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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 FFmpeg.
00007  *
00008  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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                        void *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, void *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, void *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, void *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 AVFilterInOut *avfilter_inout_alloc(void)
00172 {
00173     return av_mallocz(sizeof(AVFilterInOut));
00174 }
00175 
00176 void avfilter_inout_free(AVFilterInOut **inout)
00177 {
00178     while (*inout) {
00179         AVFilterInOut *next = (*inout)->next;
00180         av_freep(&(*inout)->name);
00181         av_freep(inout);
00182         *inout = next;
00183     }
00184 }
00185 
00186 static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)
00187 {
00188     AVFilterInOut *ret;
00189 
00190     while (*links && strcmp((*links)->name, label))
00191         links = &((*links)->next);
00192 
00193     ret = *links;
00194 
00195     if (ret)
00196         *links = ret->next;
00197 
00198     return ret;
00199 }
00200 
00201 static void insert_inout(AVFilterInOut **inouts, AVFilterInOut *element)
00202 {
00203     element->next = *inouts;
00204     *inouts = element;
00205 }
00206 
00207 static int link_filter_inouts(AVFilterContext *filt_ctx,
00208                               AVFilterInOut **curr_inputs,
00209                               AVFilterInOut **open_inputs, void *log_ctx)
00210 {
00211     int pad = filt_ctx->input_count, ret;
00212 
00213     while (pad--) {
00214         AVFilterInOut *p = *curr_inputs;
00215         if (!p) {
00216             av_log(log_ctx, AV_LOG_ERROR,
00217                    "Not enough inputs specified for the \"%s\" filter.\n",
00218                    filt_ctx->filter->name);
00219             return AVERROR(EINVAL);
00220         }
00221 
00222         *curr_inputs = (*curr_inputs)->next;
00223 
00224         if (p->filter_ctx) {
00225             if ((ret = link_filter(p->filter_ctx, p->pad_idx, filt_ctx, pad, log_ctx)) < 0)
00226                 return ret;
00227             av_free(p->name);
00228             av_free(p);
00229         } else {
00230             p->filter_ctx = filt_ctx;
00231             p->pad_idx = pad;
00232             insert_inout(open_inputs, p);
00233         }
00234     }
00235 
00236     if (*curr_inputs) {
00237         av_log(log_ctx, AV_LOG_ERROR,
00238                "Too many inputs specified for the \"%s\" filter.\n",
00239                filt_ctx->filter->name);
00240         return AVERROR(EINVAL);
00241     }
00242 
00243     pad = filt_ctx->output_count;
00244     while (pad--) {
00245         AVFilterInOut *currlinkn = av_mallocz(sizeof(AVFilterInOut));
00246         if (!currlinkn)
00247             return AVERROR(ENOMEM);
00248         currlinkn->filter_ctx  = filt_ctx;
00249         currlinkn->pad_idx = pad;
00250         insert_inout(curr_inputs, currlinkn);
00251     }
00252 
00253     return 0;
00254 }
00255 
00256 static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,
00257                         AVFilterInOut **open_outputs, void *log_ctx)
00258 {
00259     int pad = 0;
00260 
00261     while (**buf == '[') {
00262         char *name = parse_link_name(buf, log_ctx);
00263         AVFilterInOut *match;
00264 
00265         if (!name)
00266             return AVERROR(EINVAL);
00267 
00268         /* First check if the label is not in the open_outputs list */
00269         match = extract_inout(name, open_outputs);
00270 
00271         if (match) {
00272             av_free(name);
00273         } else {
00274             /* Not in the list, so add it as an input */
00275             if (!(match = av_mallocz(sizeof(AVFilterInOut))))
00276                 return AVERROR(ENOMEM);
00277             match->name    = name;
00278             match->pad_idx = pad;
00279         }
00280 
00281         insert_inout(curr_inputs, match);
00282 
00283         *buf += strspn(*buf, WHITESPACES);
00284         pad++;
00285     }
00286 
00287     return pad;
00288 }
00289 
00290 static int parse_outputs(const char **buf, AVFilterInOut **curr_inputs,
00291                          AVFilterInOut **open_inputs,
00292                          AVFilterInOut **open_outputs, void *log_ctx)
