Apollo records two channels of audio for each video signal (eight channels total). SDI A/HDMI can be either embedded audio within the SDI or HDMI signal from the camera, or it can be Analog Audio from the 3.5mm AUDIO INPUT socket near the bottom right corner of the unit.
If Analog Audio is used, the audio will always be recorded to Camera A.
Note that if recording Live-Switch or Quad-View, the SDI A/HDMI audio (either embedded or analog input) will be used for this recording and embedded in the SDI B OUTPUT. SDI B, SDI C, and SDI D will always record the two-channel embedded audio from the SDI stream.