@@ -91,11 +91,11 @@ void avfilter_graph_free(AVFilterGraph **graph);

 /**

  * A linked-list of the inputs/outputs of the filter chain.

  *

- * This is mainly useful for avfilter_graph_parse(), since this

- * function may accept a description of a graph with not connected

- * input/output pads. This struct specifies, per each not connected

- * pad contained in the graph, the filter context and the pad index

- * required for establishing a link.

+ * This is mainly useful for avfilter_graph_parse() / avfilter_graph_parse2(),

+ * where it is used to communicate open (unlinked) inputs and outputs from and

+ * to the caller.

+ * This struct specifies, per each not connected pad contained in the graph, the

+ * filter context and the pad index required for establishing a link.

  */

 typedef struct AVFilterInOut {

     /** unique name for this input/output in the list */

@@ -124,4 +124,38 @@ int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,

                          AVFilterInOut *inputs, AVFilterInOut *outputs,

                          void *log_ctx);

+/**

+ * Add a graph described by a string to a graph.

+ *

+ * @param[in]  graph   the filter graph where to link the parsed graph context

+ * @param[in]  filters string to be parsed

+ * @param[out] inputs  a linked list of all free (unlinked) inputs of the

+ *                     parsed graph will be returned here. It is to be freed

+ *                     by the caller using avfilter_inout_free().

+ * @param[out] outputs a linked list of all free (unlinked) outputs of the

+ *                     parsed graph will be returned here. It is to be freed by the

+ *                     caller using avfilter_inout_free().

+ * @return zero on success, a negative AVERROR code on error

+ *

+ * @note the difference between avfilter_graph_parse2() and

+ * avfilter_graph_parse() is that in avfilter_graph_parse(), the caller provides

+ * the lists of inputs and outputs, which therefore must be known before calling

+ * the function. On the other hand, avfilter_graph_parse2() \em returns the

+ * inputs and outputs that are left unlinked after parsing the graph and the

+ * caller then deals with them. Another difference is that in

+ * avfilter_graph_parse(), the inputs parameter describes inputs of the

+ * <em>already existing</em> part of the graph; i.e. from the point of view of

+ * the newly created part, they are outputs. Similarly the outputs parameter

+ * describes outputs of the already existing filters, which are provided as

+ * inputs to the parsed filters.

+ * avfilter_graph_parse2() takes the opposite approach -- it makes no reference

+ * whatsoever to already existing parts of the graph and the inputs parameter

+ * will on return contain inputs of the newly parsed part of the graph.

+ * Analogously the outputs parameter will contain outputs of the newly created

+ * filters.

+ */

+int avfilter_graph_parse2(AVFilterGraph *graph, const char *filters,

+                          AVFilterInOut **inputs,

+                          AVFilterInOut **outputs);

+

 #endif /* AVFILTER_AVFILTERGRAPH_H */

@@ -184,13 +184,15 @@ static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)

 {

     AVFilterInOut *ret;

-    while (*links && strcmp((*links)->name, label))

+    while (*links && (!(*links)->name || strcmp((*links)->name, label)))

         links = &((*links)->next);

     ret = *links;

-    if (ret)

+    if (ret) {

         *links = ret->next;

+        ret->next = NULL;

+    }

     return ret;

 }

@@ -201,6 +203,18 @@ static void insert_inout(AVFilterInOut **inouts, AVFilterInOut *element)

     *inouts = element;

 }

+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)

@@ -209,14 +223,11 @@ static int link_filter_inouts(AVFilterContext *filt_ctx,

     while (pad--) {

         AVFilterInOut *p = *curr_inputs;

-        if (!p) {

-            av_log(log_ctx, AV_LOG_ERROR,

-                   "Not enough inputs specified for the \"%s\" filter.\n",

-                   filt_ctx->filter->name);

-            return AVERROR(EINVAL);

-        }

-        *curr_inputs = (*curr_inputs)->next;

+        if (p)

+            *curr_inputs = (*curr_inputs)->next;

+        else if (!(p = av_mallocz(sizeof(*p))))

