+extern bool ids_equal (std::string a, std::string b);
+extern std::string remove_urn_uuid (std::string raw);
+
+/** Set up various bits that the library needs. Should be called once
+ * by client applications.
+ *
+ * @param tags_directory Path to a copy of the tags directory from the source code;
+ * if none is specified libdcp will look for a tags directory in the environment
+ * variable LIBDCP_RESOURCES or based on where the current executable is.
+ */
+extern void init (boost::optional<boost::filesystem::path> tags_directory = boost::optional<boost::filesystem::path>());
+
+/** Decode a base64 string. The base64 decode routine in KM_util.cpp
+ * gives different values to both this and the command-line base64
+ * for some inputs. Not sure why.
+ *
+ * @param in base64-encoded string
+ * @param out Output buffer
+ * @param out_length Length of output buffer
+ * @return Number of characters written to the output buffer
+ */