The EN-91 is a ultra-low delay AVC (H.264) high definition encoder. Ultra-low delay mode requires the use of Adtec's RD-71 IRD and delivers picture-to-picture services in 100 milliseconds! The EN-91 standard delay mode is fully interoperable with other IRDs making it ideal for mission critical trunking and ad-hoc applications. 
The EN-91 offers amazing features and specifications in its 1-RU chassis, including redundant AC power supplies, enhanced control and monitoring via its front panel, browser and SNMP. In addition to encoding audio, the EN-91 pass-through support includes PCM, DolbyE (16 and 20 bit) and Dolby AC3 (2.0 and 5.1 ).