avfilter/avfilter: add AVFilterGraph->max_buffered_frames to limit buffered frames

Signed-off-by: Marton Balint <cus@passwd.hu>

doc/APIchanges

@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2025-03-28
 
 API changes, most recent first:
 
+2025-07-xx - xxxxxxxxxd - lavfi 11.2.100 - avfilter.h
+  Add AVFilterGraph->max_buffered_frames.
+
 2025-07-07 - eca477da52 - lavc 62.6.100 - packet.h
   Add AV_PKT_DATA_RTCP_SR.
 

libavfilter/avfilter.h

@@ -629,6 +629,14 @@ typedef struct AVFilterGraph {
     avfilter_execute_func *execute;
 
     char *aresample_swr_opts; ///< swr options to use for the auto-inserted aresample filters, Access ONLY through AVOptions
+
+    /**
+     * Sets the maximum number of buffered frames in the filtergraph combined.
+     *
+     * Zero means no limit. This field must be set before calling
+     * avfilter_graph_config().
+     */
+    unsigned max_buffered_frames;
 } AVFilterGraph;
 
 /**

libavfilter/avfiltergraph.c

@@ -56,6 +56,8 @@ static const AVOption filtergraph_options[] = {
         AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, F|V },
     {"aresample_swr_opts"   , "default aresample filter options"    , OFFSET(aresample_swr_opts)    ,
         AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, F|A },
+    {"max_buffered_frames"  , "maximum number of buffered frames allowed", OFFSET(max_buffered_frames),
+        AV_OPT_TYPE_UINT,   {.i64 = 0}, 0, UINT_MAX, F|V|A },
     { NULL },
 };
 
@@ -1296,6 +1298,8 @@ int avfilter_graph_config(AVFilterGraph *graphctx, void *log_ctx)
 {
     int ret;
 
+    if (graphctx->max_buffered_frames)
+        fffiltergraph(graphctx)->frame_queues.max_queued = graphctx->max_buffered_frames;
     if ((ret = graph_check_validity(graphctx, log_ctx)))
         return ret;
     if ((ret = graph_config_formats(graphctx, log_ctx)))

libavfilter/version.h

@@ -31,8 +31,8 @@
 
 #include "version_major.h"
 
-#define LIBAVFILTER_VERSION_MINOR   1
-#define LIBAVFILTER_VERSION_MICRO 101
+#define LIBAVFILTER_VERSION_MINOR   2
+#define LIBAVFILTER_VERSION_MICRO 100
 
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \