Mp3 support is provided by libmad - MPEG audio decoder library 

Decoder	MP3
File extension	mp3, mp2, mp1
Description	MPEG-1 and the MPEG-2 extension to Lower Sampling Frequencies, as well as the so-called MPEG 2.5 format. All three audio layers (Layer I, Layer II,and Layer III a.k.a. MP3) are fully implemented. Support free format bitstream. MAD does not yet support MPEG-2 multichannel audio (although it should be backward compatible with such streams) nor does it currently support AAC.
Supported by	libmad - MPEG audio decoder library
Web	http://www.underbit.com/products/mad/
Email	support@underbit.com
Copyright ©	2000-2004 Underbit Technologies, Inc. GNU General Public License
Info tags	Supported by ID3v1, ID3v2.2, ID3v2.3, ID3v2.4
Reverse playing	Supported by prescanning whole stream and decoding mp3 frames backward with frame overlap.
Accurate length	Supported. Please read Remarks section.
Accurate seek	Supported. Please read Remarks section.
BPM detection	Supported.
Gapless playing	Supported. Please read Remarks section.
Dynamic streams	Supported.
Format autodetection	Supported by analyzing file extension and detecting ID3v2 tag at stream beginning.
Audio autodetection	Supported by analyzing mp3 frame header (samplerate, channel number).
Supported channels	1 channel (mono), 2 channels (stereo)
Recording/Encoder	Supported by LAME encoder.

Note: This feature is fully supported if LAME INFO tag is found to detect encoder delay and padding samples. 

To enable sample accurate length you need to use SetSettings function and enable accurate seek using TSettingID sidAccurateLength parameter. This will enable "sample" accurate length by scaning stream and counting all mp3 frames. If there is no LANE tag in stream, encoder delay and padding samples will not be consider and length will be inaccurate. 

Note: By default, sample accurate length is NOT enabled. 

If sample accurate length in not enabled, length is calculated from XING header, if XING header exists. If there is no XING header, length is calculated from stream size and size of first valid mp3 frame. On streams with constant bitrate this method is sample accurate. On streams with variable bitrate without XING header this method is inaccurate, very inaccurate. 

Note: This feature is fully supported if LAME INFO tag is found to detect encoder delay and padding samples. 

To enable sample accurate seek you need to use SetSettings function and enable accurate seek using TSettingID sidAccurateSee parameter. This will enable "sample" accurate seek by scaning stream and detecting all mp3 frames up to specified position. If there is no LANE tag in stream, encoder delay and padding samples will not be consider and seek will be inaccurate. 

Note: By default, sample accurate seek is NOT enabled. 

If sample accurate seek in not enabled, seek position is calculated from XING header, if XING header exists. If there is no XING header, seek position is calculated from stream size using linear interpolation. On streams with constant bitrate this method is quite accurate, but not sample accurate. On streams with variable bitrate without XING header this method is inaccurate. 

Note: This feature is fully supported if LAME INFO tag is found to detect encoder delay and padding samples. 

Gapless plaing is supported only if stream has LAME tag because we need encoder delay and padding samples to calculate correct song length and implement gapless transition from one song to another song. If there is no LAME INFO tag, encoder delay and padding samples will not be consider and some blank samples will be inserted between two song.

Free format bistream is supported (bitrate over 320 kbps and bitrate outside standard bitrates defined by MPEG standard). 

Supported formats