X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;ds=sidebyside;f=libavfilter%2Fgraphparser.c;h=da499b52c93aa2b7e239af59d04154d3ac92018b;hb=83847cc8fa97e0fc637a0962bafb837acdb6eacc;hp=1e74542dfa070cbb5953c6a54cf27d7d0790720d;hpb=2839ff5e2f8ce0a38900d2a182e0c7d952a632db;p=ffmpeg

diff --git a/libavfilter/graphparser.c b/libavfilter/graphparser.c
index 1e74542dfa0..da499b52c93 100644
--- a/libavfilter/graphparser.c
+++ b/libavfilter/graphparser.c
@@ -1,346 +1,547 @@
 /*
  * filter graph parser
- * copyright (c) 2008 Vitor Sessak
- * copyright (c) 2007 Bobby Bingham
+ * Copyright (c) 2008 Vitor Sessak
+ * Copyright (c) 2007 Bobby Bingham
  *
- * This file is part of FFmpeg.
+ * This file is part of Libav.
  *
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
- * FFmpeg is distributed in the hope that it will be useful,
+ * Libav is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
+ * License along with Libav; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#include <ctype.h>
 #include <string.h>
+#include <stdio.h>
 
+#include "libavutil/avstring.h"
+#include "libavutil/mem.h"
 #include "avfilter.h"
-#include "avfiltergraph.h"
+
+#define WHITESPACES " \n\t"
 
 /**
- * For use in av_log
+ * Link two filters together.
+ *
+ * @see avfilter_link()
  */
-static const char *log_name(void *p)
+static int link_filter(AVFilterContext *src, int srcpad,
+                       AVFilterContext *dst, int dstpad,
+                       void *log_ctx)
 {
-    return "Filter parser";
+    int ret;
+    if ((ret = avfilter_link(src, srcpad, dst, dstpad))) {
+        av_log(log_ctx, AV_LOG_ERROR,
+               "Cannot create the link %s:%d -> %s:%d\n",
+               src->filter->name, srcpad, dst->filter->name, dstpad);
+        return ret;
+    }
+
+    return 0;
 }
 
-static const AVClass filter_parser_class = {
-    "Filter parser",
-    log_name
-};
+/**
+ * Parse the name of a link, which has the format "[linkname]".
+ *
+ * @return a pointer (that need to be freed after use) to the name
+ * between parenthesis
+ */
+static char *parse_link_name(const char **buf, void *log_ctx)
+{
+    const char *start = *buf;
+    char *name;
+    (*buf)++;
+
+    name = av_get_token(buf, "]");
+    if (!name)
+        goto fail;
+
+    if (!name[0]) {
+        av_log(log_ctx, AV_LOG_ERROR,
+               "Bad (empty?) label found in the following: \"%s\".\n", start);
+        goto fail;
+    }
+
+    if (*(*buf)++ != ']') {
+        av_log(log_ctx, AV_LOG_ERROR,
+               "Mismatched '[' found in the following: \"%s\".\n", start);
+    fail:
+        av_freep(&name);
+    }
 
-static const AVClass *log_ctx = &filter_parser_class;
+    return name;
+}
 
-static AVFilterContext *create_filter(AVFilterGraph *ctx, int index,
-                                      char *name, char *args)
+#define TMP_ARGS_SIZE 256
+
+static void append_sws_flags(const char **args, const char *sws_opts, char *tmp)
 {
-    AVFilterContext *filt;
+    int nb_opts = 0;
+    const char *separator  = ":";
+    const char *opt        = *args;
+
+    if (strstr(*args, "flags"))
+        return;
+
+    if (strstr(*args, "="))
+        separator = ":flags=";
+
+    while ((opt = strstr(opt, ":")) && *opt) {
+        av_log(NULL, AV_LOG_INFO, "opts '%s' \n", opt);
+        if (nb_opts > 2) {
+            return;
+        }
+        nb_opts++;
+        opt++;
+    }
 
