Add workaround to 0. crossfade duration.

Author: toots

src/core/operators/cross.ml

@@ -65,6 +65,7 @@ class cross val_source ~duration_getter ~override_duration ~persist_override
      * Going with the same choice as above for now. *)
     method self_sync = s#self_sync
     val mutable cross_length = Lazy.force Frame.size
+    val mutable rejected_cross_length = None
     val mutable duration_getter = original_duration_getter
     method cross_duration = duration_getter ()
 
@@ -73,16 +74,19 @@ class cross val_source ~duration_getter ~override_duration ~persist_override
       let main_new_cross_length = Frame.main_of_seconds new_cross_length in
 
       if main_new_cross_length <> cross_length then
-        if new_cross_length < 0. then
-          self#log#important
-            "Cannot set crossfade duration to negative value %f!"
-            new_cross_length
+        if new_cross_length <= 0. then (
+          if rejected_cross_length <> Some new_cross_length then (
+            self#log#critical "Invalid cross duration: %.2f <= 0.!"
+              new_cross_length;
+            rejected_cross_length <- Some new_cross_length);
+          cross_length <- Lazy.force Frame.size)
         else (
           let main_new_cross_length =
             max (Lazy.force Frame.size) main_new_cross_length
           in
           self#log#info "Setting crossfade duration to %.2fs"
             (Frame.seconds_of_main main_new_cross_length);
+          rejected_cross_length <- None;
           cross_length <- main_new_cross_length)
 
     initializer self#set_cross_length