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mpv/DOCS/man/lua.rst
wm4 0a30a4a432 DOCS: explicitly mention that property observing has an initial event 
This is definitely intended from the start, and it's generally useful,
but for some reason it wasn't actually documented.
2019-10-08 21:11:55 +02:00

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LUA SCRIPTING
=============
mpv can load Lua scripts. Scripts passed to the ``--script`` option, or found in
the ``scripts`` subdirectory of the mpv configuration directory (usually
``~/.config/mpv/scripts/``) will be loaded on program start. mpv also appends the
``scripts`` subdirectory to the end of Lua's path so you can import scripts from
there too. Since it's added to the end, don't name scripts you want to import
the same as Lua libraries because they will be overshadowed by them.
mpv provides the built-in module ``mp``, which contains functions to send
commands to the mpv core and to retrieve information about playback state, user
settings, file information, and so on.
These scripts can be used to control mpv in a similar way to slave mode.
Technically, the Lua code uses the client API internally.
Example
-------
A script which leaves fullscreen mode when the player is paused:
::
function on_pause_change(name, value)
if value == true then
mp.set_property("fullscreen", "no")
end
end
mp.observe_property("pause", "bool", on_pause_change)
Details on the script initialization and lifecycle
--------------------------------------------------
Your script will be loaded by the player at program start from the ``scripts``
configuration subdirectory, or from a path specified with the ``--script``
option. Some scripts are loaded internally (like ``--osc``). 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. Note that since the
script starts execution concurrently with player initialization, some properties
may not be populated with meaningful values until the relevant subsystems have
initialized.
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).
The event loop will wait for events and dispatch events registered with
``mp.register_event``. It will also handle timers added with ``mp.add_timeout``
and similar (by waiting with a timeout).
Since mpv 0.6.0, the player will wait until the script is fully loaded before
continuing normal operation. The player considers a script as fully loaded as
soon as it starts waiting for mpv events (or it exits). In practice this means
the player will more or less hang until the script returns from the main chunk
(and ``mp_event_loop`` is called), or the script calls ``mp_event_loop`` or
``mp.dispatch_events`` directly. This is done to make it possible for a script
to fully setup event handlers etc. before playback actually starts. In older
mpv versions, this happened asynchronously. With mpv 0.29.0, this changes
slightly, and it merely waits for scripts to be loaded in this manner before
starting playback as part of the player initialization phase. Scripts run though
initialization in parallel. This might change again.
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 given command. This is similar to the commands used in input.conf.
See `List of Input Commands`_.
By default, this will show something on the OSD (depending on the command),
as if it was used in ``input.conf``. See `Input Command Prefixes`_ how
to influence OSD usage per command.
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.
Note that properties are *not* expanded. You can use either ``mp.command``,
the ``expand-properties`` prefix, or the ``mp.get_property`` family of
functions.
Unlike ``mp.command``, this will not use OSD by default either (except
for some OSD-specific commands).
``mp.command_native(table [,def])``
Similar to ``mp.commandv``, but pass the argument list as table. This has
the advantage that in at least some cases, arguments can be passed as
native types. It also allows you to use named argument.
If the table is an array, each array item is like an argument in
``mp.commandv()`` (but can be a native type instead of a string).
If the table contains string keys, it's interpreted as command with named
arguments. This requires at least an entry with the key ``name`` to be
present, which must be a string, and contains the command name. The special
entry ``_flags`` is optional, and if present, must be an array of
`Input Command Prefixes`_ to apply. All other entries are interpreted as
arguments.
Returns a result table on success (usually empty), or ``def, error`` on
error. ``def`` is the second parameter provided to the function, and is
nil if it's missing.
