[Icecast] Metadata Swapping: How do they do it?

[Ian Andrew Bell]

So we're making huge progress on our little app which reads a text file 
and re-inserts metadata on the currently playing track into the icecast 
stream.  The behaviour of course that I'm trying to replicate is where 
a user listening to pulverradio.com via iTunes or WinAmp gets to see 
the currently playing track etc. in their player just like on radio 
stations that DON'T use hundreds of thousands of dollars worth of 
production and encoding gear.  :)

So when I listen to other stations that stream using icecast/shoutcast 
and ices/shoutcast source the player is swapping and/or scrolling 
between what looks like the name of the station and the currently 
playing song.  This is what I want to achieve with our efforts.  This 
means that somehow we have to tell the player, via the relay servers, 
BOTH the static station information AND the currently playing track.

The question is, how exactly do they arrive at this information?

Is the media player:

A)  Swapping between some information element it receives on connect 
(like a global Stream Title attribute of some sort) and the StreamTitle 
attribute which is updated by ices when the song changes?

B)  Simply displaying the StreamTitle attribute, which contains both 
the name of the station and the currently playing song?

C)  Displaying the StreamTitle attribute, which contains either the 
name of the station or the currently playing song, and is updated every 
few seconds?

D)  Doing something else I haven't thought of?

-Ian.