Managing And Selecting Audio
In the camera list, you can choose which camera provides the audio track. Only one camera can be selected as audio source, and only its audio will be present in the final movie. Combining the audio from several cameras is not possible.
The camera gets the audio from its built-in microphone or from an external device (microphone, audio mixer, etc.) connected to either the headphone jack or the lightning port.
To use the headphone jack as an input, you need an special adapter with a TRRS jack. If the audio comes from a mixer output or any other line-level source, the Smartphone Pro - Line Pi from AV Resilience is a good solution. For XLR microphones, use the iRig Pre or equivalent. The headphone jack has a single input which means that audio coming from this jack is mono.
The lightning port allows you to connect an audio input device and record audio in stereo. Thanks to Apple's Lightning to USB Camera Adapter, you can connect any standard USB audio capture device working in 16-bit stereo mode as the Behringer UCA202 or the iRig Pro Duo.