-    AVFilter *filterdef;
+    opt = strstr(sws_opts, "flags=");
+    if (opt && strlen(opt) > 6)
+        opt += 6;
+    else
+        opt = sws_opts;
+
+    snprintf(tmp, TMP_ARGS_SIZE, "%s%s%s",
+             *args, separator, opt);
+
+    *args = tmp;
+}
+
+/**
+ * Create an instance of a filter, initialize and insert it in the
+ * filtergraph in *ctx.
+ *
+ * @param filt_ctx put here a filter context in case of successful creation and configuration, NULL otherwise.
+ * @param ctx the filtergraph context
+ * @param index an index which is supposed to be unique for each filter instance added to the filtergraph
+ * @param filt_name the name of the filter to create
+ * @param args the arguments provided to the filter during its initialization
+ * @param log_ctx the log context to use
+ * @return 0 in case of success, a negative AVERROR code otherwise
+ */
+static int create_filter(AVFilterContext **filt_ctx, AVFilterGraph *ctx, int index,
+                         const char *filt_name, const char *args, void *log_ctx)
+{
+    AVFilter *filt;
     char inst_name[30];
+    char tmp_args[TMP_ARGS_SIZE];
+    int ret;
+
+    snprintf(inst_name, sizeof(inst_name), "Parsed filter %d %s", index, filt_name);
 
-    snprintf(inst_name, sizeof(inst_name), "Parsed filter %d", index);
+    filt = avfilter_get_by_name(filt_name);
 
-    if(!(filterdef = avfilter_get_by_name(name))) {
-        av_log(&log_ctx, AV_LOG_ERROR,
-               "no such filter: '%s'\n", name);
-        return NULL;
+    if (!filt) {
+        av_log(log_ctx, AV_LOG_ERROR,
+               "No such filter: '%s'\n", filt_name);
+        return AVERROR(EINVAL);
     }
 
-    if(!(filt = avfilter_open(filterdef, inst_name))) {
-        av_log(&log_ctx, AV_LOG_ERROR,
-               "error creating filter '%s'\n", name);
-        return NULL;
+    *filt_ctx = avfilter_graph_alloc_filter(ctx, filt, inst_name);
+    if (!*filt_ctx) {
+        av_log(log_ctx, AV_LOG_ERROR,
+               "Error creating filter '%s'\n", filt_name);
+        return AVERROR(ENOMEM);
     }
 
-    if(avfilter_graph_add_filter(ctx, filt) < 0)
-        return NULL;
+    if (!strcmp(filt_name, "scale") && args &&
+        ctx->scale_sws_opts) {
+        append_sws_flags(&args, ctx->scale_sws_opts, tmp_args);
+    }
 
-    if(avfilter_init_filter(filt, args, NULL)) {
-        av_log(&log_ctx, AV_LOG_ERROR,
-               "error initializing filter '%s' with args '%s'\n", name, args);
-        return NULL;
+    ret = avfilter_init_str(*filt_ctx, args);
+    if (ret < 0) {
+        av_log(log_ctx, AV_LOG_ERROR,
+               "Error initializing filter '%s'", filt_name);
+        if (args)
+            av_log(log_ctx, AV_LOG_ERROR, " with args '%s'", args);
+        av_log(log_ctx, AV_LOG_ERROR, "\n");
+        avfilter_free(*filt_ctx);
+        return ret;
     }
 
-    return filt;
+    return 0;
 }
 
-static int link_filter(AVFilterContext *src, int srcpad,
-                       AVFilterContext *dst, int dstpad)
+/**
+ * Parse a string of the form FILTER_NAME[=PARAMS], and create a
+ * corresponding filter instance which is added to graph with
+ * create_filter().
+ *
+ * @param filt_ctx Pointer that is set to the created and configured filter
+ *                 context on success, set to NULL on failure.
+ * @param filt_ctx put here a pointer to the created filter context on
+ * success, NULL otherwise
+ * @param buf pointer to the buffer to parse, *buf will be updated to
+ * point to the char next after the parsed string
+ * @param index an index which is assigned to the created filter
+ * instance, and which is supposed to be unique for each filter
+ * instance added to the filtergraph
+ * @return 0 in case of success, a negative AVERROR code otherwise
+ */
+static int parse_filter(AVFilterContext **filt_ctx, const char **buf, AVFilterGraph *graph,
+                        int index, void *log_ctx)
 {
-    if(avfilter_link(src, srcpad, dst, dstpad)) {
-        av_log(&log_ctx, AV_LOG_ERROR,
-               "cannot create the link %s:%d -> %s:%d\n",
-               src->filter->name, srcpad, dst->filter->name, dstpad);
-        return -1;
+    char *opts = NULL;
+    char *name = av_get_token(buf, "=,;[\n");
+    int ret;
+
+    if (**buf == '=') {
+        (*buf)++;
+        opts = av_get_token(buf, "[],;\n");
     }
 
