I'm trying to upload custom sounds to my new Bullet hikvision camera with a built in speaker. I got two sounds to work fine but am trying to add more and the new ones play back wierd. I thought I followed the same process to prepare them - WAV format, mono, 8Hz but they play back distorted and I can't find a way to format them that works when I upload them - they play on my PC fine. Has anyone got any tips? Thanks.