1 /* Copyright (C) 2017 the mpv developers
2  * Copyright (C) 2020 fence
3  *
4  * Permission to use, copy, modify, and/or distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 /*
18  * Note: the client API is licensed under ISC (see above) to enable
19  * other wrappers outside of mpv. But keep in mind that the
20  * mpv core is by default still GPLv2+ - unless built with
21  * --enable-lgpl, which makes it LGPLv2+.
22  */
23 
24 module mpv.client;
25 
26 import core.stdc.config;
27 
28 extern (C):
29 
30 /**
31  * Mechanisms provided by this API
32  * -------------------------------
33  *
34  * This API provides general control over mpv playback. It does not give you
35  * direct access to individual components of the player, only the whole thing.
36  * It's somewhat equivalent to MPlayer's slave mode. You can send commands,
37  * retrieve or set playback status or settings with properties, and receive
38  * events.
39  *
40  * The API can be used in two ways:
41  * 1) Internally in mpv, to provide additional features to the command line
42  *    player. Lua scripting uses this. (Currently there is no plugin API to
43  *    get a client API handle in external user code. It has to be a fixed
44  *    part of the player at compilation time.)
45  * 2) Using mpv as a library with mpv_create(). This basically allows embedding
46  *    mpv in other applications.
47  *
48  * Documentation
49  * -------------
50  *
51  * The libmpv C API is documented directly in this header. Note that most
52  * actual interaction with this player is done through
53  * options/commands/properties, which can be accessed through this API.
54  * Essentially everything is done with them, including loading a file,
55  * retrieving playback progress, and so on.
56  *
57  * These are documented elsewhere:
58  *      * http://mpv.io/manual/master/#options
59  *      * http://mpv.io/manual/master/#list-of-input-commands
60  *      * http://mpv.io/manual/master/#properties
61  *
62  * You can also look at the examples here:
63  *      * https://github.com/mpv-player/mpv-examples/tree/master/libmpv
64  *
65  * Event loop
66  * ----------
67  *
68  * In general, the API user should run an event loop in order to receive events.
69  * This event loop should call mpv_wait_event(), which will return once a new
70  * mpv client API is available. It is also possible to integrate client API
71  * usage in other event loops (e.g. GUI toolkits) with the
72  * mpv_set_wakeup_callback() function, and then polling for events by calling
73  * mpv_wait_event() with a 0 timeout.
74  *
75  * Note that the event loop is detached from the actual player. Not calling
76  * mpv_wait_event() will not stop playback. It will eventually congest the
77  * event queue of your API handle, though.
78  *
79  * Synchronous vs. asynchronous calls
80  * ----------------------------------
81  *
82  * The API allows both synchronous and asynchronous calls. Synchronous calls
83  * have to wait until the playback core is ready, which currently can take
84  * an unbounded time (e.g. if network is slow or unresponsive). Asynchronous
85  * calls just queue operations as requests, and return the result of the
86  * operation as events.
87  *
88  * Asynchronous calls
89  * ------------------
90  *
91  * The client API includes asynchronous functions. These allow you to send
92  * requests instantly, and get replies as events at a later point. The
93  * requests are made with functions carrying the _async suffix, and replies
94  * are returned by mpv_wait_event() (interleaved with the normal event stream).
95  *
96  * A 64 bit userdata value is used to allow the user to associate requests
97  * with replies. The value is passed as reply_userdata parameter to the request
98  * function. The reply to the request will have the reply
99  * mpv_event->reply_userdata field set to the same value as the
100  * reply_userdata parameter of the corresponding request.
101  *
102  * This userdata value is arbitrary and is never interpreted by the API. Note
103  * that the userdata value 0 is also allowed, but then the client must be
104  * careful not accidentally interpret the mpv_event->reply_userdata if an
105  * event is not a reply. (For non-replies, this field is set to 0.)
106  *
107  * Asynchronous calls may be reordered in arbitrarily with other synchronous
108  * and asynchronous calls. If you want a guaranteed order, you need to wait
109  * until asynchronous calls report completion before doing the next call.
110  *
111  * See also the section "Asynchronous command details" in the manpage.
112  *
113  * Multithreading
114  * --------------
115  *
116  * The client API is generally fully thread-safe, unless otherwise noted.
117  * Currently, there is no real advantage in using more than 1 thread to access
118  * the client API, since everything is serialized through a single lock in the
119  * playback core.
120  *
121  * Basic environment requirements
122  * ------------------------------
123  *
124  * This documents basic requirements on the C environment. This is especially
125  * important if mpv is used as library with mpv_create().
126  *
127  * - The LC_NUMERIC locale category must be set to "C". If your program calls
128  *   setlocale(), be sure not to use LC_ALL, or if you do, reset LC_NUMERIC
129  *   to its sane default: setlocale(LC_NUMERIC, "C").
130  * - If a X11 based VO is used, mpv will set the xlib error handler. This error
131  *   handler is process-wide, and there's no proper way to share it with other
132  *   xlib users within the same process. This might confuse GUI toolkits.
133  * - mpv uses some other libraries that are not library-safe, such as Fribidi
134  *   (used through libass), ALSA, FFmpeg, and possibly more.
135  * - The FPU precision must be set at least to double precision.
136  * - On Windows, mpv will call timeBeginPeriod(1).
137  * - On memory exhaustion, mpv will kill the process.
138  * - In certain cases, mpv may start sub processes (such as with the ytdl
139  *   wrapper script).
140  * - Using UNIX IPC (off by default) will override the SIGPIPE signal handler,
141  *   and set it to SIG_IGN.
142  * - mpv will reseed the legacy C random number generator by calling srand() at
143  *   some random point once.
144  *
145  * Encoding of filenames
146  * ---------------------
147  *
148  * mpv uses UTF-8 everywhere.
149  *
150  * On some platforms (like Linux), filenames actually do not have to be UTF-8;
151  * for this reason libmpv supports non-UTF-8 strings. libmpv uses what the
152  * kernel uses and does not recode filenames. At least on Linux, passing a
153  * string to libmpv is like passing a string to the fopen() function.
154  *
155  * On Windows, filenames are always UTF-8, libmpv converts between UTF-8 and
156  * UTF-16 when using win32 API functions. libmpv never uses or accepts
157  * filenames in the local 8 bit encoding. It does not use fopen() either;
158  * it uses _wfopen().
159  *
160  * On OS X, filenames and other strings taken/returned by libmpv can have
161  * inconsistent unicode normalization. This can sometimes lead to problems.
162  * You have to hope for the best.
163  *
164  * Also see the remarks for MPV_FORMAT_STRING.
165  *
166  * Embedding the video window
167  * --------------------------
168  *
169  * Using the render API (in render_cb.h) is recommended. This API requires
170  * you to create and maintain an OpenGL context, to which you can render
171  * video using a specific API call. This API does not include keyboard or mouse
172  * input directly.
173  *
174  * There is an older way to embed the native mpv window into your own. You have
175  * to get the raw window handle, and set it as "wid" option. This works on X11,
176  * win32, and OSX only. It's much easier to use than the render API, but
177  * also has various problems.
178  *
179  * Also see client API examples and the mpv manpage. There is an extensive
180  * discussion here:
181  * https://github.com/mpv-player/mpv-examples/tree/master/libmpv#methods-of-embedding-the-video-window
182  *
183  * Compatibility
184  * -------------
185  *
186  * mpv development doesn't stand still, and changes to mpv internals as well as
187  * to its interface can cause compatibility issues to client API users.
188  *
189  * The API is versioned (see MPV_CLIENT_API_VERSION), and changes to it are
190  * documented in DOCS/client-api-changes.rst. The C API itself will probably
191  * remain compatible for a long time, but the functionality exposed by it
192  * could change more rapidly. For example, it's possible that options are
193  * renamed, or change the set of allowed values.
194  *
195  * Defensive programming should be used to potentially deal with the fact that
196  * options, commands, and properties could disappear, change their value range,
197  * or change the underlying datatypes. It might be a good idea to prefer
198  * MPV_FORMAT_STRING over other types to decouple your code from potential
199  * mpv changes.
200  *
201  * Also see: DOCS/compatibility.rst
202  *
203  * Future changes
204  * --------------
205  *
206  * This are the planned changes that will most likely be done on the next major
207  * bump of the library:
208  *
209  *  - remove all symbols and include files that are marked as deprecated
210  *  - reassign enum numerical values to remove gaps
211  *  - remove the mpv_opengl_init_params.extra_exts field
212  *  - change the type of mpv_event_end_file.reason
213  *  - disabling all events by default
214  */
215 
216 /**
217  * The version is incremented on each API change. The 16 lower bits form the
218  * minor version number, and the 16 higher bits the major version number. If
219  * the API becomes incompatible to previous versions, the major version
220  * number is incremented. This affects only C part, and not properties and
221  * options.
222  *
223  * Every API bump is described in DOCS/client-api-changes.rst
224  *
225  * You can use MPV_MAKE_VERSION() and compare the result with integer
226  * relational operators (<, >, <=, >=).
227  */
228 extern (D) auto MPV_MAKE_VERSION(T0, T1)(auto ref T0 major, auto ref T1 minor)
229 {
230     return (major << 16) | minor | 0UL;
231 }
232 
233 enum MPV_CLIENT_API_VERSION = MPV_MAKE_VERSION(1, 107);
234 
235 /**
236  * The API user is allowed to "#define MPV_ENABLE_DEPRECATED 0" before
237  * including any libmpv headers. Then deprecated symbols will be excluded
238  * from the headers. (Of course, deprecated properties and commands and
239  * other functionality will still work.)
240  */
241 
242 enum MPV_ENABLE_DEPRECATED = 1;
243 
244 /**
245  * Return the MPV_CLIENT_API_VERSION the mpv source has been compiled with.
246  */
247 c_ulong mpv_client_api_version ();
248 
249 /**
250  * Client context used by the client API. Every client has its own private
251  * handle.
252  */
253 struct mpv_handle;
254 
255 /**
256  * List of error codes than can be returned by API functions. 0 and positive
257  * return values always mean success, negative values are always errors.
258  */
259 enum mpv_error
260 {
261     /**
262      * No error happened (used to signal successful operation).
