Perspectives on the digital video world from JW Player’s SVP of Technology
First, let's clarify the difference between live and real-time video delivery.
Live video is streamed to viewers as an event happens, as opposed to on-demand video, which is prerecorded and streamed to viewers whenever they choose.
HLS and DASH, the two leading streaming protocols in use on the web, can operate in a "live" mode, but they are not real-time protocols. Both require a certain amount of video data to be buffered in the player to guard against network rebuffering and other playback glitches. These buffers create latency. In the case of Apple's HLS, their own guidelines mandate at least three segments of six seconds each, effectively putting each viewer about 20 seconds behind "real" time.