AC-3 support is provided by liba52 - free library for decoding ATSC A/52 streams 

Decoder	AC3
File extension	ac3
Description	Free library for decoding ATSC A/52 streams (AC-3).
Supported by	liba52 - free library for decoding ATSC A/52 streams
Web	http://liba52.sourceforge.net/
Email	aholtzma@ess.engr.uvic.ca
Copyright ©	GNU General Public License
Info tags	Not supported.
Reverse playing	Supported by prescanning whole stream and decoding 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.
Dynamic streams	Supported.
Format autodetection	Supported by analyzing file extension.
Audio autodetection	Supported by analyzing frame header (samplerate, channel number).
Recording/Encoder	Not supported.
Supported channels	A52_CHANNEL, A52_CHANNEL1, A52_CHANNEL2, A52_MONO, A52_STEREO, A52_DOLBY, A52_3F, A52_2F1R, A52_3F1R, A52_2F2R, A52_3F2R, A52_LFE

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 frames. 

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

If sample accurate length in not enabled, length is calculated from stream size and bitrate value. 

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 frames up to specified position. 

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

If sample accurate seek in not enabled, seek position is calculated from stream size using linear interpolation. 

Supported formats