xyz = convert_to_xyz (_frame, boost::bind(&Log::dcp_log, dcpomatic_log.get(), _1, _2));
auto size = xyz->size ();
auto pixels = size.width * size.height;
xyz = convert_to_xyz (_frame, boost::bind(&Log::dcp_log, dcpomatic_log.get(), _1, _2));
auto size = xyz->size ();
auto pixels = size.width * size.height;