The MPD command protocol exchanges line-based text records between client and server over TCP. Once the client is connected to the server, they conduct a conversation until the client closes the connection. The conversation flow is always initiated by the client. The client transmits a command sequence, terminated by the newline character \n. The server will respond with one or more lines, the last of which will be a completion code. When the client connects to the server, the server will answer with the following line: OK MPD version where version is a version identifier such as 0.12.2. This version identifier is the version of the protocol spoken, not the real version of the daemon. (There is no way to retrieve this real version identifier from the connection.)

COMMAND ARG If arguments contain spaces, they should be surrounded by double quotation marks. Argument strings are separated from the command and any other arguments by linear white-space (' ' or '\t'). All data between the client and the server is encoded in UTF-8. (Note: In UTF-8 all standard ansi characters, 0-127 are the same as a standard ansi encoding. Also, no ansi character appears in any multi-byte characters. So, you can use standard C functions like strlen, and strcpy just fine with UTF-8 encoded strings. For example: OK encoded in UTF-8 is simply OK. For more information on UTF=8: http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8)

A command returns OK on completion or ACK some error on failure. These denote the end of command execution.

The nature of the error can be gleaned from the information that follows the ACK. ACK lines are of the form: ACK [error@command_listNum] {current_command} message_text\n These responses are generated by a call to commandError. They contain four separate terms. Let's look at each of them: error: numeric value of one of the ACK_ERROR constants defined in ack.h. command_listNum: offset of the command that caused the error in a Command List. An error will always cause a command list to terminate at the command that causes the error. current_command: name of the command, in a Command List, that was executing when the error occurred. message_text: some (hopefully) informative text that describes the nature of the error. An example might help. Consider the following sequence sent from the client to the server. command_list_begin volume 86 play 10240 status command_list_end The server responds with: ACK [50@1] {play} song doesn't exist: "10240" This tells us that the play command, which was the second in the list (the first or only command is numbered 0), failed with error 50. The number 50 translates to ACK_ERROR_NO_EXIST--the song doesn't exist. This is reiterated by the message text which also tells us which song doesn't exist.

To facilitate faster adding of files etc. you can pass a list of commands all at once using a command list. The command list begins with command_list_begin or command_list_ok_begin and ends with command_list_end. It does not execute any commands until the list has ended. The return value is whatever the return for a list of commands is. On success for all commands, OK is returned. If a command fails, no more commands are executed and the appropriate ACK error is returned. If command_list_ok_begin is used, list_OK is returned for each successful command executed in the command list.

Some commands (e.g. delete) allow specifying a range in the form START:END (the END item is not included in the range, similar to ranges in the Python programming language). If END is omitted, then the maximum possible value is assumed.

Often, users run MPD with "random" enabled, but want to be able to insert songs "before" the rest of the playlist. That is commonly called "queuing". MPD implements this by allowing the client to specify a "priority" for each song in the playlist (commands prio and prioid). A higher priority means that the song is going to be played before the other songs. In "random" mode, MPD maintains an internal randomized sequence of songs. In this sequence, songs with a higher priority come first, and all songs with the same priority are shuffled (by default, all songs are shuffled, because all have the same priority "0"). When you increase the priority of a song, it is moved to the front of the sequence according to its new priority, but always after the current one. A song that has been played already (it's "before" the current song in that sequence) will only be scheduled for repeated playback if its priority has become bigger than the priority of the current song. Decreasing the priority of a song will moved it farther to the end of the sequence. Changing the priority of the current song has no effect on the sequence.

For manipulating playlists and playing, there are two sets of commands. One set uses the song id of a song in the playlist, while another set uses the playlist position of the song. The commands using song ids should be used instead of the commands that manipulate and control playback based on playlist position. Using song ids is a safer method when multiple clients are interacting with MPD.

clearerror Clears the current error message in status (this is also accomplished by any command that starts playback). currentsong Displays the song info of the current song (same song that is identified in status). idle SUBSYSTEMS Introduced with MPD 0.14 Waits until there is a noteworthy change in one or more of MPD's subsystems. As soon as there is one, it lists all changed systems in a line in the format changed: SUBSYSTEM, where SUBSYSTEM is one of the following: database: the song database has been modified after update. update: a database update has started or finished. If the database was modified during the update, the database event is also emitted. stored_playlist: a stored playlist has been modified, renamed, created or deleted playlist: the current playlist has been modified player: the player has been started, stopped or seeked mixer: the volume has been changed output: an audio output has been enabled or disabled options: options like repeat, random, crossfade, replay gain sticker: the sticker database has been modified. subscription: a client has subscribed or unsubscribed to a channel message: a message was received on a channel this client is subscribed to; this event is only emitted when the queue is empty While a client is waiting for idle results, the server disables timeouts, allowing a client to wait for events as long as mpd runs. The idle command can be canceled by sending the command noidle (no other commands are allowed). MPD will then leave idle mode and print results immediately; might be empty at this time. If the optional SUBSYSTEMS argument is used, MPD will only send notifications when something changed in one of the specified subsytems. status Reports the current status of the player and the volume level. volume: 0-100 repeat: 0 or 1 random: 0 or 1 single: Introduced with MPD 0.15 0 or 1 consume: 0 or 1 playlist: 31-bit unsigned integer, the playlist version number playlistlength: integer, the length of the playlist state: play, stop, or pause song: playlist song number of the current song stopped on or playing songid: playlist songid of the current song stopped on or playing nextsong: playlist song number of the next song to be played nextsongid: playlist songid of the next song to be played time: total time elapsed (of current playing/paused song) elapsed: Introduced with MPD 0.16 Total time elapsed within the current song, but with higher resolution. bitrate: instantaneous bitrate in kbps xfade: crossfade in seconds mixrampdb: mixramp threshold in dB mixrampdelay: mixrampdelay in seconds audio: sampleRate:bits:channels updatings_db: job id error: if there is an error, returns message here stats Displays statistics. artists: number of artists songs: number of albums uptime: daemon uptime in seconds db_playtime: sum of all song times in the db db_update: last db update in UNIX time playtime: time length of music played

