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 Libav.
7  *
8  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include <ctype.h>
24 #include <string.h>
25 
26 #include "libavutil/avstring.h"
27 #include "avfilter.h"
28 #include "avfiltergraph.h"
29 
30 #define WHITESPACES " \n\t"
31 
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 
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 
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[256];
100  int ret;
101 
102  snprintf(inst_name, sizeof(inst_name), "Parsed filter %d %s", index, filt_name);
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  ret = avfilter_open(filt_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 ret;
117  }
118 
119  if ((ret = avfilter_graph_add_filter(ctx, *filt_ctx)) < 0) {
120  avfilter_free(*filt_ctx);
121  return ret;
122  }
123 
124  if (!strcmp(filt_name, "scale") && args && !strstr(args, "flags") &&
125  ctx->scale_sws_opts) {
126  snprintf(tmp_args, sizeof(tmp_args), "%s:%s",
127  args, ctx->scale_sws_opts);
128  args = tmp_args;
129  }
130 
131  if ((ret = avfilter_init_filter(*filt_ctx, args, NULL)) < 0) {
132  av_log(log_ctx, AV_LOG_ERROR,
133  "Error initializing filter '%s' with args '%s'\n", filt_name, args);
134  return ret;
135  }
136 
137  return 0;
138 }
139 
156 static int parse_filter(AVFilterContext **filt_ctx, const char **buf, AVFilterGraph *graph,
157  int index, void *log_ctx)
158 {
159  char *opts = NULL;
160  char *name = av_get_token(buf, "=,;[\n");
161  int ret;
162 
163  if (**buf == '=') {
164  (*buf)++;
165  opts = av_get_token(buf, "[],;\n");
166  }
167 
168  ret = create_filter(filt_ctx, graph, index, name, opts, log_ctx);
169  av_free(name);
170  av_free(opts);
171  return ret;
172 }
173 
174 static void free_inout(AVFilterInOut *head)
175 {
176  while (head) {
177  AVFilterInOut *next = head->next;
178  av_free(head->name);
179  av_free(head);
180  head = next;
181  }
182 }
183 
184 static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)
185 {
186  AVFilterInOut *ret;
187 
188  while (*links && strcmp((*links)->name, label))
189  links = &((*links)->next);
190 
191  ret = *links;
192 
193  if (ret)
194  *links = ret->next;
195 
196  return ret;
197 }
198 
199 static void insert_inout(AVFilterInOut **inouts, AVFilterInOut *element)
200 {
201  element->next = *inouts;
202  *inouts = element;
203 }
204 
205 static int link_filter_inouts(AVFilterContext *filt_ctx,
206  AVFilterInOut **curr_inputs,
207  AVFilterInOut **open_inputs, void *log_ctx)
208 {
209  int pad = filt_ctx->input_count, ret;
210 
211  while (pad--) {
212  AVFilterInOut *p = *curr_inputs;
213  if (!p) {
214  av_log(log_ctx, AV_LOG_ERROR,
215  "Not enough inputs specified for the \"%s\" filter.\n",
216  filt_ctx->filter->name);
217  return AVERROR(EINVAL);
218  }
219 
220  *curr_inputs = (*curr_inputs)->next;
221 
222  if (p->filter_ctx) {
223  if ((ret = link_filter(p->filter_ctx, p->pad_idx, filt_ctx, pad, log_ctx)) < 0)
224  return ret;
225  av_free(p->name);
226  av_free(p);
227  } else {
228  p->filter_ctx = filt_ctx;
229  p->pad_idx = pad;
230  insert_inout(open_inputs, p);
231  }
232  }
233 
234  if (*curr_inputs) {
235  av_log(log_ctx, AV_LOG_ERROR,
236  "Too many inputs specified for the \"%s\" filter.\n",
237  filt_ctx->filter->name);
238  return AVERROR(EINVAL);
239  }
240 
241  pad = filt_ctx->output_count;
242  while (pad--) {
243  AVFilterInOut *currlinkn = av_mallocz(sizeof(AVFilterInOut));
244  if (!currlinkn)
245  return AVERROR(ENOMEM);
246  currlinkn->filter_ctx = filt_ctx;
247  currlinkn->pad_idx = pad;
248  insert_inout(curr_inputs, currlinkn);
249  }
250 
251  return 0;
252 }
253 
254 static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,
255  AVFilterInOut **open_outputs, void *log_ctx)
256 {
257  int pad = 0;
258 
259  while (**buf == '[') {
260  char *name = parse_link_name(buf, log_ctx);