``mp.command_native_async(table [,fn])``
Like ``mp.command_native()``, but the command is ran asynchronously (as far
as possible), and upon completion, fn is called. fn has two arguments:
``fn(success, result, error)``. ``success`` is always a Boolean and is true
if the command was successful, otherwise false. The second parameter is
the result value (can be nil) in case of success, nil otherwise (as returned
by ``mp.command_native()``). The third parameter is the error string in case
of an error, nil otherwise.
Returns a table with undefined contents, which can be used as argument for
``mp.abort_async_command``.
If starting the command failed for some reason, ``nil, error`` is returned,
and ``fn`` is called indicating failure, using the same error value.
``mp.abort_async_command(t)``
Abort a ``mp.command_native_async`` call. The argument is the return value
of that command (which starts asynchronous execution of the command).
Whether this works and how long it takes depends on the command and the
situation. The abort call itself is asynchronous. Does not return anything.
``mp.get_property(name [,def])``
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 ``${=name}``
(see `Property Expansion`_).
Returns the string on success, or ``def, error`` on error. ``def`` is the
second parameter provided to the function, and is nil if it's missing.
``mp.get_property_osd(name [,def])``
Similar to ``mp.get_property``, but return the property value formatted for
OSD. This is the same string as printed with ``${name}`` when used in
input.conf.
Returns the string on success, or ``def, error`` on error. ``def`` is the
second parameter provided to the function, and is an empty string if it's
missing. Unlike ``get_property()``, assigning the return value to a variable
will always result in a string.
``mp.get_property_bool(name [,def])``
Similar to ``mp.get_property``, but return the property value as Boolean.
Returns a Boolean on success, or ``def, error`` on error.
``mp.get_property_number(name [,def])``
Similar to ``mp.get_property``, but return the property value as number.
Note that while Lua does not distinguish between integers and floats,
mpv internals do. This function simply request a double float from mpv,
and mpv will usually convert integer property values to float.
Returns a number on success, or ``def, error`` on error.
``mp.get_property_native(name [,def])``
Similar to ``mp.get_property``, but return the property value using the best
Lua type for the property. Most time, this will return a string, Boolean,
or number. Some properties (for example ``chapter-list``) are returned as
tables.
Returns a value on success, or ``def, error`` on error. Note that ``nil``
might be a possible, valid value too in some corner cases.
``mp.set_property(name, value)``
Set the given property to the given string value. See ``mp.get_property``
and `Properties`_ for more information about properties.
Returns true on success, or ``nil, error`` on error.
``mp.set_property_bool(name, value)``
Similar to ``mp.set_property``, but set the given property to the given
Boolean value.
``mp.set_property_number(name, value)``
Similar to ``mp.set_property``, but set the given property to the given
numeric value.
Note that while Lua does not distinguish between integers and floats,
mpv internals do. This function will test whether the number can be
represented as integer, and if so, it will pass an integer value to mpv,
otherwise a double float.
``mp.set_property_native(name, value)``
Similar to ``mp.set_property``, but set the given property using its native
type.
Since there are several data types which cannot represented natively in
Lua, this might not always work as expected. For example, while the Lua
wrapper can do some guesswork to decide whether a Lua table is an array
or a map, this would fail with empty tables. Also, there are not many
properties for which it makes sense to use this, instead of
``set_property``, ``set_property_bool``, ``set_property_number``.
For these reasons, this function should probably be avoided for now, except
for properties that use tables natively.
``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.add_key_binding(key, name|fn [,fn [,flags]])``
Register callback to be run on a key binding. The binding will be mapped to
the given ``key``, which is a string describing the physical key. This uses
the same key names as in input.conf, and also allows combinations
(e.g. ``ctrl+a``). If the key is empty or ``nil``, no physical key is
registered, but the user still can create own bindings (see below).
After calling this function, key presses will cause the function ``fn`` to
be called (unless the user remapped the key with another binding).
The ``name`` argument should be a short symbolic string. It allows the user
to remap the key binding via input.conf using the ``script-message``
command, and the name of the key binding (see below for
an example). The name should be unique across other bindings in the same
script - if not, the previous binding with the same name will be
overwritten. You can omit the name, in which case a random name is generated
internally.
