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graphparser.c
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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 #include "avfiltergraph.h"
30 
31 #define WHITESPACES " \n\t"
32 
33 /**
34  * Link two filters together.
35  *
36  * @see avfilter_link()
37  */
38 static int link_filter(AVFilterContext *src, int srcpad,
39  AVFilterContext *dst, int dstpad,
40  void *log_ctx)
41 {
42  int ret;
43  if ((ret = avfilter_link(src, srcpad, dst, dstpad))) {
44  av_log(log_ctx, AV_LOG_ERROR,
45  "Cannot create the link %s:%d -> %s:%d\n",
46  src->filter->name, srcpad, dst->filter->name, dstpad);
47  return ret;
48  }
49 
50  return 0;
51 }
52 
53 /**
54  * Parse the name of a link, which has the format "[linkname]".
55  *
56  * @return a pointer (that need to be freed after use) to the name
57  * between parenthesis
58  */
59 static char *parse_link_name(const char **buf, void *log_ctx)
60 {
61  const char *start = *buf;
62  char *name;
63  (*buf)++;
64 
65  name = av_get_token(buf, "]");
66 
67  if (!name[0]) {
68  av_log(log_ctx, AV_LOG_ERROR,
69  "Bad (empty?) label found in the following: \"%s\".\n", start);
70  goto fail;
71  }
72 
73  if (*(*buf)++ != ']') {
74  av_log(log_ctx, AV_LOG_ERROR,
75  "Mismatched '[' found in the following: \"%s\".\n", start);
76  fail:
77  av_freep(&name);
78  }
79 
80  return name;
81 }
82 
83 /**
84  * Create an instance of a filter, initialize and insert it in the
85  * filtergraph in *ctx.
86  *
87  * @param filt_ctx put here a filter context in case of successful creation and configuration, NULL otherwise.
88  * @param ctx the filtergraph context
89  * @param index an index which is supposed to be unique for each filter instance added to the filtergraph
90  * @param filt_name the name of the filter to create
91  * @param args the arguments provided to the filter during its initialization
92  * @param log_ctx the log context to use
93  * @return 0 in case of success, a negative AVERROR code otherwise
94  */
95 static int create_filter(AVFilterContext **filt_ctx, AVFilterGraph *ctx, int index,
96  const char *filt_name, const char *args, void *log_ctx)
97 {
98  AVFilter *filt;
99  char inst_name[30];
100  char tmp_args[256];
101  int ret;
102 
103  snprintf(inst_name, sizeof(inst_name), "Parsed_%s_%d", filt_name, index);
104 
105  filt = avfilter_get_by_name(filt_name);
106 
107  if (!filt) {
108  av_log(log_ctx, AV_LOG_ERROR,
109  "No such filter: '%s'\n", filt_name);
110  return AVERROR(EINVAL);
111  }
112 
113  ret = avfilter_open(filt_ctx, filt, inst_name);
114  if (!*filt_ctx) {
115  av_log(log_ctx, AV_LOG_ERROR,
116  "Error creating filter '%s'\n", filt_name);
117  return ret;
118  }
119 
120  if ((ret = avfilter_graph_add_filter(ctx, *filt_ctx)) < 0) {
121  avfilter_free(*filt_ctx);
122  return ret;
123  }
124 
125  if (!strcmp(filt_name, "scale") && args && !strstr(args, "flags")
126  && ctx->scale_sws_opts) {
127  snprintf(tmp_args, sizeof(tmp_args), "%s:%s",
128  args, ctx->scale_sws_opts);
129  args = tmp_args;
130  }
131 
132  if ((ret = avfilter_init_filter(*filt_ctx, args, NULL)) < 0) {
133  av_log(log_ctx, AV_LOG_ERROR,
134  "Error initializing filter '%s' with args '%s'\n", filt_name, args);
135  return ret;
136  }
137 
138  return 0;
139 }
140 
141 /**
142  * Parse a string of the form FILTER_NAME[=PARAMS], and create a
143  * corresponding filter instance which is added to graph with
144  * create_filter().
145  *
146  * @param filt_ctx Pointer that is set to the created and configured filter
147  * context on success, set to NULL on failure.
