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ffmpeg / libavfilter / graphparser.c @ 27a669ab

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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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/**
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 * For use in av_log
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 */
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static const char *log_name(void *p)
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{
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    return "Filter parser";
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}
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static const AVClass filter_parser_class = {
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    "Filter parser",
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    log_name
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};
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static const AVClass *log_ctx = &filter_parser_class;
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static int create_filter(AVFilterGraph *ctx, int index, char *name,
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                         char *args)
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{
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    AVFilterContext *filt;
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    AVFilter *filterdef;
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    char tmp[20];
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    snprintf(tmp, 20, "%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 -1;
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    }
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    if(!(filt = avfilter_open(filterdef, tmp))) {
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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 -1;
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    }
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    if (avfilter_graph_add_filter(ctx, filt) < 0)
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        return -1;
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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 -1;
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    }
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    return 0;
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}
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static int link_filter(AVFilterGraph *ctx, int src, int srcpad,
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                       int dst, int dstpad)
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{
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    AVFilterContext *filt, *filtb;
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    char tmp[20];
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    snprintf(tmp, 20, "%d", src);
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    if(!(filt = avfilter_graph_get_filter(ctx, tmp))) {
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        av_log(&log_ctx, AV_LOG_ERROR, "link source does not exist in graph\n");
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        return -1;
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    }
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    snprintf(tmp, 20, "%d", dst);
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    if(!(filtb = avfilter_graph_get_filter(ctx, tmp))) {
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        av_log(&log_ctx, AV_LOG_ERROR, "link destination does not exist in graph\n");
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        return -1;
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    }
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    if(avfilter_link(filt, srcpad, filtb, dstpad)) {
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        av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
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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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 * Copy the first size bytes of input string to a null-terminated string,
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 * removing any control character. Ex: "aaa'bb'c\'c\\" -> "aaabbc'c\"
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 */
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static void copy_unquoted(char *out, const char *in, int size)
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{
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    int i;
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    for (i=0; i < size; i++) {
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        if (in[i] == '\'')
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            continue;
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        else if (in[i] == '\\') {
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            if (i+1 == size) {
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                *out = 0;
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                return;
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            }
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            i++;
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        }
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        *out++ = in[i];
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    }
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    *out=0;
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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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    const char *start;
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    char *ret;
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    int size;
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    consume_whitespace(buf);
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    if (!(**buf))
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        return av_mallocz(1);
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    start = *buf;
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    while(1) {
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        *buf += strcspn(*buf, " ()=,'\\");
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        if (**buf == '\\')
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            *buf+=2;
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        else
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            break;
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    }
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    if (**buf == '\'') {
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        const char *p = *buf;
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        do {
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            p++;
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            p = strchr(p, '\'');
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        } while (p && p[-1] == '\\');
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        if (p)
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            *buf = p + 1;
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        else
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            *buf += strlen(*buf); // Move the pointer to the null end byte
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    }
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    size = *buf - start + 1;
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    ret = av_malloc(size);
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    copy_unquoted(ret, start, size-1);
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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)
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{
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    (*buf)++;
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    *name = consume_string(buf);
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    if (!*name[0])
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        goto fail;
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    if (*(*buf)++ != ')')
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        goto fail;
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    return;
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 fail:
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    av_freep(name);
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    av_log(&log_ctx, AV_LOG_ERROR, "Could not parse link name!\n");
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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 int parse_filter(const char **buf, AVFilterGraph *graph, int index)
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{
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    char *name, *opts;
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    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);
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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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    char *name;
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    int instance;
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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;
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        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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/**
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 * Parse "(a1)(link2) ... (etc)"
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 */
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static int parse_inouts(const char **buf, AVFilterInOut **inout, int firstpad,
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                        enum LinkType type, int instance)