The last argument is used for optional flags. This is a table, which can
have the following entries:
``repeatable``
If set to ``true``, enables key repeat for this specific binding.
``complex``
If set to ``true``, then ``fn`` is called on both key up and down
events (as well as key repeat, if enabled), with the first
argument being a table. This table has an ``event`` entry, which
is set to one of the strings ``down``, ``repeat``, ``up`` or
``press`` (the latter if key up/down can't be tracked). It further
has an ``is_mouse`` entry, which tells whether the event was caused
by a mouse button.
Internally, key bindings are dispatched via the ``script-message-to`` or
``script-binding`` input commands and ``mp.register_script_message``.
Trying to map multiple commands to a key will essentially prefer a random
binding, while the other bindings are not called. It is guaranteed that
user defined bindings in the central input.conf are preferred over bindings
added with this function (but see ``mp.add_forced_key_binding``).
Example:
::
function something_handler()
print("the key was pressed")
end
mp.add_key_binding("x", "something", something_handler)
This will print the message ``the key was pressed`` when ``x`` was pressed.
The user can remap these key bindings. Then the user has to put the
following into their input.conf to remap the command to the ``y`` key:
::
y script-binding something
This will print the message when the key ``y`` is pressed. (``x`` will
still work, unless the user remaps it.)
You can also explicitly send a message to a named script only. Assume the
above script was using the filename ``fooscript.lua``:
::
y script-binding fooscript/something
``mp.add_forced_key_binding(...)``
This works almost the same as ``mp.add_key_binding``, but registers the
key binding in a way that will overwrite the user's custom bindings in their
input.conf. (``mp.add_key_binding`` overwrites default key bindings only,
but not those by the user's input.conf.)
``mp.remove_key_binding(name)``
Remove a key binding added with ``mp.add_key_binding`` or
``mp.add_forced_key_binding``. Use the same name as you used when adding
the bindings. It's not possible to remove bindings for which you omitted
the name.
``mp.register_event(name, fn)``
Call a specific function when an event happens. The event name is a string,
and the function fn is a Lua function value.
Some events have associated data. This is put into a Lua table and passed
as argument to fn. The Lua table by default contains a ``name`` field,
which is a string containing the event name. If the event has an error
associated, the ``error`` field is set to a string describing the error,
on success it's not set.
If multiple functions are registered for the same event, they are run in
registration order, which the first registered function running before all
the other ones.
Returns true if such an event exists, false otherwise.
See `Events`_ and `List of events`_ for details.
``mp.unregister_event(fn)``
Undo ``mp.register_event(..., fn)``. This removes all event handlers that
are equal to the ``fn`` parameter. This uses normal Lua ``==`` comparison,
so be careful when dealing with closures.
``mp.observe_property(name, type, fn)``
Watch a property for changes. If the property ``name`` is changed, then
the function ``fn(name)`` will be called. ``type`` can be ``nil``, or be
set to one of ``none``, ``native``, ``bool``, ``string``, or ``number``.
``none`` is the same as ``nil``. For all other values, the new value of
the property will be passed as second argument to ``fn``, using
``mp.get_property_<type>`` to retrieve it. This means if ``type`` is for
example ``string``, ``fn`` is roughly called as in
``fn(name, mp.get_property_string(name))``.
If possible, change events are coalesced. If a property is changed a bunch
of times in a row, only the last change triggers the change function. (The
exact behavior depends on timing and other things.)
In some cases the function is not called even if the property changes.
This depends on the property, and it's a valid feature request to ask for
better update handling of a specific property.
If the ``type`` is ``none`` or ``nil``, sporadic property change events are
possible. This means the change function ``fn`` can be called even if the
property doesn't actually change.
You always get an initial change notification. This is meant to initialize
the user's state to the current value of the property.