148  * @param filt_ctx put here a pointer to the created filter context on
149  * success, NULL otherwise
150  * @param buf pointer to the buffer to parse, *buf will be updated to
151  * point to the char next after the parsed string
152  * @param index an index which is assigned to the created filter
153  * instance, and which is supposed to be unique for each filter
154  * instance added to the filtergraph
155  * @return 0 in case of success, a negative AVERROR code otherwise
156  */
157 static int parse_filter(AVFilterContext **filt_ctx, const char **buf, AVFilterGraph *graph,
158  int index, void *log_ctx)
159 {
160  char *opts = NULL;
161  char *name = av_get_token(buf, "=,;[\n");
162  int ret;
163 
164  if (**buf == '=') {
165  (*buf)++;
166  opts = av_get_token(buf, "[],;\n");
167  }
168 
169  ret = create_filter(filt_ctx, graph, index, name, opts, log_ctx);
170  av_free(name);
171  av_free(opts);
172  return ret;
173 }
174 
176 {
177  return av_mallocz(sizeof(AVFilterInOut));
178 }
179 
181 {
182  while (*inout) {
183  AVFilterInOut *next = (*inout)->next;
184  av_freep(&(*inout)->name);
185  av_freep(inout);
186  *inout = next;
187  }
188 }
189 
190 static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)
191 {
192  AVFilterInOut *ret;
193 
194  while (*links && (!(*links)->name || strcmp((*links)->name, label)))
195  links = &((*links)->next);
196 
197  ret = *links;
198 
199  if (ret) {
200  *links = ret->next;
201  ret->next = NULL;
202  }
203 
204  return ret;
205 }
206 
207 static void insert_inout(AVFilterInOut **inouts, AVFilterInOut *element)
208 {
209  element->next = *inouts;
210  *inouts = element;
211 }
212 
213 static void append_inout(AVFilterInOut **inouts, AVFilterInOut **element)
214 {
215  while (*inouts && (*inouts)->next)
216  inouts = &((*inouts)->next);
217 
218  if (!*inouts)
219  *inouts = *element;
220  else
221  (*inouts)->next = *element;
222  *element = NULL;
223 }
224 
225 static int link_filter_inouts(AVFilterContext *filt_ctx,
226  AVFilterInOut **curr_inputs,
227  AVFilterInOut **open_inputs, void *log_ctx)
228 {
229  int pad, ret;
230 
231  for (pad = 0; pad < filt_ctx->nb_inputs; pad++) {
232  AVFilterInOut *p = *curr_inputs;
233 
234  if (p) {
235  *curr_inputs = (*curr_inputs)->next;
236  p->next = NULL;
237  } else if (!(p = av_mallocz(sizeof(*p))))
238  return AVERROR(ENOMEM);
239 
240  if (p->filter_ctx) {
241  ret = link_filter(p->filter_ctx, p->pad_idx, filt_ctx, pad, log_ctx);
242  av_free(p->name);
243  av_free(p);
244  if (ret < 0)
245  return ret;
246  } else {
247  p->filter_ctx = filt_ctx;
248  p->pad_idx = pad;
249  append_inout(open_inputs, &p);
250  }
251  }
252 
253  if (*curr_inputs) {
254  av_log(log_ctx, AV_LOG_ERROR,
255  "Too many inputs specified for the \"%s\" filter.\n",
256  filt_ctx->filter->name);
257  return AVERROR(EINVAL);
258  }
259 
260  pad = filt_ctx->nb_outputs;
261  while (pad--) {
262  AVFilterInOut *currlinkn = av_mallocz(sizeof(AVFilterInOut));
263  if (!currlinkn)
264  return AVERROR(ENOMEM);
265  currlinkn->filter_ctx = filt_ctx;
266  currlinkn->pad_idx = pad;
267  insert_inout(curr_inputs, currlinkn);
268  }
269 
270  return 0;
271 }
272 
273 static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,
274  AVFilterInOut **open_outputs, void *log_ctx)
275 {
276  AVFilterInOut *parsed_inputs = NULL;
277  int pad = 0;
278 
279  while (**buf == '[') {
280  char *name = parse_link_name(buf, log_ctx);
282 
283  if (!name)
284  return AVERROR(EINVAL);
285 
286  /* First check if the label is not in the open_outputs list */
287  match = extract_inout(name, open_outputs);
288 
289  if (match) {
