Better error messages
[libav.git] / libavfilter / graphparser.c
CommitLineData
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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 <ctype.h>
24#include <string.h>
25
26#include "avfilter.h"
27#include "avfiltergraph.h"
28
29/**
30 * For use in av_log
31 */
32static const char *log_name(void *p)
33{
34 return "Filter parser";
35}
36
37static const AVClass filter_parser_class = {
38 "Filter parser",
39 log_name
40};
41
42static const AVClass *log_ctx = &filter_parser_class;
43
44static int create_filter(AVFilterGraph *ctx, int index, char *name,
45 char *args)
46{
47 AVFilterContext *filt;
48
49 AVFilter *filterdef;
50 char tmp[20];
51
52 snprintf(tmp, 20, "%d", index);
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53
54 if(!(filterdef = avfilter_get_by_name(name))) {
55 av_log(&log_ctx, AV_LOG_ERROR,
56 "no such filter: '%s'\n", name);
57 return -1;
58 }
59
60 if(!(filt = avfilter_open(filterdef, tmp))) {
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61 av_log(&log_ctx, AV_LOG_ERROR,
62 "error creating filter '%s'\n", name);
63 return -1;
64 }
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65
66 if (avfilter_graph_add_filter(ctx, filt) < 0)
67 return -1;
68
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69 if(avfilter_init_filter(filt, args, NULL)) {
70 av_log(&log_ctx, AV_LOG_ERROR,
27a669ab 71 "error initializing filter '%s' with args '%s'\n", name, args);
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72 return -1;
73 }
74
75 return 0;
76}
77
78static int link_filter(AVFilterGraph *ctx, int src, int srcpad,
79 int dst, int dstpad)
80{
81 AVFilterContext *filt, *filtb;
82
83 char tmp[20];
84
85 snprintf(tmp, 20, "%d", src);
86 if(!(filt = avfilter_graph_get_filter(ctx, tmp))) {
87 av_log(&log_ctx, AV_LOG_ERROR, "link source does not exist in graph\n");
88 return -1;
89 }
90 snprintf(tmp, 20, "%d", dst);
91 if(!(filtb = avfilter_graph_get_filter(ctx, tmp))) {
92 av_log(&log_ctx, AV_LOG_ERROR, "link destination does not exist in graph\n");
93 return -1;
94 }
95 if(avfilter_link(filt, srcpad, filtb, dstpad)) {
96 av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
97 return -1;
98 }
99
100 return 0;
101}
102
103static void consume_whitespace(const char **buf)
104{
105 *buf += strspn(*buf, " \n\t");
106}
107
108/**
109 * Copy the first size bytes of input string to a null-terminated string,
110 * removing any control character. Ex: "aaa'bb'c\'c\\" -> "aaabbc'c\"
111 */
112static void copy_unquoted(char *out, const char *in, int size)
113{
114 int i;
115 for (i=0; i < size; i++) {
116 if (in[i] == '\'')
117 continue;
118 else if (in[i] == '\\') {
119 if (i+1 == size) {
120 *out = 0;
121 return;
122 }
123 i++;
124 }
125 *out++ = in[i];
126 }
127 *out=0;
128}
129
130/**
131 * Consumes a string from *buf.
132 * @return a copy of the consumed string, which should be free'd after use
133 */
134static char *consume_string(const char **buf)
135{
136 const char *start;
137 char *ret;
138 int size;
139
140 consume_whitespace(buf);
141
142 if (!(**buf))
143 return av_mallocz(1);
144
145 start = *buf;
146
147 while(1) {
148 *buf += strcspn(*buf, " ()=,'\\");
149 if (**buf == '\\')
150 *buf+=2;
151 else
152 break;
153 }
154
155 if (**buf == '\'') {
156 const char *p = *buf;
157 do {
158 p++;
159 p = strchr(p, '\'');
160 } while (p && p[-1] == '\\');
161 if (p)
162 *buf = p + 1;
163 else
164 *buf += strlen(*buf); // Move the pointer to the null end byte
165 }
166
167 size = *buf - start + 1;
168 ret = av_malloc(size);
169 copy_unquoted(ret, start, size-1);
170
171 return ret;
172}
173
174/**
175 * Parse "(linkname)"
176 * @arg name a pointer (that need to be free'd after use) to the name between
177 * parenthesis
178 */
179static void parse_link_name(const char **buf, char **name)
180{
181 (*buf)++;
182
183 *name = consume_string(buf);
184
185 if (!*name[0])
186 goto fail;
187
188 if (*(*buf)++ != ')')
189 goto fail;
190
191 return;
192 fail:
193 av_freep(name);
194 av_log(&log_ctx, AV_LOG_ERROR, "Could not parse link name!\n");
195}
196
197/**
198 * Parse "filter=params"
199 * @arg name a pointer (that need to be free'd after use) to the name of the
200 * filter
201 * @arg ars a pointer (that need to be free'd after use) to the args of the
202 * filter
203 */
204static int parse_filter(const char **buf, AVFilterGraph *graph, int index)
205{
206 char *name, *opts;
207 name = consume_string(buf);
208
209 if (**buf == '=') {
210 (*buf)++;
211 opts = consume_string(buf);
212 } else {
213 opts = NULL;
214 }
215
216 return create_filter(graph, index, name, opts);
217}
218
219enum LinkType {
220 LinkTypeIn,
221 LinkTypeOut,
222};
223
224/**
225 * A linked-list of the inputs/outputs of the filter chain.
