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ffmpeg / libavfilter / graphparser.c @ 7baa6210

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/*
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 * filter graph parser
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 * copyright (c) 2008 Vitor Sessak
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 * copyright (c) 2007 Bobby Bingham
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include <ctype.h>
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#include <string.h>
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#include "avfilter.h"
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#include "avfiltergraph.h"
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static AVFilterContext *create_filter(AVFilterGraph *ctx, int index,
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                                      const char *name, const char *args,
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                                      AVClass *log_ctx)
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{
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    AVFilterContext *filt;
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    AVFilter *filterdef;
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    char inst_name[30];
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    snprintf(inst_name, sizeof(inst_name), "Parsed filter %d", index);
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    if(!(filterdef = avfilter_get_by_name(name))) {
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        av_log(log_ctx, AV_LOG_ERROR,
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               "no such filter: '%s'\n", name);
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        return NULL;
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    }
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    if(!(filt = avfilter_open(filterdef, inst_name))) {
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        av_log(log_ctx, AV_LOG_ERROR,
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               "error creating filter '%s'\n", name);
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        return NULL;
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    }
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    if(avfilter_graph_add_filter(ctx, filt) < 0)
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        return NULL;
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    if(avfilter_init_filter(filt, args, NULL)) {
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        av_log(log_ctx, AV_LOG_ERROR,
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               "error initializing filter '%s' with args '%s'\n", name, args);
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        return NULL;
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    }
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    return filt;
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}
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static int link_filter(AVFilterContext *src, int srcpad,
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                       AVFilterContext *dst, int dstpad,
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                       AVClass *log_ctx)
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{
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    if(avfilter_link(src, srcpad, dst, dstpad)) {
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        av_log(log_ctx, AV_LOG_ERROR,
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               "cannot create the link %s:%d -> %s:%d\n",
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               src->filter->name, srcpad, dst->filter->name, dstpad);
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        return -1;
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    }
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    return 0;
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}
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static void consume_whitespace(const char **buf)
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{
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    *buf += strspn(*buf, " \n\t");
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}
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/**
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 * Consumes a string from *buf.
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 * @return a copy of the consumed string, which should be free'd after use
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 */
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static char *consume_string(const char **buf)
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{
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    char *out = av_malloc(strlen(*buf) + 1);
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    char *ret = out;
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    consume_whitespace(buf);
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    do{
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        char c = *(*buf)++;
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        switch (c) {
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        case '\\':
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            *out++= *(*buf)++;
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            break;
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        case '\'':
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            while(**buf && **buf != '\'')
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                *out++= *(*buf)++;
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            if(**buf) (*buf)++;
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            break;
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        case 0:
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        case ']':
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        case '[':
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        case '=':
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        case ',':
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        case ';':
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        case ' ':
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        case '\n':
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            *out++= 0;
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            break;
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        default:
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            *out++= c;
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        }
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    } while(out[-1]);
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    (*buf)--;
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    consume_whitespace(buf);
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    return ret;
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}
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/**
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 * Parse "[linkname]"
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 * @arg name a pointer (that need to be free'd after use) to the name between
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 *           parenthesis
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 */
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static void parse_link_name(const char **buf, char **name, AVClass *log_ctx)
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{
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    const char *start = *buf;
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    (*buf)++;
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    *name = consume_string(buf);
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    if(!*name[0]) {
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        av_log(log_ctx, AV_LOG_ERROR,
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               "Bad (empty?) label found in the following: \"%s\".\n", start);
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        goto fail;
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    }
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    if(*(*buf)++ != ']') {
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        av_log(log_ctx, AV_LOG_ERROR,
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               "Mismatched '[' found in the following: \"%s\".\n", start);
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    fail:
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        av_freep(name);
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    }
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}
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enum LinkType {
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    LinkTypeIn,
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    LinkTypeOut,
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};
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/**
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 * A linked-list of the inputs/outputs of the filter chain.
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 */
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typedef struct AVFilterInOut {
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    enum LinkType type;
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    const char *name;
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    AVFilterContext *filter;
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    int pad_idx;
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    struct AVFilterInOut *next;
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} AVFilterInOut;
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static void free_inout(AVFilterInOut *head)
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{
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    while (head) {