00293 {
00294     int ret, pad = 0;
00295 
00296     while (**buf == '[') {
00297         char *name = parse_link_name(buf, log_ctx);
00298         AVFilterInOut *match;
00299 
00300         AVFilterInOut *input = *curr_inputs;
00301         if (!input) {
00302             av_log(log_ctx, AV_LOG_ERROR,
00303                    "No output pad can be associated to link label '%s'.\n",
00304                    name);
00305             return AVERROR(EINVAL);
00306         }
00307         *curr_inputs = (*curr_inputs)->next;
00308 
00309         if (!name)
00310             return AVERROR(EINVAL);
00311 
00312         /* First check if the label is not in the open_inputs list */
00313         match = extract_inout(name, open_inputs);
00314 
00315         if (match) {
00316             if ((ret = link_filter(input->filter_ctx, input->pad_idx,
00317                                    match->filter_ctx, match->pad_idx, log_ctx)) < 0)
00318                 return ret;
00319             av_free(match->name);
00320             av_free(name);
00321             av_free(match);
00322             av_free(input);
00323         } else {
00324             /* Not in the list, so add the first input as a open_output */
00325             input->name = name;
00326             insert_inout(open_outputs, input);
00327         }
00328         *buf += strspn(*buf, WHITESPACES);
00329         pad++;
00330     }
00331 
00332     return pad;
00333 }
00334 
00335 int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
00336                          AVFilterInOut **open_inputs, AVFilterInOut **open_outputs,
00337                          void *log_ctx)
00338 {
00339     int index = 0, ret;
00340     char chr = 0;
00341 
00342     AVFilterInOut *curr_inputs = NULL;
00343 
00344     do {
00345         AVFilterContext *filter;
00346         const char *filterchain = filters;
00347         filters += strspn(filters, WHITESPACES);
00348 
00349         if ((ret = parse_inputs(&filters, &curr_inputs, open_outputs, log_ctx)) < 0)
00350             goto fail;
00351 
00352         if ((ret = parse_filter(&filter, &filters, graph, index, log_ctx)) < 0)
00353             goto fail;
00354 
00355         if (filter->input_count == 1 && !curr_inputs && !index) {
00356             /* First input can be omitted if it is "[in]" */
00357             const char *tmp = "[in]";
00358             if ((ret = parse_inputs(&tmp, &curr_inputs, open_outputs, log_ctx)) < 0)
00359                 goto fail;
00360         }
00361 
00362         if ((ret = link_filter_inouts(filter, &curr_inputs, open_inputs, log_ctx)) < 0)
00363             goto fail;
00364 
00365         if ((ret = parse_outputs(&filters, &curr_inputs, open_inputs, open_outputs,
00366                                  log_ctx)) < 0)
00367             goto fail;
00368 
00369         filters += strspn(filters, WHITESPACES);
00370         chr = *filters++;
00371 
00372         if (chr == ';' && curr_inputs) {
00373             av_log(log_ctx, AV_LOG_ERROR,
00374                    "Invalid filterchain containing an unlabelled output pad: \"%s\"\n",
00375                    filterchain);
00376             ret = AVERROR(EINVAL);
00377             goto fail;
00378         }
00379         index++;
00380     } while (chr == ',' || chr == ';');
00381 
00382     if (chr) {
00383         av_log(log_ctx, AV_LOG_ERROR,
00384                "Unable to parse graph description substring: \"%s\"\n",
00385                filters - 1);
00386         ret = AVERROR(EINVAL);
00387         goto fail;
00388     }
00389 
00390     if (open_inputs && *open_inputs && !strcmp((*open_inputs)->name, "out") && curr_inputs) {
00391         /* Last output can be omitted if it is "[out]" */
00392         const char *tmp = "[out]";
00393         if ((ret = parse_outputs(&tmp, &curr_inputs, open_inputs, open_outputs,
00394                                  log_ctx)) < 0)
00395             goto fail;
00396     }
00397 
00398     return 0;
00399 
00400  fail:
00401     for (; graph->filter_count > 0; graph->filter_count--)
00402         avfilter_free(graph->filters[graph->filter_count - 1]);
00403     av_freep(&graph->filters);
00404     avfilter_inout_free(open_inputs);
00405     avfilter_inout_free(open_outputs);
00406     avfilter_inout_free(&curr_inputs);
00407     return ret;
00408 }

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