mpv ### ############## a media player ############## :Copyright: GPLv2+ :Manual section: 1 :Manual group: multimedia .. contents:: Table of Contents SYNOPSIS ======== | **mpv** [options] [file|URL|PLAYLIST|-] | **mpv** [options] files DESCRIPTION =========== **mpv** is a media player based on MPlayer and mplayer2. It supports a wide variety of video file formats, audio and video codecs, and subtitle types. Special input URL types are available to read input from a variety of sources other than disk files. Depending on platform, a variety of different video and audio output methods are supported. Usage examples to get you started quickly can be found at the end of this man page. INTERACTIVE CONTROL =================== mpv has a fully configurable, command-driven control layer which allows you to control mpv using keyboard, mouse, or remote control (there is no LIRC support - configure remotes as input devices instead). See the ``--input-`` options for ways to customize it. The following listings are not necessarily complete. See ``etc/input.conf`` in the mpv source files for a list of default bindings. User ``input.conf`` files and Lua scripts can define additional key bindings. See `COMMAND INTERFACE`_ and `Key names`_ sections for more details on configuring keybindings. See also ``--input-test`` for interactive binding details by key, and the `stats`_ built-in script for key bindings list (including print to terminal). Keyboard Control ---------------- LEFT and RIGHT Seek backward/forward 5 seconds. Shift+arrow does a 1 second exact seek (see ``--hr-seek``). UP and DOWN Seek forward/backward 1 minute. Shift+arrow does a 5 second exact seek (see ``--hr-seek``). Ctrl+LEFT and Ctrl+RIGHT Seek to the previous/next subtitle. Subject to some restrictions and might not always work; see ``sub-seek`` command. Ctrl+Shift+Left and Ctrl+Shift+Right Adjust subtitle delay so that the next or previous subtitle is displayed now. This is especially useful to sync subtitles to audio. [ and ] Decrease/increase current playback speed by 10%. { and } Halve/double current playback speed. BACKSPACE Reset playback speed to normal. Shift+BACKSPACE Undo the last seek. This works only if the playlist entry was not changed. Hitting it a second time will go back to the original position. See ``revert-seek`` command for details. Shift+Ctrl+BACKSPACE Mark the current position. This will then be used by ``Shift+BACKSPACE`` as revert position (once you seek back, the marker will be reset). You can use this to seek around in the file and then return to the exact position where you left off. < and > Go backward/forward in the playlist. ENTER Go forward in the playlist. p / SPACE Pause (pressing again unpauses). \. Step forward. Pressing once will pause, every consecutive press will play one frame and then go into pause mode again. , Step backward. Pressing once will pause, every consecutive press will play one frame in reverse and then go into pause mode again. q Stop playing and quit. Q Like ``q``, but store the current playback position. Playing the same file later will resume at the old playback position if possible. See `RESUMING PLAYBACK`_. / and * Decrease/increase volume. 9 and 0 Decrease/increase volume. m Mute sound. \_ Cycle through the available video tracks. \# Cycle through the available audio tracks. E Cycle through the available Editions. f Toggle fullscreen (see also ``--fs``). ESC Exit fullscreen mode. T Toggle stay-on-top (see also ``--ontop``). w and W Decrease/increase pan-and-scan range. The ``e`` key does the same as ``W`` currently, but use is discouraged. o (also P) Show progression bar, elapsed time and total duration on the OSD. O Toggle OSD states between normal and playback time/duration. v Toggle subtitle visibility. j and J Cycle through the available subtitles. z and Z Adjust subtitle delay by +/- 0.1 seconds. The ``x`` key does the same as ``Z`` currently, but use is discouraged. l Set/clear A-B loop points. See ``ab-loop`` command for details. L Toggle infinite looping. Ctrl + and Ctrl - Adjust audio delay (A/V sync) by +/- 0.1 seconds. Shift+g and Shift+f Adjust subtitle font size by +/- 10%. u Switch between applying no style overrides to SSA/ASS subtitles, and overriding them almost completely with the normal subtitle style. See ``--sub-ass-override`` for more info. V Toggle subtitle VSFilter aspect compatibility mode. See ``--sub-ass-vsfilter-aspect-compat`` for more info. r and R Move subtitles up/down. The ``t`` key does the same as ``R`` currently, but use is discouraged. s Take a screenshot. S Take a screenshot, without subtitles. (Whether this works depends on VO driver support.) Ctrl s Take a screenshot, as the window shows it (with subtitles, OSD, and scaled video). PGUP and PGDWN Seek to the beginning of the previous/next chapter. In most cases, "previous" will actually go to the beginning of the current chapter; see ``--chapter-seek-threshold``. Shift+PGUP and Shift+PGDWN Seek backward or forward by 10 minutes. (This used to be mapped to PGUP/PGDWN without Shift.) d Activate/deactivate deinterlacer. A Cycle aspect ratio override. Ctrl h Toggle hardware video decoding on/off. Alt+LEFT, Alt+RIGHT, Alt+UP, Alt+DOWN Move the video rectangle (panning). Alt + and Alt - Combining ``Alt`` with the ``+`` or ``-`` keys changes video zoom. Alt+BACKSPACE Reset the pan/zoom settings. F8 Show the playlist and the current position in it (useful only if a UI window is used, broken on the terminal). F9 Show the list of audio and subtitle streams (useful only if a UI window is used, broken on the terminal). i and I Show/toggle an overlay displaying statistics about the currently playing file such as codec, framerate, number of dropped frames and so on. See `STATS`_ for more information. del Cycle OSC visibility between never / auto (mouse-move) / always \` Show the console. (ESC closes it again. See `CONSOLE`_.) (The following keys are valid only when using a video output that supports the corresponding adjustment.) 1 and 2 Adjust contrast. 3 and 4 Adjust brightness. 5 and 6 Adjust gamma. 7 and 8 Adjust saturation. Alt+0 (and command+0 on macOS) Resize video window to half its original size. Alt+1 (and command+1 on macOS) Resize video window to its original size. Alt+2 (and command+2 on macOS) Resize video window to double its original size. command + f (macOS only) Toggle fullscreen (see also ``--fs``). (The following keys are valid if you have a keyboard with multimedia keys.) PAUSE Pause. STOP Stop playing and quit. PREVIOUS and NEXT Seek backward/forward 1 minute. If you miss some older key bindings, look at ``etc/restore-old-bindings.conf`` in the mpv git repository. Mouse Control ------------- Left double click Toggle fullscreen on/off. Right click Toggle pause on/off. Forward/Back button Skip to next/previous entry in playlist. Wheel up/down Seek forward/backward 10 seconds. Wheel left/right Decrease/increase volume. USAGE ===== Command line arguments starting with ``-`` are interpreted as options, everything else as filenames or URLs. All options except *flag* options (or choice options which include ``yes``) require a parameter in the form ``--option=value``. One exception is the lone ``-`` (without anything else), which means media data will be read from stdin. Also, ``--`` (without anything else) will make the player interpret all following