libavfilter/graphparser.c

   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 "graphparser.h"
  27 #include "avfilter.h"
  28 #include "avfiltergraph.h"
  29
  30 static int link_filter(AVFilterContext *src, int srcpad,
  31                        AVFilterContext *dst, int dstpad,
  32                        AVClass *log_ctx)
  33 {
  34     if(avfilter_link(src, srcpad, dst, dstpad)) {
  35         av_log(log_ctx, AV_LOG_ERROR,
  36                "cannot create the link %s:%d -> %s:%d\n",
  37                src->filter->name, srcpad, dst->filter->name, dstpad);
  38         return -1;
  39     }
  40
  41     return 0;
  42 }
  43
  44 static int consume_whitespace(const char *buf)
  45 {
  46     return strspn(buf, " \n\t");
  47 }
  48
  49 /**
  50  * Consumes a string from *buf.
  51  * @return a copy of the consumed string, which should be free'd after use
  52  */
  53 static char *consume_string(const char **buf)
  54 {
  55     char *out = av_malloc(strlen(*buf) + 1);
  56     char *ret = out;
  57
  58     *buf += consume_whitespace(*buf);
  59
  60     do{
  61         char c = *(*buf)++;
  62         switch (c) {
  63         case '\\':
  64             *out++ = *(*buf)++;
  65             break;
  66         case '\'':
  67             while(**buf && **buf != '\'')
  68                 *out++ = *(*buf)++;
  69             if(**buf) (*buf)++;
  70             break;
  71         case 0:
  72         case ']':
  73         case '[':
  74         case '=':
  75         case ',':
  76         case ';':
  77         case ' ':
  78         case '\n':
  79             *out++ = 0;
  80             break;
  81         default:
  82             *out++ = c;
  83         }
  84     } while(out[-1]);
  85
  86     (*buf)--;
  87     *buf += consume_whitespace(*buf);
  88
  89     return ret;
  90 }
  91
  92 /**
  93  * Parse "[linkname]"
  94  * @param name a pointer (that need to be free'd after use) to the name between
  95  *        parenthesis
  96  */
  97 static char *parse_link_name(const char **buf, AVClass *log_ctx)
  98 {
  99     const char *start = *buf;
 100     char *name;
 101     (*buf)++;
 102
 103     name = consume_string(buf);
 104
 105     if(!name[0]) {
 106         av_log(log_ctx, AV_LOG_ERROR,
 107                "Bad (empty?) label found in the following: \"%s\".\n", start);
 108         goto fail;
 109     }
 110
 111     if(*(*buf)++ != ']') {
 112         av_log(log_ctx, AV_LOG_ERROR,
 113                "Mismatched '[' found in the following: \"%s\".\n", start);
 114     fail:
 115         av_freep(&name);
 116     }
 117
 118     return name;
 119 }
 120
 121 static AVFilterContext *create_filter(AVFilterGraph *ctx, int index,
 122                                       const char *filt_name, const char *args,
 123                                       AVClass *log_ctx)
 124 {
 125     AVFilterContext *filt_ctx;
 126
 127     AVFilter *filt;
 128     char inst_name[30];
 129
 130     snprintf(inst_name, sizeof(inst_name), "Parsed filter %d", index);
 131
 132     filt = avfilter_get_by_name(filt_name);
 133
 134     if(!filt) {
 135         av_log(log_ctx, AV_LOG_ERROR,
 136                "no such filter: '%s'\n", filt_name);
 137         return NULL;
 138     }
 139
 140     filt_ctx = avfilter_open(filt, inst_name);
 141     if(!filt_ctx) {
 142         av_log(log_ctx, AV_LOG_ERROR,
 143                "error creating filter '%s'\n", filt_name);
 144         return NULL;
 145     }
 146
 147     if(avfilter_graph_add_filter(ctx, filt_ctx) < 0) {
 148         avfilter_destroy(filt_ctx);
 149         return NULL;
 150     }
 151
 152     if(avfilter_init_filter(filt_ctx, args, NULL)) {
 153         av_log(log_ctx, AV_LOG_ERROR,
 154                "error initializing filter '%s' with args '%s'\n", filt_name, args);
 155         return NULL;
 156     }
 157
 158     return filt_ctx;
 159 }
 160
 161 /**
 162  * Parse "filter=params"
 163  */
 164 static AVFilterContext *parse_filter(const char **buf, AVFilterGraph *graph,
 165                                      int index, AVClass *log_ctx)
 166 {
 167     char *opts = NULL;
 168     char *name = consume_string(buf);
 169     AVFilterContext *ret;
 170
 171     if(**buf == '=') {
 172         (*buf)++;
 173         opts = consume_string(buf);
 174     }
 175
 176     ret = create_filter(graph, index, name, opts, log_ctx);
 177     av_free(name);
 178     av_free(opts);
 179     return ret;
 180 }
 181
 182 static void free_inout(AVFilterInOut *head)
 183 {
 184     while(head) {
 185         AVFilterInOut *next = head->next;
 186         av_free(head->name);
 187         av_free(head);
 188         head = next;
 189     }
 190 }
 191
 192 static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)
 193 {
 194     AVFilterInOut *ret;
 195
 196     while(*links && strcmp((*links)->name, label))
 197         links = &((*links)->next);
 198
 199     ret = *links;
 200
 201     if(ret)
 202         *links = ret->next;
 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 int link_filter_inouts(AVFilterContext *filter,
 214                               AVFilterInOut **curr_inputs,
 215                               AVFilterInOut **open_inputs, AVClass *log_ctx)
 216 {
 217     int pad = filter->input_count;
 218
 219     while(pad--) {
 220         AVFilterInOut *p = *curr_inputs;
 221         if(!p) {
 222             av_log(log_ctx, AV_LOG_ERROR,
 223                    "Not enough inputs specified for the \"%s\" filter.\n",
 224                    filter->filter->name);
