4 channel h.264 dvr Video Compression:H.264 support VGA, HDMI ... .0. Support SATA HDD&USB disk RS485 PTZ controller Model4CHVideoInput4 channel, BNC(1.0Vp-p, 75?)StandardNTSC(525Line, 60f/s), PAL ... , File download, Log informationAuxiliary InterfaceUSB Interface2 ports, 1 for mouse control, 1 for backupRS232Dahua keyboard, PC communicationRS485PTZ control 4 channel h.264 dvr