arguments as filenames, even if they start with ``-``. (To play a file named ``-``, you need to use ``./-``.) Every *flag* option has a *no-flag* counterpart, e.g. the opposite of the ``--fs`` option is ``--no-fs``. ``--fs=yes`` is same as ``--fs``, ``--fs=no`` is the same as ``--no-fs``. If an option is marked as *(XXX only)*, it will only work in combination with the *XXX* option or if *XXX* is compiled in. Legacy option syntax -------------------- The ``--option=value`` syntax is not strictly enforced, and the alternative legacy syntax ``-option value`` and ``-option=value`` will also work. This is mostly for compatibility with MPlayer. Using these should be avoided. Their semantics can change any time in the future. For example, the alternative syntax will consider an argument following the option a filename. ``mpv -fs no`` will attempt to play a file named ``no``, because ``--fs`` is a flag option that requires no parameter. If an option changes and its parameter becomes optional, then a command line using the alternative syntax will break. Until mpv 0.31.0, there was no difference whether an option started with ``--`` or a single ``-``. Newer mpv releases strictly expect that you pass the option value after a ``=``. For example, before ``mpv --log-file f.txt`` would write a log to ``f.txt``, but now this command line fails, as ``--log-file`` expects an option value, and ``f.txt`` is simply considered a normal file to be played (as in ``mpv f.txt``). The future plan is that ``-option value`` will not work anymore, and options with a single ``-`` behave the same as ``--`` options. Escaping spaces and other special characters -------------------------------------------- Keep in mind that the shell will partially parse and mangle the arguments you pass to mpv. For example, you might need to quote or escape options and filenames: ``mpv "filename with spaces.mkv" --title="window title"`` It gets more complicated if the suboption parser is involved. The suboption parser puts several options into a single string, and passes them to a component at once, instead of using multiple options on the level of the command line. The suboption parser can quote strings with ``"`` and ``[...]``. Additionally, there is a special form of quoting with ``%n%`` described below. For example, assume the hypothetical ``foo`` filter can take multiple options: ``mpv test.mkv --vf=foo:option1=value1:option2:option3=value3,bar`` This passes ``option1`` and ``option3`` to the ``foo`` filter, with ``option2`` as flag (implicitly ``option2=yes``), and adds a ``bar`` filter after that. If an option contains spaces or characters like ``,`` or ``:``, you need to quote them: ``mpv '--vf=foo:option1="option value with spaces",bar'`` Shells may actually strip some quotes from the string passed to the commandline, so the example quotes the string twice, ensuring that mpv receives the ``"`` quotes. The ``[...]`` form of quotes wraps everything between ``[`` and ``]``. It's useful with shells that don't interpret these characters in the middle of an argument (like bash). These quotes are balanced (since mpv 0.9.0): the ``[`` and ``]`` nest, and the quote terminates on the last ``]`` that has no matching ``[`` within the string. (For example, ``[a[b]c]`` results in ``a[b]c``.) The fixed-length quoting syntax is intended for use with external scripts and programs. It is started with ``%`` and has the following format:: %n%string_of_length_n .. admonition:: Examples ``mpv '--vf=foo:option1=%11%quoted text' test.avi`` Or in a script: ``mpv --vf=foo:option1=%`expr length "$NAME"`%"$NAME" test.avi`` Note: where applicable with JSON-IPC, ``%n%`` is the length in UTF-8 bytes, after decoding the JSON data. Suboptions passed to the client API are also subject to escaping. Using ``mpv_set_option_string()`` is exactly like passing ``--name=data`` to the command line (but without shell processing of the string). Some options support passing values in a more structured way instead of flat strings, and can avoid the suboption parsing mess. For example, ``--vf`` supports ``MPV_FORMAT_NODE``, which lets you pass suboptions as a nested data structure of maps and arrays. Paths ----- Some care must be taken when passing arbitrary paths and filenames to mpv. For example, paths starting with ``-`` will be interpreted as options. Likewise, if a path contains the sequence ``://``, the string before that might be interpreted as protocol prefix, even though ``://`` can be part of a legal UNIX path. To avoid problems with arbitrary paths, you should be sure that absolute paths passed to mpv start with ``/``, and prefix relative paths with ``./``. Using the ``file://`` pseudo-protocol is discouraged, because it involves strange URL unescaping rules. The name ``-`` itself is interpreted as stdin, and will cause mpv to disable console controls. (Which makes it suitable for playing data piped to stdin.) The special argument ``--`` can be used to stop mpv from interpreting the following arguments as options. When using the client API, you should strictly avoid using ``mpv_command_string`` for invoking the ``loadfile`` command, and instead prefer e.g. ``mpv_command`` to avoid the need for filename escaping. For paths passed to suboptions, the situation is further complicated by the need to escape special characters. To work this around, the path can be additionally wrapped in the fixed-length syntax, e.g. ``%n%string_of_length_n`` (see above). Some mpv options interpret paths starting with ``~``. Currently, the prefix ``~~home/`` expands to the mpv configuration directory (usually ``~/.config/mpv/``). ``~/`` expands to the user's home directory. (The trailing ``/`` is always required.) The following paths are currently recognized: ================ =============================================================== Name Meaning ================ =============================================================== ``~~/`` If the subpath exists in any of the mpv's config directories the path of the existing file/dir is returned. Otherwise this is equivalent to ``~~home/``. Note that if --no-config is used ``~~/foobar`` will resolve to ``foobar`` which can be unexpected. ``~/`` user home directory root (similar to shell, ``$HOME``) ``~~home/`` mpv config dir (for example ``~/.config/mpv/``) ``~~global/`` the global config path, if available (not on win32) ``~~osxbundle/`` the macOS bundle resource path (macOS only) ``~~desktop/`` the path to the desktop (win32, macOS) ``~~exe_dir/`` win32 only: the path to the directory containing the exe (for config file purposes; ``$MPV_HOME`` overrides it) ``~~old_home/`` do not use ================ =============================================================== Per-File Options ---------------- When playing multiple files, any option given on the command line usually affects all files. Example:: mpv --a file1.mkv --b file2.mkv --c =============== =========================== File Active options =============== =========================== file1.mkv ``--a --b --c`` file2.mkv ``--a --b --c`` =============== =========================== (This is different from MPlayer and mplayer2.) Also, if any option is changed at runtime (via input commands), they are not reset when a new file is played. Sometimes, it is useful to change options per-file. This can be achieved by adding the special per-file markers ``--{`` and ``--}``. (Note that you must escape these on some shells.) Example:: mpv --a file1.mkv --b --\{ --c file2.mkv --d file3.mkv --e --\} file4.mkv --f =============== =========================== File Active options =============== =========================== file1.mkv ``--a --b --f`` file2.mkv ``--a --b --f --c --d --e`` file3.mkv ``--a --b --f --c --d --e`` file4.mkv ``--a --b --f`` =============== =========================== Additionally, any file-local option changed at runtime is reset when the current file stops playing. If option ``--c`` is changed during playback of ``file2.mkv``, it is reset when advancing to ``file3.mkv``. This only affects file-local options. The option ``--a`` is never reset here. List Options ------------ Some options which store lists of option values can have action suffixes. For example, the ``--display-tags`` option takes a ``,``-separated list of tags, but the option also allows you to append a single tag with ``--display-tags-append``, and the tag name can for example contain a literal ``,`` without the need for escaping. String list and path list options ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ String lists are separated by ``,``. The strings are not parsed or interpreted by the option system itself. However, most Path or file list options use ``:`` (Unix) or ``;`` (Windows) as separator, instead of ``,``. They support the following operations: ============= =============================================== Suffix Meaning ============= =============================================== -set Set a list of items (using the list separator, escaped with backslash) -append Append single item (does not interpret escapes) -add Append 1 or more items (same syntax as -set) -pre Prepend 1 or more items (same syntax as -set) -clr Clear the option (remove all items) -remove Delete item if present (does not interpret escapes) -del Delete 1 or more items by integer index (deprecated) -toggle Append an item, or remove if if it already exists (no escapes) ============= =============================================== ``-append`` is meant as a simple way to append a single item without having to escape the argument (you may still need to escape on the shell level). Key/value list options ~~~~~~~~~~~~~~~~~~~~~~ A key/value list is a list of key/value string pairs. In programming languages, this type of data structure is often called a map or a dictionary. The order normally does not matter, although in some cases the order might matter. They support the following operations: ============= =============================================== Suffix Meaning ============= =============================================== -set Set a list of items (using ``,`` as separator) -append Append a single item (escapes for the key, no escapes for the value) -add Append 1 or more items (same syntax as -set) -remove Delete item by key if present (does not interpret escapes) ============= =============================================== Keys are unique within the list. If an already present key is set, the existing key is removed before the new value is appended. If you want to pass a value without interpreting it for escapes or ``,``, it is recommended to use the ``-add`` variant. When using libmpv, prefer using ``MPV_FORMAT_NODE_MAP``; when using a scripting backend or the JSON IPC, use an appropriate structured data type. Prior to mpv 0.33, ``:`` was also recognized as separator by ``-set``. Filter options ~~~~~~~~~~~~~~ This is a very complex option type for the ``--af`` and ``--vf`` options only. They often require complicated escaping. See `VIDEO FILTERS`_ for details. They support the following operations: ============= =============================================== Suffix Meaning ============= =============================================== -set Set a list of filters (using ``,`` as separator) -append Append single filter -add Append 1 or more filters (same syntax as -set) -pre Prepend 1 or more filters (same syntax as -set) -clr Clear the option (remove all filters) -remove Delete filter if present -del Delete 1 or more filters by integer index or filter label (deprecated) -toggle Append a filter, or remove if if it already exists -help Pseudo operation that prints a help text to the terminal ============= =============================================== General ~~~~~~~ Without suffix, the operation used is normally ``-set``. Although some operations allow specifying multiple items, using this is strongly discouraged and deprecated, except for ``-set``. There is a chance that operations like ``-add`` and ``-pre`` will work like ``-append`` and accept a single, unescaped item only (so the ``,`` separator will not be interpreted and is passed on as part of the value). Some options (like ``--sub-file``, ``--audio-file``, ``--glsl-shader``) are aliases for the proper option with ``-append`` action. For example, ``--sub-file`` is an alias for ``--sub-files-append``. Options of this type can be changed at runtime using the ``change-list`` command, which takes the suffix (without the ``-``) as separate operation parameter. CONFIGURATION FILES =================== Location and Syntax ------------------- You can put all of the options in configuration files which will be read every time mpv is run. The system-wide configuration file 'mpv.conf' is in your configuration directory (e.g. ``/etc/mpv`` or ``/usr/local/etc/mpv``), the user-specific one is ``~/.config/mpv/mpv.conf``. For details and platform specifics (in particular Windows paths) see the `FILES`_ section. User-specific options override system-wide options and options given on the command line override either. The syntax of the configuration files is ``option=value``. Everything after a *#* is considered a comment. Options that work without values can be enabled by setting them to *yes* and disabled by setting them to *no*. Even suboptions can be specified in this way. .. admonition:: Example configuration file :: # Use GPU-accelerated video output by default. vo=gpu # Use quotes for text that can contain spaces: term-status-msg="Time: ${time-pos}" Escaping spaces and special characters -------------------------------------- This is done like with command line options. The shell is not involved here, but option values still need to be quoted as a whole if it contains certain characters like spaces. A config entry can be quoted with ``"``, as well as with the fixed-length syntax (``%n%``) mentioned before. This is like passing the exact contents of the quoted string as command line option. C-style escapes are currently _not_ interpreted on this level, although some options do this manually. (This is a mess and should probably be changed at some point.) Putting Command Line Options into the Configuration File -------------------------------------------------------- Almost all command line options can be put into the configuration file. Here is a small guide: ======================= ======================== Option Configuration file entry ======================= ======================== ``--flag`` ``flag`` ``-opt val`` ``opt=val`` ``--opt=val`` ``opt=val`` ``-opt "has spaces"`` ``opt="has spaces"`` ======================= ======================== File-specific Configuration Files --------------------------------- You can also write file-specific configuration files. If you wish to have a