LUA SCRIPTING ============= mpv can load Lua scripts. These scripts can be used to control mpv in a similar way to slave mode. mpv provides the builtin module ``mp`` (can be loaded with ``require 'mp'``), which provides functions to send commands to the mpv core and to retrieve information about playback state, user settings, file information, and so on. .. admonition:: Warning Lua scripting is work in progress, and it's in a very early stage. When writing scripts, rely only on the features and functions documented here. Everything else is subject to change. Mode of operation ----------------- Your script will be loaded by the player at program start if you pass it to the ``--lua`` option. Each script runs in its own thread. Your script is first run "as is", and once that is done, the event loop is entered. This event loop will dispatch events received by mpv and call your own event handlers which you have registered with ``mp.register_event``, or timers added with ``mp.add_timeout`` or similar. When the player quits, all scripts will be asked to terminate. This happens via a ``shutdown`` event, which by default will make the event loop return. If your script got into an endless loop, mpv will probably behave fine during playback, but it won't terminate when quitting because it's waiting on your script. Internally, the C code will call the Lua function ``mp_event_loop`` after loading a Lua script. This function is normally defined by the default prelude loaded before your script (see ``player/lua/defaults.lua`` in the mpv sources). mp functions ------------ The ``mp`` module is preloaded, although it can be loaded manually with ``require 'mp'``. It provides the core client API. ``mp.command(string)`` Run the command the given command. This is similar to the commands used in input.conf. See `List of Input Commands`_. Returns true on success, or ``nil, error`` on error. ``mp.commandv(arg1, arg2, ...)`` Similar to ``mp.command``, but pass each command argument as separate parameter. This has the advantage that you don't have to care about quoting and escaping in some cases. Example: :: mp.command("loadfile " + filename + " append") mp.commandv("loadfile", filename, "append") These two commands are equivalent, except that the first version breaks if the filename contains spaces or certain special characters. ``mp.get_property(name)`` Return the value of the given property as string. These are the same properties as used in input.conf. See `Properties`_ for a list of properties. The returned string is formatted similar to ``${=name}`` (see `Property Expansion`_). Returns the string on success, or ``nil, error`` on error. ``mp.get_property_osd(name)`` Similar to ``mp.get_property``, but return the property value formatted for OSD. This is the same string as printed with ``${name}`` when used in input.conf. Returns the string on success, or ``"", error`` on error. Unlike ``get_property()``, assigning the return value to a variable will always result in a string. ``mp.set_property(name, value)`` Set the given property to the given value. See ``mp.get_property`` and `Properties`_ for more information about properties. Returns true on success, or ``nil, error`` on error. ``mp.get_time()`` Return the current mpv internal time in seconds as a number. This is basically the system time, with an arbitrary offset. ``mp.register_event(name, fn)`` Call a specific function when an event happens. The event name is a string, and the function is a Lua function value. Returns true if such an event exists, false otherwise. ====================== ===================================================== Name Comment ====================== ===================================================== ``shutdown`` ``log-message`` for ``mp.enable_messages`` (undocumented) ``get-property-reply`` (undocumented) ``set-property-reply`` (undocumented) ``command-reply`` (undocumented) ``start-file`` happens right before a new file is loaded ``end-file`` happens after a file was unloaded ``playback-start`` happens atfer a file was loaded and begins playback ``tracks-changed`` list of tracks was updated ``track-switched`` a video/audio/sub track was switched ``idle`` idle mode is entered (no file is loaded, ``--idle``) ``pause`` player was paused ``unpause`` player was unpaused ``tick`` called after a video frame was displayed ====================== ===================================================== Example: :: function my_fn() print("start of playback!") end mp.register_event("playback-start", my_fn) ``mp.add_timeout(seconds, fn)`` Call the given function fn when the given number of seconds has elapsed. Note that the number of seconds can be fractional. As of now, the timer precision may be as worse as 50 ms, though. (This will be improved in the future.) This is a one-shot timer: it will be removed when it's fired. Returns a timer handle. See ``mp.cancel_timer``. ``mp.add_periodic_timer(seconds, fn)`` Call the given function periodically. This is like ``mp.add_timeout``, but the timer is re-added after the function fn is run. Returns a timer handle. See ``mp.cancel_timer``. ``mp.cancel_timer(t)`` Terminate the given timer. t is the value returned by ``mp.add_timeout`` or ``mp.add_periodic_timer``. ``mp.get_opt(key)`` Return a setting from the ``--lua-opts`` option. It's up to the user and the script how this mechanism is used. Currently, all scripts can access this equally, so you should be careful about collisions. ``mp.get_script_name()`` Return the name of the current script. ``mp.suspend()`` Suspend the mpv main loop. There is a long-winded explanation of this in the C API function ``mpv_suspend()``. In short, this prevents the player from displaying the next video frame, so that you don't get blocked when trying to access the player. This is automatically called by the event handler. ``mp.resume()`` Undo one ``mp.suspend()`` call. ``mp.suspend()`` increments an internal counter, and ``mp.resume()`` decrements it. When 0 is reached, the player is actually resumed. ``mp.resume_all()`` This resets the internal suspend counter and resumes the player. (It's like calling ``mp.resume()`` until the player is actually resumed.) You might want to call this if you're about to do something that takes a long time, but doesn't really need access to the player (like a network operation). Note that you still can access the player at any time. mp.msg functions ---------------- This module allows outputting messages to the terminal, and can be loaded with ``require 'mp.msg'``. ``msg.log(level, ...)`` The level parameter is the message priority. It's a string and one of ``fatal``, ``error``, ``warn``, ``info``, ``v``, ``debug``. The user's settings will determine which of these messages will be visible. Normally, all messages are visible, except ``v`` and ``debug``. The parameters after that are all converted to strings. Spaces are inserted to separate multiple parameters. You don't need to add newlines. ``msg.fatal(...)``, ``msg.error(...)``, ``msg.warn(...)``, ``msg.info(...)``, ``msg.verbose(...)``, ``msg.debug(...)`` All of these are shortcuts and equivalent to the corresponding ``msg.log(level, ...)`` call.