263      * Keep in mind that many API functions returning error codes can also
264      * return positive values, which also indicate success. API users can
265      * hardcode the fact that ">= 0" means success.
266      */
267     MPV_ERROR_SUCCESS = 0,
268     /**
269      * The event ringbuffer is full. This means the client is choked, and can't
270      * receive any events. This can happen when too many asynchronous requests
271      * have been made, but not answered. Probably never happens in practice,
272      * unless the mpv core is frozen for some reason, and the client keeps
273      * making asynchronous requests. (Bugs in the client API implementation
274      * could also trigger this, e.g. if events become "lost".)
275      */
276     MPV_ERROR_EVENT_QUEUE_FULL = -1,
277     /**
278      * Memory allocation failed.
279      */
280     MPV_ERROR_NOMEM = -2,
281     /**
282      * The mpv core wasn't configured and initialized yet. See the notes in
283      * mpv_create().
284      */
285     MPV_ERROR_UNINITIALIZED = -3,
286     /**
287      * Generic catch-all error if a parameter is set to an invalid or
288      * unsupported value. This is used if there is no better error code.
289      */
290     MPV_ERROR_INVALID_PARAMETER = -4,
291     /**
292      * Trying to set an option that doesn't exist.
293      */
294     MPV_ERROR_OPTION_NOT_FOUND = -5,
295     /**
296      * Trying to set an option using an unsupported MPV_FORMAT.
297      */
298     MPV_ERROR_OPTION_FORMAT = -6,
299     /**
300      * Setting the option failed. Typically this happens if the provided option
301      * value could not be parsed.
302      */
303     MPV_ERROR_OPTION_ERROR = -7,
304     /**
305      * The accessed property doesn't exist.
306      */
307     MPV_ERROR_PROPERTY_NOT_FOUND = -8,
308     /**
309      * Trying to set or get a property using an unsupported MPV_FORMAT.
310      */
311     MPV_ERROR_PROPERTY_FORMAT = -9,
312     /**
313      * The property exists, but is not available. This usually happens when the
314      * associated subsystem is not active, e.g. querying audio parameters while
315      * audio is disabled.
316      */
317     MPV_ERROR_PROPERTY_UNAVAILABLE = -10,
318     /**
319      * Error setting or getting a property.
320      */
321     MPV_ERROR_PROPERTY_ERROR = -11,
322     /**
323      * General error when running a command with mpv_command and similar.
324      */
325     MPV_ERROR_COMMAND = -12,
326     /**
327      * Generic error on loading (usually used with mpv_event_end_file.error).
328      */
329     MPV_ERROR_LOADING_FAILED = -13,
330     /**
331      * Initializing the audio output failed.
332      */
333     MPV_ERROR_AO_INIT_FAILED = -14,
334     /**
335      * Initializing the video output failed.
336      */
337     MPV_ERROR_VO_INIT_FAILED = -15,
338     /**
339      * There was no audio or video data to play. This also happens if the
340      * file was recognized, but did not contain any audio or video streams,
341      * or no streams were selected.
342      */
343     MPV_ERROR_NOTHING_TO_PLAY = -16,
344     /**
345      * When trying to load the file, the file format could not be determined,
346      * or the file was too broken to open it.
347      */
348     MPV_ERROR_UNKNOWN_FORMAT = -17,
349     /**
350      * Generic error for signaling that certain system requirements are not
351      * fulfilled.
352      */
353     MPV_ERROR_UNSUPPORTED = -18,
354     /**
355      * The API function which was called is a stub only.
356      */
357     MPV_ERROR_NOT_IMPLEMENTED = -19,
358     /**
359      * Unspecified error.
360      */
361     MPV_ERROR_GENERIC = -20
362 }
363 
364 /**
365  * Return a string describing the error. For unknown errors, the string
366  * "unknown error" is returned.
367  *
368  * @param error error number, see enum mpv_error
369  * @return A static string describing the error. The string is completely
370  *         static, i.e. doesn't need to be deallocated, and is valid forever.
371  */
372 const(char)* mpv_error_string (int error);
373 
374 /**
375  * General function to deallocate memory returned by some of the API functions.
376  * Call this only if it's explicitly documented as allowed. Calling this on
377  * mpv memory not owned by the caller will lead to undefined behavior.
378  *
379  * @param data A valid pointer returned by the API, or NULL.
380  */
381 void mpv_free (void* data);
382 
383 /**
384  * Return the name of this client handle. Every client has its own unique
385  * name, which is mostly used for user interface purposes.
386  *
387  * @return The client name. The string is read-only and is valid until the
388  *         mpv_handle is destroyed.
389  */
390 const(char)* mpv_client_name (mpv_handle* ctx);
391 
392 /**
393  * Create a new mpv instance and an associated client API handle to control
394  * the mpv instance. This instance is in a pre-initialized state,
395  * and needs to be initialized to be actually used with most other API
396  * functions.
397  *
398  * Some API functions will return MPV_ERROR_UNINITIALIZED in the uninitialized
399  * state. You can call mpv_set_property() (or mpv_set_property_string() and
400  * other variants, and before mpv 0.21.0 mpv_set_option() etc.) to set initial
401  * options. After this, call mpv_initialize() to start the player, and then use
402  * e.g. mpv_command() to start playback of a file.
403  *
404  * The point of separating handle creation and actual initialization is that
405  * you can configure things which can't be changed during runtime.
406  *
407  * Unlike the command line player, this will have initial settings suitable
408  * for embedding in applications. The following settings are different:
409  * - stdin/stdout/stderr and the terminal will never be accessed. This is
410  *   equivalent to setting the --no-terminal option.
411  *   (Technically, this also suppresses C signal handling.)
412  * - No config files will be loaded. This is roughly equivalent to using
413  *   --config=no. Since libmpv 1.15, you can actually re-enable this option,
414  *   which will make libmpv load config files during mpv_initialize(). If you
415  *   do this, you are strongly encouraged to set the "config-dir" option too.
416  *   (Otherwise it will load the mpv command line player's config.)
417  *   For example:
418  *      mpv_set_option_string(mpv, "config-dir", "/my/path"); // set config root
419  *      mpv_set_option_string(mpv, "config", "yes"); // enable config loading
420  *      (call mpv_initialize() _after_ this)
421  * - Idle mode is enabled, which means the playback core will enter idle mode
422  *   if there are no more files to play on the internal playlist, instead of
423  *   exiting. This is equivalent to the --idle option.
424  * - Disable parts of input handling.
425  * - Most of the different settings can be viewed with the command line player
426  *   by running "mpv --show-profile=libmpv".
427  *
428  * All this assumes that API users want a mpv instance that is strictly
429  * isolated from the command line player's configuration, user settings, and
430  * so on. You can re-enable disabled features by setting the appropriate
431  * options.
432  *
433  * The mpv command line parser is not available through this API, but you can
434  * set individual options with mpv_set_property(). Files for playback must be
435  * loaded with mpv_command() or others.
436  *
437  * Note that you should avoid doing concurrent accesses on the uninitialized
438  * client handle. (Whether concurrent access is definitely allowed or not has
439  * yet to be decided.)
440  *
441  * @return a new mpv client API handle. Returns NULL on error. Currently, this
442  *         can happen in the following situations:
443  *         - out of memory
444  *         - LC_NUMERIC is not set to "C" (see general remarks)
445  */
446 mpv_handle* mpv_create ();
447 
448 /**
449  * Initialize an uninitialized mpv instance. If the mpv instance is already
450  * running, an error is returned.
451  *
452  * This function needs to be called to make full use of the client API if the
453  * client API handle was created with mpv_create().
454  *
455  * Only the following options are required to be set _before_ mpv_initialize():
456  *      - options which are only read at initialization time:
457  *        - config
458  *        - config-dir
459  *        - input-conf
460  *        - load-scripts
461  *        - script
462  *        - player-operation-mode
463  *        - input-app-events (OSX)
464  *      - all encoding mode options
465  *
466  * @return error code
467  */
468 int mpv_initialize (mpv_handle* ctx);
469 
470 /**
471  * Disconnect and destroy the mpv_handle. ctx will be deallocated with this
472  * API call.
473  *
474  * If the last mpv_handle is detached, the core player is destroyed. In
475  * addition, if there are only weak mpv_handles (such as created by
476  * mpv_create_weak_client() or internal scripts), these mpv_handles will
477  * be sent MPV_EVENT_SHUTDOWN. This function may block until these clients
478  * have responded to the shutdown event, and the core is finally destroyed.
479  */
480 void mpv_destroy (mpv_handle* ctx);
481 
482 /**
483  * @deprecated use mpv_destroy(), which has exactly the same semantics (the
484  * deprecation is a mere rename)
485  *
486  * Since mpv client API version 1.29:
487  *  If the last mpv_handle is detached, the core player is destroyed. In
488  *  addition, if there are only weak mpv_handles (such as created by
489  *  mpv_create_weak_client() or internal scripts), these mpv_handles will
490  *  be sent MPV_EVENT_SHUTDOWN. This function may block until these clients
491  *  have responded to the shutdown event, and the core is finally destroyed.
492  *
493  * Before mpv client API version 1.29:
494  *  This left the player running. If you want to be sure that the
495  *  player is terminated, send a "quit" command, and wait until the
496  *  MPV_EVENT_SHUTDOWN event is received, or use mpv_terminate_destroy().
497  */
498 void mpv_detach_destroy (mpv_handle* ctx);
499 
500 /**
501  * Similar to mpv_destroy(), but brings the player and all clients down
502  * as well, and waits until all of them are destroyed. This function blocks. The
503  * advantage over mpv_destroy() is that while mpv_destroy() merely
504  * detaches the client handle from the player, this function quits the player,
505  * waits until all other clients are destroyed (i.e. all mpv_handles are
506  * detached), and also waits for the final termination of the player.
507  *
508  * Since mpv_destroy() is called somewhere on the way, it's not safe to
509  * call other functions concurrently on the same context.
510  *
511  * Since mpv client API version 1.29:
512  *  The first call on any mpv_handle will block until the core is destroyed.