configuration file for a file called 'video.avi', create a file named 'video.avi.conf' with the file-specific options in it and put it in ``~/.config/mpv/``. You can also put the configuration file in the same directory as the file to be played. Both require you to set the ``--use-filedir-conf`` option (either on the command line or in your global config file). If a file-specific configuration file is found in the same directory, no file-specific configuration is loaded from ``~/.config/mpv``. In addition, the ``--use-filedir-conf`` option enables directory-specific configuration files. For this, mpv first tries to load a mpv.conf from the same directory as the file played and then tries to load any file-specific configuration. Profiles -------- To ease working with different configurations, profiles can be defined in the configuration files. A profile starts with its name in square brackets, e.g. ``[my-profile]``. All following options will be part of the profile. A description (shown by ``--profile=help``) can be defined with the ``profile-desc`` option. To end the profile, start another one or use the profile name ``default`` to continue with normal options. You can list profiles with ``--profile=help``, and show the contents of a profile with ``--show-profile=`` (replace ```` with the profile name). You can apply profiles on start with the ``--profile=`` option, or at runtime with the ``apply-profile `` command. .. admonition:: Example mpv config file with profiles :: # normal top-level option fullscreen=yes # a profile that can be enabled with --profile=big-cache [big-cache] cache=yes demuxer-max-bytes=123400KiB demuxer-readahead-secs=20 [slow] profile-desc="some profile name" # reference a builtin profile profile=gpu-hq [fast] vo=vdpau # using a profile again extends it [slow] framedrop=no # you can also include other profiles profile=big-cache Runtime profiles ---------------- Profiles can be set at runtime with ``apply-profile`` command. Since this operation is "destructive" (every item in a profile is simply set as an option, overwriting the previous value), you can't just enable and disable profiles again. As a partial remedy, there is a way to make profiles save old option values before overwriting them with the profile values, and then restoring the old values at a later point using ``apply-profile restore``. This can be enabled with the ``profile-restore`` option, which takes one of the following options: ``default`` Does nothing, and nothing can be restored (default). ``copy`` When applying a profile, copy the old values of all profile options to a backup before setting them from the profile. These options are reset to their old values using the backup when restoring. Every profile has its own list of backed up values. If the backup already exists (e.g. if ``apply-profile name`` was called more than once in a row), the existing backup is no changed. The restore operation will remove the backup. It's important to know that restoring does not "undo" setting an option, but simply copies the old option value. Consider for example ``vf-add``, appends an entry to ``vf``. This mechanism will simply copy the entire ``vf`` list, and does _not_ execute the inverse of ``vf-add`` (that would be ``vf-remove``) on restoring. Note that if a profile contains recursive profiles (via the ``profile`` option), the options in these recursive profiles are treated as if they were part of this profile. The referenced profile's backup list is not used when creating or using the backup. Restoring a profile does not restore referenced profiles, only the options of referenced profiles (as if they were part of the main profile). ``copy-equal`` Similar to ``copy``, but restore an option only if it has the same value as the value effectively set by the profile. This tries to deal with the situation when the user does not want the option to be reset after interactively changing it. .. admonition:: Example :: [something] profile-restore=copy-equal vf-add=rotate=PI/2 # rotate by 90 degrees Then running these commands will result in behavior as commented: :: set vf vflip apply-profile something vf add hflip apply-profile something # vf == vflip,rotate=PI/2,hflip,rotate=PI/2 apply-profile something restore # vf == vflip Conditional auto profiles ------------------------- Profiles which have the ``profile-cond`` option set are applied automatically if the associated condition matches (unless auto profiles are disabled). The option takes a string, which is interpreted as Lua condition. If evaluating the expression returns true, the profile is applied, if it returns false, it is ignored. This Lua code execution is not sandboxed. Any variables in condition expressions can reference properties. If an identifier is not already defined by Lua or mpv, it is interpreted as property. For example, ``pause`` would return the current pause status. You cannot reference properties with ``-`` this way since that would denote a subtraction, but if the variable name contains any ``_`` characters, they are turned into ``-``. For example, ``playback_time`` would return the property ``playback-time``. A more robust way to access properties is using ``p.property_name`` or ``get("property-name", default_value)``. The automatic variable to property magic will break if a new identifier with the same name is introduced (for example, if a function named ``pause()`` were added, ``pause`` would return a function value instead of the value of the ``pause`` property). Note that if a property is not available, it will return ``nil``, which can cause errors if used in expressions. These are logged in verbose mode, and the expression is considered to be false. Whenever a property referenced by a profile condition changes, the condition is re-evaluated. If the return value of the condition changes from false or error to true, the profile is applied. This mechanism tries to "unapply" profiles once the condition changes from true to false. If you want to use this, you need to set ``profile-restore`` for the profile. Another possibility it to create another profile with an inverse condition to undo the other profile. Recursive profiles can be used. But it is discouraged to reference other conditional profiles in a conditional profile, since this can lead to tricky and unintuitive behavior. .. admonition:: Example Make only HD video look funny: :: [something] profile-desc=HD video sucks profile-cond=width >= 1280 hue=-50 If you want the profile to be reverted if the condition goes to false again, you can set ``profile-restore``: :: [something] profile-desc=Mess up video when entering fullscreen profile-cond=fullscreen profile-restore=copy vf-add=rotate=PI/2 # rotate by 90 degrees This appends the ``rotate`` filter to the video filter chain when entering fullscreen. When leaving fullscreen, the ``vf`` option is set to the value it had before entering fullscreen. Note that this would also remove any other filters that were added during fullscreen mode by the user. Avoiding this is trickier, and could for example be solved by adding a second profile with an inverse condition and operation: :: [something] profile-cond=fullscreen vf-add=@rot:rotate=PI/2 [something-inv] profile-cond=not fullscreen vf-remove=@rot .. warning:: Every time an involved property changes, the condition is evaluated again. If your condition