Implement RTSP streaming

[skitzi]

FFserver supports RTSP streaming, if this could be cooked into Suubsonic that would be awesome. Perhaps a player option of RTSP that will give the streaming link to plug into other apps rather than show the JW player interface.. This would make is much easer to stream files with out the overhead of transcoding.

I have not been able to get the "external player" option to work at all and RTSP seemed like a good solution (also will work with Android for streaming without transcoding using apps like Rockplayer or Moboplayer).