consume STATE Sets consume state to STATE, STATE should be 0 or 1. When consume is activated, each song played is removed from playlist. crossfade SECONDS Sets crossfading between songs. mixrampdb deciBels Sets the threshold at which songs will be overlapped. Like crossfading but doesn't fade the track volume, just overlaps. The songs need to have MixRamp tags added by an external tool. 0dB is the normalized maximum volume so use negative values, I prefer -17dB. In the absence of mixramp tags crossfading will be used. See http://sourceforge.net/projects/mixramp mixrampdelay SECONDS Additional time subtracted from the overlap calculated by mixrampdb. A value of "nan" disables MixRamp overlapping and falls back to crossfading. random STATE Sets random state to STATE, STATE should be 0 or 1. repeat STATE Sets repeat state to STATE, STATE should be 0 or 1. setvol VOL Sets volume to VOL, the range of volume is 0-100. single STATE Sets single state to STATE, STATE should be 0 or 1. When single is activated, playback is stopped after current song, or song is repeated if the 'repeat' mode is enabled. replay_gain_mode MODE Sets the replay gain mode. One of off, track, album, auto added in MPD 0.16 . Changing the mode during playback may take several seconds, because the new settings does not affect the buffered data. This command triggers the options idle event. replay_gain_status Prints replay gain options. Currently, only the variable replay_gain_mode is returned.

next Plays next song in the playlist. pause PAUSE Toggles pause/resumes playing, PAUSE is 0 or 1. The use of pause command w/o the PAUSE argument is deprecated. play SONGPOS Begins playing the playlist at song number SONGPOS. playid SONGID Begins playing the playlist at song SONGID. previous Plays previous song in the playlist. seek SONGPOS TIME Seeks to the position TIME (in seconds) of entry SONGPOS in the playlist. seekid SONGID TIME Seeks to the position TIME (in seconds) of song SONGID. seekcur TIME Seeks to the position TIME within the current song. If prefixed by '+' or '-', then the time is relative to the current playing position. stop Stops playing.

add URI Adds the file URI to the playlist (directories add recursively). URI can also be a single file. addid URI POSITION Adds a song to the playlist (non-recursive) and returns the song id. URI is always a single file or URL. For example: addid "foo.mp3" Id: 999 OK clear Clears the current playlist. delete POS START:END Deletes a song from the playlist. deleteid SONGID Deletes the song SONGID from the playlist move FROM START:END TO Moves the song at FROM or range of songs at START:END to TO in the playlist. Ranges are supported since MPD 0.15 moveid FROM TO Moves the song with FROM (songid) to TO (playlist index) in the playlist. If TO is negative, it is relative to the current song in the playlist (if there is one). playlist Displays the current playlist. Do not use this, instead use playlistinfo. playlistfind TAG NEEDLE Finds songs in the current playlist with strict matching. playlistid SONGID Displays a list of songs in the playlist. SONGID is optional and specifies a single song to display info for. playlistinfo SONGPOS START:END Displays a list of all songs in the playlist, or if the optional argument is given, displays information only for the song SONGPOS or the range of songs START:END playlistsearch TAG NEEDLE Searches case-sensitively for partial matches in the current playlist. plchanges VERSION Displays changed songs currently in the playlist since VERSION. To detect songs that were deleted at the end of the playlist, use playlistlength returned by status command. plchangesposid VERSION Displays changed songs currently in the playlist since VERSION. This function only returns the position and the id of the changed song, not the complete metadata. This is more bandwidth efficient. To detect songs that were deleted at the end of the playlist, use playlistlength returned by status command. prio PRIORITY START:END Set the priority of the specified songs. A higher priority means that it will be played first when "random" mode is enabled. A priority is an integer between 0 and 255. The default priority of new songs is 0. prioid PRIORITY ID Same as prio, but address the songs with their id. shuffle START:END Shuffles the current playlist. START:END is optional and specifies a range of songs. swap SONG1 SONG2 Swaps the positions of SONG1 and SONG2. swapid SONG1 SONG2 Swaps the positions of SONG1 and SONG2 (both song ids).