uses ``p.playback_time`` for example, the condition is re-evaluated approximately on every video frame. This is probably slow. This feature is managed by an internal Lua script. Conditions are executed as Lua code within this script. Its environment contains at least the following things: ``(function environment table)`` Every Lua function has an environment table. This is used for identifier access. There is no named Lua symbol for it; it is implicit. The environment does "magic" accesses to mpv properties. If an identifier is not already defined in ``_G``, it retrieves the mpv property of the same name. Any occurrences of ``_`` in the name are replaced with ``-`` before reading the property. The returned value is as retrieved by ``mp.get_property_native(name)``. Internally, a cache of property values, updated by observing the property is used instead, so properties that are not observable will be stuck at the initial value forever. If you want to access properties, that actually contain ``_`` in the name, use ``get()`` (which does not perform transliteration). Internally, the environment table has a ``__index`` meta method set, which performs the access logic. ``p`` A "magic" table similar to the environment table. Unlike the latter, this does not prefer accessing variables defined in ``_G`` - it always accesses properties. ``get(name [, def])`` Read a property and return its value. If the property value is ``nil`` (e.g. if the property does not exist), ``def`` is returned. This is superficially similar to ``mp.get_property_native(name)``. An important difference is that this accesses the property cache, and enables the change detection logic (which is essential to the dynamic runtime behavior of auto profiles). Also, it does not return an error value as second return value. The "magic" tables mentioned above use this function as backend. It does not perform the ``_`` transliteration. In addition, the same environment as in a blank mpv Lua script is present. For example, ``math`` is defined and gives access to the Lua standard math library. .. warning:: This feature is subject to change indefinitely. You might be forced to adjust your profiles on mpv updates. Legacy auto profiles -------------------- Some profiles are loaded automatically using a legacy mechanism. The following example demonstrates this: .. admonition:: Auto profile loading :: [extension.mkv] profile-desc="profile for .mkv files" vf=vflip The profile name follows the schema ``type.name``, where type can be ``protocol`` for the input/output protocol in use (see ``--list-protocols``), and ``extension`` for the extension of the path of the currently played file (*not* the file format). This feature is very limited, and is considered soft-deprecated. Use conditional auto profiles. Using mpv from other programs or scripts ======================================== There are three choices for using mpv from other programs or scripts: 1. Calling it as UNIX process. If you do this, *do not parse terminal output*. The terminal output is intended for humans, and may change any time. In addition, terminal behavior itself may change any time. Compatibility cannot be guaranteed. Your code should work even if you pass ``--no-terminal``. Do not attempt to simulate user input by sending terminal control codes to mpv's stdin. If you need interactive control, using ``--input-ipc-server`` is recommended. This gives you access to the `JSON IPC`_ over unix domain sockets (or named pipes on Windows). Depending on what you do, passing ``--no-config`` or ``--config-dir`` may be a good idea to avoid conflicts with the normal mpv user configuration intended for CLI playback. Using ``--input-ipc-server`` is also suitable for purposes like remote control (however, the IPC protocol itself is not "secure" and not intended to be so). 2. Using libmpv. This is generally recommended when mpv is used as playback backend for a completely different application. The provided C API is very close to CLI mechanisms and the scripting API. Note that even though libmpv has different defaults, it can be configured to work exactly like the CLI player (except command line parsing is unavailable). See `EMBEDDING INTO OTHER PROGRAMS (LIBMPV)`_. 3. As a user script (`LUA SCRIPTING`_, `JAVASCRIPT`_, `C PLUGINS`_). This is recommended when the goal is to "enhance" the CLI player. Scripts get access to the entire client API of mpv. This is the standard way to create third-party extensions for the player. All these access the client API, which is the sum of the various mechanisms provided by the player core, as documented here: `OPTIONS`_, `List of Input Commands`_, `Properties`_, `List of events`_ (also see C API), `Hooks`_. TAKING SCREENSHOTS ================== Screenshots of the currently played file can be taken using the 'screenshot' input mode command, which is by default bound to the ``s`` key. Files named ``mpv-shotNNNN.jpg`` will be saved in the working directory, using the first available number - no files will be overwritten. In pseudo-GUI mode, the screenshot will be saved somewhere else. See `PSEUDO GUI MODE`_. A screenshot will usually contain the unscaled video contents at the end of the video filter chain and subtitles. By default, ``S`` takes screenshots without subtitles, while ``s`` includes subtitles. Unlike with MPlayer, the ``screenshot`` video filter is not required. This filter was never required in mpv, and has been removed. TERMINAL STATUS LINE ==================== During playback, mpv shows the playback status on the terminal. It looks like something like this: ``AV: 00:03:12 / 00:24:25 (13%) A-V: -0.000`` The status line can be overridden with the ``--term-status-msg`` option. The following is a list of things that can show up in the status line. Input properties, that can be used to get the same information manually, are also listed. - ``AV:`` or ``V:`` (video only) or ``A:`` (audio only) - The current time position in ``HH:MM:SS`` format (``playback-time`` property) - The total file duration (absent if unknown) (``duration`` property) - Playback speed, e.g. ``x2.0``. Only visible if the speed is not normal. This is the user-requested speed, and not the actual speed (usually they should be the same, unless playback is too slow). (``speed`` property.) - Playback percentage, e.g. ``(13%)``. How much of the file has been played. Normally calculated out of playback position and duration, but can fallback to other methods (like byte position) if these are not available. (``percent-pos`` property.) - The audio/video sync as ``A-V: 0.000``. This is the difference between audio and video time. Normally it should be 0 or close to 0. If it's growing, it might indicate a playback problem. (``avsync`` property.) - Total A/V sync change, e.g. ``ct: -0.417``. Normally invisible. Can show up if there is audio "missing", or not enough frames can be dropped. Usually this will indicate a problem. (``total-avsync-change`` property.) - Encoding state in ``{...