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{
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    int pad = firstpad;
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    while (**buf == '(') {
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        AVFilterInOut *inoutn = av_malloc(sizeof(AVFilterInOut));
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        parse_link_name(buf, &inoutn->name);
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        inoutn->type = type;
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        inoutn->instance = instance;
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        inoutn->pad_idx = pad++;
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        inoutn->next = *inout;
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        *inout = inoutn;
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    }
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    return pad;
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}
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/**
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 * Parse a string describing a filter graph.
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 */
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int avfilter_graph_parse_chain(AVFilterGraph *graph, const char *filters, AVFilterContext *in, int inpad, AVFilterContext *out, int outpad)
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{
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    AVFilterInOut *inout=NULL;
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    AVFilterInOut  *head=NULL;
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    int index = 0;
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    char chr = 0;
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    int pad = 0;
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    int has_out = 0;
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    char tmp[20];
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    AVFilterContext *filt;
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    consume_whitespace(&filters);
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    do {
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        int oldpad = pad;
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        pad = parse_inouts(&filters, &inout, chr == ',', LinkTypeIn, index);
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        if (parse_filter(&filters, graph, index) < 0)
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            goto fail;
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        // If the first filter has an input and none was given, it is
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        // implicitly the input of the whole graph.
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        if (pad == 0 && graph->filters[graph->filter_count-1]->input_count == 1) {
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            snprintf(tmp, 20, "%d", index);
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            if(!(filt = avfilter_graph_get_filter(graph, tmp))) {
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                av_log(&log_ctx, AV_LOG_ERROR, "filter owning exported pad does not exist\n");
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                goto fail;
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            }
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            if(avfilter_link(in, inpad, filt, 0)) {
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                av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
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                goto fail;
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            }
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        }
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        if(chr == ',') {
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            if (link_filter(graph, index-1, oldpad, index, 0) < 0)
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                goto fail;
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        }
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        pad = parse_inouts(&filters, &inout, 0, LinkTypeOut, index);
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        chr = *filters++;
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        index++;
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    } while (chr == ',' || chr == ';');
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    head = inout;
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    for (; inout != NULL; inout = inout->next) {
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        if (inout->instance == -1)
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            continue; // Already processed
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320
        if (!strcmp(inout->name, "in")) {
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            snprintf(tmp, 20, "%d", inout->instance);
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            if(!(filt = avfilter_graph_get_filter(graph, tmp))) {
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                av_log(&log_ctx, AV_LOG_ERROR, "filter owning exported pad does not exist\n");
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                goto fail;
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            }
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            if(avfilter_link(in, inpad, filt, inout->pad_idx)) {
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                av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
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                goto fail;
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            }
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        } else if (!strcmp(inout->name, "out")) {
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            has_out = 1;
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            snprintf(tmp, 20, "%d", inout->instance);
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            if(!(filt = avfilter_graph_get_filter(graph, tmp))) {
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                av_log(&log_ctx, AV_LOG_ERROR, "filter owning exported pad does not exist\n");
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                goto fail;
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            }
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            if(avfilter_link(filt, inout->pad_idx, out, outpad)) {
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                av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
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                goto fail;
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        }
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        } else {
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            AVFilterInOut *p, *src, *dst;
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            for (p = inout->next;
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                 p && strcmp(p->name,inout->name); p = p->next);
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348
            if (!p) {
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                av_log(&log_ctx, AV_LOG_ERROR, "Unmatched link: %s.\n",
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                       inout->name);
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                goto fail;
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            }
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            if (p->type == LinkTypeIn && inout->type == LinkTypeOut) {
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                src = inout;
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                dst = p;
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            } else if (p->type == LinkTypeOut && inout->type == LinkTypeIn) {
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                src = p;
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                dst = inout;
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            } else {
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                av_log(&log_ctx, AV_LOG_ERROR, "Two links named '%s' are either both input or both output\n",
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                       inout->name);
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                goto fail;
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            }
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            if (link_filter(graph, src->instance, src->pad_idx, dst->instance, dst->pad_idx) < 0)
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                goto fail;
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            src->instance = -1;
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            dst->instance = -1;
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        }
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    }
373

    
374
    free_inout(head);
375

    
376
    if (!has_out) {
377
        snprintf(tmp, 20, "%d", index-1);
378
        if(!(filt = avfilter_graph_get_filter(graph, tmp))) {
379
            av_log(&log_ctx, AV_LOG_ERROR, "filter owning exported pad does not exist\n");
380
            goto fail;
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        }
382

    
383
        if(avfilter_link(filt, pad, out, outpad)) {
384
            av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
385
            goto fail;
386
        }
387

    
388
    }
389

    
390
    return 0;
391

    
392
 fail:
393
    free_inout(head);
394
    avfilter_destroy_graph(graph);
395
    return -1;
396
}