boost::optional<DCPTime> _last_video_time;
/** Time just after the last audio frame we emitted, or the last seek time */
boost::optional<DCPTime> _last_audio_time;
boost::optional<DCPTime> _last_video_time;
/** Time just after the last audio frame we emitted, or the last seek time */
boost::optional<DCPTime> _last_audio_time;