lavfi: make avfilter_free() remove the filter from its graph.

libavfilter/avfilter.c

@@ -430,6 +430,9 @@ void avfilter_free(AVFilterContext *filter)
     int i;
     AVFilterLink *link;
 
+    if (filter->graph)
+        ff_filter_graph_remove_filter(filter->graph, filter);
+
     if (filter->filter->uninit)
         filter->filter->uninit(filter);
 

libavfilter/avfilter.h

@@ -658,7 +658,8 @@ int avfilter_open(AVFilterContext **filter_ctx, AVFilter *filter, const char *in
 int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque);
 
 /**
- * Free a filter context.
+ * Free a filter context. This will also remove the filter from its
+ * filtergraph's list of filters.
  *
  * @param filter the filter to free
  */

libavfilter/avfiltergraph.c

@@ -46,12 +46,27 @@ AVFilterGraph *avfilter_graph_alloc(void)
     return ret;
 }
 
+void ff_filter_graph_remove_filter(AVFilterGraph *graph, AVFilterContext *filter)
+{
+    int i;
+    for (i = 0; i < graph->nb_filters; i++) {
+        if (graph->filters[i] == filter) {
+            FFSWAP(AVFilterContext*, graph->filters[i],
+                   graph->filters[graph->nb_filters - 1]);
+            graph->nb_filters--;
+            return;
+        }
+    }
+}
+
 void avfilter_graph_free(AVFilterGraph **graph)
 {
     if (!*graph)
         return;
-    for (; (*graph)->nb_filters > 0; (*graph)->nb_filters--)
-        avfilter_free((*graph)->filters[(*graph)->nb_filters - 1]);
+
+    while ((*graph)->nb_filters)
+        avfilter_free((*graph)->filters[0]);
+
     av_freep(&(*graph)->scale_sws_opts);
     av_freep(&(*graph)->resample_lavr_opts);
     av_freep(&(*graph)->filters);

libavfilter/graphparser.c

@@ -430,8 +430,8 @@ int avfilter_graph_parse2(AVFilterGraph *graph, const char *filters,
     return 0;
 
  fail:
-    for (; graph->nb_filters > 0; graph->nb_filters--)
-        avfilter_free(graph->filters[graph->nb_filters - 1]);
+    while (graph->nb_filters)
+        avfilter_free(graph->filters[0]);
     av_freep(&graph->filters);
     avfilter_inout_free(&open_inputs);
     avfilter_inout_free(&open_outputs);
@@ -495,8 +495,8 @@ int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
 
  fail:
     if (ret < 0) {
-        for (; graph->nb_filters > 0; graph->nb_filters--)
-            avfilter_free(graph->filters[graph->nb_filters - 1]);
+        while (graph->nb_filters)
+            avfilter_free(graph->filters[0]);
         av_freep(&graph->filters);
     }
     avfilter_inout_free(&inputs);

libavfilter/internal.h

@@ -206,4 +206,9 @@ int ff_filter_frame(AVFilterLink *link, AVFrame *frame);
  */
 AVFilterContext *ff_filter_alloc(const AVFilter *filter, const char *inst_name);
 
+/**
+ * Remove a filter from a graph;
+ */
+void ff_filter_graph_remove_filter(AVFilterGraph *graph, AVFilterContext *filter);
+
 #endif /* AVFILTER_INTERNAL_H */