The Emms Manual

Table of Contents

Emms Manual

This is the Manual for the Emacs Multimedia System.

© 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2014 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".

Starting out

Emms basics

Advanced Features

Modules and Extensions

Copying and license

Indices

— The Detailed Node Listing —

Here are some other nodes which are really inferiors of the ones
already listed, mentioned here so you can get to them in one step:

Installation

The Core File

Track Information

Extending Emms

1 Introduction

Emms is the Emacs Multi-Media System. It tries to be a clean and small application to play multimedia files from Emacs using external players. Many of its ideas are derived from MpthreePlayer, but it tries to be more general and more clean.

This manual tries to be the definitive source of information about Emms, an online version of the manual is available at: http://www.gnu.org/software/emms/manual/.

The basic functionality of Emms consists of three parts: The core, the sources, and the players.

The core resides in emms.el, and provides a simple playlist and the basic functionality to use all the other features of Emms. It provides the common user commands and interfaces for other parts. It thinks in tracks, where a track is the combination of a type and a name - e.g. the track type ’file has a name that is the file name. Other track types are possible.

To get to tracks, the core needs sources. The file emms-source-file.el provides simple sources to interact with the file system.

When Emms finally has the sources in the playlist, it needs a player to play them. emms-player-simple.el defines a few useful players, and allows you to define your own in a very simple way.

The way Emms works is easy to customize with your own code or by using ‘M-x customize’.

2 Installation

You need to put all the .el files of emms in a directory in your load-path. For example, if you put all those files into ~/elisp/emms/, then in your ~/.emacs, you should do:

(add-to-list 'load-path "~/elisp/emms/lisp/")

2.1 Compiling Emms

If you are using XEmacs, you will need to edit Makefile as follows before continuing.

EMACS=xemacs
SITEFLAG=-no-site-file

You can byte-compile Emms by first entering the directory containing the Emms source code, followed by invoking:

make

Which will byte compile Emms. You can then invoke:

make install

Which will install Emms into your Emacs directories (provided you have the appropriate permissions to do so on your system).

Note that Emms is a light-weight and agile program, you can therefore run Emms just fine without byte compiling it.

3 Simple Setup

After adding the location of the Emms code to the load-path variable, see See Installation. We invoke the following using the ‘emms-setup’ feature which allows for quick and simple Emms setup.

(require 'emms-setup)
(emms-standard)
(emms-default-players)

After which Emms is set-up and ready to go!

The above will setup Emms with standard features (interactive playlists, audio track tag reading etc.) and a default list of players (ogg, mp3, mplayer etc.).

The ‘emms-setup’ feature is provided by the file emms-setup.el. It is essentially a collection of shortcuts for setting up Emms quickly and simply. Everything you can do with ‘emms-setup’ can also be done manually.

We use ‘emms-setup’ by calling one of the setup functions. Each of the functions sets up Emms to include a number of features.

Function: emms-minimalistic

An Emms setup script. Invisible playlists and all the basics for playing media.

Function: emms-standard

An Emms setup script. Everything included in the emms-minimalistic setup, the Emms interactive playlist mode and reading information from tagged audio files.

Function: emms-all

An Emms setup script. Everything included in the emms-standard setup and adds all the stable features which come with the Emms distribution.

Function: emms-devel

An Emms setup script. Everything included in the emms-all setup and adds all of the features which come with the Emms distribution regardless of if they are considered stable or not. Use this if you like living on the edge.

‘emms-setup’ also comes with a convenience function to set a default list of media players.

Function: emms-default-players

Set emms-player-list to emms-setup-default-player-list.

It is also worth noting that you can write your own Emms setup functions like the above by looking at the existing function definitions in emms-setup.el.

4 Configuration

This chapter discusses the configuration of Emms in more detail.

The following code fragment provides a minimal Emms setup without using the layer of ‘emms-setup’. It can maybe be used to better understand the internals of Emms. You can see how Emms needs to know about players (these are defined in ‘emms-player-simple’) and about sources for tracks (trivial file system based sources, such as this ‘emms-directory-tree’, are defined in ‘emms-source-file’).

(require 'emms-player-simple)
(require 'emms-source-file)
(require 'emms-source-playlist)
(setq emms-player-list '(emms-player-mpg321
                         emms-player-ogg123
                         emms-player-mplayer))

For a discussion on how to define additional players, see See Simple Players.

Much of the behaviour of Emms can be changed by setting variables. For example:

(setq emms-info-asynchronously nil)
(setq emms-playlist-buffer-name "*Music*")

The first setq turns off the asynchronous updating of info tags. The second sets the default name of the Emms playlist buffer.

Another way to change Emms variables is to use the M-x customize mechanism provided by Emacs.

4.1 Finding files and speed

Emms needs to traverse directories in order to find playable media. The default method Emms uses to achive this is emms-source-file-directory-tree-internal as defined in emms-source-file.el. The above method is written portably and will always work, but might be too slow if we want to load several hundred tracks (or more).

emms-source-file.el defines another method for finding files, emms-source-file-directory-tree-find which uses GNU/find. emms-source-file-directory-tree-find is usually an order of magnitude faster, but of course will not work if you do not have GNU/find installed.

The method Emms will use is defined in the customisable variable emms-source-file-directory-tree-function.

5 Quickstart Guide

This chapter demonstrates how to setup EMMS so that you can start listening to your music without having to read all of the documentation first.

The first thing you have to do is telling Emacs where the sources of EMMS are located. Let’s say you have them in ~/elisp/emms/. So add this line to your .emacs.

(add-to-list 'load-path "~/elisp/emms/lisp/")

Further informations about installing EMMS can be found in the installation chapter, See Installation.

Let’s say you want to enable all features which are considered stable by the EMMS developers. To achieve this you invoke the emms-all setup function by adding the following three lines to your .emacs.

(require 'emms-setup)
(emms-all)
(emms-default-players)

The function emms-default-players in the last line sets up the list of default players. The list contains lightweight specialized players like ogg123 or mpg321 and we-play-everything-players like mplayer or xine. To be sure that emms can play all your music you should check that the needed players are installed.

Further informations about the several setup scripts can be found in the simple setup chapter, See Simple Setup.

Of course EMMS tries to display the tags of the music files you listen to. For this to work you have to make sure that the appropriate programs are installed. For mp3 files you need ‘mp3info’, and for ogg files you need ‘ogginfo’.

The last thing to do is to tell EMMS the root directory of our music collection. Let’s say all your music is in ~/Music or in subdirectories thereof.

(setq emms-source-file-default-directory "~/Music/")

OK, now we’ve set up EMMS. Reload your .emacs or restart Emacs to let the changes have an effect.

Now we will add all our music to a playlist by invoking M-x emms-add-directory-tree RET ~/Music/ RET. We do this because then EMMS will read the tags of all your music files and cache them. This is required for the browser, See The Browser.

To switch to the playlist buffer, invoke M-x emms-playlist-mode-go or simply M-x emms. You can see that most tracks are displayed with their file name, but track by track the filename gets replaced with the artist and track name of the file’s tag.

Hit RET on a track to start playback.

Now you can start exploring EMMS. It’s probably best to begin with the basic commands (see Basic Commands), the interactive playlists (see Interactive Playlists), and the browser (see The Browser).

6 Getting Help

If you have a bug to report, need help, or wish to suggest a feature, please feel free to use the Emms mailing list. The address of the list is emms-help@gnu.org. To subscribe to it, visit http://lists.gnu.org/mailman/listinfo/emms-help.

If you are familiar with the Gmane service, there is a Gmane newsgroup which mirrors this mailing address at gmane.emacs.emms.user.

Emms also has a website at http://www.gnu.org/software/emms/.

7 Formats and Freedom

Emms is free software, but some of the file formats it can play carry restrictions, they are proprietary file formats. Proprietary software companies are pushing out audio and video formats which restrict when, where and how you can play them, and restrict developers from writing free software which interacts with them.

Restrictive file formats put the corporate bottom-line before the public interest.

Fortunately there are alternatives like Ogg. Ogg is a professional grade multimedia format. Ogg Vorbis is the compressed audio format (like MP3), and Ogg Theora is the video format. For more information, go to http://www.xiph.org/.

If you want to transcode audio into a lossless format, you can try FLAC (Free Lossless Audio Codec). FLAC stands out as the fastest and most widely supported lossless audio codec, and the only one that at once is non-proprietary, is unencumbered by patents and has the source code for a reference implementation freely available. For more information about FLAC, go to http://flac.sourceforge.net/.

8 Basic Commands

Before you can use the interface commands, you need a playlist to start with. The following commands allow you to add to the current playlist from different sources:

Note that the commands with the “emms-add-” prefix add the source to the playlist but do not start playing it immediately. Conversely, the commands with the “emms-play-” prefix begin playing the track immediately.

Function: emms-play-file file

A source for a single file - either file, or queried from the user. If called with a prefix the file will be added like emms-add-file.

Function: emms-add-file file

A source for a single file - either file, or queried from the user. If called with a prefix the file will be played like emms-play-file.

Function: emms-play-directory dir

A source for a whole directory tree - either dir, or queried from the user.

