"
31 
32 /**
33  * Link two filters together.
34  *
35  * @see avfilter_link()
36  */
37 static int link_filter(AVFilterContext *src, int srcpad,
38  AVFilterContext *dst, int dstpad,
39  void *log_ctx)
40 {
41  int ret;
42  if ((ret = avfilter_link(src, srcpad, dst, dstpad))) {
43  av_log(log_ctx, AV_LOG_ERROR,
44  "Cannot create the link %s:%d -> %s:%d\n",
45  src->filter->name, srcpad, dst->filter->name, dstpad);
46  return ret;
47  }
48 
49  return 0;
50 }
51 
52 /**
53  * Parse the name of a link, which has the format "[linkname]".
54  *
55  * @return a pointer (that need to be freed after use) to the name
56  * between parenthesis
57  */
58 static char *parse_link_name(const char **buf, void *log_ctx)
59 {
60  const char *start = *buf;
61  char *name;
62  (*buf)++;
63 
64  name = av_get_token(buf, "]");
65 
66  if (!name[0]) {
67  av_log(log_ctx, AV_LOG_ERROR,
68  "Bad (empty?) label found in the following: \"%s\".\n", start);
69  goto fail;
70  }
71 
72  if (*(*buf)++ != ']') {
73  av_log(log_ctx, AV_LOG_ERROR,
74  "Mismatched '[' found in the following: \"%s\".\n", start);
75  fail:
76  av_freep(&name);
77  }
78 
79  return name;
80 }
81 
82 /**
83  * Create an instance of a filter, initialize and insert it in the
84  * filtergraph in *ctx.
85  *
86  * @param filt_ctx put here a filter context in case of successful creation and configuration, NULL otherwise.
87  * @param ctx the filtergraph context
88  * @param index an index which is supposed to be unique for each filter instance added to the filtergraph
89  * @param filt_name the name of the filter to create
90  * @param args the arguments provided to the filter during its initialization
91  * @param log_ctx the log context to use
92  * @return >= 0 in case of success, a negative AVERROR code otherwise
93  */
94 static int create_filter(AVFilterContext **filt_ctx, AVFilterGraph *ctx, int index,
95  const char *filt_name, const char *args, void *log_ctx)
96 {
97  AVFilter *filt;
98  char inst_name[30];
99  char *tmp_args = NULL;
100  int ret;
101 
102  snprintf(inst_name, sizeof(inst_name), "Parsed_%s_%d", filt_name, index);
103 
104  filt = avfilter_get_by_name(filt_name);
105 
106  if (!filt) {
107  av_log(log_ctx, AV_LOG_ERROR,
108  "No such filter: '%s'\n", filt_name);
109  return AVERROR(EINVAL);
110  }
111 
112  *filt_ctx = avfilter_graph_alloc_filter(ctx, filt, inst_name);
113  if (!*filt_ctx) {
114  av_log(log_ctx, AV_LOG_ERROR,
115  "Error creating filter '%s'\n", filt_name);
116  return AVERROR(ENOMEM);
117  }
118 
119  if (!strcmp(filt_name, "scale") && args && !strstr(args, "flags") &&
120  ctx->scale_sws_opts) {
121  tmp_args = av_asprintf("%s:%s",
122  args, ctx->scale_sws_opts);
123  if (!tmp_args)
124  return AVERROR(ENOMEM);
125  args = tmp_args;
126  }
127 
128  ret = avfilter_init_str(*filt_ctx, args);
129  if (ret < 0) {
130  av_log(log_ctx, AV_LOG_ERROR,
131  "Error initializing filter '%s'", filt_name);
132  if (args)
133  av_log(log_ctx, AV_LOG_ERROR, " with args '%s'", args);
134  av_log(log_ctx, AV_LOG_ERROR, "\n");
135  avfilter_free(*filt_ctx);
136  *filt_ctx = NULL;
137  }
138 
139  av_free(tmp_args);
140  return ret;
141 }
142 
143 /**
144  * Parse a string of the form FILTER_NAME[=PARAMS], and create a
145  * corresponding filter instance which is added to graph with
146  * create_filter().
