... 4 channel composite video, PAL or NTSC BNC interface,1.0Vp-p,impedance 75OhmsVideo Compression H.264 Main Profile ... impedance: 75Ω,Audio Compression G.726, G711, ADPCMAudio Input1 channel, RCA port, liner input, Impedance:1KOhmsAudio Output1channel,RCA port ... , linear outputAudio talk-back input1 channel ,MIC portOverlaid CaptionChannel Name, Date, Bit rate, position ...