-    return 0;
+    ret = create_filter(filt_ctx, graph, index, name, opts, log_ctx);
+    av_free(name);
+    av_free(opts);
+    return ret;
 }
 
-static void consume_whitespace(const char **buf)
+AVFilterInOut *avfilter_inout_alloc(void)
 {
-    *buf += strspn(*buf, " \n\t");
+    return av_mallocz(sizeof(AVFilterInOut));
 }
 
-/**
- * Consumes a string from *buf.
- * @return a copy of the consumed string, which should be free'd after use
- */
-static char *consume_string(const char **buf)
+void avfilter_inout_free(AVFilterInOut **inout)
 {
-    char *out = av_malloc(strlen(*buf) + 1);
-    const char *in = *buf;
-    char *ret = out;
-
-    consume_whitespace(buf);
-
-    do{
-        char c = *in++;
-        switch (c) {
-        case '\\':
-            *out++= *in++;
-            break;
-        case '\'':
-            while(*in && *in != '\'')
-                *out++= *in++;
-            if(*in) in++;
-            break;
-        case 0:
-        case ']':
-        case '[':
-        case '=':
-        case ',':
-            *out++= 0;
-            break;
-        default:
-            *out++= c;
-        }
-    } while(out[-1]);
-
-    *buf = in-1;
-    return ret;
+    while (*inout) {
+        AVFilterInOut *next = (*inout)->next;
+        av_freep(&(*inout)->name);
+        av_freep(inout);
+        *inout = next;
+    }
 }
 
-/**
- * Parse "[linkname]"
- * @arg name a pointer (that need to be free'd after use) to the name between
- *           parenthesis
- */
-static void parse_link_name(const char **buf, char **name)
+static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)
 {
-    (*buf)++;
+    AVFilterInOut *ret;
 
-    *name = consume_string(buf);
+    while (*links && (!(*links)->name || strcmp((*links)->name, label)))
+        links = &((*links)->next);
 
-    if(!*name[0])
-        goto fail;
+    ret = *links;
 
-    if(*(*buf)++ != ']')
-        goto fail;
+    if (ret) {
+        *links = ret->next;
+        ret->next = NULL;
+    }
 
-    return;
- fail:
-    av_freep(name);
-    av_log(&log_ctx, AV_LOG_ERROR, "Could not parse link name!\n");
+    return ret;
 }
 
-/**
- * Parse "filter=params"
- * @arg name a pointer (that need to be free'd after use) to the name of the
- *           filter
- * @arg ars  a pointer (that need to be free'd after use) to the args of the
- *           filter
- */
-static AVFilterContext *parse_filter(const char **buf, AVFilterGraph *graph, int index)
+static void insert_inout(AVFilterInOut **inouts, AVFilterInOut *element)
 {
-    char *name, *opts;
-    name = consume_string(buf);
+    element->next = *inouts;
+    *inouts = element;
+}
 
-    if(**buf == '=') {
-        (*buf)++;
-        opts = consume_string(buf);
-    } else {
-        opts = NULL;
+static void append_inout(AVFilterInOut **inouts, AVFilterInOut **element)
+{
+    while (*inouts && (*inouts)->next)
+        inouts = &((*inouts)->next);
+
+    if (!*inouts)
+        *inouts = *element;
+    else
+        (*inouts)->next = *element;
+    *element = NULL;
+}
+
+static int link_filter_inouts(AVFilterContext *filt_ctx,
+                              AVFilterInOut **curr_inputs,
+                              AVFilterInOut **open_inputs, void *log_ctx)
+{
+    int pad, ret;
+
+    for (pad = 0; pad < filt_ctx->nb_inputs; pad++) {
+        AVFilterInOut *p = *curr_inputs;
+
+        if (p) {
+            *curr_inputs = (*curr_inputs)->next;
+            p->next = NULL;
+        } else if (!(p = av_mallocz(sizeof(*p))))
+            return AVERROR(ENOMEM);
+
+        if (p->filter_ctx) {
+            ret = link_filter(p->filter_ctx, p->pad_idx, filt_ctx, pad, log_ctx);
+            av_free(p->name);
+            av_free(p);
+            if (ret < 0)
+                return ret;
+        } else {
+            p->filter_ctx = filt_ctx;
+            p->pad_idx = pad;
+            append_inout(open_inputs, &p);
+        }
+    }
+
+    if (*curr_inputs) {
+        av_log(log_ctx, AV_LOG_ERROR,
+               "Too many inputs specified for the \"%s\" filter.\n",
+               filt_ctx->filter->name);
+        return AVERROR(EINVAL);
+    }
+
+    pad = filt_ctx->nb_outputs;
+    while (pad--) {
+        AVFilterInOut *currlinkn = av_mallocz(sizeof(AVFilterInOut));
+        if (!currlinkn)
+            return AVERROR(ENOMEM);
+        currlinkn->filter_ctx  = filt_ctx;
+        currlinkn->pad_idx = pad;
+        insert_inout(curr_inputs, currlinkn);
     }
 
