Transpose

src/vamp_zero/notation.cpp

@@ -93,6 +93,13 @@ auto vamp_zero::parse_notation_document(std::string_view json, std::string sourc
     }
     document.arrangement_part_type = std::move(*type);
   }
+  if (document.arrangement_part_type == "practice" && document.key_signature == "No key" && metadata->if_contains("variant_tonic")) {
+    auto tonic = string_field(*metadata, "variant_tonic");
+    if (!tonic) {
+      return invalid(std::string{tonic.error().message()});
+    }
+    document.key_signature = *tonic + " (no key)";
+  }
   for (auto const &item : *pages) {
     if (!item.is_object()) {
       return invalid("page must be an object");