Playlists are stored inside the configured playlist directory. They are addressed with their file name (without the directory and without the .m3u suffix). Some of the commands described in this section can be used to run playlist plugins instead of the hard-coded simple m3u parser. They can access playlists in the music directory (relative path including the suffix) or remote playlists (absolute URI with a supported scheme). listplaylist NAME Lists the songs in the playlist. Playlist plugins are supported. listplaylistinfo NAME Lists the songs with metadata in the playlist. Playlist plugins are supported. listplaylists Prints a list of the playlist directory. After each playlist name the server sends its last modification time as attribute "Last-Modified" in ISO 8601 format. To avoid problems due to clock differences between clients and the server, clients should not compare this value with their local clock. load NAME Loads the playlist into the current queue. Playlist plugins are supported. playlistadd NAME URI Adds URI to the playlist NAME.m3u. NAME.m3u will be created if it does not exist. playlistclear NAME Clears the playlist NAME.m3u. playlistdelete NAME SONGPOS Deletes SONGPOS from the playlist NAME.m3u. playlistmove NAME SONGID SONGPOS Moves SONGID in the playlist NAME.m3u to the position SONGPOS. rename NAME NEW_NAME Renames the playlist NAME.m3u to NEW_NAME.m3u. rm NAME Removes the playlist NAME.m3u from the playlist directory. save NAME Saves the current playlist to NAME.m3u in the playlist directory.

count TAG NEEDLE Counts the number of songs and their total playtime in the db matching TAG exactly. find TYPE WHAT ... Finds songs in the db that are exactly WHAT. TYPE can be any tag supported by MPD, or one of the two special parameters — file to search by full path (relative to database root), and any to match against all available tags. WHAT is what to find. findadd TYPE WHAT ... Finds songs in the db that are exactly WHAT and adds them to current playlist. Parameters have the same meaning as for find. list TYPE ARTIST Lists all tags of the specified type. TYPE can be any tag supported by MPD or file. ARTIST is an optional parameter when type is album, this specifies to list albums by an artist. listall URI Lists all songs and directories in URI. listallinfo URI Same as listall, except it also returns metadata info in the same format as lsinfo. lsinfo URI Lists the contents of the directory URI. When listing the root directory, this currently returns the list of stored playlists. This behavior is deprecated; use "listplaylists" instead. search TYPE WHAT ... Searches for any song that contains WHAT. Parameters have the same meaning as for find, except that search is not case sensitive. update URI Updates the music database: find new files, remove deleted files, update modified files. URI is a particular directory or song/file to update. If you do not specify it, everything is updated. Prints "updating_db: JOBID" where JOBID is a positive number identifying the update job. You can read the current job id in the status response. rescan URI Same as update, but also rescans unmodified files.

"Stickers" are pieces of information attached to existing MPD objects (e.g. song files, directories, albums). Clients can create arbitrary name/value pairs. MPD itself does not assume any special meaning in them. The goal is to allow clients to share additional (possibly dynamic) information about songs, which is neither stored on the client (not available to other clients), nor stored in the song files (MPD has no write access). Client developers should create a standard for common sticker names, to ensure interoperability. Objects which may have stickers are addressed by their object type ("song" for song objects) and their URI (the path within the database for songs). sticker get TYPE URI NAME Reads a sticker value for the specified object. sticker set TYPE URI NAME VALUE Adds a sticker value to the specified object. If a sticker item with that name already exists, it is replaced. sticker delete TYPE URI NAME Deletes a sticker value from the specified object. If you do not specify a sticker name, all sticker values are deleted. sticker list TYPE URI Lists the stickers for the specified object. sticker find TYPE URI NAME Searches the sticker database for stickers with the specified name, below the specified directory (URI). For each matching song, it prints the URI and that one sticker's value.

close Closes the connection to MPD. kill Kills MPD. password PASSWORD This is used for authentication with the server. PASSWORD is simply the plaintext password. ping Does nothing but return "OK".

disableoutput ID Turns an output off. enableoutput ID Turns an output on. outputs Shows information about all outputs.

commands Shows which commands the current user has access to. notcommands Shows which commands the current user does not have access to. tagtypes Shows a list of available song metadata. urlhandlers Gets a list of available URL handlers. decoders Print a list of decoder plugins, followed by their supported suffixes and MIME types. Example response: plugin: mad suffix: mp3 suffix: mp2 mime_type: audio/mpeg plugin: mpcdec suffix: mpc

Clients can communicate with each others over "channels". A channel is created by a client subscribing to it. More than one client can be subscribed to a channel at a time; all of them will receive the messages which get sent to it. Each time a client subscribes or unsubscribes, the global idle event subscription is generated. In conjunction with the channels command, this may be used to auto-detect clients providing additional services. A new messages is indicated by the message idle event. subscribe NAME Subscribe to a channel. The channel is created if it does not exist already. The name may consist of alphanumeric ASCII characters plus underscore, dash, dot and colon. unsubscribe NAME Unsubscribe from a channel. channels Obtain a list of all channels. The response is a list of "channel:" lines. readmessages Reads messages for this client. The response is a list of "channel:" and "message:" lines. sendmessage CHANNEL TEXT Send a message to the specified channel.