Vivotek ND9542P 32-Channel 4K UHD NVR (No HDD) - Manual (Page 114)

VIVOTEK - Built with Reliability
114 - User's Manual
Audio
The Audio window allows you to configure all audio codec, sampling rate, and Microphone input
gains. Depending on design of the camera models, some codecs may not be available. Also,
there are cameras that come without embedded mircrophones.