}``, only shown in encoding mode. - Display sync state. If display sync is active (``display-sync-active`` property), this shows ``DS: 2.500/13``, where the first number is average number of vsyncs per video frame (e.g. 2.5 when playing 24Hz videos on 60Hz screens), which might jitter if the ratio doesn't round off, or there are mistimed frames (``vsync-ratio``), and the second number of estimated number of vsyncs which took too long (``vo-delayed-frame-count`` property). The latter is a heuristic, as it's generally not possible to determine this with certainty. - Dropped frames, e.g. ``Dropped: 4``. Shows up only if the count is not 0. Can grow if the video framerate is higher than that of the display, or if video rendering is too slow. May also be incremented on "hiccups" and when the video frame couldn't be displayed on time. (``frame-drop-count`` property.) If the decoder drops frames, the number of decoder-dropped frames is appended to the display as well, e.g.: ``Dropped: 4/34``. This happens only if decoder frame dropping is enabled with the ``--framedrop`` options. (``decoder-frame-drop-count`` property.) - Cache state, e.g. ``Cache: 2s/134KB``. Visible if the stream cache is enabled. The first value shows the amount of video buffered in the demuxer in seconds, the second value shows the estimated size of the buffered amount in kilobytes. (``demuxer-cache-duration`` and ``demuxer-cache-state`` properties.) LOW LATENCY PLAYBACK ==================== mpv is optimized for normal video playback, meaning it actually tries to buffer as much data as it seems to make sense. This will increase latency. Reducing latency is possible only by specifically disabling features which increase latency. The builtin ``low-latency`` profile tries to apply some of the options which can reduce latency. You can use ``--profile=low-latency`` to apply all of them. You can list the contents with ``--show-profile=low-latency`` (some of the options are quite obscure, and may change every mpv release). Be aware that some of the options can reduce playback quality. Most latency is actually caused by inconvenient timing behavior. You can disable this with ``--untimed``, but it will likely break, unless the stream has no audio, and the input feeds data to the player at a constant rate. Another common problem is with MJPEG streams. These do not signal the correct framerate. Using ``--untimed`` or ``--no-correct-pts --fps=60`` might help. For livestreams, data can build up due to pausing the stream, due to slightly lower playback rate, or "buffering" pauses. If the demuxer cache is enabled, these can be skipped manually. The experimental ``drop-buffers`` command can be used to discard any buffered data, though it's very disruptive. In some cases, manually tuning TCP buffer sizes and such can help to reduce latency. Additional options that can be tried: - ``--opengl-glfinish=yes``, can reduce buffering in the graphics driver - ``--opengl-swapinterval=0``, same - ``--vo=xv``, same - without audio ``--framedrop=no --speed=1.01`` may help for live sources (results can be mixed) RESUMING PLAYBACK ================= mpv is capable of storing the playback position of the currently playing file and resume from there the next time that file is played. This is done with the commands ``quit-watch-later`` (bound to Shift+Q by default) and ``write-watch-later-config``, and with the ``--save-position-on-quit`` option. The difference between always quitting with a key bound to ``quit-watch-later`` and using ``--save-position-on-quit`` is that the latter will save the playback position even when mpv is closed with a method other than a keybinding, for example if you shutdown your system without closing mpv beforehand, unless of course mpv is terminated abruptly and doesn't have the time to save (e.g. with the KILL Unix signal). mpv also stores options other than the playback position when they have been modified after playback began, for example the volume and the fullscreen state, and restores their values the next time the file is played. Which options are saved can be configured with the ``--watch-later-options`` option. When playing multiple playlist entries, mpv checks if one them has a resume config file associated, and if it finds one it restarts playback from it. For example, if you use ``quit-watch-later`` on the 5th episode of a show, and later play all the episodes, mpv will automatically resume playback from episode 5. More options to configure this functionality are listed in `Watch Later`_. PROTOCOLS ========= ``http://...``, ``https://``, ... Many network protocols are supported, but the protocol prefix must always be specified. mpv will never attempt to guess whether a filename is actually a network address. A protocol prefix is always required. Note that not all prefixes are documented here. Undocumented prefixes are either aliases to documented protocols, or are just redirections to protocols implemented and documented in FFmpeg. ``data:`` is supported in FFmpeg (not in Libav), but needs to be in the format ``data://``. This is done to avoid ambiguity with filenames. You can also prefix it with ``lavf://`` or ``ffmpeg://``. ``ytdl://...`` By default, the youtube-dl hook script only looks at http(s) URLs. Prefixing an URL with ``ytdl://`` forces it to be always processed by the script. This can also be used to invoke special youtube-dl functionality like playing a video by ID or invoking search. Keep in mind that you can't pass youtube-dl command line options by this, and you have to use ``--ytdl-raw-options`` instead. ``-`` Play data from stdin. ``smb://PATH`` Play a path from Samba share. (Requires FFmpeg support.) ``bd://[title][/device]`` ``--bluray-device=PATH`` Play a Blu-ray disc. Since libbluray 1.0.1, you can read from ISO files by passing them to ``--bluray-device``. ``title`` can be: ``longest`` or ``first`` (selects the default playlist); ``mpls/`` (selects .mpls playlist); ```` (select playlist with the same index). mpv will list the available playlists on loading. ``bluray://`` is an alias. ``dvd://[title][/device]`` ``--dvd-device=PATH`` Play a DVD. DVD menus are not supported. If no title is given, the longest title is auto-selected. Without ``--dvd-device``, it will probably try to open an actual optical drive, if available and implemented for the OS. ``dvdnav://`` is an old alias for ``dvd://`` and does exactly the same thing. ``dvb://[cardnumber@]channel`` ``--dvbin-...`` Digital TV via DVB. (Linux only.) ``mf://[filemask|@listfile]`` ``--mf-...`` Play a series of images as video. ``cdda://[device]`` ``--cdrom-device=PATH`` ``--cdda-...`` Play CD. ``lavf://...