Function: emms-add-directory dir

A source for a whole directory tree - either dir, or queried from the user.

Function: emms-play-directory-tree dir

A source for multiple directory trees - either dir, or the value of emms-source-file-default-directory.

Function: emms-add-directory-tree dir

A source for multiple directory trees - either dir, or the value of emms-source-file-default-directory.

Function: emms-play-url url

A source for an url - for example, for streaming.

Function: emms-add-url url

A source for an url - for example, for streaming.

Function: emms-play-playlist playlist

A source for the M3u or PLS playlist format from the file playlist.

Function: emms-add-playlist playlist

A source for the M3u or PLS playlist format from the file playlist.

Function: emms-play-find dir regexp

A source that will find files in dir or emms-source-file-default-directory which match regexp.

Function: emms-add-find dir regexp

A source that will find files in dir or emms-source-file-default-directory which match regexp.

The basic functionality of Emms is just to play music without being noticed. It provides a few commands to skip the current track and such, but other than that it doesn’t show up. Emms provides the following basic user commands (which you might want to bind to keystrokes):

Function: emms-start

Start playing the current playlist

Function: emms-stop

Stop playing

Function: emms-next

Start playing the next track in the playlist

Function: emms-previous

Start playing previous track in the playlist

Function: emms-shuffle

Shuffle the current playlist. This uses emms-playlist-shuffle-function.

Function: emms-sort

Sort the current playlist. This uses emms-playlist-sort-function.

Function: emms-show &optional insertp

Describe the current Emms track in the minibuffer. If insertp is non-nil, insert the description into the current buffer instead. This function uses emms-show-format to format the current track.

9 The Core File

The core file emms.el provides the all basic functions for playing music, generating playlists and defining players.

9.1 User Variables

The core file defines a number of user variables.

User Option: emms-player-list

A list of players Emms can use. You need to set this in order to use Emms to play media.

User Option: emms-show-format

The format to use for emms-show. Any "%s" is replaced by what emms-track-description-function returns for the currently playing track.

User Option: emms-repeat-playlist

Non-nil if the Emms playlist should automatically repeat the playlist. If nil, playback will stop when the last track finishes playing.

User Option: emms-track-description-function

Function for describing an Emms track in a user-friendly way.

User Option: emms-sort-lessp-function

A function that compares two tracks, and returns non-nil if the first track should be sorted before the second (see also sort).

9.2 Hooks

The core file provides hook variables for the basic functionality of Emms.

User Option: emms-player-started-hook

A hook run when an Emms player started playing.

User Option: emms-player-stopped-hook

A hook run when an Emms player stopped playing. See also emms-player-finished-hook.

User Option: emms-playlist-source-inserted-hook

Hook run when a source got inserted into the playlist. The buffer is narrowed to the new tracks.

User Option: emms-playlist-selection-changed-hook

Hook run after another track is selected in the Emms playlist.

User Option: emms-playlist-cleared-hook

Hook run after the current Emms playlist is cleared. This happens both when the playlist is cleared and when a new buffer is created for it.

User Option: emms-player-finished-hook

Hook run when an Emms player finishes playing a track. Please pay attention to the differences between emms-player-finished-hook and emms-player-stopped-hook. The former is called only when the player is stopped interactively; the latter, only when the player actually finishes playing a track.

User Option: emms-player-paused-hook

Hook run when a player is paused or resumed. Use emms-player-paused-p to find the current state.

9.3 Core Functions

The core file also defines all the functions important to the basic use of Emms.

There are functions which deal with movement in the playlist.

Function: emms-next-noerror

Start playing the next track in the Emms playlist. Unlike emms-next, this function doesn’t signal an error when called at the end of the playlist. This function should only be called when no player is playing. This is a good function to put in emms-player-finished-hook.

Function: emms-playlist-next

Move to the previous track in the current buffer.

Function: emms-playlist-previous

Move to the previous track in the current buffer.

Function: emms-random

Jump to a random track.

Function: emms-toggle-repeat-playlist

Toggle whether emms repeats the playlist after it is done. See emms-repeat-playlist.

Function: emms-toggle-repeat-track

Toggle whether emms repeats the current track. See emms-repeat-track.

Function: emms-toggle-random-playlist

Toggle whether emms plays the tracks randomly or sequentially. See

emms-random-playlist.

Some functions deal with the getting and setting track information.

Function: emms-track type name

Create a track with type type and name name.

Function: emms-track-type track

Return the type of track.

Function: emms-track-name track

Return the name of track.

Function: emms-track-get name track &optional inexistent

Return the value of name for track. If there is no value, return default (or nil, if not given).

Function: emms-track-set track name value

Set the value of name for track to value.

Function: emms-track-description track

Return a description of track. This function uses emms-track-description-function.

Function: emms-player-for track

Return an Emms player capable of playing track. This will be the first player whose PLAYABLEP function returns non-nil, or nil if no such player exists.

Function: emms-playlist-current-selected-track

Return the currently selected track in the current playlist.

There are also functions which deal with the playing itself.

Function: emms-player-start track

Start playing track.

Function: emms-player-stop

Stop the currently playing player.

Function: emms-player-stopped

Declare that the current Emms player is finished. This should only be done by the current player itself.

Function: emms-seek seconds

Seek the current player seconds seconds. This can be a floating point number for sub-second fractions. It can also be negative to seek backwards.

Function: emms-seek-forward

Seek ten seconds forward.

Function: emms-seek-backward

Seek ten seconds backward.

For more basic commands defined in the core file see See Basic Commands.

10 Sources

Sources allow Emms to add and play tracks. Emms comes with a number of sources of its own. Sources are designed so that creating new ones will be easy.

For examples of Emms sources for files and directories see emms-source-file.el.

User Option: emms-source-file-default-directory

The default directory to look for media files.

Function: emms-play-find

Play all files in emms-source-file-default-directory that match a specific regular expression.

Function: emms-source-file &optional file

An Emms source for a single file - either file, or queried from the user.

Function: emms-source-files files

An Emms source for a list of files.

Function: emms-source-directory &optional dir

An Emms source for a whole directory tree - either dir, or queried from the user

Function: emms-source-directory-tree & optional dir

An Emms source for multiple directory trees - either dir, or the value of emms-source-file-default-directory.

Function: emms-source-playlist file

An EMMS source for playlists. See emms-source-playlist-formats for a list of supported formats.

Function: emms-source-playlist-native file

An EMMS source for a native EMMS playlist file.

Function: emms-source-playlist-m3u file

An EMMS source for an m3u playlist file.

Function: emms-source-playlist-pls file

An EMMS source for a pls playlist file.

Function: emms-source-find &optional dir regex

An Emms source that will find files in dir or emms-source-file-default-directory that match regexp.

Function: emms-source-file-directory-tree &optional dir

Return a list of all files under dir which match regex.

Function: emms-source-dired

Play all marked files of a dired buffer

Function: emms-source-file-regex

Return a regexp that matches everything any player (that supports files) can play.

Function: emms-locate regexp

Search for regexp and display the results in a locate buffer

11 Simple Players

Macro: define-emms-simple-player name types regex command &rest args

Define a simple player with the use of ‘emms-define-player’. name is used to construct the name of the function like emms-player-name. types is a list of track types understood by this player. regex must be a regexp that matches the filenames the player can play. command specifies the command line argument to call the player and args are the command line arguments.

For a discussion on how to define new players see See New Player.

Function: emms-player-simple-stop

Stop the currently playing process, if indeed there is one.

Function: emms-player-simple-start filename cmdname params

Starts a process playing filename using the specified cmdname with the specified params.

Function: emms-player-simple-sentinel proc str

Sentinel for determining the end of process for the process proc and the sentinel string str.

12 Playlists

Emms uses Emacs buffers to store the media tracks for playing. We call one such buffer a “playlist buffer” or an “Emms playlist buffer”. Emms then proceeds to play the media tracks in the buffer from top to bottom until the end of the playlist.

The name of the playlist buffer is defined in the variable emms-playlist-buffer-name and is set to be an invisible Emacs buffer by default. You can change to any name you want. For an example configuration see See Configuration.

You can create any number of playlist buffers you wish. At any time Emms has a single “current” buffer through which it proceeds track by track.

Function: emms-playlist-new &optional name

Create a new playlist buffer. The buffer is named name, but made unique. name defaults to ‘emms-playlist-buffer-name’. If called interactively, the new buffer is also selected.

Function: emms-playlist-save &optional format file

Store the current playlist to FILE as the type FORMAT. The default format is specified by emms-source-playlist-default-format.

The current Emms playlist buffer is stored in the variable emms-playlist-buffer.

13 Track Information

Emms is distributed with three predefined methods for retrieving info, provided by emms-info-mp3info.el, emms-info-ogginfo.el and emms-cue.el. The first two packages are front-ends for command-line tools. Ogg track information is retrieved using the ogginfo software. Likewise, mp3 track information is available using mp3info. While, emms-cue.el retrieves tracks information for ape/flac files by parsing a cue sheet file, which is plain text.

Automatic track information retrieval is enabled by default in the ‘emms-standard’, ‘emms-all’ and ‘emms-devel’ setup levels provided by emms-setup.el. For more information about emms-setup.el see See Simple Setup.