``mp.unobserve_property(fn)``
Undo ``mp.observe_property(..., fn)``. This removes all property handlers
that are equal to the ``fn`` parameter. This uses normal Lua ``==``
comparison, so be careful when dealing with closures.
``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. For now, the timer's
resolution may be as low as 50 ms, although this will be improved in the
future.
This is a one-shot timer: it will be removed when it's fired.
Returns a timer object. See ``mp.add_periodic_timer`` for details.
``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 object. The timer object provides the following methods:
``stop()``
Disable the timer. Does nothing if the timer is already disabled.
This will remember the current elapsed time when stopping, so that
``resume()`` essentially unpauses the timer.
``kill()``
Disable the timer. Resets the elapsed time. ``resume()`` will
restart the timer.
``resume()``
Restart the timer. If the timer was disabled with ``stop()``, this
will resume at the time it was stopped. If the timer was disabled
with ``kill()``, or if it's a previously fired one-shot timer (added
with ``add_timeout()``), this starts the timer from the beginning,
using the initially configured timeout.
``is_enabled()``
Whether the timer is currently enabled or was previously disabled
(e.g. by ``stop()`` or ``kill()``).
``timeout`` (RW)
This field contains the current timeout period. This value is not
updated as time progresses. It's only used to calculate when the
timer should fire next when the timer expires.
If you write this, you can call ``t:kill() ; t:resume()`` to reset
the current timeout to the new one. (``t:stop()`` won't use the
new timeout.)
``oneshot`` (RW)
Whether the timer is periodic (``false``) or fires just once
(``true``). This value is used when the timer expires (but before
the timer callback function fn is run).
Note that these are methods, and you have to call them using ``:`` instead
of ``.`` (Refer to http://www.lua.org/manual/5.2/manual.html#3.4.9 .)
Example:
::
seconds = 0
timer = mp.add_periodic_timer(1, function()
print("called every second")
# stop it after 10 seconds
seconds = seconds + 1
if seconds >= 10 then
timer:kill()
end
end)
``mp.get_opt(key)``
Return a setting from the ``--script-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. The name is usually made of the
filename of the script, with directory and file extension removed. If
there are several scripts which would have the same name, it's made unique
by appending a number.
.. admonition:: Example
The script ``/path/to/fooscript.lua`` becomes ``fooscript``.
``mp.osd_message(text [,duration])``
Show an OSD message on the screen. ``duration`` is in seconds, and is
optional (uses ``--osd-duration`` by default).
Advanced mp functions
---------------------
These also live in the ``mp`` module, but are documented separately as they
are useful only in special situations.
``mp.suspend()``
This function has been deprecated in mpv 0.21.0 and does nothing starting
with mpv 0.23.0 (no replacement).
``mp.resume()``
This function has been deprecated in mpv 0.21.0 and does nothing starting
with mpv 0.23.0 (no replacement).
``mp.resume_all()``
This function has been deprecated in mpv 0.21.0 and does nothing starting
with mpv 0.23.0 (no replacement).
``mp.get_wakeup_pipe()``
Calls ``mpv_get_wakeup_pipe()`` and returns the read end of the wakeup
pipe. This is deprecated, but still works. (See ``client.h`` for details.)
``mp.get_next_timeout()``
Return the relative time in seconds when the next timer (``mp.add_timeout``
and similar) expires. If there is no timer, return ``nil``.
``mp.dispatch_events([allow_wait])``
This can be used to run custom event loops. If you want to have direct
control what the Lua script does (instead of being called by the default
event loop), you can set the global variable ``mp_event_loop`` to your
own function running the event loop. From your event loop, you should call
``mp.dispatch_events()`` to dequeue and dispatch mpv events.
If the ``allow_wait`` parameter is set to ``true``, the function will block
until the next event is received or the next timer expires. Otherwise (and
this is the default behavior), it returns as soon as the event loop is
emptied. It's strongly recommended to use ``mp.get_next_timeout()`` and
``mp.get_wakeup_pipe()`` if you're interested in properly working
notification of new events and working timers.