-    return create_filter(graph, index, name, opts);
+    return 0;
 }
 
-enum LinkType {
-    LinkTypeIn,
-    LinkTypeOut,
-};
+static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,
+                        AVFilterInOut **open_outputs, void *log_ctx)
+{
+    AVFilterInOut *parsed_inputs = NULL;
+    int pad = 0;
 
-/**
- * A linked-list of the inputs/outputs of the filter chain.
- */
-typedef struct AVFilterInOut {
-    enum LinkType type;
-    char *name;
-    AVFilterContext *filter;
-    int pad_idx;
+    while (**buf == '[') {
+        char *name = parse_link_name(buf, log_ctx);
+        AVFilterInOut *match;
 
-    struct AVFilterInOut *next;
-} AVFilterInOut;
+        if (!name)
+            return AVERROR(EINVAL);
 
-static void free_inout(AVFilterInOut *head)
-{
-    while (head) {
-        AVFilterInOut *next;
-        next = head->next;
-        av_free(head);
-        head = next;
+        /* First check if the label is not in the open_outputs list */
+        match = extract_inout(name, open_outputs);
+
+        if (match) {
+            av_free(name);
+        } else {
+            /* Not in the list, so add it as an input */
+            if (!(match = av_mallocz(sizeof(AVFilterInOut)))) {
+                av_free(name);
+                return AVERROR(ENOMEM);
+            }
+            match->name    = name;
+            match->pad_idx = pad;
+        }
+
+        append_inout(&parsed_inputs, &match);
+
+        *buf += strspn(*buf, WHITESPACES);
+        pad++;
     }
+
+    append_inout(&parsed_inputs, curr_inputs);
+    *curr_inputs = parsed_inputs;
+
+    return pad;
 }
 
-/**
- * Parse "[a1][link2] ... [etc]"
- */
-static int parse_inouts(const char **buf, AVFilterInOut **inout, int firstpad,
-                        enum LinkType type, AVFilterContext *filter)
+static int parse_outputs(const char **buf, AVFilterInOut **curr_inputs,
+                         AVFilterInOut **open_inputs,
+                         AVFilterInOut **open_outputs, void *log_ctx)
 {
-    int pad = firstpad;
+    int ret, pad = 0;
+
     while (**buf == '[') {
-        AVFilterInOut *inoutn = av_malloc(sizeof(AVFilterInOut));
-        parse_link_name(buf, &inoutn->name);
-        inoutn->type = type;
-        inoutn->filter = filter;
-        inoutn->pad_idx = pad++;
-        inoutn->next = *inout;
-        *inout = inoutn;
+        char *name = parse_link_name(buf, log_ctx);
+        AVFilterInOut *match;
+
+        AVFilterInOut *input = *curr_inputs;
+
+        if (!name)
+            return AVERROR(EINVAL);
+
+        if (!input) {
+            av_log(log_ctx, AV_LOG_ERROR,
+                   "No output pad can be associated to link label '%s'.\n", name);
+            av_free(name);
+            return AVERROR(EINVAL);
+        }
+        *curr_inputs = (*curr_inputs)->next;
+
+        /* First check if the label is not in the open_inputs list */
+        match = extract_inout(name, open_inputs);
+
+        if (match) {
+            if ((ret = link_filter(input->filter_ctx, input->pad_idx,
+                                   match->filter_ctx, match->pad_idx, log_ctx)) < 0) {
+                av_free(name);
+                return ret;
+            }
+            av_free(match->name);
+            av_free(name);
+            av_free(match);
+            av_free(input);
+        } else {
+            /* Not in the list, so add the first input as a open_output */
+            input->name = name;
+            insert_inout(open_outputs, input);
+        }
+        *buf += strspn(*buf, WHITESPACES);
+        pad++;
     }
+
     return pad;
 }
 
