Canon EOS-1DX Instruction Manual page 243

Using the microphone
The built-in microphone records monaural sound. Stereo sound
recording is possible by connecting an external stereo microphone
(commercially-available) equipped with a miniature stereo plug (3.5
mm) to the camera's external microphone IN terminal (p.21). When
an external microphone is connected, sound recording will switch
automatically to the external microphone.
The sound volume balance between L (left) and R (right) cannot be
adjusted.
Both L and R record audio at a 48 kHz/16-bit sampling rate.
If [z5: Silent Control] is set to [Enable h] (p.244), you can adjust the
sound-recording level with the <
noise during movie shooting.
3 Setting the Sound Recording
h
> touch pad to reduce the operation
243