`` Access any FFmpeg/Libav libavformat protocol. Basically, this passed the string after the ``//`` directly to libavformat. ``av://type:options`` This is intended for using libavdevice inputs. ``type`` is the libavdevice demuxer name, and ``options`` is the (pseudo-)filename passed to the demuxer. .. admonition:: Example :: mpv av://v4l2:/dev/video0 --profile=low-latency --untimed This plays video from the first v4l input with nearly the lowest latency possible. It's a good replacement for the removed ``tv://`` input. Using ``--untimed`` is a hack to output a captured frame immediately, instead of respecting the input framerate. (There may be better ways to handle this in the future.) ``avdevice://`` is an alias. ``file://PATH`` A local path as URL. Might be useful in some special use-cases. Note that ``PATH`` itself should start with a third ``/`` to make the path an absolute path. ``appending://PATH`` Play a local file, but assume it's being appended to. This is useful for example for files that are currently being downloaded to disk. This will block playback, and stop playback only if no new data was appended after a timeout of about 2 seconds. Using this is still a bit of a bad idea, because there is no way to detect if a file is actually being appended, or if it's still written. If you're trying to play the output of some program, consider using a pipe (``something | mpv -``). If it really has to be a file on disk, use tail to make it wait forever, e.g. ``tail -f -c +0 file.mkv | mpv -``. ``fd://123`` Read data from the given file descriptor (for example 123). This is similar to piping data to stdin via ``-``, but can use an arbitrary file descriptor. mpv may modify some file descriptor properties when the stream layer "opens" it. ``fdclose://123`` Like ``fd://``, but the file descriptor is closed after use. When using this you need to ensure that the same fd URL will only be used once. ``edl://[edl specification as in edl-mpv.rst]`` Stitch together parts of multiple files and play them. ``slice://start[-end]@URL`` Read a slice of a stream. ``start`` and ``end`` represent a byte range and accept suffixes such as ``KiB`` and ``MiB``. ``end`` is optional. if ``end`` starts with ``+``, it is considered as offset from ``start``. Only works with seekable streams. Examples:: mpv slice://1g-2g@cap.ts This starts reading from cap.ts after seeking 1 GiB, then reads until reaching 2 GiB or end of file. mpv slice://1g-+2g@cap.ts This starts reading from cap.ts after seeking 1 GiB, then reads until reaching 3 GiB or end of file. mpv slice://100m@appending://cap.ts This starts reading from cap.ts after seeking 100MiB, then reads until end of file. ``null://`` Simulate an empty file. If opened for writing, it will discard all data. The ``null`` demuxer will specifically pass autoprobing if this protocol is used (while it's not automatically invoked for empty files). ``memory://data`` Use the ``data`` part as source data. ``hex://data`` Like ``memory://``, but the string is interpreted as hexdump. PSEUDO GUI MODE =============== mpv has no official GUI, other than the OSC (`ON SCREEN CONTROLLER`_), which is not a full GUI and is not meant to be. However, to compensate for the lack of expected GUI behavior, mpv will in some cases start with some settings changed to behave slightly more like a GUI mode. Currently this happens only in the following cases: - if started using the ``mpv.desktop`` file on Linux (e.g. started from menus or file associations provided by desktop environments) - if started from explorer.exe on Windows (technically, if it was started on Windows, and all of the stdout/stderr/stdin handles are unset) - started out of the bundle on macOS - if you manually use ``--player-operation-mode=pseudo-gui`` on the command line This mode applies options from the builtin profile ``builtin-pseudo-gui``, but only if these haven't been set in the user's config file or on the command line, which is the main difference to using ``--profile=builtin-pseudo-gui``. The profile is currently defined as follows: :: [builtin-pseudo-gui] terminal=no force-window=yes idle=once screenshot-directory=~~desktop/ The ``pseudo-gui`` profile exists for compatibility. The options in the ``pseudo-gui`` profile are applied unconditionally. In addition, the profile makes sure to enable the pseudo-GUI mode, so that ``--profile=pseudo-gui`` works like in older mpv releases: :: [pseudo-gui] player-operation-mode=pseudo-gui .. warning:: Currently, you can extend the ``pseudo-gui`` profile in the config file the normal way. This is deprecated. In future mpv releases, the behavior might change, and not apply your additional settings, and/or use a different profile name. Linux desktop issues ==================== This subsection describes common problems on the Linux desktop. None of these problems exist on systems like Windows or macOS. Disabling Screensaver --------------------- By default, mpv tries to disable the OS screensaver during playback (only if a VO using the OS GUI API is active). ``--stop-screensaver=no`` disables this. A common problem is that Linux desktop environments ignore the standard screensaver APIs on which mpv relies. In particular, mpv uses the Screen Saver extension (XSS) on X11, and the idle-inhibit protocol on Wayland. GNOME in particular still ignores the idle-inhibit protocol, and has its own D-Bus interfaces for display power management, which mpv does not support. Before mpv 0.33.0, the X11 backend ran ``xdg-screensaver reset`` in 10 second intervals when not paused in order to support screensaver inhibition in these environments. This functionality was removed in 0.33.0, but it is possible to call the ``xdg-screensaver`` command line program from a user script instead. .. include:: options.rst .. include:: ao.rst .. include:: vo.rst .. include:: af.rst .. include:: vf.rst .. include:: encode.rst .. include:: input.rst .. include:: osc.rst .. include:: stats.rst .. include:: console.rst .. include:: lua.rst .. include:: javascript.rst .. include:: ipc.rst .. include:: changes.rst .. include:: libmpv.rst ENVIRONMENT VARIABLES ===================== There are a number of environment variables that can be used to control the behavior of mpv. ``HOME``, ``XDG_CONFIG_HOME`` Used to determine mpv config directory. If ``XDG_CONFIG_HOME`` is not set, ``$HOME/.config/mpv`` is used. ``$HOME/.mpv`` is always added to the list of config search paths with a lower priority. ``MPV_HOME`` Directory where mpv looks for user settings. Overrides ``HOME``, and mpv will try to load the config file as ``$MPV_HOME/mpv.conf``. ``MPV_VERBOSE`` (see also ``-v`` and ``--msg-level``) Set the initial verbosity level across all message modules (default: 0). This is an integer, and the resulting verbosity corresponds to the number of ``--v`` options passed to the command line. ``MPV_LEAK_REPORT`` If set to ``1``, enable internal talloc leak reporting. If set to another value, disable leak reporting. If unset, use the default, which normally is ``0``. If mpv was built with ``--enable-ta-leak-report``, the default is ``1``. If leak reporting was disabled at compile time (``NDEBUG`` in custom ``CFLAGS``), this environment variable is ignored. ``LADSPA_PATH`` Specifies the search path for LADSPA plugins. If it is unset, fully qualified path names must be used. ``DISPLAY`` Standard X11 display name to use. FFmpeg/Libav: This library accesses various environment variables. However, they are not centrally documented, and documenting them is not our job. Therefore, this list is incomplete. Notable environment variables: ``http_proxy`` URL to proxy for ``http://`` and ``https://`` URLs. ``no_proxy`` List of domain patterns for which no proxy should be used. List entries are separated by ``,``. Patterns can include ``*``. libdvdcss: ``DVDCSS_CACHE`` Specify a directory in which to store title key values. This will speed up descrambling of DVDs which are in the cache. The ``DVDCSS_CACHE`` directory is created if it does not exist, and a subdirectory is created named after the DVD's title or manufacturing date. If ``DVDCSS_CACHE`` is not set or is empty, libdvdcss will use the default value which is ``${HOME}/.dvdcss/`` under Unix and the roaming application data directory (``%APPDATA%``) under Windows. The special value "off" disables caching. ``DVDCSS_METHOD`` Sets the authentication and decryption method that libdvdcss will use to read scrambled discs. Can be one