Support http stream with seek and support selecting subtitles

[MVasuki1]

At the moment it only supports rtmp (which is done via ffmpeg)
It would be nice if it supports playing an http stream (allowing the admin to set the stream in browser)

[zorchenhimer]

This sounds like you want a coordinated play server, not a stream server. If so, that's out of scope for this project. See the comments on #131 and #159 for some more context.