... SATA port IP Video server AST-5804D-WS Four-Channel Encoder (with IDE storage)Technical Specification:Video Input ... 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 ...