In as far as I know BS.Player (and/or BSPlayer Light for that matter) is proprietary software, so its source code isn't freely available for download.
Like it says at the very bottom of BS.Player's webpage for its Android player
(
http://www.bsplayer.com/bsplayer-eng...r-android.html)
under
About... "This software uses code of FFmpeg licensed under the LGPLv2.1 and its source can be downloaded here"