fincs updates his SSEQ player. SSEQ is the official music format used in Nintendo DS games. As distributing a ROM with copyrighted music would be a copyright infringement, you can only get the sources for the player routine for now.
You can discuss about the player here, at the GBAdev.org board.
Changes:
– Added support for multiple SWAR files
– Added StopSeq() function
– Implemented per-track ADSR (thanks KazoWAR)
– Implemented loop start/end events (thanks KazoWAR)
– Implemented PSG instruments
http://fincs.drunkencoders.com/2011/06/26/homebrew-sseq-player/