If you would like to know how Emms track retreival works and how we can define new methods for track retrieval see See Defining Info Methods.

There are a number of user variables which control the behaviour of ‘emms-info’.

User Option: emms-info-auto-update

Non-nil when Emms should update track information if the file changes. This will cause hard drive activity on track loading. If this is too annoying for you, set this variable to nil.

User Option: emms-info-asynchronously

Non-nil when track information should be loaded asynchronously. This requires the feature ‘later-do’ which is provided by the file later-do.el, which should come with Emms.

User Option: emms-info-functions

Functions which add information to tracks. Each is called with a track as argument.

13.1 Defining Info Methods

An info method essentially consists of a function which given an Emms track returns the appropriate info for that track.

We can for example look at the predefined method for retrieving information about audio tracks in the Ogg format.

The function emms-info-ogginfo provided by emms-info-ogginfo.el accepts an Emms track as a single argument and returns the appropriate information string.

We then register our info function with Emms by adding it to the emms-info-functions list. The function will then be called at the right time to provide track info.

(add-to-list 'emms-info-functions 'emms-info-ogginfo)

14 Interactive Playlists

Emms provides a visual, interactive playlist mode as well as the ability to use playlists without ever looking at then. This visual, interactive mode is called the ‘emms-playlist-mode’ and is defined in emms-playlist-mode.el.

The interactive playlist mode is enabled by default in the ‘emms-standard’, ‘emms-all’ and ‘emms-devel’ setup levels. For more information about Emms setup levels see See Simple Setup.

Function: emms-playlist-mode-go

Switch to the current emms-playlist buffer and use emms-playlist-mode.

If you wish to make this the default EMMS playlist mode, add the following to your .emacs.

(setq emms-playlist-default-major-mode 'emms-playlist-mode)

The interactive playlist buffer shows the tracks in the current Emms playlist in the order in which they will be played. The current track will be highlighted.

When in the interactive playlist mode we can perform different actions on the current playlist.

a

Add files in the playlist at point to the current playlist buffer. If we are in the current playlist, make a new playlist buffer and set it as current.

b

Set the current playlist buffer.

n

Start playing the next track in the playlist.

p

Start playing the previous track in the playlist.

s

Stop playing.

P

Pause.

>

Seek ten seconds forward.

<

Seek ten seconds backward.

f

Describe the currently playing track in the minibuffer.

c

Display the current track in the center of the screen.

RET

Start playing the track under point. Note that this is also available with <mouse-2>.

SPC

Scroll up a near full page.

M-<

Go to the first track in the playlist.

M->

Go to the last track in the playlist.

r

Go to a randomly selected track in the playlist.

q

Put the interactive playlist buffer at the end of the list of all buffers.

C-x C-s

Save the current playlist buffer to a file. By default, Emms will ask you for confirmation before overwriting an existing playlist. You can silently overwrite existing playlist by setting emms-source-playlist-ask-before-overwrite to nil.

?

Describe the mode.

We can also edit the playlist using familiar GNU/Emacs commands:

C-k

Remove the track under point from the playlist buffer. Also available using the d key.

C-y

See the command yank

C-w

See the command kill-region

M-y

See the command yank-pop.

C-j

Insert a newline at point.

We can use the regular GNU/Emacs killing and yanking commands to move and copy tracks in between playlist buffers. We can use the same commands to insert arbitrary text into the playlist buffers together with the playlist tracks. Text which is not a track is ignored by the program and can therefore be used to include titles and annotations within the playlist.

15 Markable Playlists

The Markable Playlists provided by the file emms-mark.el are an alternative to the default interactive playlists, See Interactive Playlists. They allow marking tracks with keybindings familiar to users of dired.

To enable the Markable Playlists you have to add

(require 'emms-mark)

to your .emacs. Then you can activate emms-mark-mode by executing M-x emms-mark-mode in a playlist buffer. You can return to the default interactive playlist mode with M-x emms-mark-mode-disable.

If you wish to make this the default EMMS playlist mode, add the following to your .emacs.

(setq emms-playlist-default-major-mode 'emms-mark-mode)

m

Marks the current track and sets point one line forward. If a prefix argument ARG is given, it will mark the next ARG tracks and set point accordingly. A negative argument marks backward.

U

Unmarks all tracks in the playlist.

t

Toggles mark on the current track.

u

Unmarks same way as emms-mark-forward marks.

% m

Marks all tracks in the playlist matching the given regular expression. A prefix argument means to unmark them instead.

When tracks are marked you can operate on them:

D

Deletes the marked tracks from the playlist.

K

Deletes the marked tracks from the playlist and places them in the kill-ring, so that you can yank in into another playlist.

W

Adds the marked tracks to the kill-ring, so that you can yank them into another playlist.

emms-mark is also intent to provide a way for user to select tracks for other command to operate on them. Currently, emms-tag-editor.el used the emms-mark to edit tags of selected tracks. Two function is useful for elisp programer to handle marked tracks.

Function: emms-mark-do-with-marked-track

This function take a function to perform on all marked tracks. A optional argument ‘move-flag’ to tell the function to move forward line after calling given function. If the given function didn’t change position, the second argument should set to non-nil.

Function: emms-mark-mapcar-marked-track

This function is very similar to ‘emms-mark-do-with-marked-track’ except it collects result of given function (that’s why named with ‘mapcar’).

16 APE / FLAC Commands

Often, a single APE or FLAC file contains a complete ablum. We can still play next or previous track in the ablum with the help of emms-cue.el package, provided there is a corresponding cue sheet file. This package also defines emms-info-cueinfo for retreiving the track information for APE / FLAC itself.

To load emms-cue.el:

(require 'emms-cue)
(add-to-list 'emms-info-functions 'emms-info-cueinfo)

Function: emms-cue-next

Play next track from .cue file

Function: emms-cue-previous

Play previous track from .cue file

17 Bookmarks

Emms can save a “temporal bookmark” in a media file via emms-bookmarks. The file emms-bookmarks.el provides the package emms-bookmarks.

While some media is playing, invoking M-x emms-bookmarks-add will first pause the playback and then prompt for a name describing the bookmark. Tracks can have multiple bookmarks associated with them.

To jump to the next and previous bookmarks in the current track invoke M-x emms-bookmarks-next and M-x emms-bookmarks-prev respectively.

To clear all of the bookmarks for the current track invoke M-x emms-bookmarks-clear.

18 GNU FM

GNU FM is free software for running music community websites. It was created for the music community site, Libre.fm.

Emms can send track information, and stream music from GNU FM servers using emms-librefm-scrobbler.el and emms-librefm-stream.el, respectively.

Emms is configured by default to use Libre.fm, but can work with any GNU FM server by configuring the variable emms-librefm-scrobbler-handshake-url to the URL of the GNU FM server.

Provide your credentials on the GNU FM server by setting the appropriate variables:

(setq emms-librefm-scrobbler-username "USERNAME"
      emms-librefm-scrobbler-password "PASSWORD")

18.1 Uploading Track Information

GNU FM servers, such as Libre.fm can optionally store a user’s listening habits using information sent to the website’s server from the Emms. By utilizing the records of users’ listening habits, the website aims to be able to recommend music to users by analyzing their musical taste.

Load the feature into Emms with:

(require 'emms-librefm-scrobbler)

This feature can also be enabled via See Simple Setup, in the ‘emms-devel’ setup level.

Enable uploading the details of the tracks Emms plays to the GNU FM server with emms-librefm-scrobbler-enable. The track’s details will be uploaded to the server when the track’s playback ends. You can disable this behavior with emms-librefm-scrobbler-disable.

18.2 GNU FM Streaming

If the GNU FM server provides a streaming music service you can take advantage of it by loading:

(require 'emms-librefm-stream)

This feature can also be enabled via See Simple Setup, in the ‘emms-devel’ setup level.

Then invoke emms-librefm-stream and enter the URL of the station you wish to listen to, for example “librefm://globaltags/Classical”.

19 Extending Emms

Emms introduces a high abstraction layer for playing music so you can customise it to your needs.

19.1 New Player

The file emms-player-simple.el defines some easy players to start with, but it shouldn’t be hard to provide a function for your favourite player. We will start with an easy example that shows how we can use the play command under Unix to play our WAV files.

19.2 Simple Player for ‘play’

Play is a very easy command line player for various format. If you want your emms to play WAV files just put the following lines in you .emacs:

(require 'emms-player-simple)
(define-emms-simple-player play '(file) "\\.wav$" "play")

Huh! Wasn’t that easy?

The macro function define-emms-simple-player takes a minimum of three arguments. The first argument (play in our example) defines the name of the player. It’s used to name the player functions. The second is a regexp, that defines which files to play with our player. \\.wav$ matches any filename ending with a dot and the string wav. The last argument is the actual command line command we use to play our files. You can also add the path but we just assume that the command is in your path. All arguments you add to these three are optional. They define the command line arguments you want to add to your argument. If you want to hear the wav file of your favourite artist in the most possible volume use the following line:

(require 'emms-player-simple)

(define-emms-simple-player play
                           '(file)
                           "\\artist-*.wav$"
                           "play"
                           "--volume=100")

Please notice that you have to add the arguments as strings!