290  av_free(name);
291  } else {
292  /* Not in the list, so add it as an input */
293  if (!(match = av_mallocz(sizeof(AVFilterInOut)))) {
294  av_free(name);
295  return AVERROR(ENOMEM);
296  }
297  match->name = name;
298  match->pad_idx = pad;
299  }
300 
301  append_inout(&parsed_inputs, &match);
302 
303  *buf += strspn(*buf, WHITESPACES);
304  pad++;
305  }
306 
307  append_inout(&parsed_inputs, curr_inputs);
308  *curr_inputs = parsed_inputs;
309 
310  return pad;
311 }
312 
313 static int parse_outputs(const char **buf, AVFilterInOut **curr_inputs,
314  AVFilterInOut **open_inputs,
315  AVFilterInOut **open_outputs, void *log_ctx)
316 {
317  int ret, pad = 0;
318 
319  while (**buf == '[') {
320  char *name = parse_link_name(buf, log_ctx);
322 
323  AVFilterInOut *input = *curr_inputs;
324 
325  if (!name)
326  return AVERROR(EINVAL);
327 
328  if (!input) {
329  av_log(log_ctx, AV_LOG_ERROR,
330  "No output pad can be associated to link label '%s'.\n", name);
331  av_free(name);
332  return AVERROR(EINVAL);
333  }
334  *curr_inputs = (*curr_inputs)->next;
335 
336  /* First check if the label is not in the open_inputs list */
337  match = extract_inout(name, open_inputs);
338 
339  if (match) {
340  if ((ret = link_filter(input->filter_ctx, input->pad_idx,
341  match->filter_ctx, match->pad_idx, log_ctx)) < 0) {
342  av_free(name);
343  return ret;
344  }
345  av_free(match->name);
346  av_free(name);
347  av_free(match);
348  av_free(input);
349  } else {
350  /* Not in the list, so add the first input as a open_output */
351  input->name = name;
352  insert_inout(open_outputs, input);
353  }
354  *buf += strspn(*buf, WHITESPACES);
355  pad++;
356  }
357 
358  return pad;
359 }
360 
361 static int parse_sws_flags(const char **buf, AVFilterGraph *graph)
362 {
363  char *p = strchr(*buf, ';');
364 
365  if (strncmp(*buf, "sws_flags=", 10))
366  return 0;
367 
368  if (!p) {
369  av_log(graph, AV_LOG_ERROR, "sws_flags not terminated with ';'.\n");
370  return AVERROR(EINVAL);
371  }
372 
373  *buf += 4; // keep the 'flags=' part
374 
375  av_freep(&graph->scale_sws_opts);
376  if (!(graph->scale_sws_opts = av_mallocz(p - *buf + 1)))
377  return AVERROR(ENOMEM);
378  av_strlcpy(graph->scale_sws_opts, *buf, p - *buf + 1);
379 
380  *buf = p + 1;
381  return 0;
382 }
383 
387 {
388  int index = 0, ret = 0;
389  char chr = 0;
390 
391  AVFilterInOut *curr_inputs = NULL, *open_inputs = NULL, *open_outputs = NULL;
392 
393  filters += strspn(filters, WHITESPACES);
394 
395  if ((ret = parse_sws_flags(&filters, graph)) < 0)
396  goto fail;
397 
398  do {
400  filters += strspn(filters, WHITESPACES);
401 
402  if ((ret = parse_inputs(&filters, &curr_inputs, &open_outputs, graph)) < 0)
403  goto end;
404  if ((ret = parse_filter(&filter, &filters, graph, index, graph)) < 0)
405  goto end;
406 
407 
408  if ((ret = link_filter_inouts(filter, &curr_inputs, &open_inputs, graph)) < 0)
409  goto end;
410 
411  if ((ret = parse_outputs(&filters, &curr_inputs, &open_inputs, &open_outputs,
412  graph)) < 0)
413  goto end;
414 
415  filters += strspn(filters, WHITESPACES);
416  chr = *filters++;
417 
418  if (chr == ';' && curr_inputs)
419  append_inout(&open_outputs, &curr_inputs);
420  index++;
421  } while (chr == ',' || chr == ';');
422 
423  if (chr) {
424  av_log(graph, AV_LOG_ERROR,
425  "Unable to parse graph description substring: \"%s\"\n",
426  filters - 1);
427  ret = AVERROR(EINVAL);
428  goto end;
429  }
430 
431  append_inout(&open_outputs, &curr_inputs);
432 
433 
434  *inputs = open_inputs;
435  *outputs = open_outputs;
436  return 0;
437 
438  fail:end:
439  for (; graph->filter_count > 0; graph->filter_count--)
