- boost::optional<dcpomatic::DCPTime> content_time_to_dcp (std::shared_ptr<const Content> content, dcpomatic::ContentTime t);
- boost::optional<dcpomatic::ContentTime> dcp_to_content_time (std::shared_ptr<const Content> content, dcpomatic::DCPTime t);
+ boost::optional<dcpomatic::DCPTime> content_time_to_dcp (std::shared_ptr<const Content> content, dcpomatic::ContentTime t) const;
+ boost::optional<dcpomatic::ContentTime> dcp_to_content_time (std::shared_ptr<const Content> content, dcpomatic::DCPTime t) const;