We recently implemented a simple streaming server based on Openresty and Redis. Redis is used as buffer. We load tested it up to 2000 mountpoints (128kbit mp3 streams) with 15.000 clients.
The architecture has some nice properties. For example the buffer being not in-process means (besides an obvious performance hit) that the streaming server can be seamlessly redeployed without loosing the buffer.
PITA still.