513  *  This means it will wait until other mpv_handle have been destroyed. If you
514  *  want asynchronous destruction, just run the "quit" command, and then react
515  *  to the MPV_EVENT_SHUTDOWN event.
516  *  If another mpv_handle already called mpv_terminate_destroy(), this call will
517  *  not actually block. It will destroy the mpv_handle, and exit immediately,
518  *  while other mpv_handles might still be uninitializing.
519  *
520  * Before mpv client API version 1.29:
521  *  If this is called on a mpv_handle that was not created with mpv_create(),
522  *  this function will merely send a quit command and then call
523  *  mpv_destroy(), without waiting for the actual shutdown.
524  */
525 void mpv_terminate_destroy (mpv_handle* ctx);
526 
527 /**
528  * Create a new client handle connected to the same player core as ctx. This
529  * context has its own event queue, its own mpv_request_event() state, its own
530  * mpv_request_log_messages() state, its own set of observed properties, and
531  * its own state for asynchronous operations. Otherwise, everything is shared.
532  *
533  * This handle should be destroyed with mpv_destroy() if no longer
534  * needed. The core will live as long as there is at least 1 handle referencing
535  * it. Any handle can make the core quit, which will result in every handle
536  * receiving MPV_EVENT_SHUTDOWN.
537  *
538  * This function can not be called before the main handle was initialized with
539  * mpv_initialize(). The new handle is always initialized, unless ctx=NULL was
540  * passed.
541  *
542  * @param ctx Used to get the reference to the mpv core; handle-specific
543  *            settings and parameters are not used.
544  *            If NULL, this function behaves like mpv_create() (ignores name).
545  * @param name The client name. This will be returned by mpv_client_name(). If
546  *             the name is already in use, or contains non-alphanumeric
547  *             characters (other than '_'), the name is modified to fit.
548  *             If NULL, an arbitrary name is automatically chosen.
549  * @return a new handle, or NULL on error
550  */
551 mpv_handle* mpv_create_client (mpv_handle* ctx, const(char)* name);
552 
553 /**
554  * This is the same as mpv_create_client(), but the created mpv_handle is
555  * treated as a weak reference. If all mpv_handles referencing a core are
556  * weak references, the core is automatically destroyed. (This still goes
557  * through normal uninit of course. Effectively, if the last non-weak mpv_handle
558  * is destroyed, then the weak mpv_handles receive MPV_EVENT_SHUTDOWN and are
559  * asked to terminate as well.)
560  *
561  * Note if you want to use this like refcounting: you have to be aware that
562  * mpv_terminate_destroy() _and_ mpv_destroy() for the last non-weak
563  * mpv_handle will block until all weak mpv_handles are destroyed.
564  */
565 mpv_handle* mpv_create_weak_client (mpv_handle* ctx, const(char)* name);
566 
567 /**
568  * Load a config file. This loads and parses the file, and sets every entry in
569  * the config file's default section as if mpv_set_option_string() is called.
570  *
571  * The filename should be an absolute path. If it isn't, the actual path used
572  * is unspecified. (Note: an absolute path starts with '/' on UNIX.) If the
573  * file wasn't found, MPV_ERROR_INVALID_PARAMETER is returned.
574  *
575  * If a fatal error happens when parsing a config file, MPV_ERROR_OPTION_ERROR
576  * is returned. Errors when setting options as well as other types or errors
577  * are ignored (even if options do not exist). You can still try to capture
578  * the resulting error messages with mpv_request_log_messages(). Note that it's
579  * possible that some options were successfully set even if any of these errors
580  * happen.
581  *
582  * @param filename absolute path to the config file on the local filesystem
583  * @return error code
584  */
585 int mpv_load_config_file (mpv_handle* ctx, const(char)* filename);
586 
587 /**
588  * This does nothing since mpv 0.23.0 (API version 1.24). Below is the
589  * description of the old behavior.
590  *
591  * Stop the playback thread. This means the core will stop doing anything, and
592  * only run and answer to client API requests. This is sometimes useful; for
593  * example, no new frame will be queued to the video output, so doing requests
594  * which have to wait on the video output can run instantly.
595  *
596  * Suspension is reentrant and recursive for convenience. Any thread can call
597  * the suspend function multiple times, and the playback thread will remain
598  * suspended until the last thread resumes it. Note that during suspension, all
599  * clients still have concurrent access to the core, which is serialized through
600  * a single mutex.
601  *
602  * Call mpv_resume() to resume the playback thread. You must call mpv_resume()
603  * for each mpv_suspend() call. Calling mpv_resume() more often than
604  * mpv_suspend() is not allowed.
605  *
606  * Calling this on an uninitialized player (see mpv_create()) will deadlock.
607  *
608  * @deprecated This function, as well as mpv_resume(), are deprecated, and
609  *             will stop doing anything soon. Their semantics were never
610  *             well-defined, and their usefulness is extremely limited. The
611  *             calls will remain stubs in order to keep ABI compatibility.
612  */
613 void mpv_suspend (mpv_handle* ctx);
614 
615 /**
616  * See mpv_suspend().
617  */
618 void mpv_resume (mpv_handle* ctx);
619 
620 /**
621  * Return the internal time in microseconds. This has an arbitrary start offset,
622  * but will never wrap or go backwards.
623  *
624  * Note that this is always the real time, and doesn't necessarily have to do
625  * with playback time. For example, playback could go faster or slower due to
626  * playback speed, or due to playback being paused. Use the "time-pos" property
627  * instead to get the playback status.
628  *
629  * Unlike other libmpv APIs, this can be called at absolutely any time (even
630  * within wakeup callbacks), as long as the context is valid.
631  *
632  * Safe to be called from mpv render API threads.
633  */
634 long mpv_get_time_us (mpv_handle* ctx);
635 
636 /**
637  * Data format for options and properties. The API functions to get/set
638  * properties and options support multiple formats, and this enum describes
639  * them.
640  */
641 enum mpv_format
642 {
643     /**
644      * Invalid. Sometimes used for empty values.
645      */
646     MPV_FORMAT_NONE = 0,
647     /**
648      * The basic type is char*. It returns the raw property string, like
649      * using ${=property} in input.conf (see input.rst).
650      *
651      * NULL isn't an allowed value.
652      *
653      * Warning: although the encoding is usually UTF-8, this is not always the
654      *          case. File tags often store strings in some legacy codepage,
655      *          and even filenames don't necessarily have to be in UTF-8 (at
656      *          least on Linux). If you pass the strings to code that requires
657      *          valid UTF-8, you have to sanitize it in some way.
658      *          On Windows, filenames are always UTF-8, and libmpv converts
659      *          between UTF-8 and UTF-16 when using win32 API functions. See
660      *          the "Encoding of filenames" section for details.
661      *
662      * Example for reading:
663      *
664      *     char *result = NULL;
665      *     if (mpv_get_property(ctx, "property", MPV_FORMAT_STRING, &result) < 0)
666      *         goto error;
667      *     printf("%s\n", result);
668      *     mpv_free(result);
669      *
670      * Or just use mpv_get_property_string().
671      *
672      * Example for writing:
673      *
674      *     char *value = "the new value";
675      *     // yep, you pass the address to the variable
676      *     // (needed for symmetry with other types and mpv_get_property)
677      *     mpv_set_property(ctx, "property", MPV_FORMAT_STRING, &value);
678      *
679      * Or just use mpv_set_property_string().
680      *
681      */
682     MPV_FORMAT_STRING = 1,
683     /**
684      * The basic type is char*. It returns the OSD property string, like
685      * using ${property} in input.conf (see input.rst). In many cases, this
686      * is the same as the raw string, but in other cases it's formatted for
687      * display on OSD. It's intended to be human readable. Do not attempt to
688      * parse these strings.
689      *
690      * Only valid when doing read access. The rest works like MPV_FORMAT_STRING.
691      */
692     MPV_FORMAT_OSD_STRING = 2,
693     /**
694      * The basic type is int. The only allowed values are 0 ("no")
695      * and 1 ("yes").
696      *
697      * Example for reading:
698      *
699      *     int result;
700      *     if (mpv_get_property(ctx, "property", MPV_FORMAT_FLAG, &result) < 0)
701      *         goto error;
702      *     printf("%s\n", result ? "true" : "false");
703      *
704      * Example for writing:
705      *
706      *     int flag = 1;
707      *     mpv_set_property(ctx, "property", MPV_FORMAT_FLAG, &flag);
708      */
709     MPV_FORMAT_FLAG = 3,
710     /**
711      * The basic type is int64_t.
712      */
713     MPV_FORMAT_INT64 = 4,
714     /**
715      * The basic type is double.
716      */
717     MPV_FORMAT_DOUBLE = 5,
718     /**
719      * The type is mpv_node.
720      *
721      * For reading, you usually would pass a pointer to a stack-allocated
722      * mpv_node value to mpv, and when you're done you call
723      * mpv_free_node_contents(&node).
724      * You're expected not to write to the data - if you have to, copy it
725      * first (which you have to do manually).
726      *
727      * For writing, you construct your own mpv_node, and pass a pointer to the
728      * API. The API will never write to your data (and copy it if needed), so
729      * you're free to use any form of allocation or memory management you like.
730      *
731      * Warning: when reading, always check the mpv_node.format member. For
732      *          example, properties might change their type in future versions
733      *          of mpv, or sometimes even during runtime.
734      *
735      * Example for reading:
736      *
737      *     mpv_node result;
738      *     if (mpv_get_property(ctx, "property", MPV_FORMAT_NODE, &result) < 0)
739      *         goto error;
740      *     printf("format=%d\n", (int)result.format);
741      *     mpv_free_node_contents(&result).
742      *
743      * Example for writing:
744      *
745      *     mpv_node value;
746      *     value.format = MPV_FORMAT_STRING;
747      *     value.u.string = "hello";
748      *     mpv_set_property(ctx, "property", MPV_FORMAT_NODE, &value);
749      */
750     MPV_FORMAT_NODE = 6,
751     /**
752      * Used with mpv_node only. Can usually not be used directly.
753      */
754     MPV_FORMAT_NODE_ARRAY = 7,
755     /**
756      * See MPV_FORMAT_NODE_ARRAY.