261  AVFilterInOut *match;
262 
263  if (!name)
264  return AVERROR(EINVAL);
265 
266  /* First check if the label is not in the open_outputs list */
267  match = extract_inout(name, open_outputs);
268 
269  if (match) {
270  av_free(name);
271  } else {
272  /* Not in the list, so add it as an input */
273  if (!(match = av_mallocz(sizeof(AVFilterInOut))))
274  return AVERROR(ENOMEM);
275  match->name = name;
276  match->pad_idx = pad;
277  }
278 
279  insert_inout(curr_inputs, match);
280 
281  *buf += strspn(*buf, WHITESPACES);
282  pad++;
283  }
284 
285  return pad;
286 }
287 
288 static int parse_outputs(const char **buf, AVFilterInOut **curr_inputs,
289  AVFilterInOut **open_inputs,
290  AVFilterInOut **open_outputs, void *log_ctx)
291 {
292  int ret, pad = 0;
293 
294  while (**buf == '[') {
295  char *name = parse_link_name(buf, log_ctx);
296  AVFilterInOut *match;
297 
298  AVFilterInOut *input = *curr_inputs;
299  if (!input) {
300  av_log(log_ctx, AV_LOG_ERROR,
301  "No output pad can be associated to link label '%s'.\n",
302  name);
303  return AVERROR(EINVAL);
304  }
305  *curr_inputs = (*curr_inputs)->next;
306 
307  if (!name)
308  return AVERROR(EINVAL);
309 
310  /* First check if the label is not in the open_inputs list */
311  match = extract_inout(name, open_inputs);
312 
313  if (match) {
314  if ((ret = link_filter(input->filter_ctx, input->pad_idx,
315  match->filter_ctx, match->pad_idx, log_ctx)) < 0)
316  return ret;
317  av_free(match->name);
318  av_free(name);
319  av_free(match);
320  av_free(input);
321  } else {
322  /* Not in the list, so add the first input as a open_output */
323  input->name = name;
324  insert_inout(open_outputs, input);
325  }
326  *buf += strspn(*buf, WHITESPACES);
327  pad++;
328  }
329 
330  return pad;
331 }
332 
334  AVFilterInOut *open_inputs,
335  AVFilterInOut *open_outputs, void *log_ctx)
336 {
337  int index = 0, ret;
338  char chr = 0;
339 
340  AVFilterInOut *curr_inputs = NULL;
341 
342  do {
344  const char *filterchain = filters;
345  filters += strspn(filters, WHITESPACES);
346 
347  if ((ret = parse_inputs(&filters, &curr_inputs, &open_outputs, log_ctx)) < 0)
348  goto fail;
349 
350  if ((ret = parse_filter(&filter, &filters, graph, index, log_ctx)) < 0)
351  goto fail;
352 
353  if (filter->input_count == 1 && !curr_inputs && !index) {
354  /* First input can be omitted if it is "[in]" */
355  const char *tmp = "[in]";
356  if ((ret = parse_inputs(&tmp, &curr_inputs, &open_outputs, log_ctx)) < 0)
357  goto fail;
358  }
359 
360  if ((ret = link_filter_inouts(filter, &curr_inputs, &open_inputs, log_ctx)) < 0)
361  goto fail;
362 
363  if ((ret = parse_outputs(&filters, &curr_inputs, &open_inputs, &open_outputs,
364  log_ctx)) < 0)
365  goto fail;
366 
367  filters += strspn(filters, WHITESPACES);
368  chr = *filters++;
369 
370  if (chr == ';' && curr_inputs) {
371  av_log(log_ctx, AV_LOG_ERROR,
372  "Invalid filterchain containing an unlabelled output pad: \"%s\"\n",
373  filterchain);
374  ret = AVERROR(EINVAL);
375  goto fail;
376  }
377  index++;
378  } while (chr == ',' || chr == ';');
379 
380  if (chr) {
381  av_log(log_ctx, AV_LOG_ERROR,
382  "Unable to parse graph description substring: \"%s\"\n",
383  filters - 1);
384  ret = AVERROR(EINVAL);
385  goto fail;
386  }
387 
388  if (open_inputs && !strcmp(open_inputs->name, "out") && curr_inputs) {
389  /* Last output can be omitted if it is "[out]" */
390  const char *tmp = "[out]";
391  if ((ret = parse_outputs(&tmp, &curr_inputs, &open_inputs, &open_outputs,
392  log_ctx)) < 0)
393  goto fail;
394  }
395 
396  return 0;
397 
398  fail:
399  for (; graph->filter_count > 0; graph->filter_count--)
400  avfilter_free(graph->filters[graph->filter_count - 1]);
401  av_freep(&graph->filters);
402  free_inout(open_inputs);
403  free_inout(open_outputs);
404  free_inout(curr_inputs);
405  return ret;
406 }