avfilter/vf_readeia608: add support for commands

doc/filters.texi

@@ -15910,6 +15910,10 @@ Enable checking the parity bit. In the event of a parity error, the filter will
 Lowpass lines prior to further processing. Default is enabled.
 @end table
 
+@subsection Commands
+
+This filter supports the all above options as @ref{commands}.
+
 @subsection Examples
 
 @itemize

libavfilter/vf_readeia608.c

@@ -74,7 +74,7 @@ typedef struct ReadEIA608Context {
 } ReadEIA608Context;
 
 #define OFFSET(x) offsetof(ReadEIA608Context, 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 readeia608_options[] = {
     { "scan_min", "set from which line to scan for codes",               OFFSET(start), AV_OPT_TYPE_INT,   {.i64=0},     0, INT_MAX, FLAGS },
@@ -440,4 +440,5 @@ AVFilter ff_vf_readeia608 = {
     .outputs       = readeia608_outputs,
     .uninit        = uninit,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
+    .process_command = ff_filter_process_command,
 };