Via Buildroot, you can build your own mp3 player.
##Branch
There are two branches:
No_Lcd_Version
master
"no-lcd-version" can play music but no gpio output,
"master" branch can show the name of the song which is playing, but you have to prepare a set of 16X2 LCD
##Detail
I writed all the detail about this mp3 in my blog and gitbook, https://www.gitbook.com/book/hugh712/raspberry\_mp3/details
only chinese version,if there is someone need Eng. version, just let me know.
##Build
only thing you have to do is:
cd mp3\_player
make
##Image to SDCard
The result is a image file, assume your sdcard path is "/dev/sdd", only thing you have to do is:
sudo dd if=/image/sdcard.img of=/dev/sdd
When you power on your pi2 with a speaker coneected on it, then plug in your USB stick with mp3 in it, your pi2 will play songs soon.