It's also only available on the song level through JSON RPC..
This will give you all the Musicbrainz ID's if they are available.
Code:
{"jsonrpc": "2.0", "method": "AudioLibrary.GetSongDetails", "params": { "properties": ["file", "musicbrainzalbumartistid", "musicbrainzalbumid", "musicbrainztrackid", "musicbrainzartistid" ], "songid": put song id here }, "id": 1}
If you're using Frodo, you should be able to use the following to get the XBMC's Song ID
Code:
$INFO[ListItem.DBID]
The MusicBrainz integration still hasn't fully been added to XBMC ->
https://github.com/xbmc/xbmc/pull/1213. Though as Martijn said, if they are in your tags, XBMC does store them in the Database.
EDIT:
Just was checking out the JSON RPC Introspec and found the following would be what you are craving:
Code:
{"jsonrpc": "2.0", "method": "Player.GetItem", "params": { "playerid": 0,"properties": ["musicbrainztrackid", "musicbrainzartistid", "musicbrainzalbumid", "musicbrainzalbumartistid"] }, "id": 1}