757      */
758     MPV_FORMAT_NODE_MAP = 8,
759     /**
760      * A raw, untyped byte array. Only used only with mpv_node, and only in
761      * some very special situations. (Currently, only for the screenshot-raw
762      * command.)
763      */
764     MPV_FORMAT_BYTE_ARRAY = 9
765 }
766 
767 /**
768  * Generic data storage.
769  *
770  * If mpv writes this struct (e.g. via mpv_get_property()), you must not change
771  * the data. In some cases (mpv_get_property()), you have to free it with
772  * mpv_free_node_contents(). If you fill this struct yourself, you're also
773  * responsible for freeing it, and you must not call mpv_free_node_contents().
774  */
775 struct mpv_node
776 {
777     /** valid if format==MPV_FORMAT_STRING */
778     /** valid if format==MPV_FORMAT_FLAG   */
779     /** valid if format==MPV_FORMAT_INT64  */
780     /** valid if format==MPV_FORMAT_DOUBLE */
781     /**
782      * valid if format==MPV_FORMAT_NODE_ARRAY
783      *    or if format==MPV_FORMAT_NODE_MAP
784      */
785 
786     /**
787      * valid if format==MPV_FORMAT_BYTE_ARRAY
788      */
789     union _Anonymous_0
790     {
791         char* string;
792         int flag;
793         long int64;
794         double double_;
795         mpv_node_list* list;
796         mpv_byte_array* ba;
797     }
798 
799     _Anonymous_0 u;
800     /**
801      * Type of the data stored in this struct. This value rules what members in
802      * the given union can be accessed. The following formats are currently
803      * defined to be allowed in mpv_node:
804      *
805      *  MPV_FORMAT_STRING       (u.string)
806      *  MPV_FORMAT_FLAG         (u.flag)
807      *  MPV_FORMAT_INT64        (u.int64)
808      *  MPV_FORMAT_DOUBLE       (u.double_)
809      *  MPV_FORMAT_NODE_ARRAY   (u.list)
810      *  MPV_FORMAT_NODE_MAP     (u.list)
811      *  MPV_FORMAT_BYTE_ARRAY   (u.ba)
812      *  MPV_FORMAT_NONE         (no member)
813      *
814      * If you encounter a value you don't know, you must not make any
815      * assumptions about the contents of union u.
816      */
817     mpv_format format;
818 }
819 
820 /**
821  * (see mpv_node)
822  */
823 struct mpv_node_list
824 {
825     /**
826      * Number of entries. Negative values are not allowed.
827      */
828     int num;
829     /**
830      * MPV_FORMAT_NODE_ARRAY:
831      *  values[N] refers to value of the Nth item
832      *
833      * MPV_FORMAT_NODE_MAP:
834      *  values[N] refers to value of the Nth key/value pair
835      *
836      * If num > 0, values[0] to values[num-1] (inclusive) are valid.
837      * Otherwise, this can be NULL.
838      */
839     mpv_node* values;
840     /**
841      * MPV_FORMAT_NODE_ARRAY:
842      *  unused (typically NULL), access is not allowed
843      *
844      * MPV_FORMAT_NODE_MAP:
845      *  keys[N] refers to key of the Nth key/value pair. If num > 0, keys[0] to
846      *  keys[num-1] (inclusive) are valid. Otherwise, this can be NULL.
847      *  The keys are in random order. The only guarantee is that keys[N] belongs
848      *  to the value values[N]. NULL keys are not allowed.
849      */
850     char** keys;
851 }
852 
853 /**
854  * (see mpv_node)
855  */
856 struct mpv_byte_array
857 {
858     /**
859      * Pointer to the data. In what format the data is stored is up to whatever
860      * uses MPV_FORMAT_BYTE_ARRAY.
861      */
862     void* data;
863     /**
864      * Size of the data pointed to by ptr.
865      */
866     size_t size;
867 }
868 
869 /**
870  * Frees any data referenced by the node. It doesn't free the node itself.
871  * Call this only if the mpv client API set the node. If you constructed the
872  * node yourself (manually), you have to free it yourself.
873  *
874  * If node->format is MPV_FORMAT_NONE, this call does nothing. Likewise, if
875  * the client API sets a node with this format, this function doesn't need to
876  * be called. (This is just a clarification that there's no danger of anything
877  * strange happening in these cases.)
878  */
879 void mpv_free_node_contents (mpv_node* node);
880 
881 /**
882  * Set an option. Note that you can't normally set options during runtime. It
883  * works in uninitialized state (see mpv_create()), and in some cases in at
884  * runtime.
885  *
886  * Using a format other than MPV_FORMAT_NODE is equivalent to constructing a
887  * mpv_node with the given format and data, and passing the mpv_node to this
888  * function.
889  *
890  * Note: this is semi-deprecated. For most purposes, this is not needed anymore.
891  *       Starting with mpv version 0.21.0 (version 1.23) most options can be set
892  *       with mpv_set_property() (and related functions), and even before
893  *       mpv_initialize(). In some obscure corner cases, using this function
894  *       to set options might still be required (see below, and also section
895  *       "Inconsistencies between options and properties" on the manpage). Once
896  *       these are resolved, the option setting functions might be fully
897  *       deprecated.
898  *
899  *       The following options still need to be set either _before_
900  *       mpv_initialize() with mpv_set_property() (or related functions), or
901  *       with mpv_set_option() (or related functions) at any time:
902  *              - options shadowed by deprecated properties:
903  *                - demuxer (property deprecated in 0.21.0)
904  *                - idle (property deprecated in 0.21.0)
905  *                - fps (property deprecated in 0.21.0)
906  *                - cache (property deprecated in 0.21.0)
907  *                - length (property deprecated in 0.10.0)
908  *                - audio-samplerate (property deprecated in 0.10.0)
909  *                - audio-channels (property deprecated in 0.10.0)
910  *                - audio-format (property deprecated in 0.10.0)
911  *              - deprecated options shadowed by properties:
912  *                - chapter (option deprecated in 0.21.0)
913  *                - playlist-pos (option deprecated in 0.21.0)
914  *       The deprecated properties were removed in mpv 0.23.0.
915  *
916  * @param name Option name. This is the same as on the mpv command line, but
917  *             without the leading "--".
918  * @param format see enum mpv_format.
919  * @param[in] data Option value (according to the format).
920  * @return error code
921  */
922 int mpv_set_option (
923     mpv_handle* ctx,
924     const(char)* name,
925     mpv_format format,
926     void* data);
927 
928 /**
929  * Convenience function to set an option to a string value. This is like
930  * calling mpv_set_option() with MPV_FORMAT_STRING.
931  *
932  * @return error code
933  */
934 int mpv_set_option_string (mpv_handle* ctx, const(char)* name, const(char)* data);
935 
936 /**
937  * Send a command to the player. Commands are the same as those used in
938  * input.conf, except that this function takes parameters in a pre-split
939  * form.
940  *
941  * The commands and their parameters are documented in input.rst.
942  *
943  * Does not use OSD and string expansion by default (unlike mpv_command_string()
944  * and input.conf).
945  *
946  * @param[in] args NULL-terminated list of strings. Usually, the first item
947  *                 is the command, and the following items are arguments.
948  * @return error code
949  */
950 int mpv_command (mpv_handle* ctx, const(char*)* args);
951 
952 /**
953  * Same as mpv_command(), but allows passing structured data in any format.
954  * In particular, calling mpv_command() is exactly like calling
955  * mpv_command_node() with the format set to MPV_FORMAT_NODE_ARRAY, and
956  * every arg passed in order as MPV_FORMAT_STRING.
957  *
958  * Does not use OSD and string expansion by default.
959  *
960  * The args argument can have one of the following formats:
961  *
962  * MPV_FORMAT_NODE_ARRAY:
963  *      Positional arguments. Each entry is an argument using an arbitrary
964  *      format (the format must be compatible to the used command). Usually,
965  *      the first item is the command name (as MPV_FORMAT_STRING). The order
966  *      of arguments is as documented in each command description.
967  *
968  * MPV_FORMAT_NODE_MAP:
969  *      Named arguments. This requires at least an entry with the key "name"
970  *      to be present, which must be a string, and contains the command name.
971  *      The special entry "_flags" is optional, and if present, must be an
972  *      array of strings, each being a command prefix to apply. All other
973  *      entries are interpreted as arguments. They must use the argument names
974  *      as documented in each command description. Some commands do not
975  *      support named arguments at all, and must use MPV_FORMAT_NODE_ARRAY.
976  *
977  * @param[in] args mpv_node with format set to one of the values documented
978  *                 above (see there for details)
979  * @param[out] result Optional, pass NULL if unused. If not NULL, and if the
980  *                    function succeeds, this is set to command-specific return
981  *                    data. You must call mpv_free_node_contents() to free it
982  *                    (again, only if the command actually succeeds).
983  *                    Not many commands actually use this at all.
984  * @return error code (the result parameter is not set on error)
985  */
986 int mpv_command_node (mpv_handle* ctx, mpv_node* args, mpv_node* result);
987 
988 /**
989  * This is essentially identical to mpv_command() but it also returns a result.
990  *
991  * Does not use OSD and string expansion by default.
992  *
993  * @param[in] args NULL-terminated list of strings. Usually, the first item
994  *                 is the command, and the following items are arguments.
995  * @param[out] result Optional, pass NULL if unused. If not NULL, and if the
996  *                    function succeeds, this is set to command-specific return
997  *                    data. You must call mpv_free_node_contents() to free it
998  *                    (again, only if the command actually succeeds).
999  *                    Not many commands actually use this at all.
1000  * @return error code (the result parameter is not set on error)
1001  */
1002 int mpv_command_ret (mpv_handle* ctx, const(char*)* args, mpv_node* result);
1003 
1004 /**
1005  * Same as mpv_command, but use input.conf parsing for splitting arguments.
1006  * This is slightly simpler, but also more error prone, since arguments may
1007  * need quoting/escaping.
1008  *
1009  * This also has OSD and string expansion enabled by default.
1010  */
1011 int mpv_command_string (mpv_handle* ctx, const(char)* args);
1012 
1013 /**
1014  * Same as mpv_command, but run the command asynchronously.
