FLAC support is provided by libFLAC 

Decoder	FLAC
File extension	flac, oga
Description	FLAC stands for Free Lossless Audio Codec, an audio format similar to MP3, but lossless. Supports native flac and ogg flac streams. See Remarks.
Supported by	libFLAC library
Web	http://flac.sourceforge.net/
Email	jcoalson@users.sourceforge.net
Copyright ©	2001,2002,2003,2004,2005,2006,2007 Josh Coalson more info here.
Info tags	Supported by VORBIS COMMENT.
Reverse playing	Supported.
Accurate length	Supported.
Accurate seek	Supported.
BPM detection	Supported.
Gapless playing	Supported.
Dynamic streams	Supported.
Format autodetection	Supported by analyzing file extension and detecting VORBIS COMMENT tag at stream beginning.
Audio autodetection	Supported.
Recording/Encoder	Supported by libFLAC library.
Supported channels	1 channel (mono), 2 channels (stereo)

There are 2 types of FLAC streams, native stream and ogg stream. This decoder supports both streams. 

Supported formats