|Internet media type||
|Type of format||Playlist|
Each entry carries one specification. The specification can be any one of the following:
- an absolute local pathname; e.g., C:\My Music\Heavysets.mp3
- a local pathname relative to the M3U file location; e.g. Heavysets.mp3
- a URL.
The M3U file can also include comments, prefaced by the "#" character. In extended M3U, "#" also introduces extended M3U directives.
One common use of the M3U file format is creating a single-entry playlist file pointing to a stream on the Internet. The created file provides easy access to that stream and is often used in downloads from a website, for emailing, and for listening to Internet radio .
If an m3u file is edited with a text editor, it must be saved in the Windows-1252 format. "m3u" files properly use the Latin-1 character set. The Unicode version of "m3u" is "m3u8", which uses UTF-8 Unicode characters.
Extended M3U directives 
#EXTM3U - header - must be first line of file #EXTINF - extra info - length (seconds), title
It is a common convention to include the name of the artist in the title, separated by a dash, e.g.:
#EXTINF - extra info - length (seconds), artist '-' title
This is an example of an extended M3U file on the Windows platform. Sample.mp3 and Example.ogg are the media files. 123 and 321 are the lengths in seconds. A length of -1 may be used when the media file is a streaming file, as there is no actual, predefined length value. The value after the length is the title to be shown, which is generally the same as the location of the file which is on the second line. On the Mac OS X and Linux platforms, Unix paths are used.
#EXTM3U #EXTINF:123, Sample artist - Sample title C:\Documents and Settings\I\My Music\Sample.mp3 #EXTINF:321,Example Artist - Example title C:\Documents and Settings\I\My Music\Greatest Hits\Example.ogg
This example shows how to create an m3u file linking to a specified directory (for example, a flash drive, or CD-ROM). The m3u file should contain only one string: the path to the directory. After starting, the media player will play all contents of the directory:
Here is another example, using relative format. The M3U file is placed in the same directory as the music, and directories must be preserved when moving the playlist to another device if subdirectories are used. This method is more flexible, as it does not rely on the file path staying the same.
This is the same file as above, saved as sample.m3u in C:\Documents and Settings\I\My Music\
#EXTM3U #EXTINF:123, Sample artist - Sample title Sample.mp3 #EXTINF:321,Example Artist - Example title Greatest Hits\Example.ogg
This format in an M3U allows copying to another device for playback. All files and directories referred to must also be copied.
Here is a mixed example.
Alternative\Band - Song.mp3 Classical\Other Band - New Song.mp3 Stuff.mp3 D:\More Music\Foo.mp3 ..\Other Music\Bar.mp3 http://emp.cx:8000/Listen.pls http://www.example.com/~user/Mine.mp3
- Alternative and Classical are sub-directories of the directory that this playlist is stored in.
- "Song" and "New Song" are in sub-directories that this playlist is stored in.
- "Stuff" is in the same directory that the playlist is stored in.
- "Foo" is in the specified (Windows) volume and directory, which may or may not be the same directory the playlist is in.
- "Bar" is in a different directory at the same level as the playlist directory. The double-dots reference the parent directory of the playlist directory, then into the sub-directory "Other Music" to reach "Bar".
- "Listen" is a Shoutcast stream.
- "Mine" is an MP3 stored on a web server.
References to other M3U playlists, for example, are generally not well-supported.
#EXTM3U #EXTINF:419,Alice In Chains - Rotten Apple Alice In Chains_Jar Of Flies_01_Rotten Apple.mp3 #EXTINF:260,Alice In Chains - Nutshell Alice In Chains_Jar Of Flies_02_Nutshell.mp3 #EXTINF:255,Alice In Chains - I Stay Away Alice In Chains_Jar Of Flies_03_I Stay Away.mp3 #EXTINF:256,Alice In Chains - No Excuses Alice In Chains_Jar Of Flies_04_No Excuses.mp3 #EXTINF:157,Alice In Chains - Whale And Wasp Alice In Chains_Jar Of Flies_05_Whale And Wasp.mp3 #EXTINF:263,Alice In Chains - Don't Follow Alice In Chains_Jar Of Flies_06_Don't Follow.mp3 #EXTINF:245,Alice In Chains - Swing On This Alice In Chains_Jar Of Flies_07_Swing On This.mp3
See also 
- mp3tag (M3U, EXTM3U)
- Advanced Stream Redirector (ASX)
- B4S - Winamp3 XML based playlist format
- Windows Media Player Playlist (WPL)