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.
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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"