avfilter/vf_feedback: add timeline support

libavfilter/vf_feedback.c

@@ -185,13 +185,16 @@ static int activate(AVFilterContext *ctx)
         return ret;
     }
 
-    if (!s->feed) {
+    if (!s->feed || ctx->is_disabled) {
         AVFrame *in = NULL;
 
         ret = ff_inlink_consume_frame(ctx->inputs[0], &in);
         if (ret < 0)
             return ret;
 
+        if (ret > 0 && ctx->is_disabled)
+            return ff_filter_frame(ctx->outputs[0], in);
+
         if (ret > 0) {
             AVFrame *frame;
 
@@ -239,10 +242,11 @@ static int activate(AVFilterContext *ctx)
         return 0;
     }
 
-    if (!s->feed) {
+    if (!s->feed || ctx->is_disabled) {
         if (ff_outlink_frame_wanted(ctx->outputs[0])) {
             ff_inlink_request_frame(ctx->inputs[0]);
-            ff_inlink_request_frame(ctx->inputs[1]);
+            if (!ctx->is_disabled)
+                ff_inlink_request_frame(ctx->inputs[1]);
             return 0;
         }
     }
@@ -330,5 +334,6 @@ const AVFilter ff_vf_feedback = {
     FILTER_INPUTS(inputs),
     FILTER_OUTPUTS(outputs),
     FILTER_QUERY_FUNC(query_formats),
+    .flags       = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
     .process_command = ff_filter_process_command,
 };