147  *
148  * @param filt_ctx Pointer that is set to the created and configured filter
149  * context on success, set to NULL on failure.
150  * @param filt_ctx put here a pointer to the created filter context on
151  * success, NULL otherwise
152  * @param buf pointer to the buffer to parse, *buf will be updated to
153  * point to the char next after the parsed string
154  * @param index an index which is assigned to the created filter
155  * instance, and which is supposed to be unique for each filter
156  * instance added to the filtergraph
157  * @return >= 0 in case of success, a negative AVERROR code otherwise
158  */
159 static int parse_filter(AVFilterContext **filt_ctx, const char **buf, AVFilterGraph *graph,
160  int index, void *log_ctx)
161 {
162  char *opts = NULL;
163  char *name = av_get_token(buf, "=,;[\n");
164  int ret;
165 
166  if (**buf == '=') {
167  (*buf)++;
168  opts = av_get_token(buf, "[],;\n");
169  }
170 
171  ret = create_filter(filt_ctx, graph, index, name, opts, log_ctx);
172  av_free(name);
173  av_free(opts);
174  return ret;
175 }
176 
178 {
179  return av_mallocz(sizeof(AVFilterInOut));
180 }
181 
183 {
184  while (*inout) {
185  AVFilterInOut *next = (*inout)->next;
186  av_freep(&(*inout)->name);
187  av_freep(inout);
188  *inout = next;
189  }
190 }
191 
192 static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)
193 {
195 
196  while (*links && (!(*links)->name || strcmp((*links)->name, label)))
197  links = &((*links)->next);
198 
199  ret = *links;
200 
201  if (ret) {
202  *links = ret->next;
203  ret->next = NULL;
204  }
205 
206  return ret;
207 }
208 
209 static void insert_inout(AVFilterInOut **inouts, AVFilterInOut *element)
210 {
211  element->next = *inouts;
212  *inouts = element;
213 }
214 
215 static void append_inout(AVFilterInOut **inouts, AVFilterInOut **element)
216 {
217  while (*inouts && (*inouts)->next)
218  inouts = &((*inouts)->next);
219 
220  if (!*inouts)
221  *inouts = *element;
222  else
223  (*inouts)->next = *element;
224  *element = NULL;
225 }
226 
227 static int link_filter_inouts(AVFilterContext *filt_ctx,
228  AVFilterInOut **curr_inputs,
229  AVFilterInOut **open_inputs, void *log_ctx)
230 {
231  int pad, ret;
232 
233  for (pad = 0; pad < filt_ctx->nb_inputs; pad++) {
234  AVFilterInOut *p = *curr_inputs;
235 
236  if (p) {
237  *curr_inputs = (*curr_inputs)->next;
238  p->next = NULL;
239  } else if (!(p = av_mallocz(sizeof(*p))))
240  return AVERROR(ENOMEM);
241 
242  if (p->filter_ctx) {
243  ret = link_filter(p->filter_ctx, p->pad_idx, filt_ctx, pad, log_ctx);
244  av_free(p->name);
245  av_free(p);
246  if (ret < 0)
247  return ret;
248  } else {
249  p->filter_ctx = filt_ctx;
250  p->pad_idx = pad;
251  append_inout(open_inputs, &p);
252  }
253  }
254 
255  if (*curr_inputs) {
256  av_log(log_ctx, AV_LOG_ERROR,
257  "Too many inputs specified for the \"%s\" filter.\n",
258  filt_ctx->filter->name);
259  return AVERROR(EINVAL);
260  }
261 
262  pad = filt_ctx->nb_outputs;
263  while (pad--) {
264  AVFilterInOut *currlinkn = av_mallocz(sizeof(AVFilterInOut));
265  if (!currlinkn)