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        AVFilterInOut *next = head->next;
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        av_free(head);
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        head = next;
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    }
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}
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static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)
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{
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    AVFilterInOut *ret;
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    while(*links && strcmp((*links)->name, label))
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        links= &((*links)->next);
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    ret= *links;
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    if(ret)
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        *links= ret->next;
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    return ret;
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}
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static int link_filter_inouts(AVFilterContext *filter,
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                              AVFilterInOut **currInputs,
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                              AVFilterInOut **openLinks, AVClass *log_ctx)
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{
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    AVFilterInOut *p;
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    int pad = 0;
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    pad = filter->input_count;
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    while(pad--) {
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        p = *currInputs;
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        if(!p) {
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            av_log(log_ctx, AV_LOG_ERROR,
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                   "Not enough inputs specified for the \"%s\" filter.\n",
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                   filter->name);
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            return -1;
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        }
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        if(p->filter) {
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            if(link_filter(p->filter, p->pad_idx, filter, pad, log_ctx))
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                return -1;
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            *currInputs = (*currInputs)->next;
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            av_free(p);
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        } else {
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            *currInputs = (*currInputs)->next;
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            p->filter = filter;
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            p->pad_idx = pad;
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            p->next = *openLinks;
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            *openLinks = p;
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        }
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    }
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    if(*currInputs) {
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        av_log(log_ctx, AV_LOG_ERROR,
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               "Too many inputs specified for the \"%s\" filter.\n",
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               filter->name);
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        return -1;
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    }
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    pad = filter->output_count;
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    while(pad--) {
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        AVFilterInOut *currlinkn = av_malloc(sizeof(AVFilterInOut));
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        currlinkn->name    = NULL;
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        currlinkn->type    = LinkTypeOut;
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        currlinkn->filter  = filter;
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        currlinkn->pad_idx = pad;
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        currlinkn->next    = *currInputs;
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        *currInputs = currlinkn;
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    }
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    return 0;
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}
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/**
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 * Parse "filter=params"
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 * @arg name a pointer (that need to be free'd after use) to the name of the
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 *           filter
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 * @arg ars  a pointer (that need to be free'd after use) to the args of the
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 *           filter
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 */
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static AVFilterContext *parse_filter(const char **buf, AVFilterGraph *graph,
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                                     int index, AVClass *log_ctx)
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{
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    char *opts;
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    char *name = consume_string(buf);
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    if(**buf == '=') {
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        (*buf)++;
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        opts = consume_string(buf);
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    } else {
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        opts = NULL;
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    }
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    return create_filter(graph, index, name, opts, log_ctx);
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}
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static int parse_inputs(const char **buf, AVFilterInOut **currInputs,
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                        AVFilterInOut **openLinks, AVClass *log_ctx)
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{
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    int pad = 0;
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    while (**buf == '[') {
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        char *name;
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        AVFilterInOut *match;
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        parse_link_name(buf, &name, log_ctx);
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        if(!name)
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            return -1;
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        /* First check if the label is not in the openLinks list */
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        match = extract_inout(name, openLinks);
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        if(match) {
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            /* A label of a open link. Make it one of the inputs of the next
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               filter */
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            AVFilterInOut *currlinkn = match;
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            if (match->type != LinkTypeOut) {
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                av_log(log_ctx, AV_LOG_ERROR,
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                       "Label \"%s\" appears twice as input!\n", match->name);
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                return -1;
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            }
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            currlinkn->next = *currInputs;
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            *currInputs = currlinkn;
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        } else {
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            /* Not in the list, so add it as an input */
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            AVFilterInOut *currlinkn = av_malloc(sizeof(AVFilterInOut));
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            currlinkn->name    = name;
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            currlinkn->type    = LinkTypeIn;
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            currlinkn->filter  = NULL;
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            currlinkn->pad_idx = pad;
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            currlinkn->next    = *currInputs;
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            *currInputs = currlinkn;
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        }
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        consume_whitespace(buf);
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        pad++;
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    }
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    return pad;
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}
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static int parse_outputs(const char **buf, AVFilterInOut **currInputs,
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                         AVFilterInOut **openLinks, AVClass *log_ctx)
320
{
321
    int pad = 0;
322