1015  *
1016  * Commands are executed asynchronously. You will receive a
1017  * MPV_EVENT_COMMAND_REPLY event. This event will also have an
1018  * error code set if running the command failed. For commands that
1019  * return data, the data is put into mpv_event_command.result.
1020  *
1021  * Safe to be called from mpv render API threads.
1022  *
1023  * @param reply_userdata the value mpv_event.reply_userdata of the reply will
1024  *                       be set to (see section about asynchronous calls)
1025  * @param args NULL-terminated list of strings (see mpv_command())
1026  * @return error code (if parsing or queuing the command fails)
1027  */
1028 int mpv_command_async (
1029     mpv_handle* ctx,
1030     ulong reply_userdata,
1031     const(char*)* args);
1032 
1033 /**
1034  * Same as mpv_command_node(), but run it asynchronously. Basically, this
1035  * function is to mpv_command_node() what mpv_command_async() is to
1036  * mpv_command().
1037  *
1038  * See mpv_command_async() for details.
1039  *
1040  * Safe to be called from mpv render API threads.
1041  *
1042  * @param reply_userdata the value mpv_event.reply_userdata of the reply will
1043  *                       be set to (see section about asynchronous calls)
1044  * @param args as in mpv_command_node()
1045  * @return error code (if parsing or queuing the command fails)
1046  */
1047 int mpv_command_node_async (
1048     mpv_handle* ctx,
1049     ulong reply_userdata,
1050     mpv_node* args);
1051 
1052 /**
1053  * Signal to all async requests with the matching ID to abort. This affects
1054  * the following API calls:
1055  *
1056  *      mpv_command_async
1057  *      mpv_command_node_async
1058  *
1059  * All of these functions take a reply_userdata parameter. This API function
1060  * tells all requests with the matching reply_userdata value to try to return
1061  * as soon as possible. If there are multiple requests with matching ID, it
1062  * aborts all of them.
1063  *
1064  * This API function is mostly asynchronous itself. It will not wait until the
1065  * command is aborted. Instead, the command will terminate as usual, but with
1066  * some work not done. How this is signaled depends on the specific command (for
1067  * example, the "subprocess" command will indicate it by "killed_by_us" set to
1068  * true in the result). How long it takes also depends on the situation. The
1069  * aborting process is completely asynchronous.
1070  *
1071  * Not all commands may support this functionality. In this case, this function
1072  * will have no effect. The same is true if the request using the passed
1073  * reply_userdata has already terminated, has not been started yet, or was
1074  * never in use at all.
1075  *
1076  * You have to be careful of race conditions: the time during which the abort
1077  * request will be effective is _after_ e.g. mpv_command_async() has returned,
1078  * and before the command has signaled completion with MPV_EVENT_COMMAND_REPLY.
1079  *
1080  * @param reply_userdata ID of the request to be aborted (see above)
1081  */
1082 void mpv_abort_async_command (mpv_handle* ctx, ulong reply_userdata);
1083 
1084 /**
1085  * Set a property to a given value. Properties are essentially variables which
1086  * can be queried or set at runtime. For example, writing to the pause property
1087  * will actually pause or unpause playback.
1088  *
1089  * If the format doesn't match with the internal format of the property, access
1090  * usually will fail with MPV_ERROR_PROPERTY_FORMAT. In some cases, the data
1091  * is automatically converted and access succeeds. For example, MPV_FORMAT_INT64
1092  * is always converted to MPV_FORMAT_DOUBLE, and access using MPV_FORMAT_STRING
1093  * usually invokes a string parser. The same happens when calling this function
1094  * with MPV_FORMAT_NODE: the underlying format may be converted to another
1095  * type if possible.
1096  *
1097  * Using a format other than MPV_FORMAT_NODE is equivalent to constructing a
1098  * mpv_node with the given format and data, and passing the mpv_node to this
1099  * function. (Before API version 1.21, this was different.)
1100  *
1101  * Note: starting with mpv 0.21.0 (client API version 1.23), this can be used to
1102  *       set options in general. It even can be used before mpv_initialize()
1103  *       has been called. If called before mpv_initialize(), setting properties
1104  *       not backed by options will result in MPV_ERROR_PROPERTY_UNAVAILABLE.
1105  *       In some cases, properties and options still conflict. In these cases,
1106  *       mpv_set_property() accesses the options before mpv_initialize(), and
1107  *       the properties after mpv_initialize(). These conflicts will be removed
1108  *       in mpv 0.23.0. See mpv_set_option() for further remarks.
1109  *
1110  * @param name The property name. See input.rst for a list of properties.
1111  * @param format see enum mpv_format.
1112  * @param[in] data Option value.
1113  * @return error code
1114  */
1115 int mpv_set_property (
1116     mpv_handle* ctx,
1117     const(char)* name,
1118     mpv_format format,
1119     void* data);
1120 
1121 /**
1122  * Convenience function to set a property to a string value.
1123  *
1124  * This is like calling mpv_set_property() with MPV_FORMAT_STRING.
1125  */
1126 int mpv_set_property_string (mpv_handle* ctx, const(char)* name, const(char)* data);
1127 
1128 /**
1129  * Set a property asynchronously. You will receive the result of the operation
1130  * as MPV_EVENT_SET_PROPERTY_REPLY event. The mpv_event.error field will contain
1131  * the result status of the operation. Otherwise, this function is similar to
1132  * mpv_set_property().
1133  *
1134  * Safe to be called from mpv render API threads.
1135  *
1136  * @param reply_userdata see section about asynchronous calls
1137  * @param name The property name.
1138  * @param format see enum mpv_format.
1139  * @param[in] data Option value. The value will be copied by the function. It
1140  *                 will never be modified by the client API.
1141  * @return error code if sending the request failed
1142  */
1143 int mpv_set_property_async (
1144     mpv_handle* ctx,
1145     ulong reply_userdata,
1146     const(char)* name,
1147     mpv_format format,
1148     void* data);
1149 
1150 /**
1151  * Read the value of the given property.
1152  *
1153  * If the format doesn't match with the internal format of the property, access
1154  * usually will fail with MPV_ERROR_PROPERTY_FORMAT. In some cases, the data
1155  * is automatically converted and access succeeds. For example, MPV_FORMAT_INT64
1156  * is always converted to MPV_FORMAT_DOUBLE, and access using MPV_FORMAT_STRING
1157  * usually invokes a string formatter.
1158  *
1159  * @param name The property name.
1160  * @param format see enum mpv_format.
1161  * @param[out] data Pointer to the variable holding the option value. On
1162  *                  success, the variable will be set to a copy of the option
1163  *                  value. For formats that require dynamic memory allocation,
1164  *                  you can free the value with mpv_free() (strings) or
1165  *                  mpv_free_node_contents() (MPV_FORMAT_NODE).
1166  * @return error code
1167  */
1168 int mpv_get_property (
1169     mpv_handle* ctx,
1170     const(char)* name,
1171     mpv_format format,
1172     void* data);
1173 
1174 /**
1175  * Return the value of the property with the given name as string. This is
1176  * equivalent to mpv_get_property() with MPV_FORMAT_STRING.
1177  *
1178  * See MPV_FORMAT_STRING for character encoding issues.
1179  *
1180  * On error, NULL is returned. Use mpv_get_property() if you want fine-grained
1181  * error reporting.
1182  *
1183  * @param name The property name.
1184  * @return Property value, or NULL if the property can't be retrieved. Free
1185  *         the string with mpv_free().
1186  */
1187 char* mpv_get_property_string (mpv_handle* ctx, const(char)* name);
1188 
1189 /**
1190  * Return the property as "OSD" formatted string. This is the same as
1191  * mpv_get_property_string, but using MPV_FORMAT_OSD_STRING.
1192  *
1193  * @return Property value, or NULL if the property can't be retrieved. Free
1194  *         the string with mpv_free().
1195  */
1196 char* mpv_get_property_osd_string (mpv_handle* ctx, const(char)* name);
1197 
1198 /**
1199  * Get a property asynchronously. You will receive the result of the operation
1200  * as well as the property data with the MPV_EVENT_GET_PROPERTY_REPLY event.
1201  * You should check the mpv_event.error field on the reply event.
1202  *
1203  * Safe to be called from mpv render API threads.
1204  *
1205  * @param reply_userdata see section about asynchronous calls
1206  * @param name The property name.
1207  * @param format see enum mpv_format.
1208  * @return error code if sending the request failed
1209  */
1210 int mpv_get_property_async (
1211     mpv_handle* ctx,
1212     ulong reply_userdata,
1213     const(char)* name,
1214     mpv_format format);
1215 
1216 /**
1217  * Get a notification whenever the given property changes. You will receive
1218  * updates as MPV_EVENT_PROPERTY_CHANGE. Note that this is not very precise:
1219  * for some properties, it may not send updates even if the property changed.
1220  * This depends on the property, and it's a valid feature request to ask for
1221  * better update handling of a specific property. (For some properties, like
1222  * ``clock``, which shows the wall clock, this mechanism doesn't make too
1223  * much sense anyway.)
1224  *
1225  * Property changes are coalesced: the change events are returned only once the
1226  * event queue becomes empty (e.g. mpv_wait_event() would block or return
1227  * MPV_EVENT_NONE), and then only one event per changed property is returned.
1228  *
1229  * You always get an initial change notification. This is meant to initialize
1230  * the user's state to the current value of the property.
1231  *
1232  * Normally, change events are sent only if the property value changes according
1233  * to the requested format. mpv_event_property will contain the property value
1234  * as data member.
1235  *
1236  * Warning: if a property is unavailable or retrieving it caused an error,
1237  *          MPV_FORMAT_NONE will be set in mpv_event_property, even if the
1238  *          format parameter was set to a different value. In this case, the
1239  *          mpv_event_property.data field is invalid.
1240  *
1241  * If the property is observed with the format parameter set to MPV_FORMAT_NONE,
1242  * you get low-level notifications whether the property _may_ have changed, and
1243  * the data member in mpv_event_property will be unset. With this mode, you
1244  * will have to determine yourself whether the property really changed. On the
1245  * other hand, this mechanism can be faster and uses less resources.