``mp.register_idle(fn)``
Register an event loop idle handler. Idle handlers are called before the
script goes to sleep after handling all new events. This can be used for
example to delay processing of property change events: if you're observing
multiple properties at once, you might not want to act on each property
change, but only when all change notifications have been received.
``mp.unregister_idle(fn)``
Undo ``mp.register_idle(fn)``. This removes all idle handlers that
are equal to the ``fn`` parameter. This uses normal Lua ``==`` comparison,
so be careful when dealing with closures.
``mp.enable_messages(level)``
Set the minimum log level of which mpv message output to receive. These
messages are normally printed to the terminal. By calling this function,
you can set the minimum log level of messages which should be received with
the ``log-message`` event. See the description of this event for details.
The level is a string, see ``msg.log`` for allowed log levels.
``mp.register_script_message(name, fn)``
This is a helper to dispatch ``script-message`` or ``script-message-to``
invocations to Lua functions. ``fn`` is called if ``script-message`` or
``script-message-to`` (with this script as destination) is run
with ``name`` as first parameter. The other parameters are passed to ``fn``.
If a message with the given name is already registered, it's overwritten.
Used by ``mp.add_key_binding``, so be careful about name collisions.
``mp.unregister_script_message(name)``
Undo a previous registration with ``mp.register_script_message``. Does
nothing if the ``name`` wasn't registered.
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``, ``trace``. The
user's settings will determine which of these messages will be
visible. Normally, all messages are visible, except ``v``, ``debug`` and
``trace``.
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(...)``, ``msg.trace(...)``
All of these are shortcuts and equivalent to the corresponding
``msg.log(level, ...)`` call.
mp.options functions
--------------------
mpv comes with a built-in module to manage options from config-files and the
command-line. All you have to do is to supply a table with default options to
the read_options function. The function will overwrite the default values
with values found in the config-file and the command-line (in that order).
``options.read_options(table [, identifier])``
A ``table`` with key-value pairs. The type of the default values is
important for converting the values read from the config file or
command-line back. Do not use ``nil`` as a default value!
The ``identifier`` is used to identify the config-file and the command-line
options. These needs to unique to avoid collisions with other scripts.
Defaults to ``mp.get_script_name()``.
Example implementation::
require 'mp.options'
local options = {
optionA = "defaultvalueA",
optionB = -0.5,
optionC = true,
}
read_options(options, "myscript")
print(options.optionA)
The config file will be stored in ``script-opts/identifier.conf`` in mpv's user
folder. Comment lines can be started with # and stray spaces are not removed.
Boolean values will be represented with yes/no.
Example config::
# comment
optionA=Hello World
optionB=9999
optionC=no
Command-line options are read from the ``--script-opts`` parameter. To avoid
collisions, all keys have to be prefixed with ``identifier-``.
Example command-line::
--script-opts=myscript-optionA=TEST,myscript-optionB=0,myscript-optionC=yes
mp.utils functions
------------------
This built-in module provides generic helper functions for Lua, and have
strictly speaking nothing to do with mpv or video/audio playback. They are
provided for convenience. Most compensate for Lua's scarce standard library.
Be warned that any of these functions might disappear any time. They are not
strictly part of the guaranteed API.
``utils.getcwd()``
Returns the directory that mpv was launched from. On error, ``nil, error``
is returned.
``utils.readdir(path [, filter])``
Enumerate all entries at the given path on the filesystem, and return them
as array. Each entry is a directory entry (without the path).
The list is unsorted (in whatever order the operating system returns it).
If the ``filter`` argument is given, it must be one of the following
strings:
``files``
List regular files only. This excludes directories, special files
(like UNIX device files or FIFOs), and dead symlinks. It includes
UNIX symlinks to regular files.