-static const char *skip_inouts(const char *buf)
+static int parse_sws_flags(const char **buf, AVFilterGraph *graph)
 {
-    while (*buf == '[') {
-        buf += strcspn(buf, "]");
-        buf++;
+    char *p = strchr(*buf, ';');
+
+    if (strncmp(*buf, "sws_flags=", 10))
+        return 0;
+
+    if (!p) {
+        av_log(graph, AV_LOG_ERROR, "sws_flags not terminated with ';'.\n");
+        return AVERROR(EINVAL);
     }
-    return buf;
-}
 
+    *buf += 4;  // keep the 'flags=' part
 
-/**
- * Parse a string describing a filter graph.
- */
-int avfilter_parse_graph(AVFilterGraph *graph, const char *filters,
-                         AVFilterContext *in, int inpad,
-                         AVFilterContext *out, int outpad)
-{
-    AVFilterInOut *inout=NULL;
-    AVFilterInOut  *head=NULL;
+    av_freep(&graph->scale_sws_opts);
+    if (!(graph->scale_sws_opts = av_mallocz(p - *buf + 1)))
+        return AVERROR(ENOMEM);
+    av_strlcpy(graph->scale_sws_opts, *buf, p - *buf + 1);
 
-    int index = 0;
+    *buf = p + 1;
+    return 0;
+}
+
+int avfilter_graph_parse2(AVFilterGraph *graph, const char *filters,
+                          AVFilterInOut **inputs,
+                          AVFilterInOut **outputs)
+{
+    int index = 0, ret;
     char chr = 0;
-    int pad = 0;
-    int has_out = 0;
 
-    AVFilterContext *last_filt = NULL;
+    AVFilterInOut *curr_inputs = NULL, *open_inputs = NULL, *open_outputs = NULL;
+
+    filters += strspn(filters, WHITESPACES);
 
-    consume_whitespace(&filters);
+    if ((ret = parse_sws_flags(&filters, graph)) < 0)
+        goto fail;
 
     do {
         AVFilterContext *filter;
-        int oldpad = pad;
-        const char *inouts = filters;
+        filters += strspn(filters, WHITESPACES);
 
-        // We need to parse the inputs of the filter after we create it, so
-        // skip it by now
-        filters = skip_inouts(filters);
+        if ((ret = parse_inputs(&filters, &curr_inputs, &open_outputs, graph)) < 0)
+            goto fail;
 
-        if(!(filter = parse_filter(&filters, graph, index)))
+        if ((ret = parse_filter(&filter, &filters, graph, index, graph)) < 0)
             goto fail;
 
-        pad = parse_inouts(&inouts, &inout, chr == ',', LinkTypeIn, filter);
 
-        // If the first filter has an input and none was given, it is
-        // implicitly the input of the whole graph.
-        if(pad == 0 && filter->input_count == 1) {
-            if(link_filter(in, inpad, filter, 0))
-                goto fail;
-        }
+        if ((ret = link_filter_inouts(filter, &curr_inputs, &open_inputs, graph)) < 0)
+            goto fail;
 
-        if(chr == ',') {
-            if(link_filter(last_filt, oldpad, filter, 0) < 0)
-                goto fail;
-        }
+        if ((ret = parse_outputs(&filters, &curr_inputs, &open_inputs, &open_outputs,
+                                 graph)) < 0)
+            goto fail;
 
-        pad = parse_inouts(&filters, &inout, 0, LinkTypeOut, filter);
+        filters += strspn(filters, WHITESPACES);
         chr = *filters++;
+
+        if (chr == ';' && curr_inputs)
+            append_inout(&open_outputs, &curr_inputs);
         index++;
-        last_filt = filter;
     } while (chr == ',' || chr == ';');
 
-    head = inout;
-    for (; inout != NULL; inout = inout->next) {
-        if(inout->filter == NULL)
-            continue; // Already processed
+    if (chr) {
+        av_log(graph, AV_LOG_ERROR,
+               "Unable to parse graph description substring: \"%s\"\n",
+               filters - 1);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    append_inout(&open_outputs, &curr_inputs);
 