1246  *
1247  * Observing a property that doesn't exist is allowed. (Although it may still
1248  * cause some sporadic change events.)
1249  *
1250  * Keep in mind that you will get change notifications even if you change a
1251  * property yourself. Try to avoid endless feedback loops, which could happen
1252  * if you react to the change notifications triggered by your own change.
1253  *
1254  * Only the mpv_handle on which this was called will receive the property
1255  * change events, or can unobserve them.
1256  *
1257  * Safe to be called from mpv render API threads.
1258  *
1259  * @param reply_userdata This will be used for the mpv_event.reply_userdata
1260  *                       field for the received MPV_EVENT_PROPERTY_CHANGE
1261  *                       events. (Also see section about asynchronous calls,
1262  *                       although this function is somewhat different from
1263  *                       actual asynchronous calls.)
1264  *                       If you have no use for this, pass 0.
1265  *                       Also see mpv_unobserve_property().
1266  * @param name The property name.
1267  * @param format see enum mpv_format. Can be MPV_FORMAT_NONE to omit values
1268  *               from the change events.
1269  * @return error code (usually fails only on OOM or unsupported format)
1270  */
1271 int mpv_observe_property (
1272     mpv_handle* mpv,
1273     ulong reply_userdata,
1274     const(char)* name,
1275     mpv_format format);
1276 
1277 /**
1278  * Undo mpv_observe_property(). This will remove all observed properties for
1279  * which the given number was passed as reply_userdata to mpv_observe_property.
1280  *
1281  * Safe to be called from mpv render API threads.
1282  *
1283  * @param registered_reply_userdata ID that was passed to mpv_observe_property
1284  * @return negative value is an error code, >=0 is number of removed properties
1285  *         on success (includes the case when 0 were removed)
1286  */
1287 int mpv_unobserve_property (mpv_handle* mpv, ulong registered_reply_userdata);
1288 
1289 enum mpv_event_id
1290 {
1291     /**
1292      * Nothing happened. Happens on timeouts or sporadic wakeups.
1293      */
1294     MPV_EVENT_NONE = 0,
1295     /**
1296      * Happens when the player quits. The player enters a state where it tries
1297      * to disconnect all clients. Most requests to the player will fail, and
1298      * the client should react to this and quit with mpv_destroy() as soon as
1299      * possible.
1300      */
1301     MPV_EVENT_SHUTDOWN = 1,
1302     /**
1303      * See mpv_request_log_messages().
1304      */
1305     MPV_EVENT_LOG_MESSAGE = 2,
1306     /**
1307      * Reply to a mpv_get_property_async() request.
1308      * See also mpv_event and mpv_event_property.
1309      */
1310     MPV_EVENT_GET_PROPERTY_REPLY = 3,
1311     /**
1312      * Reply to a mpv_set_property_async() request.
1313      * (Unlike MPV_EVENT_GET_PROPERTY, mpv_event_property is not used.)
1314      */
1315     MPV_EVENT_SET_PROPERTY_REPLY = 4,
1316     /**
1317      * Reply to a mpv_command_async() or mpv_command_node_async() request.
1318      * See also mpv_event and mpv_event_command.
1319      */
1320     MPV_EVENT_COMMAND_REPLY = 5,
1321     /**
1322      * Notification before playback start of a file (before the file is loaded).
1323      */
1324     MPV_EVENT_START_FILE = 6,
1325     /**
1326      * Notification after playback end (after the file was unloaded).
1327      * See also mpv_event and mpv_event_end_file.
1328      */
1329     MPV_EVENT_END_FILE = 7,
1330     /**
1331      * Notification when the file has been loaded (headers were read etc.), and
1332      * decoding starts.
1333      */
1334     MPV_EVENT_FILE_LOADED = 8,
1335 
1336     /**
1337      * The list of video/audio/subtitle tracks was changed. (E.g. a new track
1338      * was found. This doesn't necessarily indicate a track switch; for this,
1339      * MPV_EVENT_TRACK_SWITCHED is used.)
1340      *
1341      * @deprecated This is equivalent to using mpv_observe_property() on the
1342      *             "track-list" property. The event is redundant, and might
1343      *             be removed in the far future.
1344      */
1345     MPV_EVENT_TRACKS_CHANGED = 9,
1346     /**
1347      * A video/audio/subtitle track was switched on or off.
1348      *
1349      * @deprecated This is equivalent to using mpv_observe_property() on the
1350      *             "vid", "aid", and "sid" properties. The event is redundant,
1351      *             and might be removed in the far future.
1352      */
1353     MPV_EVENT_TRACK_SWITCHED = 10,
1354 
1355     /**
1356      * Idle mode was entered. In this mode, no file is played, and the playback
1357      * core waits for new commands. (The command line player normally quits
1358      * instead of entering idle mode, unless --idle was specified. If mpv
1359      * was started with mpv_create(), idle mode is enabled by default.)
1360      */
1361     MPV_EVENT_IDLE = 11,
1362 
1363     /**
1364      * Playback was paused. This indicates the user pause state.
1365      *
1366      * The user pause state is the state the user requested (changed with the
1367      * "pause" property). There is an internal pause state too, which is entered
1368      * if e.g. the network is too slow (the "core-idle" property generally
1369      * indicates whether the core is playing or waiting).
1370      *
1371      * This event is sent whenever any pause states change, not only the user
1372      * state. You might get multiple events in a row while these states change
1373      * independently. But the event ID sent always indicates the user pause
1374      * state.
1375      *
1376      * If you don't want to deal with this, use mpv_observe_property() on the
1377      * "pause" property and ignore MPV_EVENT_PAUSE/UNPAUSE. Likewise, the
1378      * "core-idle" property tells you whether video is actually playing or not.
1379      *
1380      * @deprecated The event is redundant with mpv_observe_property() as
1381      *             mentioned above, and might be removed in the far future.
1382      */
1383     MPV_EVENT_PAUSE = 12,
1384     /**
1385      * Playback was unpaused. See MPV_EVENT_PAUSE for not so obvious details.
1386      *
1387      * @deprecated The event is redundant with mpv_observe_property() as
1388      *             explained in the MPV_EVENT_PAUSE comments, and might be
1389      *             removed in the far future.
1390      */
1391     MPV_EVENT_UNPAUSE = 13,
1392     /**
1393      * Sent every time after a video frame is displayed. Note that currently,
1394      * this will be sent in lower frequency if there is no video, or playback
1395      * is paused - but that will be removed in the future, and it will be
1396      * restricted to video frames only.
1397      *
1398      * @deprecated Use mpv_observe_property() with relevant properties instead
1399      *             (such as "playback-time").
1400      */
1401     MPV_EVENT_TICK = 14,
1402     /**
1403      * @deprecated This was used internally with the internal "script_dispatch"
1404      *             command to dispatch keyboard and mouse input for the OSC.
1405      *             It was never useful in general and has been completely
1406      *             replaced with "script-binding".
1407      *             This event never happens anymore, and is included in this
1408      *             header only for compatibility.
1409      */
1410     MPV_EVENT_SCRIPT_INPUT_DISPATCH = 15,
1411 
1412     /**
1413      * Triggered by the script-message input command. The command uses the
1414      * first argument of the command as client name (see mpv_client_name()) to
1415      * dispatch the message, and passes along all arguments starting from the
1416      * second argument as strings.
1417      * See also mpv_event and mpv_event_client_message.
1418      */
1419     MPV_EVENT_CLIENT_MESSAGE = 16,
1420     /**
1421      * Happens after video changed in some way. This can happen on resolution
1422      * changes, pixel format changes, or video filter changes. The event is
1423      * sent after the video filters and the VO are reconfigured. Applications
1424      * embedding a mpv window should listen to this event in order to resize
1425      * the window if needed.
1426      * Note that this event can happen sporadically, and you should check
1427      * yourself whether the video parameters really changed before doing
1428      * something expensive.
1429      */
1430     MPV_EVENT_VIDEO_RECONFIG = 17,
1431     /**
1432      * Similar to MPV_EVENT_VIDEO_RECONFIG. This is relatively uninteresting,
1433      * because there is no such thing as audio output embedding.
1434      */
1435     MPV_EVENT_AUDIO_RECONFIG = 18,
1436 
1437     /**
1438      * Happens when metadata (like file tags) is possibly updated. (It's left
1439      * unspecified whether this happens on file start or only when it changes
1440      * within a file.)
1441      *
1442      * @deprecated This is equivalent to using mpv_observe_property() on the
1443      *             "metadata" property. The event is redundant, and might
1444      *             be removed in the far future.
1445      */
1446     MPV_EVENT_METADATA_UPDATE = 19,
1447 
1448     /**
1449      * Happens when a seek was initiated. Playback stops. Usually it will
1450      * resume with MPV_EVENT_PLAYBACK_RESTART as soon as the seek is finished.
1451      */
1452     MPV_EVENT_SEEK = 20,
1453     /**
1454      * There was a discontinuity of some sort (like a seek), and playback
1455      * was reinitialized. Usually happens after seeking, or ordered chapter
1456      * segment switches. The main purpose is allowing the client to detect
1457      * when a seek request is finished.
1458      */
1459     MPV_EVENT_PLAYBACK_RESTART = 21,
1460     /**
1461      * Event sent due to mpv_observe_property().
1462      * See also mpv_event and mpv_event_property.
1463      */
1464     MPV_EVENT_PROPERTY_CHANGE = 22,
1465 
1466     /**
1467      * Happens when the current chapter changes.
1468      *
1469      * @deprecated This is equivalent to using mpv_observe_property() on the
1470      *             "chapter" property. The event is redundant, and might
1471      *             be removed in the far future.
1472      */
1473     MPV_EVENT_CHAPTER_CHANGE = 23,
1474 
1475     /**
1476      * Happens if the internal per-mpv_handle ringbuffer overflows, and at
1477      * least 1 event had to be dropped. This can happen if the client doesn't
1478      * read the event queue quickly enough with mpv_wait_event(), or if the
1479      * client makes a very large number of asynchronous calls at once.
1480      *
1481      * Event delivery will continue normally once this event was returned
1482      * (this forces the client to empty the queue completely).