``dirs``
List directories only, or symlinks to directories. ``.`` and ``..``
are not included.
``normal``
Include the results of both ``files`` and ``dirs``. (This is the
default.)
``all``
List all entries, even device files, dead symlinks, FIFOs, and the
``.`` and ``..`` entries.
On error, ``nil, error`` is returned.
``utils.file_info(path)``
Stats the given path for information and returns a table with the
following entries:
``mode``
protection bits (on Windows, always 755 (octal) for directories
and 644 (octal) for files)
``size``
size in bytes
``atime``
time of last access
``mtime``
time of last modification
``ctime``
time of last metadata change (Linux) / time of creation (Windows)
``is_file``
Whether ``path`` is a regular file (boolean)
``is_dir``
Whether ``path`` is a directory (boolean)
``mode`` and ``size`` are integers.
Timestamps (``atime``, ``mtime`` and ``ctime``) are integer seconds since
the Unix epoch (Unix time).
The booleans ``is_file`` and ``is_dir`` are provided as a convenience;
they can be and are derived from ``mode``.
On error (eg. path does not exist), ``nil, error`` is returned.
``utils.split_path(path)``
Split a path into directory component and filename component, and return
them. The first return value is always the directory. The second return
value is the trailing part of the path, the directory entry.
``utils.join_path(p1, p2)``
Return the concatenation of the 2 paths. Tries to be clever. For example,
if ```p2`` is an absolute path, p2 is returned without change.
``utils.subprocess(t)``
Runs an external process and waits until it exits. Returns process status
and the captured output. This is a legacy wrapper around calling the
``subprocess`` command with ``mp.command_native``. It does the following
things:
- copy the table ``t``
- rename ``cancellable`` field to ``playback_only``
- rename ``max_size`` to ``capture_size``
- set ``capture_stdout`` field to ``true`` if unset
- set ``name`` field to ``subprocess``
- call ``mp.command_native(copied_t)``
- if the command failed, create a dummy result table
- copy ``error_string`` to ``error`` field if the string is non-empty
- return the result table
It is recommended to use ``mp.command_native`` or ``mp.command_native_async``
directly, instead of calling this legacy wrapper. It is for compatibility
only.
See the ``subprocess`` documentation for semantics and further parameters.
``utils.subprocess_detached(t)``
Runs an external process and detaches it from mpv's control.
The parameter ``t`` is a table. The function reads the following entries:
``args``
Array of strings of the same semantics as the ``args`` used in the
``subprocess`` function.
The function returns ``nil``.
This is a legacy wrapper around calling the ``run`` command with
``mp.commandv`` and other functions.
``utils.getpid()``
Returns the process ID of the running mpv process. This can be used to identify
the calling mpv when launching (detached) subprocesses.
``utils.parse_json(str [, trail])``
Parses the given string argument as JSON, and returns it as a Lua table. On
error, returns ``nil, error``. (Currently, ``error`` is just a string
reading ``error``, because there is no fine-grained error reporting of any
kind.)
The returned value uses similar conventions as ``mp.get_property_native()``
to distinguish empty objects and arrays.
If the ``trail`` parameter is ``true`` (or any value equal to ``true``),
then trailing non-whitespace text is tolerated by the function, and the
trailing text is returned as 3rd return value. (The 3rd return value is
always there, but with ``trail`` set, no error is raised.)
``utils.format_json(v)``
Format the given Lua table (or value) as a JSON string and return it. On
error, returns ``nil, error``. (Errors usually only happen on value types
incompatible with JSON.)
The argument value uses similar conventions as ``mp.set_property_native()``
to distinguish empty objects and arrays.
``utils.to_string(v)``
Turn the given value into a string. Formats tables and their contents. This
doesn't do anything special; it is only needed because Lua is terrible.
Events
------
Events are notifications from player core to scripts. You can register an
event handler with ``mp.register_event``.