    
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    while (**buf == '[') {
324
        char *name;
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        AVFilterInOut *match;
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        parse_link_name(buf, &name, log_ctx);
328

    
329
        if(!name)
330
            return -1;
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        /* First check if the label is not in the openLinks list */
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        match = extract_inout(name, openLinks);
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335
        if(match) {
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            /* A label of a open link. Link it. */
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            AVFilterInOut *input = *currInputs;
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            if (match->type != LinkTypeIn) {
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                av_log(log_ctx, AV_LOG_ERROR,
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                       "Label \"%s\" appears twice as output!\n", match->name);
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                return -1;
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            }
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            *currInputs = (*currInputs)->next;
345
            if(link_filter(input->filter, input->pad_idx,
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                           match->filter, match->pad_idx, log_ctx) < 0)
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                return -1;
348
            av_free(match);
349
            av_free(input);
350
        } else {
351
            /* Not in the list, so add the first input as a openLink */
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            AVFilterInOut *input = *currInputs;
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            *currInputs = (*currInputs)->next;
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            input->next = *openLinks;
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            input->type = LinkTypeOut;
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            input->name = name;
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            *openLinks = input;
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        }
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        consume_whitespace(buf);
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        pad++;
361
    }
362

    
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    return pad;
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}
365

    
366
/**
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 * Parse a string describing a filter graph.
368
 */
369
int avfilter_parse_graph(AVFilterGraph *graph, const char *filters,
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                         AVFilterContext *in, int inpad,
371
                         AVFilterContext *out, int outpad,
372
                         AVClass *log_ctx)
373
{
374
    int index = 0;
375
    char chr = 0;
376
    int pad = 0;
377

    
378
    AVFilterInOut *currInputs=NULL;
379
    AVFilterInOut *openLinks  = av_malloc(sizeof(AVFilterInOut));
380

    
381
    openLinks->name = "in";
382
    openLinks->filter = in;
383
    openLinks->type = LinkTypeOut;
384
    openLinks->pad_idx = inpad;
385
    openLinks->next = av_malloc(sizeof(AVFilterInOut));
386

    
387
    openLinks->next->name = "out";
388
    openLinks->next->filter = out;
389
    openLinks->next->type = LinkTypeIn;
390
    openLinks->next->pad_idx = outpad;
391
    openLinks->next->next = NULL;
392

    
393
    do {
394
        AVFilterContext *filter;
395
        consume_whitespace(&filters);
396

    
397
        pad = parse_inputs(&filters, &currInputs, &openLinks, log_ctx);
398

    
399
        if(pad < 0)
400
            goto fail;
401

    
402
        if(!(filter = parse_filter(&filters, graph, index, log_ctx)))
403
            goto fail;
404

    
405
        if(filter->input_count == 1 && !currInputs && !index) {
406
            // First input can be ommitted if it is "[in]"
407
            const char *tmp = "[in]";
408
            pad = parse_inputs(&tmp, &currInputs, &openLinks, log_ctx);
409
            if (pad < 0)
410
                goto fail;
411
        }
412

    
413
        if(link_filter_inouts(filter, &currInputs, &openLinks, log_ctx) < 0)
414
            goto fail;
415

    
416
        pad = parse_outputs(&filters, &currInputs, &openLinks, log_ctx);
417

    
418
        if(pad < 0)
419
            goto fail;
420

    
421
        consume_whitespace(&filters);
422
        chr = *filters++;
423

    
424
        if (chr == ';' && currInputs) {
425
            av_log(log_ctx, AV_LOG_ERROR,
426
                   "Could not find a output to link when parsing \"%s\"\n",
427
                   filters - 1);
428
            goto fail;
429
        }
430
        index++;
431
    } while (chr == ',' || chr == ';');
432

    
433
    if(openLinks && !strcmp(openLinks->name, "out") && currInputs) {
434
        // Last output can be ommitted if it is "[out]"
435
        const char *tmp = "[out]";
436
        if(parse_outputs(&tmp, &currInputs, &openLinks, log_ctx) < 0)
437
            goto fail;
438
    }
439

    
440
    return 0;
441

    
442
 fail:
443
    avfilter_destroy_graph(graph);
444
    free_inout(openLinks);
445
    free_inout(currInputs);
446
    return -1;
447
}