 225             return -1;
 226         }
 227
 228         *curr_inputs = (*curr_inputs)->next;
 229
 230         if(p->filter) {
 231             if(link_filter(p->filter, p->pad_idx, filter, pad, log_ctx))
 232                 return -1;
 233             av_free(p->name);
 234             av_free(p);
 235         } else {
 236             p->filter = filter;
 237             p->pad_idx = pad;
 238             insert_inout(open_inputs, p);
 239         }
 240     }
 241
 242     if(*curr_inputs) {
 243         av_log(log_ctx, AV_LOG_ERROR,
 244                "Too many inputs specified for the \"%s\" filter.\n",
 245                filter->filter->name);
 246         return -1;
 247     }
 248
 249     pad = filter->output_count;
 250     while(pad--) {
 251         AVFilterInOut *currlinkn = av_mallocz(sizeof(AVFilterInOut));
 252         currlinkn->filter  = filter;
 253         currlinkn->pad_idx = pad;
 254         insert_inout(curr_inputs, currlinkn);
 255     }
 256
 257     return 0;
 258 }
 259
 260 static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,
 261                         AVFilterInOut **open_outputs, AVClass *log_ctx)
 262 {
 263     int pad = 0;
 264
 265     while(**buf == '[') {
 266         char *name = parse_link_name(buf, log_ctx);
 267         AVFilterInOut *match;
 268
 269         if(!name)
 270             return -1;
 271
 272         /* First check if the label is not in the open_outputs list */
 273         match = extract_inout(name, open_outputs);
 274
 275         if(match) {
 276             av_free(name);
 277         } else {
 278             /* Not in the list, so add it as an input */
 279             match = av_mallocz(sizeof(AVFilterInOut));
 280             match->name    = name;
 281             match->pad_idx = pad;
 282         }
 283
 284         insert_inout(curr_inputs, match);
 285
 286         *buf += consume_whitespace(*buf);
 287         pad++;
 288     }
 289
 290     return pad;
 291 }
 292
 293 static int parse_outputs(const char **buf, AVFilterInOut **curr_inputs,
 294                          AVFilterInOut **open_inputs,
 295                          AVFilterInOut **open_outputs, AVClass *log_ctx)
 296 {
 297     int pad = 0;
 298
 299     while(**buf == '[') {
 300         char *name = parse_link_name(buf, log_ctx);
 301         AVFilterInOut *match;
 302
 303         AVFilterInOut *input = *curr_inputs;
 304         *curr_inputs = (*curr_inputs)->next;
 305
 306         if(!name)
 307             return -1;
 308
 309         /* First check if the label is not in the open_inputs list */
 310         match = extract_inout(name, open_inputs);
 311
 312         if(match) {
 313             if(link_filter(input->filter, input->pad_idx,
 314                            match->filter, match->pad_idx, log_ctx) < 0)
 315                 return -1;
 316             av_free(match->name);
 317             av_free(name);
 318             av_free(match);
 319             av_free(input);
 320         } else {
 321             /* Not in the list, so add the first input as a open_output */
 322             input->name = name;
 323             insert_inout(open_outputs, input);
 324         }
 325         *buf += consume_whitespace(*buf);
 326         pad++;
 327     }
 328
 329     return pad;
 330 }
 331
 332 int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
 333                          AVFilterInOut *open_inputs,
 334                          AVFilterInOut *open_outputs, AVClass *log_ctx)
 335 {
 336     int index = 0;
 337     char chr = 0;
 338
 339     AVFilterInOut *curr_inputs = NULL;
 340
 341     do {
 342         AVFilterContext *filter;
 343         filters += consume_whitespace(filters);
 344
 345         if(parse_inputs(&filters, &curr_inputs, &open_outputs, log_ctx) < 0)
 346             goto fail;
 347
 348         filter = parse_filter(&filters, graph, index, log_ctx);
 349
 350         if(!filter)
 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(parse_inputs(&tmp, &curr_inputs, &open_outputs, log_ctx) < 0)
 357                 goto fail;
 358         }
 359
 360         if(link_filter_inouts(filter, &curr_inputs, &open_inputs, log_ctx) < 0)
 361             goto fail;
 362
 363         if(parse_outputs(&filters, &curr_inputs, &open_inputs, &open_outputs,
 364                          log_ctx) < 0)
 365             goto fail;
 366
 367         filters += consume_whitespace(filters);
 368         chr = *filters++;
 369
 370         if(chr == ';' && curr_inputs) {
 371             av_log(log_ctx, AV_LOG_ERROR,
 372                    "Could not find a output to link when parsing \"%s\"\n",
 373                    filters - 1);
 374             goto fail;
 375         }
 376         index++;
 377     } while(chr == ',' || chr == ';');
 378
 379     if (chr) {
 380         av_log(log_ctx, AV_LOG_ERROR,
 381                "Unable to parse graph description substring: \"%s\"\n",
 382                filters - 1);
 383         goto fail;
 384     }
 385
 386     if(open_inputs && !strcmp(open_inputs->name, "out") && curr_inputs) {
 387         /* Last output can be omitted if it is "[out]" */
 388         const char *tmp = "[out]";
 389         if(parse_outputs(&tmp, &curr_inputs, &open_inputs,
 390                          &open_outputs, log_ctx) < 0)
 391             goto fail;
 392     }
 393
 394     return 0;
 395
 396  fail:
 397     avfilter_graph_destroy(graph);
 398     free_inout(open_inputs);
 399     free_inout(open_outputs);
 400     free_inout(curr_inputs);
 401     return -1;
 402 }