The M3U (.m3u) Playlist File Format (December 2001, <xunker@pyxidis.org>)

M3U is a media queue format, also generally known to humans as a playlist. It is the default playlist save format of WinAMP and most other media programs. It allows multiple files to be queued in a program in a specific format.

The actual format is really simple, though; not complicated at all. A sample M3U list could be:

#EXTM3U
#EXTINF:111,3rd Bass - Al z A-B-Cee z
mp3/3rd Bass/3rd bass - Al z A-B-Cee z.mp3
#EXTINF:462,Apoptygma Berzerk - Kathy�s song (VNV Nation rmx)
mp3/Apoptygma Berzerk/Apoptygma Berzerk - Kathy's Song (Victoria Mix by VNV Nation).mp3
#EXTINF:394,Apoptygma Berzerk - Kathy's Song
mp3/Apoptygma Berzerk/Apoptygma Berzerk - Kathy's Song.mp3
#EXTINF:307,Apoptygma Bezerk - Starsign
mp3/Apoptygma Berzerk/Apoptygma Berzerk - Starsign.mp3
#EXTINF:282,Various_Artists - Butthole Surfers: They Came In
mp3/Butthole_Surfers-They_Came_In.mp3

The First line, "#EXTM3U" is the format descriptor, in this case M3U (or Extended M3U as it can be called). It does not change, it's always this.

The second and third operate in a pair. The second begins "#EXTINF:" which serves as the record marker. The "#EXTINF" is unchanging. After the colon is a number: this number is the length of the track in whole seconds (not minutes:seconds or anything else. Then comes a comma and the name of the tune (not the FILE NAME). A good list generator will suck this data from the ID3 tag if there is one, and if not it will take the file name with the extension chopped off.

The second line of this pair (the third line) is the actual file name of the media in question. In my example they aren't fully qualified because I run this list by typing "noatun foo.m3u" in my home directory and my music is in ~/mp3, so it just follows the paths as relative from the path of invocation.