Q. Audio fails
A.  Check the audio cable coming into the sound system.

      Check if the driver of sound card is correctly installed.
      If a sound card is used, set up the level of record input high at audio setting.

      Check the setting of DVR program.

      DVR program -> Environment set-up –> Audio –> System selection/Input selection/Record channel selection

      Note: Real time play- back is possible with video but not with audio.