.. SPDX-FileCopyrightText: 2018-2021 kaliko .. SPDX-License-Identifier: GPL-3.0-or-later Using the client library ========================= Introduction ------------ The client library can be used as follows: .. code-block:: python client = musicpd.MPDClient() # create client object client.connect() # use MPD_HOST/MPD_PORT if set else # test ${XDG_RUNTIME_DIR}/mpd/socket for existence # fallback to localhost:6600 # connect support host/port argument as well print(client.mpd_version) # print the mpd protocol version print(client.cmd('foo', 42)) # print result of the request "cmd foo 42" # (nb. for actual command, see link to the protocol below) client.disconnect() # disconnect from the server In the example above `cmd` in not an actual MPD command, for a list of supported commands, their arguments (as MPD currently understands them), and the functions used to parse their responses see :ref:`commands`. See the `MPD protocol documentation`_ for more details. .. _environment_variables: Environment variables --------------------- The client honors the following environment variables: * ``MPD_HOST`` MPD host (:abbr:`FQDN (fully qualified domain name)`, socket path or abstract socket) and password. | To define a password set MPD_HOST to "`password@host`" (password only "`password@`") | For abstract socket use "@" as prefix : "`@socket`" and then with a password "`pass@@socket`" | Regular unix socket are set with an absolute path: "`/run/mpd/socket`" * ``MPD_PORT`` MPD port, relevant for TCP socket only, ie with :abbr:`FQDN (fully qualified domain name)` defined host * ``MPD_TIMEOUT`` timeout for connecting to MPD and waiting for MPD’s response in seconds * ``XDG_RUNTIME_DIR`` path to look for potential socket: ``${XDG_RUNTIME_DIR}/mpd/socket`` .. _default_settings: Default settings ---------------- * If ``MPD_HOST`` is not set, then look for a socket in ``${XDG_RUNTIME_DIR}/mpd/socket`` * If there is no socket use ``localhost`` * If ``MPD_PORT`` is not set, then use ``6600`` * If ``MPD_TIMEOUT`` is not set, then uses :py:obj:`musicpd.CONNECTION_TIMEOUT` Context manager --------------- Calling MPDClient in a context manager :py:obj:`musicpd.MPDClient.connect` is transparently called with :ref:`default setting` (use :ref:`environment variables` to override defaults). Leaving the context manager :py:obj:`musicpd.MPDClient.disconnect` is called. .. code-block:: python import os os.environ['MPD_HOST'] = 'mpdhost' with MPDClient() as c: c.status() c.next() Command lists ------------- Command lists are also supported using `command_list_ok_begin()` and `command_list_end()` : .. code-block:: python client.command_list_ok_begin() # start a command list client.update() # insert the update command into the list client.status() # insert the status command into the list results = client.command_list_end() # results will be a list with the results Ranges ------ Provide a 2-tuple as argument for command supporting ranges (cf. `MPD protocol documentation`_ for more details). Possible ranges are: "START:END", "START:" and ":" : .. code-block:: python # An intelligent clear # clears played track in the queue, currentsong included pos = client.currentsong().get('pos', 0) # the 2-tuple range object accepts str, no need to convert to int client.delete((0, pos)) # missing end interpreted as highest value possible, pay attention still need a tuple. client.delete((pos,)) # purge queue from current to the end A notable case is the `rangeid` command allowing an empty range specified as a single colon as argument (i.e. sending just ":"): .. code-block:: python # sending "rangeid :" to clear the range, play everything client.rangeid(()) # send an empty tuple Empty start in range (i.e. ":END") are not possible and will raise a CommandError. Iterators ---------- Commands may also return iterators instead of lists if `iterate` is set to `True`: .. code-block:: python client.iterate = True for song in client.playlistinfo(): print song['file'] Idle prefixed commands ---------------------- Each command have a *send\_* and a *fetch\_* variant, which allows to send a MPD command and then fetch the result later (non-blocking call). This is useful for the idle command: .. code-block:: python >>> client.send_idle() # do something else or use function like select() # http://docs.python.org/howto/sockets.html#non-blocking-sockets # ex. select([client], [], []) >>> events = client.fetch_idle() # more complex use for example, with glib/gobject: >>> def callback(source, condition): >>> changes = client.fetch_idle() >>> print changes >>> return False # removes the IO watcher >>> client.send_idle() >>> gobject.io_add_watch(client, gobject.IO_IN, callback) >>> gobject.MainLoop().run() See also use of :ref:`socket timeout` with idle command. Fetching binary content (cover art) ----------------------------------- Fetching album covers is possible with albumart, here is an example: .. code-block:: python >>> cli = musicpd.MPDClient() >>> cli.connect() >>> track = "Steve Reich/1978-Music for 18 Musicians" >>> aart = cli.albumart(track, 0) >>> received = int(aart.get('binary')) >>> size = int(aart.get('size')) >>> with open('/tmp/cover', 'wb') as cover: >>> # aart = {'size': 42, 'binary': 2051, data: bytes(...)} >>> cover.write(aart.get('data')) >>> while received < size: >>> aart = cli.albumart(track, received) >>> cover.write(aart.get('data')) >>> received += int(aart.get('binary')) >>> if received != size: >>> print('something went wrong', file=sys.stderr) >>> cli.disconnect() A `CommandError` is raised if the album does not expose a cover. You can also use `readpicture` command to fetch embedded picture: .. code-block:: python >>> cli = musicpd.MPDClient() >>> cli.connect() >>> track = 'muse/Amon Tobin/2011-ISAM/01-Amon Tobin - Journeyman.mp3' >>> rpict = cli.readpicture(track, 0) >>> if not rpict: >>> print('No embedded picture found', file=sys.stderr) >>> sys.exit(1) >>> size = int(rpict['size']) >>> done = int(rpict['binary']) >>> with open('/tmp/cover', 'wb') as cover: >>> cover.write(rpict['data']) >>> while size > done: >>> rpict = cli.readpicture(track, done) >>> done += int(rpict['binary']) >>> print(f'writing {rpict["binary"]}, done {100*done/size:03.0f}%') >>> cover.write(rpict['data']) >>> cli.disconnect() Refer to `MPD protocol documentation`_ for the meaning of `binary`, `size` and `data`. .. _socket_timeout: Socket timeout -------------- .. note:: When the timeout is reached it raises a :py:obj:`socket.timeout` exception. An :py:obj:`OSError` subclass. A timeout is used for the initial MPD connection (``connect`` command), then the socket is put in blocking mode with no timeout. Its value is set in :py:obj:`musicpd.CONNECTION_TIMEOUT` at module level and :py:obj:`musicpd.MPDClient.mpd_timeout` in MPDClient instances . However it is possible to set socket timeout for all command setting :py:obj:`musicpd.MPDClient.socket_timeout` attribute to a value in second. Having ``socket_timeout`` enabled can help to detect "half-open connection". For instance loosing connectivity without the server explicitly closing the connection (switching network interface ethernet/wifi, router down, etc…). **Nota bene**: with ``socket_timeout`` enabled each command sent to MPD might timeout. A couple of seconds should be enough for commands to complete except for the special case of ``idle`` command which by definition *“ waits until there is a noteworthy change in one or more of MPD’s subsystems.”* (cf. `MPD protocol documentation`_). Here is a solution to use ``idle`` command with ``socket_timeout``: .. code-block:: python import musicpd import select import socket cli = musicpd.MPDClient() try: cli.socket_timeout = 10 # seconds select_timeout = 5 # second cli.connect() while True: cli.send_idle() # use send_ API to avoid blocking on read _read, _, _ = select.select([cli], [], [], select_timeout) if _read: # tries to read response ret = cli.fetch_idle() print(', '.join(ret)) # Do something else: # cancels idle cli.noidle() except socket.timeout as err: print(f'{err} (timeout {cli.socket_timeout})') except (OSError, musicpd.MPDError) as err: print(f'{err!r}') if cli._sock is not None: cli.disconnect() except KeyboardInterrupt: pass Some explanations: * First launch a non blocking ``idle`` command. This call do not wait for a response to avoid socket timeout waiting for an MPD event. * ``select`` waits for something to read on the socket (the idle response in this case), returns after ``select_timeout`` seconds anyway. * In case there is something to read read it using ``fetch_idle`` * Nothing to read, cancel idle with ``noidle`` All three commands in the while loop (send_idle, fetch_idle, noidle) are not triggering a socket timeout unless the connection is actually lost (actually it could also be that MPD took too much time to answer, but MPD taking more than a couple of seconds for these commands should never occur). .. _MPD protocol documentation: http://www.musicpd.org/doc/protocol/ .. vim: spell spelllang=en