1483      */
1484     MPV_EVENT_QUEUE_OVERFLOW = 24,
1485     /**
1486      * Triggered if a hook handler was registered with mpv_hook_add(), and the
1487      * hook is invoked. If you receive this, you must handle it, and continue
1488      * the hook with mpv_hook_continue().
1489      * See also mpv_event and mpv_event_hook.
1490      */
1491     MPV_EVENT_HOOK = 25
1492     // Internal note: adjust INTERNAL_EVENT_BASE when adding new events.
1493 }
1494 
1495 /**
1496  * Return a string describing the event. For unknown events, NULL is returned.
1497  *
1498  * Note that all events actually returned by the API will also yield a non-NULL
1499  * string with this function.
1500  *
1501  * @param event event ID, see see enum mpv_event_id
1502  * @return A static string giving a short symbolic name of the event. It
1503  *         consists of lower-case alphanumeric characters and can include "-"
1504  *         characters. This string is suitable for use in e.g. scripting
1505  *         interfaces.
1506  *         The string is completely static, i.e. doesn't need to be deallocated,
1507  *         and is valid forever.
1508  */
1509 const(char)* mpv_event_name (mpv_event_id event);
1510 
1511 struct mpv_event_property
1512 {
1513     /**
1514      * Name of the property.
1515      */
1516     const(char)* name;
1517     /**
1518      * Format of the data field in the same struct. See enum mpv_format.
1519      * This is always the same format as the requested format, except when
1520      * the property could not be retrieved (unavailable, or an error happened),
1521      * in which case the format is MPV_FORMAT_NONE.
1522      */
1523     mpv_format format;
1524     /**
1525      * Received property value. Depends on the format. This is like the
1526      * pointer argument passed to mpv_get_property().
1527      *
1528      * For example, for MPV_FORMAT_STRING you get the string with:
1529      *
1530      *    char *value = *(char **)(event_property->data);
1531      *
1532      * Note that this is set to NULL if retrieving the property failed (the
1533      * format will be MPV_FORMAT_NONE).
1534      */
1535     void* data;
1536 }
1537 
1538 /**
1539  * Numeric log levels. The lower the number, the more important the message is.
1540  * MPV_LOG_LEVEL_NONE is never used when receiving messages. The string in
1541  * the comment after the value is the name of the log level as used for the
1542  * mpv_request_log_messages() function.
1543  * Unused numeric values are unused, but reserved for future use.
1544  */
1545 enum mpv_log_level
1546 {
1547     MPV_LOG_LEVEL_NONE = 0, /// "no"    - disable absolutely all messages
1548     MPV_LOG_LEVEL_FATAL = 10, /// "fatal" - critical/aborting errors
1549     MPV_LOG_LEVEL_ERROR = 20, /// "error" - simple errors
1550     MPV_LOG_LEVEL_WARN = 30, /// "warn"  - possible problems
1551     MPV_LOG_LEVEL_INFO = 40, /// "info"  - informational message
1552     MPV_LOG_LEVEL_V = 50, /// "v"     - noisy informational message
1553     MPV_LOG_LEVEL_DEBUG = 60, /// "debug" - very noisy technical information
1554     MPV_LOG_LEVEL_TRACE = 70 /// "trace" - extremely noisy
1555 }
1556 
1557 struct mpv_event_log_message
1558 {
1559     /**
1560      * The module prefix, identifies the sender of the message. As a special
1561      * case, if the message buffer overflows, this will be set to the string
1562      * "overflow" (which doesn't appear as prefix otherwise), and the text
1563      * field will contain an informative message.
1564      */
1565     const(char)* prefix;
1566     /**
1567      * The log level as string. See mpv_request_log_messages() for possible
1568      * values. The level "no" is never used here.
1569      */
1570     const(char)* level;
1571     /**
1572      * The log message. It consists of 1 line of text, and is terminated with
1573      * a newline character. (Before API version 1.6, it could contain multiple
1574      * or partial lines.)
1575      */
1576     const(char)* text;
1577     /**
1578      * The same contents as the level field, but as a numeric ID.
1579      * Since API version 1.6.
1580      */
1581     mpv_log_level log_level;
1582 }
1583 
1584 /// Since API version 1.9.
1585 enum mpv_end_file_reason
1586 {
1587     /**
1588      * The end of file was reached. Sometimes this may also happen on
1589      * incomplete or corrupted files, or if the network connection was
1590      * interrupted when playing a remote file. It also happens if the
1591      * playback range was restricted with --end or --frames or similar.
1592      */
1593     MPV_END_FILE_REASON_EOF = 0,
1594     /**
1595      * Playback was stopped by an external action (e.g. playlist controls).
1596      */
1597     MPV_END_FILE_REASON_STOP = 2,
1598     /**
1599      * Playback was stopped by the quit command or player shutdown.
1600      */
1601     MPV_END_FILE_REASON_QUIT = 3,
1602     /**
1603      * Some kind of error happened that lead to playback abort. Does not
1604      * necessarily happen on incomplete or broken files (in these cases, both
1605      * MPV_END_FILE_REASON_ERROR or MPV_END_FILE_REASON_EOF are possible).
1606      *
1607      * mpv_event_end_file.error will be set.
1608      */
1609     MPV_END_FILE_REASON_ERROR = 4,
1610     /**
1611      * The file was a playlist or similar. When the playlist is read, its
1612      * entries will be appended to the playlist after the entry of the current
1613      * file, the entry of the current file is removed, and a MPV_EVENT_END_FILE
1614      * event is sent with reason set to MPV_END_FILE_REASON_REDIRECT. Then
1615      * playback continues with the playlist contents.
1616      * Since API version 1.18.
1617      */
1618     MPV_END_FILE_REASON_REDIRECT = 5
1619 }
1620 
1621 struct mpv_event_end_file
1622 {
1623     /**
1624      * Corresponds to the values in enum mpv_end_file_reason (the "int" type
1625      * will be replaced with mpv_end_file_reason on the next ABI bump).
1626      *
1627      * Unknown values should be treated as unknown.
1628      */
1629     int reason;
1630     /**
1631      * If reason==MPV_END_FILE_REASON_ERROR, this contains a mpv error code
1632      * (one of MPV_ERROR_...) giving an approximate reason why playback
1633      * failed. In other cases, this field is 0 (no error).
1634      * Since API version 1.9.
1635      */
1636     int error;
1637 }
1638 
1639 /** @deprecated see MPV_EVENT_SCRIPT_INPUT_DISPATCH for remarks
1640  */
1641 struct mpv_event_script_input_dispatch
1642 {
1643     int arg0;
1644     const(char)* type;
1645 }
1646 
1647 struct mpv_event_client_message
1648 {
1649     /**
1650      * Arbitrary arguments chosen by the sender of the message. If num_args > 0,
1651      * you can access args[0] through args[num_args - 1] (inclusive). What
1652      * these arguments mean is up to the sender and receiver.
1653      * None of the valid items are NULL.
1654      */
1655     int num_args;
1656     const(char*)* args;
1657 }
1658 
1659 struct mpv_event_hook
1660 {
1661     /**
1662      * The hook name as passed to mpv_hook_add().
1663      */
1664     const(char)* name;
1665     /**
1666      * Internal ID that must be passed to mpv_hook_continue().
1667      */
1668     ulong id;
1669 }
1670 
1671 // Since API version 1.102.
1672 struct mpv_event_command
1673 {
1674     /**
1675      * Result data of the command. Note that success/failure is signaled
1676      * separately via mpv_event.error. This field is only for result data
1677      * in case of success. Most commands leave it at MPV_FORMAT_NONE. Set
1678      * to MPV_FORMAT_NONE on failure.
1679      */
1680     mpv_node result;
1681 }
1682 
1683 struct mpv_event
1684 {
1685     /**
1686      * One of mpv_event. Keep in mind that later ABI compatible releases might
1687      * add new event types. These should be ignored by the API user.
1688      */
1689     mpv_event_id event_id;
1690     /**
1691      * This is mainly used for events that are replies to (asynchronous)
1692      * requests. It contains a status code, which is >= 0 on success, or < 0
1693      * on error (a mpv_error value). Usually, this will be set if an
1694      * asynchronous request fails.
1695      * Used for:
1696      *  MPV_EVENT_GET_PROPERTY_REPLY
1697      *  MPV_EVENT_SET_PROPERTY_REPLY
1698      *  MPV_EVENT_COMMAND_REPLY
1699      */
1700     int error;
1701     /**
1702      * If the event is in reply to a request (made with this API and this
1703      * API handle), this is set to the reply_userdata parameter of the request
1704      * call. Otherwise, this field is 0.
1705      * Used for:
1706      *  MPV_EVENT_GET_PROPERTY_REPLY
1707      *  MPV_EVENT_SET_PROPERTY_REPLY
1708      *  MPV_EVENT_COMMAND_REPLY
1709      *  MPV_EVENT_PROPERTY_CHANGE
1710      *  MPV_EVENT_HOOK
1711      */
1712     ulong reply_userdata;
1713     /**
1714      * The meaning and contents of the data member depend on the event_id:
1715      *  MPV_EVENT_GET_PROPERTY_REPLY:     mpv_event_property*
1716      *  MPV_EVENT_PROPERTY_CHANGE:        mpv_event_property*
1717      *  MPV_EVENT_LOG_MESSAGE:            mpv_event_log_message*
1718      *  MPV_EVENT_CLIENT_MESSAGE:         mpv_event_client_message*
1719      *  MPV_EVENT_END_FILE:               mpv_event_end_file*
1720      *  MPV_EVENT_HOOK:                   mpv_event_hook*
1721      *  MPV_EVENT_COMMAND_REPLY*          mpv_event_command*
1722      *  other: NULL
1723      *
1724      * Note: future enhancements might add new event structs for existing or new
1725      *       event types.
1726      */
1727     void* data;
1728 }
1729 
1730 /**
1731  * Enable or disable the given event.
1732  *
1733  * Some events are enabled by default. Some events can't be disabled.
1734  *
1735  * (Informational note: currently, all events are enabled by default, except
1736  *  MPV_EVENT_TICK.)
1737  *
1738  * Safe to be called from mpv render API threads.
1739  *
1740  * @param event See enum mpv_event_id.
