How do I play my music files on the Nintendo DSi?
In order to listen to songs on your Nintendo DSi, you will first need to copy the songs you want to listen to onto a compatible SD or SDHC card. Not all songs are compatible with the Nintendo DSi. Some songs may be copy protected and will not work. The Nintendo DSi is compatible with AAC audio files with a filename extension of .m4a, .mp4, or .3gp.