16 channel 960h dvr system main processor hi 3521 video video compression h264 high profile video recording d1 25fps video playback 1chn d1 25fps audio audio compression g711a bidirectional talk supported recording amp playback playback 4 pure local input mode storage and backup space occupation 960h 1220g daychannel audio 6912m daychannel backup mode network backup usb hdd usb writer sata writer interface video input 16 bnc video output 1ch v