Libav 0.7.1
libavfilter/graphparser.c
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00001 /*
00002  * filter graph parser
00003  * Copyright (c) 2008 Vitor Sessak
00004  * Copyright (c) 2007 Bobby Bingham
00005  *
00006  * This file is part of Libav.
00007  *
00008  * Libav is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * Libav is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with Libav; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00023 #include <ctype.h>
00024 #include <string.h>
00025 
00026 #include "libavutil/avstring.h"
00027 #include "avfilter.h"
00028 #include "avfiltergraph.h"
00029 
00030 #define WHITESPACES " \n\t"
00031 
00037 static int link_filter(AVFilterContext *src, int srcpad,
00038                        AVFilterContext *dst, int dstpad,
00039                        AVClass *log_ctx)
00040 {
00041     int ret;
00042     if ((ret = avfilter_link(src, srcpad, dst, dstpad))) {
00043         av_log(log_ctx, AV_LOG_ERROR,
00044                "Cannot create the link %s:%d -> %s:%d\n",
00045                src->filter->name, srcpad, dst->filter->name, dstpad);
00046         return ret;
00047     }
00048 
00049     return 0;
00050 }
00051 
00058 static char *parse_link_name(const char **buf, AVClass *log_ctx)
00059 {
00060     const char *start = *buf;
00061     char *name;
00062     (*buf)++;
00063 
00064     name = av_get_token(buf, "]");
00065 
00066     if (!name[0]) {
00067         av_log(log_ctx, AV_LOG_ERROR,
00068                "Bad (empty?) label found in the following: \"%s\".\n", start);
00069         goto fail;
00070     }
00071 
00072     if (*(*buf)++ != ']') {
00073         av_log(log_ctx, AV_LOG_ERROR,
00074                "Mismatched '[' found in the following: \"%s\".\n", start);
00075     fail:
00076         av_freep(&name);
00077     }
00078 
00079     return name;
00080 }
00081 
00094 static int create_filter(AVFilterContext **filt_ctx, AVFilterGraph *ctx, int index,
00095                          const char *filt_name, const char *args, AVClass *log_ctx)
00096 {
00097     AVFilter *filt;
00098     char inst_name[30];
00099     char tmp_args[256];
00100     int ret;
00101 
00102     snprintf(inst_name, sizeof(inst_name), "Parsed filter %d %s", index, filt_name);
00103 
00104     filt = avfilter_get_by_name(filt_name);
00105 
00106     if (!filt) {
00107         av_log(log_ctx, AV_LOG_ERROR,
00108                "No such filter: '%s'\n", filt_name);
00109         return AVERROR(EINVAL);
00110     }
00111 
00112     ret = avfilter_open(filt_ctx, filt, inst_name);
00113     if (!*filt_ctx) {
00114         av_log(log_ctx, AV_LOG_ERROR,
00115                "Error creating filter '%s'\n", filt_name);
00116         return ret;
00117     }
00118 
00119     if ((ret = avfilter_graph_add_filter(ctx, *filt_ctx)) < 0) {
00120         avfilter_free(*filt_ctx);
00121         return ret;
00122     }
00123 
00124     if (!strcmp(filt_name, "scale") && args && !strstr(args, "flags")) {
00125         snprintf(tmp_args, sizeof(tmp_args), "%s:%s",
00126                  args, ctx->scale_sws_opts);
00127         args = tmp_args;
00128     }
00129 
00130     if ((ret = avfilter_init_filter(*filt_ctx, args, NULL)) < 0) {
00131         av_log(log_ctx, AV_LOG_ERROR,
00132                "Error initializing filter '%s' with args '%s'\n", filt_name, args);
00133         return ret;
00134     }
00135 
00136     return 0;
00137 }
00138 
00153 static int parse_filter(AVFilterContext **filt_ctx, const char **buf, AVFilterGraph *graph,
00154                         int index, AVClass *log_ctx)
00155 {
00156     char *opts = NULL;
00157     char *name = av_get_token(buf, "=,;[\n");
00158     int ret;
00159 
00160     if (**buf == '=') {
00161         (*buf)++;
00162         opts = av_get_token(buf, "[],;\n");
00163     }
00164 
00165     ret = create_filter(filt_ctx, graph, index, name, opts, log_ctx);
00166     av_free(name);
00167     av_free(opts);
00168     return ret;
00169 }
00170 
00171 static void free_inout(AVFilterInOut *head)
