avfilter/vf_colorbalance: add support for commands

doc/filters.texi

@@ -7095,6 +7095,10 @@ colorbalance=rs=.3
 @end example
 @end itemize
 
+@subsection Commands
+
+This filter supports the all above options as @ref{commands}.
+
 @section colorchannelmixer
 
 Adjust video input frames by re-mixing color channels.

libavfilter/vf_colorbalance.c

@@ -57,7 +57,7 @@ typedef struct ColorBalanceContext {
 } ColorBalanceContext;
 
 #define OFFSET(x) offsetof(ColorBalanceContext, x)
-#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
 static const AVOption colorbalance_options[] = {
     { "rs", "set red shadows",      OFFSET(cyan_red.shadows),         AV_OPT_TYPE_FLOAT, {.dbl=0}, -1, 1, FLAGS },
     { "gs", "set green shadows",    OFFSET(magenta_green.shadows),    AV_OPT_TYPE_FLOAT, {.dbl=0}, -1, 1, FLAGS },
@@ -448,4 +448,5 @@ AVFilter ff_vf_colorbalance = {
     .inputs        = colorbalance_inputs,
     .outputs       = colorbalance_outputs,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
+    .process_command = ff_filter_process_command,
 };