Canon EOS-1D X Mark III EOS-1DX Mark III Advanced User Guide - Page 287

Time Code Count Up Start Time Setting Movie Recording Count Movie Play Count HDMI Drop Frame Time codes record the time automatically as movies are recorded. Time codes always record elapsed hours, minutes, seconds, and frames. They are mainly used when movies are edited. To set up the time code, use [ : Time code]. Caution Time codes may not be displayed correctly if your movies are played back on devices other than the camera. 287