00172 {
00173     while (head) {
00174         AVFilterInOut *next = head->next;
00175         av_free(head->name);
00176         av_free(head);
00177         head = next;
00178     }
00179 }
00180 
00181 static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)
00182 {
00183     AVFilterInOut *ret;
00184 
00185     while (*links && strcmp((*links)->name, label))
00186         links = &((*links)->next);
00187 
00188     ret = *links;
00189 
00190     if (ret)
00191         *links = ret->next;
00192 
00193     return ret;
00194 }
00195 
00196 static void insert_inout(AVFilterInOut **inouts, AVFilterInOut *element)
00197 {
00198     element->next = *inouts;
00199     *inouts = element;
00200 }
00201 
00202 static int link_filter_inouts(AVFilterContext *filt_ctx,
00203                               AVFilterInOut **curr_inputs,
00204                               AVFilterInOut **open_inputs, AVClass *log_ctx)
00205 {
00206     int pad = filt_ctx->input_count, ret;
00207 
00208     while (pad--) {
00209         AVFilterInOut *p = *curr_inputs;
00210         if (!p) {
00211             av_log(log_ctx, AV_LOG_ERROR,
00212                    "Not enough inputs specified for the \"%s\" filter.\n",
00213                    filt_ctx->filter->name);
00214             return AVERROR(EINVAL);
00215         }
00216 
00217         *curr_inputs = (*curr_inputs)->next;
00218 
00219         if (p->filter_ctx) {
00220             if ((ret = link_filter(p->filter_ctx, p->pad_idx, filt_ctx, pad, log_ctx)) < 0)
00221                 return ret;
00222             av_free(p->name);
00223             av_free(p);
00224         } else {
00225             p->filter_ctx = filt_ctx;
00226             p->pad_idx = pad;
00227             insert_inout(open_inputs, p);
00228         }
00229     }
00230 
00231     if (*curr_inputs) {
00232         av_log(log_ctx, AV_LOG_ERROR,
00233                "Too many inputs specified for the \"%s\" filter.\n",
00234                filt_ctx->filter->name);
00235         return AVERROR(EINVAL);
00236     }
00237 
00238     pad = filt_ctx->output_count;
00239     while (pad--) {
00240         AVFilterInOut *currlinkn = av_mallocz(sizeof(AVFilterInOut));
00241         if (!currlinkn)
00242             return AVERROR(ENOMEM);
00243         currlinkn->filter_ctx  = filt_ctx;
00244         currlinkn->pad_idx = pad;
00245         insert_inout(curr_inputs, currlinkn);
00246     }
00247 
00248     return 0;
00249 }
00250 
00251 static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,
00252                         AVFilterInOut **open_outputs, AVClass *log_ctx)
00253 {
00254     int pad = 0;
00255 
00256     while (**buf == '[') {
00257         char *name = parse_link_name(buf, log_ctx);
00258         AVFilterInOut *match;
00259 
00260         if (!name)
00261             return AVERROR(EINVAL);
00262 
00263         /* First check if the label is not in the open_outputs list */
00264         match = extract_inout(name, open_outputs);
00265 
00266         if (match) {
00267             av_free(name);
00268         } else {
00269             /* Not in the list, so add it as an input */
00270             if (!(match = av_mallocz(sizeof(AVFilterInOut))))
00271                 return AVERROR(ENOMEM);
00272             match->name    = name;
00273             match->pad_idx = pad;
00274         }
00275 
00276         insert_inout(curr_inputs, match);
00277 
00278         *buf += strspn(*buf, WHITESPACES);
00279         pad++;
00280     }
00281 
00282     return pad;
00283 }
00284 
00285 static int parse_outputs(const char **buf, AVFilterInOut **curr_inputs,
00286                          AVFilterInOut **open_inputs,
00287                          AVFilterInOut **open_outputs, AVClass *log_ctx)
00288 {
00289     int ret, pad = 0;
00290 
00291     while (**buf == '[') {
00292         char *name = parse_link_name(buf, log_ctx);
00293         AVFilterInOut *match;
00294 
00295         AVFilterInOut *input = *curr_inputs;
00296         if (!input) {