266  return AVERROR(ENOMEM);
267  currlinkn->filter_ctx = filt_ctx;
268  currlinkn->pad_idx = pad;
269  insert_inout(curr_inputs, currlinkn);
270  }
271 
272  return 0;
273 }
274 
275 static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,
276  AVFilterInOut **open_outputs, void *log_ctx)
277 {
278  AVFilterInOut *parsed_inputs = NULL;
279  int pad = 0;
280 
281  while (**buf == '[') {
282  char *name = parse_link_name(buf, log_ctx);
283  AVFilterInOut *match;
284 
285  if (!name)
286  return AVERROR(EINVAL);
287 
288  /* First check if the label is not in the open_outputs list */
289  match = extract_inout(name, open_outputs);
290 
291  if (match) {
292  av_free(name);
293  } else {
294  /* Not in the list, so add it as an input */
295  if (!(match = av_mallocz(sizeof(AVFilterInOut)))) {
296  av_free(name);
297  return AVERROR(ENOMEM);
298  }
299  match->name = name;
300  match->pad_idx = pad;
301  }
302 
303  append_inout(&parsed_inputs, &match);
304 
305  *buf += strspn(*buf, WHITESPACES);
306  pad++;
307  }
308 
309  append_inout(&parsed_inputs, curr_inputs);
310  *curr_inputs = parsed_inputs;
311 
312  return pad;
313 }
314 
315 static int parse_outputs(const char **buf, AVFilterInOut **curr_inputs,
316  AVFilterInOut **open_inputs,
317  AVFilterInOut **open_outputs, void *log_ctx)
318 {
319  int ret, pad = 0;
320 
321  while (**buf == '[') {
322  char *name = parse_link_name(buf, log_ctx);
323  AVFilterInOut *match;
324 
325  AVFilterInOut *input = *curr_inputs;
326 
327  if (!name)
328  return AVERROR(EINVAL);
329 
330  if (!input) {
331  av_log(log_ctx, AV_LOG_ERROR,
332  "No output pad can be associated to link label '%s'.\n", name);
333  av_free(name);
334  return AVERROR(EINVAL);
335  }
336  *curr_inputs = (*curr_inputs)->next;
337 
338  /* First check if the label is not in the open_inputs list */
339  match = extract_inout(name, open_inputs);
340 
341  if (match) {
342  if ((ret = link_filter(input->filter_ctx, input->pad_idx,
343  match->filter_ctx, match->pad_idx, log_ctx)) < 0) {
344  av_free(name);
345  return ret;
346  }
347  av_free(match->name);
348  av_free(name);
349  av_free(match);
350  av_free(input);
351  } else {
352  /* Not in the list, so add the first input as a open_output */
353  input->name = name;
354  insert_inout(open_outputs, input);
355  }
356  *buf += strspn(*buf, WHITESPACES);
357  pad++;
358  }
359 
360  return pad;
361 }
362 
363 static int parse_sws_flags(const char **buf, AVFilterGraph *graph)
364 {
365  char *p = strchr(*buf, ';');
366 
367  if (strncmp(*buf, "sws_flags=", 10))
368  return 0;
369 
370  if (!p) {
371  av_log(graph, AV_LOG_ERROR, "sws_flags not terminated with ';'.\n");
372  return AVERROR(EINVAL);
373  }
374 
375  *buf += 4; // keep the 'flags=' part
376 
377  av_freep(&graph->scale_sws_opts);
378  if (!(graph->scale_sws_opts = av_mallocz(p - *buf + 1)))
379  return AVERROR(ENOMEM);
380  av_strlcpy(graph->scale_sws_opts, *buf, p - *buf + 1);
381 
382  *buf = p + 1;
383  return 0;
384 }
385 
389 {
390  int index = 0, ret = 0;
391  char chr = 0;
392 
393  AVFilterInOut *curr_inputs = NULL, *open_inputs = NULL, *open_outputs = NULL;