-        if(!strcmp(inout->name, "in")) {
-            if(link_filter(in, inpad, inout->filter, inout->pad_idx))
-                goto fail;
+    *inputs  = open_inputs;
+    *outputs = open_outputs;
+    return 0;
 
-        } else if(!strcmp(inout->name, "out")) {
-            has_out = 1;
+ fail:
+    while (graph->nb_filters)
+        avfilter_free(graph->filters[0]);
+    av_freep(&graph->filters);
+    avfilter_inout_free(&open_inputs);
+    avfilter_inout_free(&open_outputs);
+    avfilter_inout_free(&curr_inputs);
 
-            if(link_filter(inout->filter, inout->pad_idx, out, outpad))
-                goto fail;
+    *inputs  = NULL;
+    *outputs = NULL;
 
-        } else {
-            AVFilterInOut *p, *src, *dst;
-            for (p = inout->next;
-                 p && strcmp(p->name,inout->name); p = p->next);
-
-            if(!p) {
-                av_log(&log_ctx, AV_LOG_ERROR, "Unmatched link: %s.\n",
-                       inout->name);
-                goto fail;
-            }
+    return ret;
+}
 
-            if(p->type == LinkTypeIn && inout->type == LinkTypeOut) {
-                src = inout;
-                dst = p;
-            } else if(p->type == LinkTypeOut && inout->type == LinkTypeIn) {
-                src = p;
-                dst = inout;
-            } else {
-                av_log(&log_ctx, AV_LOG_ERROR, "Two links named '%s' are either both input or both output\n",
-                       inout->name);
-                goto fail;
-            }
+int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
+                         AVFilterInOut *open_inputs,
+                         AVFilterInOut *open_outputs, void *log_ctx)
+{
+    int ret;
+    AVFilterInOut *cur, *match, *inputs = NULL, *outputs = NULL;
 
-            if(link_filter(src->filter, src->pad_idx, dst->filter, dst->pad_idx) < 0)
-                goto fail;
+    if ((ret = avfilter_graph_parse2(graph, filters, &inputs, &outputs)) < 0)
+        goto fail;
 
-            src->filter = NULL;
-            dst->filter = NULL;
+    /* First input can be omitted if it is "[in]" */
+    if (inputs && !inputs->name)
+        inputs->name = av_strdup("in");
+    for (cur = inputs; cur; cur = cur->next) {
+        if (!cur->name) {
+              av_log(log_ctx, AV_LOG_ERROR,
+                     "Not enough inputs specified for the \"%s\" filter.\n",
+                     cur->filter_ctx->filter->name);
+              ret = AVERROR(EINVAL);
+              goto fail;
         }
+        if (!(match = extract_inout(cur->name, &open_outputs)))
+            continue;
+        ret = avfilter_link(match->filter_ctx, match->pad_idx,
+                            cur->filter_ctx,   cur->pad_idx);
+        avfilter_inout_free(&match);
+        if (ret < 0)
+            goto fail;
     }
 
-    free_inout(head);
-
-    if(!has_out) {
-        if(link_filter(last_filt, pad, out, outpad))
+    /* Last output can be omitted if it is "[out]" */
+    if (outputs && !outputs->name)
+        outputs->name = av_strdup("out");
+    for (cur = outputs; cur; cur = cur->next) {
+        if (!cur->name) {
+            av_log(log_ctx, AV_LOG_ERROR,
+                   "Invalid filterchain containing an unlabelled output pad: \"%s\"\n",
+                   filters);
+            ret = AVERROR(EINVAL);
+            goto fail;
+        }
+        if (!(match = extract_inout(cur->name, &open_inputs)))
+            continue;
+        ret = avfilter_link(cur->filter_ctx,   cur->pad_idx,
+                            match->filter_ctx, match->pad_idx);
+        avfilter_inout_free(&match);
+        if (ret < 0)
             goto fail;
     }
 
-    return 0;
-
  fail:
-    free_inout(head);
-    avfilter_destroy_graph(graph);
-    return -1;
+    if (ret < 0) {
+        while (graph->nb_filters)
+            avfilter_free(graph->filters[0]);
+        av_freep(&graph->filters);
+    }
+    avfilter_inout_free(&inputs);
+    avfilter_inout_free(&outputs);
+    avfilter_inout_free(&open_inputs);
+    avfilter_inout_free(&open_outputs);
+    return ret;
 }