The command line tool you use for define-emms-simple-player has to take one song as argument and stop after playing that particular song. For any other concept you will need to customise emms a bit more...

19.3 More Complex Player

The most players you use will be simple players so you don’t need to read this chapter. But if you are curious how you can use (almost) every player in emms read further...

In this chapter we will use mpg321 to construct a player that actually can pause a track, restart it and show rest time. We won’t implement all of that, but after that chapter you will know how to define it.

The command define-emms-simple-player is just a abstraction layer for define-emms-player, which is a little bit more complicated but much more powerful!

(define-emms-player "emms-mpg321-remote"
  :start 'emms-mpg321-remote-start
  :stop 'emms-mpg321-remote-stop
  :playablep 'emms-mpg321-remote-playable-p)

So, that is almost all! define-emms-player takes a minimum of three arguments. The first is the name of the player. The rest are methods with functions to call. Three methods are required: start, stop and playable. Start says Emms how to start a track (sic!), stop how to stop a player and playablep should return non-nil if the player can play the track.

So we just need these three functions to get our mpg321-remote:

First we code the start function. We will check if there’s a open process and start one otherwise. Then we send a string to the process with the filename and set a filter.

(defun emms-mpg321-remote-start ()
  (unless (get-process ``mpg321-remote'')
    (setq emms-mpg321-remote-process
          (start-process "mpg321-remote-process"
                         "*mpg321*" "mpg321" "-R" "abc"))
  (process-send-string "mpg321-remote-process"
                       (concat "l " (emms-track-name track)))
  (set-process-filter emms-mpg321-remote-process 'emms-mpg321-remote-filter)))

We need the filter, as mpg321-remote won’t quit after playing the track as the simple player do. We wait until the process sends the output “(at-sign)P 0” (the signal of mpg321 that the song ended) to the filter and call emms-mpg321-remote-stop.

(defun emms-mpg321-remote-filter (process output)
  (when (string-match "(at-sign)P 0" output)
    (emms-mpg321-remote-stop)))

emms-mpg321-remote-stop won’t do anything interesting. It just test if there are other files to play and close the process otherwise.

(defun emms-mpg321-remote-stop ()
  (unless emms-playlist
    (process-send-string "mpg321-remote-process" "Q\n"))

And to make that a playable example I also added emms-mpg321-remote-playablep, which I really just steal from emms-player-simple.el

(defun emms-mpg321-remote-playablep (track)
       "Return non-nil when we can play this track."
       (and (eq 'file (emms-track-type track))

Now we have a ready player and we could add commands like emms-mpg321-remote-pause for example.

20 The Browser

The Browser allows you to browse the metadata cache and add tracks to your playlist. It includes a powerful interactive mode.

The Browser is defined in emms-browser.el and is included in the emms-all setup level. For more information about Emms setup levels see See Simple Setup.

You can also manually add the Browser to your Emms setup by loading it explicitly with:

(require 'emms-browser)

To be properly useful, you should do M-x emms-add-directory-tree to all the files you own at least once so that the cache is fully populated.

20.1 Browser Interface

The browser interface allows you to display and interact with your tracks in many different ways. There are a number of ways to start the browser.

Function: emms-smart-browse

Display browser and playlist. Toggle between selecting browser, playlist or hiding both. Tries to behave sanely if the user has manually changed the window configuration.

Function: emms-browse-by-artist

Display the browser and order the tracks by artist.

Function: emms-browse-by-album

Display the browser and order the tracks by album.

Function: emms-browse-by-genre

Display the browser and order the tracks by genre.

Function: emms-browse-by-year

Display the browser and order the tracks by year.

Once the Browser is displayed you can use it to managed your track collection and playlists. The Browser is interactive and has its own keybindings.

C-j

Add all tracks at point, and play the first added track.

RET

Add all tracks at point.

SPC

Show or hide (kill) subitems under the current line.

1

Collapse everything.

2

Expand all top level items one level.

3

Expand all top level items two levels.

4

Expand all top level items three levels.

C

Clear the playlist.

E

Expand everything.

d

View the current directory in dired.

q

Bury the browser buffer.

r

Jump to a random track.

/

Isearch through the buffer.

<

Redisplay with the previous filter.

>

Redisplay with the next filter.

?

See the Emacs documentation for the function.

C-/

Undo the previous playlist action.

<C-return>

Add all tracks at point, and play the first added track.

<backtab>

Jump to the previous non-track element.

<tab>

Jump to the next non-track element.

s A

Search the collection by album.

s a

Search the collection by artist.

s s

Search the collection by names.

s t

Search the collection by title.

b 1

Browse the collection by artist.

b 2

Browse the collection by album.

b 3

Browse the collection by genre.

b 4

Browse the collection by year.

W a p

Lookup the album using Pitchfork.

W a w

Lookup the album using Wikipedia.

20.2 Filtering Tracks

If you want to display a subset of your collection (such as a directory of 80s music, only avi files, etc.) then you can extend the Browser by defining “filters”.

Show everything:

(emms-browser-make-filter "all" 'ignore)

Set "all" as the default filter:

(emms-browser-set-filter (assoc "all" emms-browser-filters))

Show all files (no streamlists, etc):

(emms-browser-make-filter
 "all-files" (emms-browser-filter-only-type 'file))

Show only tracks in one folder:

(emms-browser-make-filter
 "80s" (emms-browser-filter-only-dir "~/Mp3s/80s"))

Show all tracks played in the last month:

(emms-browser-make-filter
 "last-month" (emms-browser-filter-only-recent 30))

After executing the above commands, you can use M-x emms-browser-show-all, emms-browser-show-80s, etc to toggle between different collections. Alternatively you can use ’<’ and ’>’ to cycle through the available filters.

The second argument to make-filter is a function which returns t if a single track should be filtered. You can write your own filter functions to check the type of a file, etc.

Show only tracks not played in the last year:

(emms-browser-make-filter "not-played"
 (lambda (track)
  (not (funcall (emms-browser-filter-only-recent 365) track))))

Show all files that are not in the pending directory:

(emms-browser-make-filter
 "all"
 (lambda (track)
   (or
    (funcall (emms-browser-filter-only-type 'file) track)
    (not (funcall
          (emms-browser-filter-only-dir "~/Media/pending") track)))))

20.3 Displaying Covers

The browser will attempt to display cover images if they’re available. By default it looks for images cover_small.jpg, cover_med.jpg, etc. Customize emms-browser-covers to use your own covers. Note that you’ll probably want to resize your existing covers to particular sizes. Suggested sizes are 100x100 for small, and 200x200 for medium.

Also, Emacs by default will jump around a lot when scrolling a buffer with images. In order to prevent that, you can set scroll-up-aggressively and scroll-down-aggressively to the number “0.0”.

To show a ’no cover’ image for albums which don’t have a cover, add the following code to your .emacs:

(setq emms-browser-default-covers
  (list "/path/to/cover_small.jpg" nil nil)

The medium and large images can be set as well.

You can download an example ‘no cover’ image.

20.4 Changing Looks

The Browser’s look can be customised. You can change the way the tree structure looks, the display format and display faces.

Changing Tree Structure

You can change the way the tree is displayed by modifying the function emms-browser-next-mapping-type.

The following code displays artist->track instead of artist->album->track when you switch to the ’singles’ filter:

(defadvice emms-browser-next-mapping-type
                                (after no-album (current-mapping))
  (when (eq ad-return-value 'info-album)
    (setq ad-return-value 'info-title)))

(defun toggle-album-display ()
  (if (string= emms-browser-current-filter-name "singles")
      (ad-activate 'emms-browser-next-mapping-type)
    (ad-deactivate 'emms-browser-next-mapping-type)))

(add-hook 'emms-browser-filter-changed-hook 'toggle-album-display)

Changing Display Format

Format strings govern the way items are displayed in the browser and playlist. You can customize these if you wish.

emms-browser-default-format controls the format to use when no other format has been explicitly defined. By default, only track and albums deviate from the default.

To customise the format of a particular type, find the name of the field you want to use (eg ‘info-artist’, ‘info-title’, etc), and insert that into emms-browser-<type>-format or emms-browser-playlist-<type>-format. For example, if you wanted to remove track numbers from tracks in both the browser and playlist, you could do:

(defvar emms-browser-info-title-format "%i%n")
(defvar emms-browser-playlist-info-title-format
  emms-browser-info-title-format)

The format specifiers available include:

• %i indent relative to the current level
• %n the value of the item - eg -info-artist might be “pink floyd”
• %y the album year
• %A the album name
• %a the artist name of the track
• %t the title of the track
• %T the track number
• %cS a small album cover
• %cM a medium album cover
• %cL a big album cover

Note that if you use track-related items like %t, it will take the data from the first track.

Changing Display Faces

The faces used to display the various fields are also customizable. They are in the format emms-browser-<type>-face, where type is one of "year/genre", "artist", "album" or "track". Note that faces lack the initial "info-" part. For example, to change the artist face, type M-x customize-face emms-browser-artist-face.