Note that all scripts (and other parts of the player) receive events equally,
and there's no such thing as blocking other scripts from receiving events.
Example:
::
function my_fn(event)
print("start of playback!")
end
mp.register_event("file-loaded", my_fn)
List of events
--------------
``start-file``
Happens right before a new file is loaded. When you receive this, the
player is loading the file (or possibly already done with it).
``end-file``
Happens after a file was unloaded. Typically, the player will load the
next file right away, or quit if this was the last file.
The event has the ``reason`` field, which takes one of these values:
``eof``
The file has ended. This can (but doesn't have to) include
incomplete files or broken network connections under
circumstances.
``stop``
Playback was ended by a command.
``quit``
Playback was ended by sending the quit command.
``error``
An error happened. In this case, an ``error`` field is present with
the error string.
``redirect``
Happens with playlists and similar. Details see
``MPV_END_FILE_REASON_REDIRECT`` in the C API.
``unknown``
Unknown. Normally doesn't happen, unless the Lua API is out of sync
with the C API. (Likewise, it could happen that your script gets
reason strings that did not exist yet at the time your script was
written.)
``file-loaded``
Happens after a file was loaded and begins playback.
``seek``
Happens on seeking. (This might include cases when the player seeks
internally, even without user interaction. This includes e.g. segment
changes when playing ordered chapters Matroska files.)
``playback-restart``
Start of playback after seek or after file was loaded.
``idle``
Idle mode is entered. This happens when playback ended, and the player was
started with ``--idle`` or ``--force-window``. This mode is implicitly ended
when the ``start-file`` or ``shutdown`` events happen.
``tick``
Called after a video frame was displayed. This is a hack, and you should
avoid using it. Use timers instead and maybe watch pausing/unpausing events
to avoid wasting CPU when the player is paused.
``shutdown``
Sent when the player quits, and the script should terminate. Normally
handled automatically. See `Details on the script initialization and lifecycle`_.
``log-message``
Receives messages enabled with ``mp.enable_messages``. The message data
is contained in the table passed as first parameter to the event handler.
The table contains, in addition to the default event fields, the following
fields:
``prefix``
The module prefix, identifies the sender of the message. This is what
the terminal player puts in front of the message text when using the
``--v`` option, and is also what is used for ``--msg-level``.
``level``
The log level as string. See ``msg.log`` for possible log level names.
Note that later versions of mpv might add new levels or remove
(undocumented) existing ones.
``text``
The log message. The text will end with a newline character. Sometimes
it can contain multiple lines.
Keep in mind that these messages are meant to be hints for humans. You
should not parse them, and prefix/level/text of messages might change
any time.
``get-property-reply``
Undocumented (not useful for Lua scripts).
``set-property-reply``
Undocumented (not useful for Lua scripts).
``command-reply``
Undocumented (not useful for Lua scripts).
``client-message``
Undocumented (used internally).
``video-reconfig``
Happens on video output or filter reconfig.
``audio-reconfig``
Happens on audio output or filter reconfig.
The following events also happen, but are deprecated: ``tracks-changed``,
``track-switched``, ``pause``, ``unpause``, ``metadata-update``,
``chapter-change``. Use ``mp.observe_property()`` instead.
Extras
------
This documents experimental features, or features that are "too special" to
guarantee a stable interface.
``mp.add_hook(type, priority, fn)``
Add a hook callback for ``type`` (a string identifying a certain kind of
hook). These hooks allow the player to call script functions and wait for
their result (normally, the Lua scripting interface is asynchronous from
the point of view of the player core). ``priority`` is an arbitrary integer
that allows ordering among hooks of the same kind. Using the value 50 is
recommended as neutral default value. ``fn`` is the function that will be
called during execution of the hook.
See `Hooks`_ for currently existing hooks and what they do - only the hook
list is interesting; handling hook execution is done by the Lua script
function automatically.
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