The primary motivation for RTMP was to be a protocol for playing Flash video (Adobe Flash Player) maintaining persistent connections and allows low-latency communication, but in July 2017, Adobe announced that it would end support for Flash Player at the end of 2020,[1] and continued to encourage the use of open HTML5 standards in place of Flash.
Due to this RTMP streaming support is declining rapidly. But it is still very useful for broadcasting live, because of its low-latency. The Broadcaster ingest the stream through a RTMP server which then encodes and sends the resultant stream to a HLS [2] (HTTP Live Streaming) URL. Which then can use a number of players and devices from desktops to smartphones to social media sites.
As of version 1.7.8+ Can open rtmp streams if started from command prompt with the URL as argument, or with entering the URL into the "Open File..." dialog.
^"Unreal Media Server". umediaserver.net. Retrieved 2021-07-30. Unreal Media Server supports ingesting live streams from wide range of live software and hardware encoders that send streams over WebRTC, RTMP, RTSP (...)