00297             av_log(log_ctx, AV_LOG_ERROR,
00298                    "No output pad can be associated to link label '%s'.\n",
00299                    name);
00300             return AVERROR(EINVAL);
00301         }
00302         *curr_inputs = (*curr_inputs)->next;
00303 
00304         if (!name)
00305             return AVERROR(EINVAL);
00306 
00307         /* First check if the label is not in the open_inputs list */
00308         match = extract_inout(name, open_inputs);
00309 
00310         if (match) {
00311             if ((ret = link_filter(input->filter_ctx, input->pad_idx,
00312                                    match->filter_ctx, match->pad_idx, log_ctx)) < 0)
00313                 return ret;
00314             av_free(match->name);
00315             av_free(name);
00316             av_free(match);
00317             av_free(input);
00318         } else {
00319             /* Not in the list, so add the first input as a open_output */
00320             input->name = name;
00321             insert_inout(open_outputs, input);
00322         }
00323         *buf += strspn(*buf, WHITESPACES);
00324         pad++;
00325     }
00326 
00327     return pad;
00328 }
00329 
00330 int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
00331                          AVFilterInOut *open_inputs,
00332                          AVFilterInOut *open_outputs, AVClass *log_ctx)
00333 {
00334     int index = 0, ret;
00335     char chr = 0;
00336 
00337     AVFilterInOut *curr_inputs = NULL;
00338 
00339     do {
00340         AVFilterContext *filter;
00341         const char *filterchain = filters;
00342         filters += strspn(filters, WHITESPACES);
00343 
00344         if ((ret = parse_inputs(&filters, &curr_inputs, &open_outputs, log_ctx)) < 0)
00345             goto fail;
00346 
00347         if ((ret = parse_filter(&filter, &filters, graph, index, log_ctx)) < 0)
00348             goto fail;
00349 
00350         if (filter->input_count == 1 && !curr_inputs && !index) {
00351             /* First input can be omitted if it is "[in]" */
00352             const char *tmp = "[in]";
00353             if ((ret = parse_inputs(&tmp, &curr_inputs, &open_outputs, log_ctx)) < 0)
00354                 goto fail;
00355         }
00356 
00357         if ((ret = link_filter_inouts(filter, &curr_inputs, &open_inputs, log_ctx)) < 0)
00358             goto fail;
00359 
00360         if ((ret = parse_outputs(&filters, &curr_inputs, &open_inputs, &open_outputs,
00361                                  log_ctx)) < 0)
00362             goto fail;
00363 
00364         filters += strspn(filters, WHITESPACES);
00365         chr = *filters++;
00366 
00367         if (chr == ';' && curr_inputs) {
00368             av_log(log_ctx, AV_LOG_ERROR,
00369                    "Invalid filterchain containing an unlabelled output pad: \"%s\"\n",
00370                    filterchain);
00371             ret = AVERROR(EINVAL);
00372             goto fail;
00373         }
00374         index++;
00375     } while (chr == ',' || chr == ';');
00376 
00377     if (chr) {
00378         av_log(log_ctx, AV_LOG_ERROR,
00379                "Unable to parse graph description substring: \"%s\"\n",
00380                filters - 1);
00381         ret = AVERROR(EINVAL);
00382         goto fail;
00383     }
00384 
00385     if (open_inputs && !strcmp(open_inputs->name, "out") && curr_inputs) {
00386         /* Last output can be omitted if it is "[out]" */
00387         const char *tmp = "[out]";
00388         if ((ret = parse_outputs(&tmp, &curr_inputs, &open_inputs, &open_outputs,
00389                                  log_ctx)) < 0)
00390             goto fail;
00391     }
00392 
00393     return 0;
00394 
00395  fail:
00396     for (; graph->filter_count > 0; graph->filter_count--)
00397         avfilter_free(graph->filters[graph->filter_count - 1]);
00398     av_freep(&graph->filters);
00399     free_inout(open_inputs);
00400     free_inout(open_outputs);
00401     free_inout(curr_inputs);
00402     return ret;
00403 }