394 
395  filters += strspn(filters, WHITESPACES);
396 
397  if ((ret = parse_sws_flags(&filters, graph)) < 0)
398  goto fail;
399 
400  do {
402  filters += strspn(filters, WHITESPACES);
403 
404  if ((ret = parse_inputs(&filters, &curr_inputs, &open_outputs, graph)) < 0)
405  goto end;
406  if ((ret = parse_filter(&filter, &filters, graph, index, graph)) < 0)
407  goto end;
408 
409 
410  if ((ret = link_filter_inouts(filter, &curr_inputs, &open_inputs, graph)) < 0)
411  goto end;
412 
413  if ((ret = parse_outputs(&filters, &curr_inputs, &open_inputs, &open_outputs,
414  graph)) < 0)
415  goto end;
416 
417  filters += strspn(filters, WHITESPACES);
418  chr = *filters++;
419 
420  if (chr == ';' && curr_inputs)
421  append_inout(&open_outputs, &curr_inputs);
422  index++;
423  } while (chr == ',' || chr == ';');
424 
425  if (chr) {
426  av_log(graph, AV_LOG_ERROR,
427  "Unable to parse graph description substring: \"%s\"\n",
428  filters - 1);
429  ret = AVERROR(EINVAL);
430  goto end;
431  }
432 
433  append_inout(&open_outputs, &curr_inputs);
434 
435 
436  *inputs = open_inputs;
437  *outputs = open_outputs;
438  return 0;
439 
440  fail:end:
441  while (graph->nb_filters)
442  avfilter_free(graph->filters[0]);
443  av_freep(&graph->filters);
444  avfilter_inout_free(&open_inputs);
445  avfilter_inout_free(&open_outputs);
446  avfilter_inout_free(&curr_inputs);
447 
448  *inputs = NULL;
449  *outputs = NULL;
450 
451  return ret;
452 }
453 
454 #if HAVE_INCOMPATIBLE_LIBAV_ABI || !FF_API_OLD_GRAPH_PARSE
456  AVFilterInOut *open_inputs,
457  AVFilterInOut *open_outputs, void *log_ctx)
458 {
459  int ret;
460  AVFilterInOut *cur, *match, *inputs = NULL, *outputs = NULL;
461 
462  if ((ret = avfilter_graph_parse2(graph, filters, &inputs, &outputs)) < 0)
463  goto fail;
464 
465  /* First input can be omitted if it is "[in]" */
466  if (inputs && !inputs->name)
467  inputs->name = av_strdup("in");
468  for (cur = inputs; cur; cur = cur->next) {
469  if (!cur->name) {
470  av_log(log_ctx, AV_LOG_ERROR,
471  "Not enough inputs specified for the \"%s\" filter.\n",
472  cur->filter_ctx->filter->name);
473  ret = AVERROR(EINVAL);
474  goto fail;
475  }
476  if (!(match = extract_inout(cur->name, &open_outputs)))
477  continue;
478  ret = avfilter_link(match->filter_ctx, match->pad_idx,
479  cur->filter_ctx, cur->pad_idx);
480  avfilter_inout_free(&match);
481  if (ret < 0)
482  goto fail;
483  }
484 
485  /* Last output can be omitted if it is "[out]" */
486  if (outputs && !outputs->name)
487  outputs->name = av_strdup("out");
488  for (cur = outputs; cur; cur = cur->next) {
489  if (!cur->name) {
490  av_log(log_ctx, AV_LOG_ERROR,
491  "Invalid filterchain containing an unlabelled output pad: \"%s\"\n",
492  filters);
493  ret = AVERROR(EINVAL);
494  goto fail;
495  }
496  if (!(match = extract_inout(cur->name, &open_inputs)))
497  continue;
498  ret = avfilter_link(cur->filter_ctx, cur->pad_idx,
499  match->filter_ctx, match->pad_idx);
500  avfilter_inout_free(&match);
501  if (ret < 0)
502  goto fail;
503  }
504 
505  fail:
506  if (ret < 0) {
507  while (graph->nb_filters)
508  avfilter_free(graph->filters[0]);
509  av_freep(&graph->filters);
510  }
511  avfilter_inout_free(&inputs);
512  avfilter_inout_free(&outputs);
513  avfilter_inout_free(&open_inputs);
514  avfilter_inout_free(&open_outputs);
515  return ret;
516 #else
517 int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
518  AVFilterInOut **inputs, AVFilterInOut **outputs,
519  void *log_ctx)
520 {
521  return avfilter_graph_parse_ptr(graph, filters, inputs, outputs, log_ctx);
522 #endif
523 }
524 
525 int avfilter_graph_parse_ptr(AVFilterGraph *graph, const char *filters,
526  AVFilterInOut **open_inputs_ptr, AVFilterInOut **open_outputs_ptr,
527  void *log_ctx)
528 {
529  int index = 0, ret = 0;
530  char chr = 0;
531 
532  AVFilterInOut *curr_inputs = NULL;
533  AVFilterInOut *open_inputs = open_inputs_ptr ? *open_inputs_ptr : NULL;
534  AVFilterInOut *open_outputs = open_outputs_ptr ? *open_outputs_ptr : NULL;
535 
536  if ((ret = parse_sws_flags(&filters, graph)) < 0)
537  goto end;
538 
539  do {
541  const char *filterchain = filters;
542  filters += strspn(filters, WHITESPACES);
543 
544  if ((ret = parse_inputs(&filters, &curr_inputs, &open_outputs, log_ctx)) < 0)
545  goto end;
546 
547  if ((ret = parse_filter(&filter, &filters, graph, index, log_ctx)) < 0)
548  goto end;
549 
550  if (filter->nb_inputs == 1 && !curr_inputs && !index) {
551  /* First input pad, assume it is "[in]" if not specified */
552  const char *tmp = "[in]";
553  if ((ret = parse_inputs(&tmp, &curr_inputs, &open_outputs, log_ctx)) < 0)
554  goto end;
555  }
556 
557  if ((ret = link_filter_inouts(filter, &curr_inputs, &open_inputs, log_ctx)) < 0)
558  goto end;
559 
560  if ((ret = parse_outputs(&filters, &curr_inputs, &open_inputs, &open_outputs,
561  log_ctx)) < 0)
562  goto end;
563 
564  filters += strspn(filters, WHITESPACES);
565  chr = *filters++;
566 
567  if (chr == ';' && curr_inputs) {
568  av_log(log_ctx, AV_LOG_ERROR,
569  "Invalid filterchain containing an unlabelled output pad: \"%s\"\n",
570  filterchain);
571  ret = AVERROR(EINVAL);
572  goto end;
573  }
574  index++;
575  } while (chr == ',' || chr == ';');
576 
577  if (chr) {
578  av_log(log_ctx, AV_LOG_ERROR,
579  "Unable to parse graph description substring: \"%s\"\n",
580  filters - 1);
581  ret = AVERROR(EINVAL);
582  goto end;
583  }
584 
585  if (curr_inputs) {
586  /* Last output pad, assume it is "[out]" if not specified */
587  const char *tmp = "[out]";
588  if ((ret = parse_outputs(&tmp, &curr_inputs, &open_inputs, &open_outputs,
589  log_ctx)) < 0)
590  goto end;
591  }
592 
593 end:
594  /* clear open_in/outputs only if not passed as parameters */
595  if (open_inputs_ptr) *open_inputs_ptr = open_inputs;
596  else avfilter_inout_free(&open_inputs);
597  if (open_outputs_ptr) *open_outputs_ptr = open_outputs;
598  else avfilter_inout_free(&open_outputs);
599  avfilter_inout_free(&curr_inputs);
600 
601  if (ret < 0) {
602  while (graph->nb_filters)
603  avfilter_free(graph->filters[0]);
604  av_freep(&graph->filters);
605  }
606  return ret;
607 }