With regards to live video, Unreal Media Server acts as universal transmuxer: it receives live streams multiplexed (muxed) in different protocols/formats (WebRTC/RTSP-RTP, MS-WMSP/ASF, MPEG2-TS, UMS), demuxes (extracts) the actual elementary streams from these containers (no decoding or transcoding), and muxes (packages) it for specific player delivery.
A first version of Unreal Media Server, released in October 2003, supported proprietary UMS protocol only.
At that time this was the only server capable of streaming AVI files without transcoding; the first version was completely free.
Version 11.0 added time-shifted (nDVR) playback for live broadcasts, for up to 12 hours back from real-time.
[3] Version 14.0 added VOD files streaming to HTML video element via HTTP byte-range requests.