226 */
227typedef struct AVFilterInOut {
228 enum LinkType type;
229 char *name;
230 int instance;
231 int pad_idx;
232
233 struct AVFilterInOut *next;
234} AVFilterInOut;
235
236static void free_inout(AVFilterInOut *head)
237{
238 while (head) {
239 AVFilterInOut *next;
240 next = head->next;
241 av_free(head);
242 head = next;
243 }
244}
245
246/**
247 * Parse "(a1)(link2) ... (etc)"
248 */
249static int parse_inouts(const char **buf, AVFilterInOut **inout, int firstpad,
250 enum LinkType type, int instance)
251{
252 int pad = firstpad;
253 while (**buf == '(') {
254 AVFilterInOut *inoutn = av_malloc(sizeof(AVFilterInOut));
255 parse_link_name(buf, &inoutn->name);
256 inoutn->type = type;
257 inoutn->instance = instance;
258 inoutn->pad_idx = pad++;
259 inoutn->next = *inout;
260 *inout = inoutn;
261 }
262 return pad;
263}
264
265/**
266 * Parse a string describing a filter graph.
267 */
268int avfilter_graph_parse_chain(AVFilterGraph *graph, const char *filters, AVFilterContext *in, int inpad, AVFilterContext *out, int outpad)
269{
270 AVFilterInOut *inout=NULL;
271 AVFilterInOut *head=NULL;
272
273 int index = 0;
274 char chr = 0;
275 int pad = 0;
276 int has_out = 0;
277
278 char tmp[20];
279 AVFilterContext *filt;
280
281 consume_whitespace(&filters);
282
283 do {
284 int oldpad = pad;
285
286 pad = parse_inouts(&filters, &inout, chr == ',', LinkTypeIn, index);
287
288 if (parse_filter(&filters, graph, index) < 0)
289 goto fail;
290
291 // If the first filter has an input and none was given, it is
292 // implicitly the input of the whole graph.
293 if (pad == 0 && graph->filters[graph->filter_count-1]->input_count == 1) {
294 snprintf(tmp, 20, "%d", index);
295 if(!(filt = avfilter_graph_get_filter(graph, tmp))) {
296 av_log(&log_ctx, AV_LOG_ERROR, "filter owning exported pad does not exist\n");
297 goto fail;
298 }
299 if(avfilter_link(in, inpad, filt, 0)) {
300 av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
301 goto fail;
302 }
303 }
304
305 if(chr == ',') {
306 if (link_filter(graph, index-1, oldpad, index, 0) < 0)
307 goto fail;
308
309 }
310 pad = parse_inouts(&filters, &inout, 0, LinkTypeOut, index);
311 chr = *filters++;
312 index++;
313 } while (chr == ',' || chr == ';');
314
315 head = inout;
316 for (; inout != NULL; inout = inout->next) {
317 if (inout->instance == -1)
318 continue; // Already processed
319
320 if (!strcmp(inout->name, "in")) {
321 snprintf(tmp, 20, "%d", inout->instance);
322 if(!(filt = avfilter_graph_get_filter(graph, tmp))) {
323 av_log(&log_ctx, AV_LOG_ERROR, "filter owning exported pad does not exist\n");
324 goto fail;
325 }
326 if(avfilter_link(in, inpad, filt, inout->pad_idx)) {
327 av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
328 goto fail;
329 }
330 } else if (!strcmp(inout->name, "out")) {
331 has_out = 1;
332 snprintf(tmp, 20, "%d", inout->instance);
333 if(!(filt = avfilter_graph_get_filter(graph, tmp))) {
334 av_log(&log_ctx, AV_LOG_ERROR, "filter owning exported pad does not exist\n");
335 goto fail;
336 }
337
338 if(avfilter_link(filt, inout->pad_idx, out, outpad)) {
339 av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
340 goto fail;
341 }
342
343 } else {
344 AVFilterInOut *p, *src, *dst;
345 for (p = inout->next;
346 p && strcmp(p->name,inout->name); p = p->next);
347
348 if (!p) {
349 av_log(&log_ctx, AV_LOG_ERROR, "Unmatched link: %s.\n",
350 inout->name);
351 goto fail;
352 }
353
354 if (p->type == LinkTypeIn && inout->type == LinkTypeOut) {
355 src = inout;
356 dst = p;
357 } else if (p->type == LinkTypeOut && inout->type == LinkTypeIn) {
358 src = p;
359 dst = inout;
360 } else {
361 av_log(&log_ctx, AV_LOG_ERROR, "Two links named '%s' are either both input or both output\n",
362 inout->name);
363 goto fail;
364 }
365
366 if (link_filter(graph, src->instance, src->pad_idx, dst->instance, dst->pad_idx) < 0)
367 goto fail;
368
369 src->instance = -1;
370 dst->instance = -1;
371 }
372 }
373
374 free_inout(head);
375
376 if (!has_out) {
377 snprintf(tmp, 20, "%d", index-1);
378 if(!(filt = avfilter_graph_get_filter(graph, tmp))) {
379 av_log(&log_ctx, AV_LOG_ERROR, "filter owning exported pad does not exist\n");
380 goto fail;
381 }
382
383 if(avfilter_link(filt, pad, out, outpad)) {
384 av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
385 goto fail;
386 }
387
388 }
389
390 return 0;
391
392 fail:
393 free_inout(head);
394 avfilter_destroy_graph(graph);
395 return -1;
396}