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 #include "parseutils.h"
  30
  31 #define WHITESPACES " \n\t"
  32
  33 static int link_filter(AVFilterContext *src, int srcpad,
  34                        AVFilterContext *dst, int dstpad,
  35                        AVClass *log_ctx)
  36 {
  37     if(avfilter_link(src, srcpad, dst, dstpad)) {
  38         av_log(log_ctx, AV_LOG_ERROR,
  39                "cannot create the link %s:%d -> %s:%d\n",
  40                src->filter->name, srcpad, dst->filter->name, dstpad);
  41         return -1;
  42     }
  43
  44     return 0;
  45 }
  46
  47 /**
  48  * Parse "[linkname]"
  49  * @param name a pointer (that need to be free'd after use) to the name between
  50  *        parenthesis
  51  */
  52 static char *parse_link_name(const char **buf, AVClass *log_ctx)
  53 {
  54     const char *start = *buf;
  55     char *name;
  56     (*buf)++;
  57
  58     name = av_get_token(buf, "]");
  59
  60     if(!name[0]) {
  61         av_log(log_ctx, AV_LOG_ERROR,
  62                "Bad (empty?) label found in the following: \"%s\".\n", start);
  63         goto fail;
  64     }
  65
  66     if(*(*buf)++ != ']') {
  67         av_log(log_ctx, AV_LOG_ERROR,
  68                "Mismatched '[' found in the following: \"%s\".\n", start);
  69     fail:
  70         av_freep(&name);
  71     }
  72
  73     return name;
  74 }
  75
  76 static AVFilterContext *create_filter(AVFilterGraph *ctx, int index,
  77                                       const char *filt_name, const char *args,
  78                                       AVClass *log_ctx)
  79 {
  80     AVFilterContext *filt_ctx;
  81
  82     AVFilter *filt;
  83     char inst_name[30];
  84
  85     snprintf(inst_name, sizeof(inst_name), "Parsed filter %d", index);
  86
  87     filt = avfilter_get_by_name(filt_name);
  88
  89     if(!filt) {
  90         av_log(log_ctx, AV_LOG_ERROR,
  91                "no such filter: '%s'\n", filt_name);
  92         return NULL;
  93     }
  94
  95     filt_ctx = avfilter_open(filt, inst_name);
  96     if(!filt_ctx) {
  97         av_log(log_ctx, AV_LOG_ERROR,
  98                "error creating filter '%s'\n", filt_name);
  99         return NULL;
 100     }
 101
 102     if(avfilter_graph_add_filter(ctx, filt_ctx) < 0) {
 103         avfilter_destroy(filt_ctx);
 104         return NULL;
 105     }
 106
 107     if(avfilter_init_filter(filt_ctx, args, NULL)) {
 108         av_log(log_ctx, AV_LOG_ERROR,
 109                "error initializing filter '%s' with args '%s'\n", filt_name, args);
 110         return NULL;
 111     }
 112
 113     return filt_ctx;
 114 }
 115
 116 /**
 117  * Parse "filter=params"
 118  */
 119 static AVFilterContext *parse_filter(const char **buf, AVFilterGraph *graph,
 120                                      int index, AVClass *log_ctx)
 121 {
 122     char *opts = NULL;
 123     char *name = av_get_token(buf, "=,[");
 124     AVFilterContext *ret;
 125
 126     if(**buf == '=') {
 127         (*buf)++;
 128         opts = av_get_token(buf, "[],\n");
 129     }
 130
 131     ret = create_filter(graph, index, name, opts, log_ctx);
 132     av_free(name);
 133     av_free(opts);
 134     return ret;
 135 }
 136
 137 static void free_inout(AVFilterInOut *head)
 138 {
 139     while(head) {
 140         AVFilterInOut *next = head->next;
 141         av_free(head->name);
 142         av_free(head);
 143         head = next;
 144     }
 145 }
 146
 147 static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)
 148 {
 149     AVFilterInOut *ret;
 150
 151     while(*links && strcmp((*links)->name, label))
 152         links = &((*links)->next);
 153
 154     ret = *links;
 155
 156     if(ret)
 157         *links = ret->next;
 158
 159     return ret;
 160 }
 161
 162 static void insert_inout(AVFilterInOut **inouts, AVFilterInOut *element)
 163 {
 164     element->next = *inouts;
 165     *inouts = element;
 166 }
 167
 168 static int link_filter_inouts(AVFilterContext *filter,
 169                               AVFilterInOut **curr_inputs,
 170                               AVFilterInOut **open_inputs, AVClass *log_ctx)
 171 {
 172     int pad = filter->input_count;
 173
 174     while(pad--) {
 175         AVFilterInOut *p = *curr_inputs;
 176         if(!p) {
 177             av_log(log_ctx, AV_LOG_ERROR,
 178                    "Not enough inputs specified for the \"%s\" filter.\n",
 179                    filter->filter->name);
 180             return -1;
 181         }
 182
 183         *curr_inputs = (*curr_inputs)->next;
 184
 185         if(p->filter) {
 186             if(link_filter(p->filter, p->pad_idx, filter, pad, log_ctx))
 187                 return -1;
 188             av_free(p->name);
 189             av_free(p);
 190         } else {
 191             p->filter = filter;
 192             p->pad_idx = pad;
 193             insert_inout(open_inputs, p);
 194         }
 195     }
 196
 197     if(*curr_inputs) {
 198         av_log(log_ctx, AV_LOG_ERROR,
 199                "Too many inputs specified for the \"%s\" filter.\n",
