4 channel h.264 dvr Video Compression:H.264 support ... . Support SATA HDD&USB disk RS485 PTZ controller Model4CHVideoInput4 channel, BNC(1.0Vp-p, 75?)StandardNTSC(525Line, 60f/s ... p, 75?), 1 VGA, 1 HDMIAudioInput4 channel, BNC(200-2800mV, 30KΩ)Output1 channel, BNC(200-3000mV, 5KΩ)DisplayDisplay Split1/ ... control, 1 for backupRS232Dahua keyboard, PC communicationRS485PTZ control 4 channel h.264 dvr