Most of ACTi cameras support audio-in either by built-in microphone or by 3.5mm phone jack or by the terminal block. A recorded sound from the camera site is a valuable addition to video evidence; therefore ACTi has focused on providing total solution that supports both video and audio from its generation all the way to the final product, which is an exported AVI file containing both audio and video.

Supposing that you already have chosen a suitable camera that supports audio-in (see the Reference: The List of Cameras Supporting Audio-In) and made sure that the external microphone is connected in case of a model without built-in microphone, then you can move on to carry out the necessary procedures in both camera firmware as well as in the NVR.