21 Sorting Playlists

The ‘emms-playlist-sort’ module, defined in the emms-playlist-sort.el package provides functions for sorting Emms playlists. ‘emms-playlist-sort’ can be loaded by invoking:

(require 'emms-playlist-sort)

Function: emms-playlist-sort-by-name

Sort playlist by name in ascending order.

Function: emms-playlist-sort-by-info-artist

Sort playlist by artist in ascending order.

Function: emms-playlist-sort-by-info-title

Sort playlist by title in ascending order.

Function: emms-playlist-sort-by-info-album

Sort playlist by album in ascending order.

Function: emms-playlist-sort-by-info-year

Sort playlist by year in ascending order.

Function: emms-playlist-sort-by-info-note

Sort playlist by notes in ascending order.

22 Persistent Playlists

The Emms module emms-history.el makes playlists persistent over emacs sessions. To make use of this feature put this into your ~/.emacs.

(require 'emms-history)

When you kill emacs all playlists will be saved in the file given by the variable:

User Option: emms-history-file

The file to save playlists in. It defaults to "~/.emacs.d/emms-history".

After you started up emacs again, you can restore all saved playlists with this function.

Function: emms-history-load

Restore all playlists in ‘emms-history-file’.

If that should be done automatically on each startup, put these lines into your ~/.emacs.

(require 'emms-history)
(emms-history-load)

Normally emms-history only restores playlists. If you want it to start playback afterwards, you can tweak this variable.

User Option: emms-history-start-playing

If non-nil emms starts playing the current track after ‘emms-history-load’ was invoked. The default value is nil.

23 Editing Tracks

Using emms-tag-editor.el, emms can set tag informations of tracks and write them back to the file with the help of external programs, such as ‘mp3info’, ‘vorbiscomment’.

Use the keybinding E to edit the tags of track under point in the playlist or all marked tracks (see Markable Playlists for how to mark tracks). The track’s tag informations are listed in a special buffer ‘*EMMS-TAGS*’ in text format. Field names are marked in bold face and are not editable. Any tag information is placed behind an equal sign and is changable. A special field ‘name’ is the track’s file name. If any change is made in this field, the track’s file will be renamed to the new name. When you finished editing the tag infos use C-c C-c (which calls emms-tag-editor-submit-and-exit) to submit the changes and close the ‘*EMMS-TAGS*’ buffer.

There are a few commands to perform changes on all tracks.

Function: emms-tag-editor-set-all tag value

Set TAG to VALUE in all tracks.

If transient-mark-mode is turned on, you can apply the command to a selected region.

If ‘transient-mark-mode’ is on and the mark is active, the changes will only take effect on the tracks in the region.

Function: emms-tag-editor-replace-in-tag tag from to

Query and replace text in selected TAG.

For example, if the info-title tag is selected, then only perform replacement in title tags.

If ‘transient-mark-mode’ is on and the mark is active, the changes will only take effect on the tracks in the region.

Function: emms-tag-editor-transpose-tag tag1 tag2

Transpose value of TAG1 and TAG2.

If ‘transient-mark-mode’ is on and the mark is active, the changes will only take effect on the tracks in the region.

Function: emms-tag-editor-submit arg

Make modified tags take affect.

With prefix argument, bury the tag edit buffer.

If you want to extend the tag editor to work with file formats other than ‘mp3’ and ‘ogg’, have a look at these variables.

Variable: emms-tag-editor-formats

This variable determine how to insert track fields to ‘emms-tag-editor-edit-buffer’. Emms tag info editable fields is usually determined by the extension of track name. The variable ‘emms-tag-editor-tags’ contains all tags that emms track may have. A single charactar is assigned to the tag to make the ‘emms-tag-editor-formats’ easier to generate.

Variable: emms-tag-editor-tagfile-functions

To write tags to track file, an extern program should specified in this variable.

If the external program has an interface like ‘mp3info’, you don’t have to write a function. Take ‘mp3’ and ‘ogg’ as example.

Renaming Files

The tag editor is also capable to rename the file of the track at point or all files of the marked tracks according to the value this variable.

User Option: emms-tag-editor-rename-format

When ‘emms-tag-editor-rename’ is invoked the track’s file will be renamed according this format specification. The file extension will be added automatically.

It uses the format specs defined in emms-tag-editor-tags.

The default value is "%a - %l - %n - %t", so that files are named

<Artist> - <Album> - <Tracknumber> - <Title>.<extension>

after renaming.

To perform the renaming put point on the track you want to rename or mark some tracks. Then hit R which calls this function:

Function: emms-tag-editor-rename

Rename the file corresponding to track at point or all marked tracks according to the value of emms-tag-editor-rename-format.

24 Emms Mode Line

We can display information about the currenty playing track on the Emacs mode line using the package ‘emms-mode-line’ which is provided by the file emms-mode-line.el.

To activate this feature invoke:

(require 'emms-mode-line)
(emms-mode-line 1)

It is also possible to display the amount of time a track has been playing. This feature is defined in the ‘emms-playing-time’ package which is provided by the file emms-playing-time.el.

To use this feature invoke:

(require 'emms-playing-time)
(emms-playing-time 1)

Note: ‘(emms-playing-time -1)’ will disable emms-playing-time module completely, and is not recommended. (since some other emms modules may rely on it)

Instead, to toggle displaying playing time on mode line, one could call ‘emms-playing-time-enable-display’ and ‘emms-playing-time-disable-display’."

Function: emms-playing-time-enable-display

Display playing time on mode line.

Function: emms-playing-time-disable-display

Remove playing time from mode line.

25 Music Player Daemon

Emms provides an interface to the Music Player Daemon(MusicPD) software. The package is called ‘emms-player-mpd’ and is provided by the file emms-player-mpd.el.

The advantages of using MusicPD as an EMMS backend include the following.

• minimal CPU usage
• fast access of track information
• optional crossfade

Setup

To load ‘emms-player-mpd’ invoke:

(require 'emms-player-mpd)

Set the variables emms-player-mpd-server-name and emms-player-mpd-server-port to the location and port (respectively) of your MusicPD server. For example:

(setq emms-player-mpd-server-name "localhost")
(setq emms-player-mpd-server-port "6600")

If your MusicPD setup requires a password, you will to set emms-player-mpd-server-password as follows.

(setq emms-player-mpd-server-password "mypassword")

To get track information from MusicPD, invoke the following:

(add-to-list 'emms-info-functions 'emms-info-mpd)

Adding ‘emms-player-mpd’ to your Emms player list is accomplished by invoking:

(add-to-list 'emms-player-list 'emms-player-mpd)

If you use absolute file names in your m3u playlists (which is most likely), make sure you set emms-player-mpd-music-directory to the value of "music_directory" from your MusicPD config. There are additional options available as well, but the defaults should be sufficient for most uses.

You can set emms-player-mpd-sync-playlist to nil if your master EMMS playlist contains only stored playlists.

Commands provided

Function: emms-player-mpd-connect

Connect to MusicPD and retrieve its current playlist. Afterward, the status of MusicPD will be tracked.

Function: emms-player-mpd-disconnect

Terminate the MusicPD client process and disconnect from MusicPD.

Function: emms-player-mpd-show &optional insertp

Describe the current EMMS track in the minibuffer. If INSERTP is non-nil, insert the description into the current buffer instead. This function uses emms-show-format to format the current track. It differs from emms-show in that it asks MusicPD for the current track, rather than Emms.

Updating the MusicPD database

Function: emms-player-mpd-update-directory dir

Cause the tracks in DIR to be updated in the MusicPD database.

Function: emms-player-mpd-update-all

Cause all tracks in the MusicPD music directory to be updated in the MusicPD database.

emms-cache.el integration

Function: emms-cache-set-from-mpd-directory dir

Dump all MusicPD data from DIR into the EMMS cache. This is useful to do when you have recently acquired new music.

Function: emms-cache-set-from-mpd-all

Dump all MusicPD data into the EMMS cache. This is useful to do once, just before using emms-browser.el, in order to prime the cache.

emms-volume.el integration

To activate this, add the following to your .emacs.

(require 'emms-volume)
(setq emms-volume-change-function 'emms-volume-mpd-change)

26 Lyrics

We can display the lyrics of a song in time with the music using the ‘emms-lyrics’ package provided by the file emms-lyrics.el.

The lyrics files should have the extention “.lrc”, and can be placed under either the same directory as the music files or emms-lyrics-dir.

To add this feature we invoke:

(require 'emms-lyrics)
(emms-lyrics 1)

There are a number of variables we can set to define the way that ‘emms-lyrics’ behaves, we can set these directly or by using the Customize feature in Emacs.

User Option: emms-lyrics-display-on-minibuffer

If non-nil, display lyrics on minibuffer.

User Option: emms-lyrics-display-on-modeline

If non-nil, display lyrics on modeline.

User Option: emms-lyrics-dir

Local lyrics repository. emms-lyrics-find-lyric will look for lyrics in current directory(i.e., same as the music file) and this directory.

User Option: emms-lyrics-display-format

Format for displaying lyrics. "%s" will be replaced by the lyrics string.

User Option: emms-lyrics-coding-system

Coding system used in the output of lyrics.

