5.1 Surround Sound and FLAC

Suggested configuration for 5.1 music listening (Wikipedia)

Suggested configuration for 5.1 music listening (Wikipedia)

Five point one (5.1) is the name for six channel surround sound multichannel digital audio systems, most commonly used in commercial cinemas and home theaters. It uses 5 full bandwidth channels (the “five”) and one low-frequency effects channel (the “point one”). The 5.1 system is used by Dolby Digital (AC3 codec), Sony Dynamic Digital Sound (SDDS), Digital Theater Systems (DTS), and Dolby Pro Logic II.

All 5.1 systems use the same speaker channels and configuration, having a front left (L) and right (R), a center channel (C), two surround channels (SL and SR) and a subwoofer (LFE).

Audio files for 5.1 systems are often encoded with the lossless FLAC codec. FLAC is an open format with royalty-free licensing and a reference implementation which is free software. FLAC has support for metadata tagging, album cover art, and fast seeking.

Lossy compression and encoding schemes for digital audio are MP3 and its successor AAC (Advanced Audio Coding). AAC has been standardized by ISO and IEC, as part of the MPEG-2 and MPEG-4 specifications. AAC is the standard audio format for YouTube, Apple (iPhone, iPod, iPad, …) and Sony devices (Playstation, Walkman, …). AAC is more advanced than the Dolby Digital AC3 codec.

Playlist formats : m3u, pls, xspf and others

Last update : June 16, 2012;
M3U is a file format to store multimedia playlists. It was first used by Winamp. PLS does the same, but is a more expressive format than basic M3U, as it can store  information on the song title and length (this is supported in extended M3U only). With PLS version 2, playlists also include a PLS version declaration.

iTunes, QuickTime Player, Real player, Winamp, XBMC, XMPlay, VLC media player and many other programs play PLS files without any extra codecs.

Xiph.Org Foundation, a non-profit organization that produces free multimedia formats and software tools, created in 2004 the XML Shareable Playlist Format (XSPF, called spiff) for sharing the kind of playlist that can be played on every personal computer or portable device. The home of XSPF is the website xspf.org.

XSPF is supported by the DLNA server Seviio. The playlists handle not only audio, but also video or other multimedia files.