+            return AVERROR(ENOMEM);

         if (p->filter_ctx) {

             if ((ret = link_filter(p->filter_ctx, p->pad_idx, filt_ctx, pad, log_ctx)) < 0)

@@ -329,18 +340,22 @@ static int parse_outputs(const char **buf, AVFilterInOut **curr_inputs,

     return pad;

 }

-int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,

-                         AVFilterInOut *open_inputs,

-                         AVFilterInOut *open_outputs, void *log_ctx)

+#if FF_API_GRAPH_AVCLASS

+#define log_ctx graph

+#else

+#define log_ctx NULL

+#endif

+int avfilter_graph_parse2(AVFilterGraph *graph, const char *filters,

+                          AVFilterInOut **inputs,

+                          AVFilterInOut **outputs)

 {

     int index = 0, ret;

     char chr = 0;

-    AVFilterInOut *curr_inputs = NULL;

+    AVFilterInOut *curr_inputs = NULL, *open_inputs = NULL, *open_outputs = NULL;

     do {

         AVFilterContext *filter;

-        const char *filterchain = filters;

         filters += strspn(filters, WHITESPACES);

         if ((ret = parse_inputs(&filters, &curr_inputs, &open_outputs, log_ctx)) < 0)

@@ -349,12 +364,6 @@ int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,

         if ((ret = parse_filter(&filter, &filters, graph, index, log_ctx)) < 0)

             goto fail;

-        if (filter->input_count == 1 && !curr_inputs && !index) {

-            /* First input can be omitted if it is "[in]" */

-            const char *tmp = "[in]";

-            if ((ret = parse_inputs(&tmp, &curr_inputs, &open_outputs, log_ctx)) < 0)

-                goto fail;

-        }

         if ((ret = link_filter_inouts(filter, &curr_inputs, &open_inputs, log_ctx)) < 0)

             goto fail;

@@ -366,13 +375,8 @@ int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,

         filters += strspn(filters, WHITESPACES);

         chr = *filters++;

-        if (chr == ';' && curr_inputs) {

-            av_log(log_ctx, AV_LOG_ERROR,

-                   "Invalid filterchain containing an unlabelled output pad: \"%s\"\n",

-                   filterchain);

-            ret = AVERROR(EINVAL);

-            goto fail;

-        }

+        if (chr == ';' && curr_inputs)

+            append_inout(&open_outputs, &curr_inputs);

         index++;

     } while (chr == ',' || chr == ';');

@@ -384,14 +388,10 @@ int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,

         goto fail;

     }

-    if (open_inputs && !strcmp(open_inputs->name, "out") && curr_inputs) {

-        /* Last output can be omitted if it is "[out]" */

-        const char *tmp = "[out]";

-        if ((ret = parse_outputs(&tmp, &curr_inputs, &open_inputs, &open_outputs,

-                                 log_ctx)) < 0)

-            goto fail;

-    }

+    append_inout(&open_outputs, &curr_inputs);

+    *inputs  = open_inputs;

+    *outputs = open_outputs;

     return 0;

  fail:

@@ -401,5 +401,73 @@ int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,

     free_inout(open_inputs);

     free_inout(open_outputs);

     free_inout(curr_inputs);

+

+    *inputs  = NULL;

+    *outputs = NULL;

+

+    return ret;

+}

+#undef log_ctx

+

+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 ((ret = avfilter_graph_parse2(graph, filters, &inputs, &outputs)) < 0)

+        goto fail;

+

+    /* 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);

+        free_inout(match);

+        if (ret < 0)

+            goto fail;

+    }

+

+    /* 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);

+        free_inout(match);

+        if (ret < 0)

+            goto fail;

+    }

+

+ fail:

+    if (ret < 0) {

+        for (; graph->filter_count > 0; graph->filter_count--)

+            avfilter_free(graph->filters[graph->filter_count - 1]);

+        av_freep(&graph->filters);

+    }

+    free_inout(inputs);

+    free_inout(outputs);

+    free_inout(open_inputs);

+    free_inout(open_outputs);

     return ret;

 }