User Option: emms-lyrics-scroll-p

Non-nil value will enable lyrics scrolling.

User Option: emms-lyrics-scroll-timer-interval

Interval between scroller timers. The shorter, the faster.

We can control ‘emms-lyrics’ with the help of the following functions:

Function: emms-lyrics-start

Start displaying lyrics.

Function: emms-lyrics-stop

Stop displaying lyrics.

Function: emms-lyrics-toggle-display-on-minibuffer

Toggle display lyrics on minibufer.

Function: emms-lyrics-toggle-display-on-modeline

Toggle display lyrics on mode line.

Function: emms-lyrics-enable

Enable displaying Emms lyrics.

Function: emms-lyrics-disable

Disable displaying Emms lyrics.

Function: emms-lyrics-toggle

Toggle displaying Emms lyrics.

27 Volume

We can use the ‘emms-volume’ package, as provided by the emms-volume.el file, to manipulate the volume.

User Option: emms-volume-change-amount

The amount to use when raising or lowering the volume using the emms-volume interface.

This should be a positive integer.

Function: emms-volume-raise

Increase the volume.

Function: emms-volume-lower

Decrease the volume.

If you feel like binding those two functions to global keys — don’t do it or you’ll miss the convenience of ‘emms-volume-minor-mode’. Instead, bind the following two commands to some keys that you like.

Function: emms-volume-mode-plus

Raise volume and enable or extend the ‘emms-volume-minor-mode’ timeout.

Function: emms-volume-mode-minus

Lower volume and enable or extend the ‘emms-volume-minor-mode’ timeout.

Example:

(global-set-key (kbd "C-c +") 'emms-volume-mode-plus)
(global-set-key (kbd "C-c -") 'emms-volume-mode-minus)

Whenever you use one of these keys or call these functions with M-x, Emms will be put into ‘emms-volume-minor-mode’ for a short period defined by ‘emms-volume-mode-timeout’.

User Option: emms-volume-mode-timeout

The timeout in amount of seconds used by ‘emms-volume-minor-mode’.

In this interval you can raise/lower the volume simply by pressing + or -, which will also reset the timer to its initial value. So instead of pressing C-c + six times to increase volume by six steps of emms-volume-change-amount, you would simply type C-c + + + + + +.

28 Streaming Audio

Emms provides a friendly interface for managing and playing streaming audio in addition to the Emms playlist interface. The interface is defined in the emms-streams.el package and can be loaded by invoking:

(require 'emms-streams)

The Emms interface for streaming audio is enabled by default in the ‘emms-all’ and ‘emms-devel’ setup levels. For more information about Emms setup levels see See Simple Setup.

Enter the emms-streams interface by invoking M-x emms-streams. The emms-streams interface comes with a built-in, eclectic list of streaming audio channels from throughout the Web. Emms can of-course play other streams than the ones listed by default, you are free to remove any or all of them and add your own.¹

The following is a list of the key-bindings for the emms-streams interface:

RET

Perform the default action when you press RET in the Emms Stream interface. Can be either “add” or “play”. The default is “add”, which adds the station under point to the Emms playlist. When emms-stream-default-action is “play” then Emms will play the streaming audio channel under point.

q

Quit the emms-streams interface.

a

Add a bookmark to a streaming audio URL to the list.

d

Remove a bookmark to a streaming audio URL from the list.

e

Edit the details of the bookmark under point.

h

Describe the emms-streams mode.

n

Move to the next line in the emms-streams buffer (same as C-n).

p

Move to the previous line in the emms-streams buffer (same as C-p).

s

Save the bookmarks in the emms-streams interface to disk. The bookmarks will be to the location designated in the variable emms-stream-bookmarks-file.

i

Return information about the streaming audio at the URL of the bookmark under point. Note that this will only work if the ‘emms-stream-info’ has already been loaded.

GNU General Public License

Copyright © 2007 Free Software Foundation, Inc. http://fsf.org/

Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.

Preamble

The GNU General Public License is a free, copyleft license for software and other kinds of works.

The licenses for most software and other practical works are designed to take away your freedom to share and change the works. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change all versions of a program–to make sure it remains free software for all its users. We, the Free Software Foundation, use the GNU General Public License for most of our software; it applies also to any other work released this way by its authors. You can apply it to your programs, too.

When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for them if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs, and that you know you can do these things.

To protect your rights, we need to prevent others from denying you these rights or asking you to surrender the rights. Therefore, you have certain responsibilities if you distribute copies of the software, or if you modify it: responsibilities to respect the freedom of others.

For example, if you distribute copies of such a program, whether gratis or for a fee, you must pass on to the recipients the same freedoms that you received. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.

Developers that use the GNU GPL protect your rights with two steps: (1) assert copyright on the software, and (2) offer you this License giving you legal permission to copy, distribute and/or modify it.

For the developers’ and authors’ protection, the GPL clearly explains that there is no warranty for this free software. For both users’ and authors’ sake, the GPL requires that modified versions be marked as changed, so that their problems will not be attributed erroneously to authors of previous versions.

Some devices are designed to deny users access to install or run modified versions of the software inside them, although the manufacturer can do so. This is fundamentally incompatible with the aim of protecting users’ freedom to change the software. The systematic pattern of such abuse occurs in the area of products for individuals to use, which is precisely where it is most unacceptable. Therefore, we have designed this version of the GPL to prohibit the practice for those products. If such problems arise substantially in other domains, we stand ready to extend this provision to those domains in future versions of the GPL, as needed to protect the freedom of users.

Finally, every program is threatened constantly by software patents. States should not allow patents to restrict development and use of software on general-purpose computers, but in those that do, we wish to avoid the special danger that patents applied to a free program could make it effectively proprietary. To prevent this, the GPL assures that patents cannot be used to render the program non-free.

The precise terms and conditions for copying, distribution and modification follow.

1. Definitions.

   “This License” refers to version 3 of the GNU General Public License.

   “Copyright” also means copyright-like laws that apply to other kinds of works, such as semiconductor masks.

   “The Program” refers to any copyrightable work licensed under this License. Each licensee is addressed as “you”. “Licensees” and “recipients” may be individuals or organizations.

   To “modify” a work means to copy from or adapt all or part of the work in a fashion requiring copyright permission, other than the making of an exact copy. The resulting work is called a “modified version” of the earlier work or a work “based on” the earlier work.

   A “covered work” means either the unmodified Program or a work based on the Program.

   To “propagate” a work means to do anything with it that, without permission, would make you directly or secondarily liable for infringement under applicable copyright law, except executing it on a computer or modifying a private copy. Propagation includes copying, distribution (with or without modification), making available to the public, and in some countries other activities as well.

   To “convey” a work means any kind of propagation that enables other parties to make or receive copies. Mere interaction with a user through a computer network, with no transfer of a copy, is not conveying.

   An interactive user interface displays “Appropriate Legal Notices” to the extent that it includes a convenient and prominently visible feature that (1) displays an appropriate copyright notice, and (2) tells the user that there is no warranty for the work (except to the extent that warranties are provided), that licensees may convey the work under this License, and how to view a copy of this License. If the interface presents a list of user commands or options, such as a menu, a prominent item in the list meets this criterion.

2. Source Code.

   The “source code” for a work means the preferred form of the work for making modifications to it. “Object code” means any non-source form of a work.

   A “Standard Interface” means an interface that either is an official standard defined by a recognized standards body, or, in the case of interfaces specified for a particular programming language, one that is widely used among developers working in that language.

   The “System Libraries” of an executable work include anything, other than the work as a whole, that (a) is included in the normal form of packaging a Major Component, but which is not part of that Major Component, and (b) serves only to enable use of the work with that Major Component, or to implement a Standard Interface for which an implementation is available to the public in source code form. A “Major Component”, in this context, means a major essential component (kernel, window system, and so on) of the specific operating system (if any) on which the executable work runs, or a compiler used to produce the work, or an object code interpreter used to run it.

   The “Corresponding Source” for a work in object code form means all the source code needed to generate, install, and (for an executable work) run the object code and to modify the work, including scripts to control those activities. However, it does not include the work’s System Libraries, or general-purpose tools or generally available free programs which are used unmodified in performing those activities but which are not part of the work. For example, Corresponding Source includes interface definition files associated with source files for the work, and the source code for shared libraries and dynamically linked subprograms that the work is specifically designed to require, such as by intimate data communication or control flow between those subprograms and other parts of the work.

   The Corresponding Source need not include anything that users can regenerate automatically from other parts of the Corresponding Source.

   The Corresponding Source for a work in source code form is that same work.

3. Basic Permissions.

   All rights granted under this License are granted for the term of copyright on the Program, and are irrevocable provided the stated conditions are met. This License explicitly affirms your unlimited permission to run the unmodified Program. The output from running a covered work is covered by this License only if the output, given its content, constitutes a covered work. This License acknowledges your rights of fair use or other equivalent, as provided by copyright law.

   You may make, run and propagate covered works that you do not convey, without conditions so long as your license otherwise remains in force. You may convey covered works to others for the sole purpose of having them make modifications exclusively for you, or provide you with facilities for running those works, provided that you comply with the terms of this License in conveying all material for which you do not control copyright. Those thus making or running the covered works for you must do so exclusively on your behalf, under your direction and control, on terms that prohibit them from making any copies of your copyrighted material outside their relationship with you.

