Canon EOS-1D X Mark II DSLR Camera (Body Only) - Manual (Page 328)

3 Setting the Time Code
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Time code
The time code can be appended to a movie that is output via HDMI.
Enable : Appends time code to HDMI video output. When [ Enable ]
is set, [ Rec Command ] will be displayed.
Disable : Time code not appended to HDMI video output.
Record command
When a video output via HDMI is recorded by an external recording
device, the camera’s movie shooting start/stop can sync with the
recording by an external recording device.
Enable : The movie shooting start/stop syncs with the recording by
an external recording device.
Disable : The recording start/stop is controlled by the external
recording device.
HDMI
During High Frame Rate movie shooting, if [ Count up ] in [ Time code ] is
set to [ Free run ], the time code will not be appended to the HDMI video
output.
To check whether your external recording device is compatible with the
[
Time code ] or [ Rec Command ], consult the manufacturer.
Even if you set [ Time code ] to [ Disable ], time code may be appended to
the movie depending on the specifications of the external recording
device. For specifications of time code during HDMI input, consult the
manufacturer of the external recording device.