440  avfilter_free(graph->filters[graph->filter_count - 1]);
441  av_freep(&graph->filters);
442  avfilter_inout_free(&open_inputs);
443  avfilter_inout_free(&open_outputs);
444  avfilter_inout_free(&curr_inputs);
445 
446  *inputs = NULL;
447  *outputs = NULL;
448 
449  return ret;
450 }
451 
453  AVFilterInOut **open_inputs_ptr, AVFilterInOut **open_outputs_ptr,
454  void *log_ctx)
455 {
456 #if 0
457  int ret;
458  AVFilterInOut *open_inputs = open_inputs_ptr ? *open_inputs_ptr : NULL;
459  AVFilterInOut *open_outputs = open_outputs_ptr ? *open_outputs_ptr : NULL;
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  for (; graph->filter_count > 0; graph->filter_count--)
508  avfilter_free(graph->filters[graph->filter_count - 1]);
509  av_freep(&graph->filters);
510  }
511  avfilter_inout_free(&inputs);
512  avfilter_inout_free(&outputs);
513  /* clear open_in/outputs only if not passed as parameters */
514  if (open_inputs_ptr) *open_inputs_ptr = open_inputs;
515  else avfilter_inout_free(&open_inputs);
516  if (open_outputs_ptr) *open_outputs_ptr = open_outputs;
517  else avfilter_inout_free(&open_outputs);
518  return ret;
519 }
520 #else
521  int index = 0, ret = 0;
522  char chr = 0;
523 
524  AVFilterInOut *curr_inputs = NULL;
525  AVFilterInOut *open_inputs = open_inputs_ptr ? *open_inputs_ptr : NULL;
526  AVFilterInOut *open_outputs = open_outputs_ptr ? *open_outputs_ptr : NULL;
527 
528  if ((ret = parse_sws_flags(&filters, graph)) < 0)
529  goto end;
530 
531  do {
533  const char *filterchain = filters;
534  filters += strspn(filters, WHITESPACES);
535 
536  if ((ret = parse_inputs(&filters, &curr_inputs, &open_outputs, log_ctx)) < 0)
537  goto end;
538 
539  if ((ret = parse_filter(&filter, &filters, graph, index, log_ctx)) < 0)
540  goto end;
541 
542  if (filter->input_count == 1 && !curr_inputs && !index) {
543  /* First input pad, assume it is "[in]" if not specified */
544  const char *tmp = "[in]";
545  if ((ret = parse_inputs(&tmp, &curr_inputs, &open_outputs, log_ctx)) < 0)
546  goto end;
547  }
548 
549  if ((ret = link_filter_inouts(filter, &curr_inputs, &open_inputs, log_ctx)) < 0)
550  goto end;
551 
552  if ((ret = parse_outputs(&filters, &curr_inputs, &open_inputs, &open_outputs,
553  log_ctx)) < 0)
554  goto end;
555 
556  filters += strspn(filters, WHITESPACES);
557  chr = *filters++;
558 
559  if (chr == ';' && curr_inputs) {
560  av_log(log_ctx, AV_LOG_ERROR,
561  "Invalid filterchain containing an unlabelled output pad: \"%s\"\n",
562  filterchain);
563  ret = AVERROR(EINVAL);
564  goto end;
565  }
566  index++;
567  } while (chr == ',' || chr == ';');
568 
569  if (chr) {
570  av_log(log_ctx, AV_LOG_ERROR,
571  "Unable to parse graph description substring: \"%s\"\n",
572  filters - 1);
573  ret = AVERROR(EINVAL);
574  goto end;
575  }
576 
577  if (curr_inputs) {
578  /* Last output pad, assume it is "[out]" if not specified */
579  const char *tmp = "[out]";
580  if ((ret = parse_outputs(&tmp, &curr_inputs, &open_inputs, &open_outputs,
581  log_ctx)) < 0)
582  goto end;
583  }
584 
585 end:
586  /* clear open_in/outputs only if not passed as parameters */
587  if (open_inputs_ptr) *open_inputs_ptr = open_inputs;
588  else avfilter_inout_free(&open_inputs);
589  if (open_outputs_ptr) *open_outputs_ptr = open_outputs;
590  else avfilter_inout_free(&open_outputs);
591  avfilter_inout_free(&curr_inputs);
592 
593  if (ret < 0) {
594  for (; graph->filter_count > 0; graph->filter_count--)
595  avfilter_free(graph->filters[graph->filter_count - 1]);
596  av_freep(&graph->filters);
597  }
598  return ret;
599 }
600 
601 #endif