   Conveying under any other circumstances is permitted solely under the conditions stated below. Sublicensing is not allowed; section 10 makes it unnecessary.

4. Protecting Users’ Legal Rights From Anti-Circumvention Law.

   No covered work shall be deemed part of an effective technological measure under any applicable law fulfilling obligations under article 11 of the WIPO copyright treaty adopted on 20 December 1996, or similar laws prohibiting or restricting circumvention of such measures.

   When you convey a covered work, you waive any legal power to forbid circumvention of technological measures to the extent such circumvention is effected by exercising rights under this License with respect to the covered work, and you disclaim any intention to limit operation or modification of the work as a means of enforcing, against the work’s users, your or third parties’ legal rights to forbid circumvention of technological measures.

5. Conveying Verbatim Copies.

   You may convey verbatim copies of the Program’s source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice; keep intact all notices stating that this License and any non-permissive terms added in accord with section 7 apply to the code; keep intact all notices of the absence of any warranty; and give all recipients a copy of this License along with the Program.

   You may charge any price or no price for each copy that you convey, and you may offer support or warranty protection for a fee.

6. Conveying Modified Source Versions.

   You may convey a work based on the Program, or the modifications to produce it from the Program, in the form of source code under the terms of section 4, provided that you also meet all of these conditions:

   1. The work must carry prominent notices stating that you modified it, and giving a relevant date.
   2. The work must carry prominent notices stating that it is released under this License and any conditions added under section 7. This requirement modifies the requirement in section 4 to “keep intact all notices”.
   3. You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy. This License will therefore apply, along with any applicable section 7 additional terms, to the whole of the work, and all its parts, regardless of how they are packaged. This License gives no permission to license the work in any other way, but it does not invalidate such permission if you have separately received it.
   4. If the work has interactive user interfaces, each must display Appropriate Legal Notices; however, if the Program has interactive interfaces that do not display Appropriate Legal Notices, your work need not make them do so.

   A compilation of a covered work with other separate and independent works, which are not by their nature extensions of the covered work, and which are not combined with it such as to form a larger program, in or on a volume of a storage or distribution medium, is called an “aggregate” if the compilation and its resulting copyright are not used to limit the access or legal rights of the compilation’s users beyond what the individual works permit. Inclusion of a covered work in an aggregate does not cause this License to apply to the other parts of the aggregate.

7. Conveying Non-Source Forms.

   You may convey a covered work in object code form under the terms of sections 4 and 5, provided that you also convey the machine-readable Corresponding Source under the terms of this License, in one of these ways:

   1. Convey the object code in, or embodied in, a physical product (including a physical distribution medium), accompanied by the Corresponding Source fixed on a durable physical medium customarily used for software interchange.
   2. Convey the object code in, or embodied in, a physical product (including a physical distribution medium), accompanied by a written offer, valid for at least three years and valid for as long as you offer spare parts or customer support for that product model, to give anyone who possesses the object code either (1) a copy of the Corresponding Source for all the software in the product that is covered by this License, on a durable physical medium customarily used for software interchange, for a price no more than your reasonable cost of physically performing this conveying of source, or (2) access to copy the Corresponding Source from a network server at no charge.
   3. Convey individual copies of the object code with a copy of the written offer to provide the Corresponding Source. This alternative is allowed only occasionally and noncommercially, and only if you received the object code with such an offer, in accord with subsection 6b.
   4. Convey the object code by offering access from a designated place (gratis or for a charge), and offer equivalent access to the Corresponding Source in the same way through the same place at no further charge. You need not require recipients to copy the Corresponding Source along with the object code. If the place to copy the object code is a network server, the Corresponding Source may be on a different server (operated by you or a third party) that supports equivalent copying facilities, provided you maintain clear directions next to the object code saying where to find the Corresponding Source. Regardless of what server hosts the Corresponding Source, you remain obligated to ensure that it is available for as long as needed to satisfy these requirements.
   5. Convey the object code using peer-to-peer transmission, provided you inform other peers where the object code and Corresponding Source of the work are being offered to the general public at no charge under subsection 6d.

   A separable portion of the object code, whose source code is excluded from the Corresponding Source as a System Library, need not be included in conveying the object code work.

   A “User Product” is either (1) a “consumer product”, which means any tangible personal property which is normally used for personal, family, or household purposes, or (2) anything designed or sold for incorporation into a dwelling. In determining whether a product is a consumer product, doubtful cases shall be resolved in favor of coverage. For a particular product received by a particular user, “normally used” refers to a typical or common use of that class of product, regardless of the status of the particular user or of the way in which the particular user actually uses, or expects or is expected to use, the product. A product is a consumer product regardless of whether the product has substantial commercial, industrial or non-consumer uses, unless such uses represent the only significant mode of use of the product.

   “Installation Information” for a User Product means any methods, procedures, authorization keys, or other information required to install and execute modified versions of a covered work in that User Product from a modified version of its Corresponding Source. The information must suffice to ensure that the continued functioning of the modified object code is in no case prevented or interfered with solely because modification has been made.

   If you convey an object code work under this section in, or with, or specifically for use in, a User Product, and the conveying occurs as part of a transaction in which the right of possession and use of the User Product is transferred to the recipient in perpetuity or for a fixed term (regardless of how the transaction is characterized), the Corresponding Source conveyed under this section must be accompanied by the Installation Information. But this requirement does not apply if neither you nor any third party retains the ability to install modified object code on the User Product (for example, the work has been installed in ROM).

   The requirement to provide Installation Information does not include a requirement to continue to provide support service, warranty, or updates for a work that has been modified or installed by the recipient, or for the User Product in which it has been modified or installed. Access to a network may be denied when the modification itself materially and adversely affects the operation of the network or violates the rules and protocols for communication across the network.

   Corresponding Source conveyed, and Installation Information provided, in accord with this section must be in a format that is publicly documented (and with an implementation available to the public in source code form), and must require no special password or key for unpacking, reading or copying.

8. Additional Terms.

   “Additional permissions” are terms that supplement the terms of this License by making exceptions from one or more of its conditions. Additional permissions that are applicable to the entire Program shall be treated as though they were included in this License, to the extent that they are valid under applicable law. If additional permissions apply only to part of the Program, that part may be used separately under those permissions, but the entire Program remains governed by this License without regard to the additional permissions.

   When you convey a copy of a covered work, you may at your option remove any additional permissions from that copy, or from any part of it. (Additional permissions may be written to require their own removal in certain cases when you modify the work.) You may place additional permissions on material, added by you to a covered work, for which you have or can give appropriate copyright permission.

   Notwithstanding any other provision of this License, for material you add to a covered work, you may (if authorized by the copyright holders of that material) supplement the terms of this License with terms:

   1. Disclaiming warranty or limiting liability differently from the terms of sections 15 and 16 of this License; or
   2. Requiring preservation of specified reasonable legal notices or author attributions in that material or in the Appropriate Legal Notices displayed by works containing it; or
   3. Prohibiting misrepresentation of the origin of that material, or requiring that modified versions of such material be marked in reasonable ways as different from the original version; or
   4. Limiting the use for publicity purposes of names of licensors or authors of the material; or
   5. Declining to grant rights under trademark law for use of some trade names, trademarks, or service marks; or
   6. Requiring indemnification of licensors and authors of that material by anyone who conveys the material (or modified versions of it) with contractual assumptions of liability to the recipient, for any liability that these contractual assumptions directly impose on those licensors and authors.

   All other non-permissive additional terms are considered “further restrictions” within the meaning of section 10. If the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term. If a license document contains a further restriction but permits relicensing or conveying under this License, you may add to a covered work material governed by the terms of that license document, provided that the further restriction does not survive such relicensing or conveying.

   If you add terms to a covered work in accord with this section, you must place, in the relevant source files, a statement of the additional terms that apply to those files, or a notice indicating where to find the applicable terms.

   Additional terms, permissive or non-permissive, may be stated in the form of a separately written license, or stated as exceptions; the above requirements apply either way.

9. Termination.

   You may not propagate or modify a covered work except as expressly provided under this License. Any attempt otherwise to propagate or modify it is void, and will automatically terminate your rights under this License (including any patent licenses granted under the third paragraph of section 11).

   However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.

   Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.

   Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, you do not qualify to receive new licenses for the same material under section 10.

10. Acceptance Not Required for Having Copies.

    You are not required to accept this License in order to receive or run a copy of the Program. Ancillary propagation of a covered work occurring solely as a consequence of using peer-to-peer transmission to receive a copy likewise does not require acceptance. However, nothing other than this License grants you permission to propagate or modify any covered work. These actions infringe copyright if you do not accept this License. Therefore, by modifying or propagating a covered work, you indicate your acceptance of this License to do so.

11. Automatic Licensing of Downstream Recipients.

    Each time you convey a covered work, the recipient automatically receives a license from the original licensors, to run, modify and propagate that work, subject to this License. You are not responsible for enforcing compliance by third parties with this License.

