avfilter/vf_swaprect: add support for commands

doc/filters.texi

@@ -19168,6 +19168,10 @@ The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
 the position in the file of the input frame, NAN if unknown
 @end table
 
+@subsection Commands
+
+This filter supports the all above options as @ref{commands}.
+
 @section swapuv
 Swap U & V plane.
 

libavfilter/vf_swaprect.c

@@ -43,7 +43,7 @@ typedef struct SwapRectContext {
 } SwapRectContext;
 
 #define OFFSET(x) offsetof(SwapRectContext, x)
-#define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
 static const AVOption swaprect_options[] = {
     { "w",  "set rect width",                     OFFSET(w),  AV_OPT_TYPE_STRING, {.str="w/2"}, 0, 0, .flags = FLAGS },
     { "h",  "set rect height",                    OFFSET(h),  AV_OPT_TYPE_STRING, {.str="h/2"}, 0, 0, .flags = FLAGS },
@@ -253,4 +253,5 @@ AVFilter ff_vf_swaprect = {
     .inputs        = inputs,
     .outputs       = outputs,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
+    .process_command = ff_filter_process_command,
 };