Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 284)

Note
Audio is also output when the camera is connected to televisions via HDMI, except
when [
Sound rec. ] is set to [ Disable ]. In case of feedback from television audio
output, move the camera away from the television or turn down the volume.
The sound volume balance between L (left) and R (right) cannot be adjusted.
Sound is recorded at a 48 kHz/16-bit sampling rate.
Sound Recording/Sound-Recording Level
Auto
The sound-recording level is adjusted automatically. Auto level control will take effect
automatically in response to the sound level.
Manual
You can adjust the sound-recording level as needed. Select [ Rec. level ] and turn the
< > dial while looking at the level meter to adjust the sound-recording level. Look at
the peak hold indicator, and adjust so that the level meter sometimes lights up on the
right of the “12” (–12 dB) mark for the loudest sounds. If it exceeds “0”, the sound will be
distorted.
Line input
Line input can be used as the audio source. Audio supplied this way is combined with
video to record movies. You can adjust the recording level to one of 64 levels. The
adjustment method is the same as for [
Manual ].
Disable
Sound will not be recorded.
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