 200                filter->filter->name);
 201         return -1;
 202     }
 203
 204     pad = filter->output_count;
 205     while(pad--) {
 206         AVFilterInOut *currlinkn = av_mallocz(sizeof(AVFilterInOut));
 207         currlinkn->filter  = filter;
 208         currlinkn->pad_idx = pad;
 209         insert_inout(curr_inputs, currlinkn);
 210     }
 211
 212     return 0;
 213 }
 214
 215 static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,
 216                         AVFilterInOut **open_outputs, AVClass *log_ctx)
 217 {
 218     int pad = 0;
 219
 220     while(**buf == '[') {
 221         char *name = parse_link_name(buf, log_ctx);
 222         AVFilterInOut *match;
 223
 224         if(!name)
 225             return -1;
 226
 227         /* First check if the label is not in the open_outputs list */
 228         match = extract_inout(name, open_outputs);
 229
 230         if(match) {
 231             av_free(name);
 232         } else {
 233             /* Not in the list, so add it as an input */
 234             match = av_mallocz(sizeof(AVFilterInOut));
 235             match->name    = name;
 236             match->pad_idx = pad;
 237         }
 238
 239         insert_inout(curr_inputs, match);
 240
 241         *buf += strspn(*buf, WHITESPACES);
 242         pad++;
 243     }
 244
 245     return pad;
 246 }
 247
 248 static int parse_outputs(const char **buf, AVFilterInOut **curr_inputs,
 249                          AVFilterInOut **open_inputs,
 250                          AVFilterInOut **open_outputs, AVClass *log_ctx)
 251 {
 252     int pad = 0;
 253
 254     while(**buf == '[') {
 255         char *name = parse_link_name(buf, log_ctx);
 256         AVFilterInOut *match;
 257
 258         AVFilterInOut *input = *curr_inputs;
 259         *curr_inputs = (*curr_inputs)->next;
 260
 261         if(!name)
 262             return -1;
 263
 264         /* First check if the label is not in the open_inputs list */
 265         match = extract_inout(name, open_inputs);
 266
 267         if(match) {
 268             if(link_filter(input->filter, input->pad_idx,
 269                            match->filter, match->pad_idx, log_ctx) < 0)
 270                 return -1;
 271             av_free(match->name);
 272             av_free(name);
 273             av_free(match);
 274             av_free(input);
 275         } else {
 276             /* Not in the list, so add the first input as a open_output */
 277             input->name = name;
 278             insert_inout(open_outputs, input);
 279         }
 280         *buf += strspn(*buf, WHITESPACES);
 281         pad++;
 282     }
 283
 284     return pad;
 285 }
 286
 287 int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
 288                          AVFilterInOut *open_inputs,
 289                          AVFilterInOut *open_outputs, AVClass *log_ctx)
 290 {
 291     int index = 0;
 292     char chr = 0;
 293
 294     AVFilterInOut *curr_inputs = NULL;
 295
 296     do {
 297         AVFilterContext *filter;
 298         filters += strspn(filters, WHITESPACES);
 299
 300         if(parse_inputs(&filters, &curr_inputs, &open_outputs, log_ctx) < 0)
 301             goto fail;
 302
 303         filter = parse_filter(&filters, graph, index, log_ctx);
 304
 305         if(!filter)
 306             goto fail;
 307
 308         if(filter->input_count == 1 && !curr_inputs && !index) {
 309             /* First input can be omitted if it is "[in]" */
 310             const char *tmp = "[in]";
 311             if(parse_inputs(&tmp, &curr_inputs, &open_outputs, log_ctx) < 0)
 312                 goto fail;
 313         }
 314
 315         if(link_filter_inouts(filter, &curr_inputs, &open_inputs, log_ctx) < 0)
 316             goto fail;
 317
 318         if(parse_outputs(&filters, &curr_inputs, &open_inputs, &open_outputs,
 319                          log_ctx) < 0)
 320             goto fail;
 321
 322         filters += strspn(filters, WHITESPACES);
 323         chr = *filters++;
 324
 325         if(chr == ';' && curr_inputs) {
 326             av_log(log_ctx, AV_LOG_ERROR,
 327                    "Could not find a output to link when parsing \"%s\"\n",
 328                    filters - 1);
 329             goto fail;
 330         }
 331         index++;
 332     } while(chr == ',' || chr == ';');
 333
 334     if (chr) {
 335         av_log(log_ctx, AV_LOG_ERROR,
 336                "Unable to parse graph description substring: \"%s\"\n",
 337                filters - 1);
 338         goto fail;
 339     }
 340
 341     if(open_inputs && !strcmp(open_inputs->name, "out") && curr_inputs) {
 342         /* Last output can be omitted if it is "[out]" */
 343         const char *tmp = "[out]";
 344         if(parse_outputs(&tmp, &curr_inputs, &open_inputs,
 345                          &open_outputs, log_ctx) < 0)
 346             goto fail;
 347     }
 348
 349     return 0;
 350
 351  fail:
 352     avfilter_graph_destroy(graph);
 353     free_inout(open_inputs);
 354     free_inout(open_outputs);
 355     free_inout(curr_inputs);
 356     return -1;
 357 }