of ``title``, ``key`` or ``disc``. key is the default method. libdvdcss will use a set of calculated player keys to try to get the disc key. This can fail if the drive does not recognize any of the player keys. disc is a fallback method when key has failed. Instead of using player keys, libdvdcss will crack the disc key using a brute force algorithm. This process is CPU intensive and requires 64 MB of memory to store temporary data. title is the fallback when all other methods have failed. It does not rely on a key exchange with the DVD drive, but rather uses a crypto attack to guess the title key. On rare cases this may fail because there is not enough encrypted data on the disc to perform a statistical attack, but on the other hand it is the only way to decrypt a DVD stored on a hard disc, or a DVD with the wrong region on an RPC2 drive. ``DVDCSS_RAW_DEVICE`` Specify the raw device to use. Exact usage will depend on your operating system, the Linux utility to set up raw devices is raw(8) for instance. Please note that on most operating systems, using a raw device requires highly aligned buffers: Linux requires a 2048 bytes alignment (which is the size of a DVD sector). ``DVDCSS_VERBOSE`` Sets the libdvdcss verbosity level. :0: Outputs no messages at all. :1: Outputs error messages to stderr. :2: Outputs error messages and debug messages to stderr. ``DVDREAD_NOKEYS`` Skip retrieving all keys on startup. Currently disabled. ``HOME`` FIXME: Document this. EXIT CODES ========== Normally **mpv** returns 0 as exit code after finishing playback successfully. If errors happen, the following exit codes can be returned: :1: Error initializing mpv. This is also returned if unknown options are passed to mpv. :2: The file passed to mpv couldn't be played. This is somewhat fuzzy: currently, playback of a file is considered to be successful if initialization was mostly successful, even if playback fails immediately after initialization. :3: There were some files that could be played, and some files which couldn't (using the definition of success from above). :4: Quit due to a signal, Ctrl+c in a VO window (by default), or from the default quit key bindings in encoding mode. Note that quitting the player manually will always lead to exit code 0, overriding the exit code that would be returned normally. Also, the ``quit`` input command can take an exit code: in this case, that exit code is returned. FILES ===== For Windows-specifics, see `FILES ON WINDOWS`_ section. ``/usr/local/etc/mpv/mpv.conf`` mpv system-wide settings (depends on ``--prefix`` passed to configure - mpv in default configuration will use ``/usr/local/etc/mpv/`` as config directory, while most Linux distributions will set it to ``/etc/mpv/``). ``~/.config/mpv`` The standard configuration directory. This can be overridden by environment variables, in ascending order: :1: If ``$XDG_CONFIG_HOME`` is set, then the derived configuration directory will be ``$XDG_CONFIG_HOME/mpv``. :2: If ``$MPV_HOME`` is set, then the derived configuration directory will be ``$MPV_HOME``. If this directory, nor the original configuration directory (see below) do not exist, mpv tries to create this directory automatically. ``~/.mpv/`` The original (pre 0.5.0) configuration directory. It will continue to be read if present. If both this directory and the standard configuration directory are present, configuration will be read from both with the standard configuration directory content taking precedence. However, you should fully migrate to the standard directory and a warning will be shown in this situation. ``~/.config/mpv/mpv.conf`` mpv user settings (see `CONFIGURATION FILES`_ section) ``~/.config/mpv/input.conf`` key bindings (see `INPUT.CONF`_ section) ``~/.config/mpv/fonts.conf`` Fontconfig fonts.conf that is customized for mpv. You should include system fonts.conf in this file or mpv would not know about fonts that you already have in the system. Only available when libass is built with fontconfig. ``~/.config/mpv/subfont.ttf`` fallback subtitle font ``~/.config/mpv/fonts/`` Font files in this directory are used by mpv/libass for subtitles. Useful if you do not want to install fonts to your system. Note that files in this directory are loaded into memory before being used by mpv. If you have a lot of fonts, consider using fonts.conf (see above) to include additional fonts, which is more memory-efficient. ``~/.config/mpv/scripts/`` All files in this directory are loaded as if they were passed to the ``--script`` option. They are loaded in alphabetical order. The ``--load-scripts=no`` option disables loading these files. See `Script location`_ for details. ``~/.config/mpv/watch_later/`` Contains temporary config files needed for resuming playback of files with the watch later feature. See for example the ``Q`` key binding, or the ``quit-watch-later`` input command. Each file is a small config file which is loaded if the corresponding media file is loaded. It contains the playback position and some (not necessarily all) settings that were changed during playback. The filenames are hashed from the full paths of the media files. It's in general not possible to extract the media filename from this hash. However, you can set the ``--write-filename-in-watch-later-config`` option, and the player will add the media filename to the contents of the resume config file. ``~/.config/mpv/script-opts/osc.conf`` This is loaded by the OSC script. See the `ON SCREEN CONTROLLER`_ docs for details. Other files in this directory are specific to the corresponding scripts as well, and the mpv core doesn't touch them. FILES ON WINDOWS ================ On win32 (if compiled with MinGW, but not Cygwin), the default config file locations are different. They are generally located under ``%APPDATA%/mpv/``. For example, the path to mpv.conf is ``%APPDATA%/mpv/mpv.conf``, which maps to a system and user-specific path, for example ``C:\users\USERNAME\AppData\Roaming\mpv\mpv.conf`` You can find the exact path by running ``echo %APPDATA%\mpv\mpv.conf`` in cmd.exe. Other config files (such as ``input.conf``) are in the same directory. See the `FILES`_ section above. The environment variable ``$MPV_HOME`` completely overrides these, like on UNIX. If a directory named ``portable_config`` next to the mpv.exe exists, all config will be loaded from this directory only. Watch later config files are written to this directory as well. (This exists on Windows only and is redundant with ``$MPV_HOME``. However, since Windows is very scripting unfriendly, a wrapper script just setting ``$MPV_HOME``, like you could do it on other systems, won't work. ``portable_config`` is provided for convenience to get around this restriction.) Config files located in the same directory as ``mpv.exe`` are loaded with lower priority. Some config files are loaded only once, which means that e.g. of 2 ``input.conf`` files located in two config directories, only the one from the directory with higher priority will be loaded. A third config directory with the lowest priority is the directory named ``mpv`` in the same directory as ``mpv.exe``. This used to be the directory with the highest priority, but is now discouraged to use and might be removed in the future. Note that mpv likes to mix ``/`` and ``\`` path separators for simplicity. kernel32.dll accepts this, but cmd.exe does not.