    An “entity transaction” is a transaction transferring control of an organization, or substantially all assets of one, or subdividing an organization, or merging organizations. If propagation of a covered work results from an entity transaction, each party to that transaction who receives a copy of the work also receives whatever licenses to the work the party’s predecessor in interest had or could give under the previous paragraph, plus a right to possession of the Corresponding Source of the work from the predecessor in interest, if the predecessor has it or can get it with reasonable efforts.

    You may not impose any further restrictions on the exercise of the rights granted or affirmed under this License. For example, you may not impose a license fee, royalty, or other charge for exercise of rights granted under this License, and you may not initiate litigation (including a cross-claim or counterclaim in a lawsuit) alleging that any patent claim is infringed by making, using, selling, offering for sale, or importing the Program or any portion of it.

12. Patents.

    A “contributor” is a copyright holder who authorizes use under this License of the Program or a work on which the Program is based. The work thus licensed is called the contributor’s “contributor version”.

    A contributor’s “essential patent claims” are all patent claims owned or controlled by the contributor, whether already acquired or hereafter acquired, that would be infringed by some manner, permitted by this License, of making, using, or selling its contributor version, but do not include claims that would be infringed only as a consequence of further modification of the contributor version. For purposes of this definition, “control” includes the right to grant patent sublicenses in a manner consistent with the requirements of this License.

    Each contributor grants you a non-exclusive, worldwide, royalty-free patent license under the contributor’s essential patent claims, to make, use, sell, offer for sale, import and otherwise run, modify and propagate the contents of its contributor version.

    In the following three paragraphs, a “patent license” is any express agreement or commitment, however denominated, not to enforce a patent (such as an express permission to practice a patent or covenant not to sue for patent infringement). To “grant” such a patent license to a party means to make such an agreement or commitment not to enforce a patent against the party.

    If you convey a covered work, knowingly relying on a patent license, and the Corresponding Source of the work is not available for anyone to copy, free of charge and under the terms of this License, through a publicly available network server or other readily accessible means, then you must either (1) cause the Corresponding Source to be so available, or (2) arrange to deprive yourself of the benefit of the patent license for this particular work, or (3) arrange, in a manner consistent with the requirements of this License, to extend the patent license to downstream recipients. “Knowingly relying” means you have actual knowledge that, but for the patent license, your conveying the covered work in a country, or your recipient’s use of the covered work in a country, would infringe one or more identifiable patents in that country that you have reason to believe are valid.

    If, pursuant to or in connection with a single transaction or arrangement, you convey, or propagate by procuring conveyance of, a covered work, and grant a patent license to some of the parties receiving the covered work authorizing them to use, propagate, modify or convey a specific copy of the covered work, then the patent license you grant is automatically extended to all recipients of the covered work and works based on it.

    A patent license is “discriminatory” if it does not include within the scope of its coverage, prohibits the exercise of, or is conditioned on the non-exercise of one or more of the rights that are specifically granted under this License. You may not convey a covered work if you are a party to an arrangement with a third party that is in the business of distributing software, under which you make payment to the third party based on the extent of your activity of conveying the work, and under which the third party grants, to any of the parties who would receive the covered work from you, a discriminatory patent license (a) in connection with copies of the covered work conveyed by you (or copies made from those copies), or (b) primarily for and in connection with specific products or compilations that contain the covered work, unless you entered into that arrangement, or that patent license was granted, prior to 28 March 2007.

    Nothing in this License shall be construed as excluding or limiting any implied license or other defenses to infringement that may otherwise be available to you under applicable patent law.

13. No Surrender of Others’ Freedom.

    If conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot convey a covered work so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not convey it at all. For example, if you agree to terms that obligate you to collect a royalty for further conveying from those to whom you convey the Program, the only way you could satisfy both those terms and this License would be to refrain entirely from conveying the Program.

14. Use with the GNU Affero General Public License.

    Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU Affero General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such.

15. Revised Versions of this License.

    The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.

    Each version is given a distinguishing version number. If the Program specifies that a certain numbered version of the GNU General Public License “or any later version” applies to it, you have the option of following the terms and conditions either of that numbered version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of the GNU General Public License, you may choose any version ever published by the Free Software Foundation.

    If the Program specifies that a proxy can decide which future versions of the GNU General Public License can be used, that proxy’s public statement of acceptance of a version permanently authorizes you to choose that version for the Program.

    Later license versions may give you additional or different permissions. However, no additional obligations are imposed on any author or copyright holder as a result of your choosing to follow a later version.

16. Disclaimer of Warranty.

    THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.

17. Limitation of Liability.

    IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

18. Interpretation of Sections 15 and 16.

    If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the Program in return for a fee.

How to Apply These Terms to Your New Programs

If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.

To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.

one line to give the program's name and a brief idea of what it does.
Copyright (C) year name of author

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see http://www.gnu.org/licenses/.

Also add information on how to contact you by electronic and paper mail.

If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode:

program Copyright (C) year name of author
This program comes with ABSOLUTELY NO WARRANTY; for details type ‘show w’.
This is free software, and you are welcome to redistribute it under certain conditions; type ‘show c’ for details.

The hypothetical commands ‘show w’ and ‘show c’ should show the appropriate parts of the General Public License. Of course, your program’s commands might be different; for a GUI interface, you would use an “about box”.

You should also get your employer (if you work as a programmer) or school, if any, to sign a “copyright disclaimer” for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see http://www.gnu.org/licenses/.

The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read http://www.gnu.org/philosophy/why-not-lgpl.html.

29 GNU Free Documentation License

Copyright © 2000,2001,2002 Free Software Foundation, Inc.
51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.

1. PREAMBLE

   The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

   This License is a kind of “copyleft”, which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.

   We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.

2. APPLICABILITY AND DEFINITIONS

   This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The “Document”, below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as “you”. You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law.

   A “Modified Version” of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language.

   A “Secondary Section” is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document’s overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them.

   The “Invariant Sections” are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none.

   The “Cover Texts” are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words.

   A “Transparent” copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not “Transparent” is called “Opaque”.

   Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML, PostScript or PDF produced by some word processors for output purposes only.

   The “Title Page” means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, “Title Page” means the text near the most prominent appearance of the work’s title, preceding the beginning of the body of the text.

   A section “Entitled XYZ” means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as “Acknowledgements”, “Dedications”, “Endorsements”, or “History”.) To “Preserve the Title” of such a section when you modify the Document means that it remains a section “Entitled XYZ” according to this definition.

   The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License.

3. VERBATIM COPYING

   You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3.

   You may also lend copies, under the same conditions stated above, and you may publicly display copies.

4. COPYING IN QUANTITY

   If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document’s license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects.

   If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.

   If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.

   It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.

5. MODIFICATIONS

   You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:

   1. Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission.
   2. List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement.
   3. State on the Title page the name of the publisher of the Modified Version, as the publisher.
   4. Preserve all the copyright notices of the Document.
   5. Add an appropriate copyright notice for your modifications adjacent to the other copyright notices.
   6. Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.
   7. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document’s license notice.
   8. Include an unaltered copy of this License.
   9. Preserve the section Entitled “History”, Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled “History” in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence.
   10. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the “History” section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission.
   11. For any section Entitled “Acknowledgements” or “Dedications”, Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.
   12. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles.
   13. Delete any section Entitled “Endorsements”. Such a section may not be included in the Modified Version.
   14. Do not retitle any existing section to be Entitled “Endorsements” or to conflict in title with any Invariant Section.
   15. Preserve any Warranty Disclaimers.

   If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version’s license notice. These titles must be distinct from any other section titles.

   You may add a section Entitled “Endorsements”, provided it contains nothing but endorsements of your Modified Version by various parties—for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.

   You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.

   The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.

6. COMBINING DOCUMENTS

   You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers.

   The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.

   In the combination, you must combine any sections Entitled “History” in the various original documents, forming one section Entitled “History”; likewise combine any sections Entitled “Acknowledgements”, and any sections Entitled “Dedications”. You must delete all sections Entitled “Endorsements.”

7. COLLECTIONS OF DOCUMENTS

   You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.

   You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.

8. AGGREGATION WITH INDEPENDENT WORKS

   A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an “aggregate” if the copyright resulting from the compilation is not used to limit the legal rights of the compilation’s users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document.

   If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document’s Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.

9. TRANSLATION

   Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail.

   If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “History”, the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.

10. TERMINATION

    You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Document is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.

11. FUTURE REVISIONS OF THIS LICENSE

    The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See http://www.gnu.org/copyleft/.

    Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License “or any later version” applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation.

29.1 ADDENDUM: How to use this License for your documents

To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:

  Copyright (C)  year  your name.
  Permission is granted to copy, distribute and/or modify this document
  under the terms of the GNU Free Documentation License, Version 1.2
  or any later version published by the Free Software Foundation;
  with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
  Texts.  A copy of the license is included in the section entitled ``GNU
  Free Documentation License''.

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the “with...Texts.” line with this:

    with the Invariant Sections being list their titles, with
    the Front-Cover Texts being list, and with the Back-Cover Texts
    being list.

If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.

If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.

Concept Index

Function Index

Variable Index

Keybinding Index