1741  * @param enable 1 to enable receiving this event, 0 to disable it.
1742  * @return error code
1743  */
1744 int mpv_request_event (mpv_handle* ctx, mpv_event_id event, int enable);
1745 
1746 /**
1747  * Enable or disable receiving of log messages. These are the messages the
1748  * command line player prints to the terminal. This call sets the minimum
1749  * required log level for a message to be received with MPV_EVENT_LOG_MESSAGE.
1750  *
1751  * @param min_level Minimal log level as string. Valid log levels:
1752  *                      no fatal error warn info v debug trace
1753  *                  The value "no" disables all messages. This is the default.
1754  *                  An exception is the value "terminal-default", which uses the
1755  *                  log level as set by the "--msg-level" option. This works
1756  *                  even if the terminal is disabled. (Since API version 1.19.)
1757  *                  Also see mpv_log_level.
1758  * @return error code
1759  */
1760 int mpv_request_log_messages (mpv_handle* ctx, const(char)* min_level);
1761 
1762 /**
1763  * Wait for the next event, or until the timeout expires, or if another thread
1764  * makes a call to mpv_wakeup(). Passing 0 as timeout will never wait, and
1765  * is suitable for polling.
1766  *
1767  * The internal event queue has a limited size (per client handle). If you
1768  * don't empty the event queue quickly enough with mpv_wait_event(), it will
1769  * overflow and silently discard further events. If this happens, making
1770  * asynchronous requests will fail as well (with MPV_ERROR_EVENT_QUEUE_FULL).
1771  *
1772  * Only one thread is allowed to call this on the same mpv_handle at a time.
1773  * The API won't complain if more than one thread calls this, but it will cause
1774  * race conditions in the client when accessing the shared mpv_event struct.
1775  * Note that most other API functions are not restricted by this, and no API
1776  * function internally calls mpv_wait_event(). Additionally, concurrent calls
1777  * to different mpv_handles are always safe.
1778  *
1779  * As long as the timeout is 0, this is safe to be called from mpv render API
1780  * threads.
1781  *
1782  * @param timeout Timeout in seconds, after which the function returns even if
1783  *                no event was received. A MPV_EVENT_NONE is returned on
1784  *                timeout. A value of 0 will disable waiting. Negative values
1785  *                will wait with an infinite timeout.
1786  * @return A struct containing the event ID and other data. The pointer (and
1787  *         fields in the struct) stay valid until the next mpv_wait_event()
1788  *         call, or until the mpv_handle is destroyed. You must not write to
1789  *         the struct, and all memory referenced by it will be automatically
1790  *         released by the API on the next mpv_wait_event() call, or when the
1791  *         context is destroyed. The return value is never NULL.
1792  */
1793 mpv_event* mpv_wait_event (mpv_handle* ctx, double timeout);
1794 
1795 /**
1796  * Interrupt the current mpv_wait_event() call. This will wake up the thread
1797  * currently waiting in mpv_wait_event(). If no thread is waiting, the next
1798  * mpv_wait_event() call will return immediately (this is to avoid lost
1799  * wakeups).
1800  *
1801  * mpv_wait_event() will receive a MPV_EVENT_NONE if it's woken up due to
1802  * this call. But note that this dummy event might be skipped if there are
1803  * already other events queued. All what counts is that the waiting thread
1804  * is woken up at all.
1805  *
1806  * Safe to be called from mpv render API threads.
1807  */
1808 void mpv_wakeup (mpv_handle* ctx);
1809 
1810 /**
1811  * Set a custom function that should be called when there are new events. Use
1812  * this if blocking in mpv_wait_event() to wait for new events is not feasible.
1813  *
1814  * Keep in mind that the callback will be called from foreign threads. You
1815  * must not make any assumptions of the environment, and you must return as
1816  * soon as possible (i.e. no long blocking waits). Exiting the callback through
1817  * any other means than a normal return is forbidden (no throwing exceptions,
1818  * no longjmp() calls). You must not change any local thread state (such as
1819  * the C floating point environment).
1820  *
1821  * You are not allowed to call any client API functions inside of the callback.
1822  * In particular, you should not do any processing in the callback, but wake up
1823  * another thread that does all the work. The callback is meant strictly for
1824  * notification only, and is called from arbitrary core parts of the player,
1825  * that make no considerations for reentrant API use or allowing the callee to
1826  * spend a lot of time doing other things. Keep in mind that it's also possible
1827  * that the callback is called from a thread while a mpv API function is called
1828  * (i.e. it can be reentrant).
1829  *
1830  * In general, the client API expects you to call mpv_wait_event() to receive
1831  * notifications, and the wakeup callback is merely a helper utility to make
1832  * this easier in certain situations. Note that it's possible that there's
1833  * only one wakeup callback invocation for multiple events. You should call
1834  * mpv_wait_event() with no timeout until MPV_EVENT_NONE is reached, at which
1835  * point the event queue is empty.
1836  *
1837  * If you actually want to do processing in a callback, spawn a thread that
1838  * does nothing but call mpv_wait_event() in a loop and dispatches the result
1839  * to a callback.
1840  *
1841  * Only one wakeup callback can be set.
1842  *
1843  * @param cb function that should be called if a wakeup is required
1844  * @param d arbitrary userdata passed to cb
1845  */
1846 void mpv_set_wakeup_callback (mpv_handle* ctx, void function (void* d) cb, void* d);
1847 
1848 /**
1849  * Block until all asynchronous requests are done. This affects functions like
1850  * mpv_command_async(), which return immediately and return their result as
1851  * events.
1852  *
1853  * This is a helper, and somewhat equivalent to calling mpv_wait_event() in a
1854  * loop until all known asynchronous requests have sent their reply as event,
1855  * except that the event queue is not emptied.
1856  *
1857  * In case you called mpv_suspend() before, this will also forcibly reset the
1858  * suspend counter of the given handle.
1859  */
1860 void mpv_wait_async_requests (mpv_handle* ctx);
1861 
1862 /**
1863  * A hook is like a synchronous event that blocks the player. You register
1864  * a hook handler with this function. You will get an event, which you need
1865  * to handle, and once things are ready, you can let the player continue with
1866  * mpv_hook_continue().
1867  *
1868  * Currently, hooks can't be removed explicitly. But they will be implicitly
1869  * removed if the mpv_handle it was registered with is destroyed. This also
1870  * continues the hook if it was being handled by the destroyed mpv_handle (but
1871  * this should be avoided, as it might mess up order of hook execution).
1872  *
1873  * Hook handlers are ordered globally by priority and order of registration.
1874  * Handlers for the same hook with same priority are invoked in order of
1875  * registration (the handler registered first is run first). Handlers with
1876  * lower priority are run first (which seems backward).
1877  *
1878  * See the "Hooks" section in the manpage to see which hooks are currently
1879  * defined.
1880  *
1881  * Some hooks might be reentrant (so you get multiple MPV_EVENT_HOOK for the
1882  * same hook). If this can happen for a specific hook type, it will be
1883  * explicitly documented in the manpage.
1884  *
1885  * Only the mpv_handle on which this was called will receive the hook events,
1886  * or can "continue" them.
1887  *
1888  * @param reply_userdata This will be used for the mpv_event.reply_userdata
1889  *                       field for the received MPV_EVENT_HOOK events.
1890  *                       If you have no use for this, pass 0.
1891  * @param name The hook name. This should be one of the documented names. But
1892  *             if the name is unknown, the hook event will simply be never
1893  *             raised.
1894  * @param priority See remarks above. Use 0 as a neutral default.
1895  * @return error code (usually fails only on OOM)
1896  */
1897 int mpv_hook_add (
1898     mpv_handle* ctx,
1899     ulong reply_userdata,
1900     const(char)* name,
1901     int priority);
1902 
1903 /**
1904  * Respond to a MPV_EVENT_HOOK event. You must call this after you have handled
1905  * the event. There is no way to "cancel" or "stop" the hook.
1906  *
1907  * Calling this will will typically unblock the player for whatever the hook
1908  * is responsible for (e.g. for the "on_load" hook it lets it continue
1909  * playback).
1910  *
1911  * It is explicitly undefined behavior to call this more than once for each
1912  * MPV_EVENT_HOOK, to pass an incorrect ID, or to call this on a mpv_handle
1913  * different from the one that registered the handler and received the event.
1914  *
1915  * @param id This must be the value of the mpv_event_hook.id field for the
1916  *           corresponding MPV_EVENT_HOOK.
1917  * @return error code
1918  */
1919 int mpv_hook_continue (mpv_handle* ctx, ulong id);
1920 
1921 /**
1922  * Return a UNIX file descriptor referring to the read end of a pipe. This
1923  * pipe can be used to wake up a poll() based processing loop. The purpose of
1924  * this function is very similar to mpv_set_wakeup_callback(), and provides
1925  * a primitive mechanism to handle coordinating a foreign event loop and the
1926  * libmpv event loop. The pipe is non-blocking. It's closed when the mpv_handle
1927  * is destroyed. This function always returns the same value (on success).
1928  *
1929  * This is in fact implemented using the same underlying code as for
1930  * mpv_set_wakeup_callback() (though they don't conflict), and it is as if each
1931  * callback invocation writes a single 0 byte to the pipe. When the pipe
1932  * becomes readable, the code calling poll() (or select()) on the pipe should
1933  * read all contents of the pipe and then call mpv_wait_event(c, 0) until
1934  * no new events are returned. The pipe contents do not matter and can just
1935  * be discarded. There is not necessarily one byte per readable event in the
1936  * pipe. For example, the pipes are non-blocking, and mpv won't block if the
1937  * pipe is full. Pipes are normally limited to 4096 bytes, so if there are
1938  * more than 4096 events, the number of readable bytes can not equal the number
1939  * of events queued. Also, it's possible that mpv does not write to the pipe
1940  * once it's guaranteed that the client was already signaled. See the example
1941  * below how to do it correctly.
1942  *
1943  * Example:
1944  *
1945  *  int pipefd = mpv_get_wakeup_pipe(mpv);
1946  *  if (pipefd < 0)
1947  *      error();
1948  *  while (1) {
1949  *      struct pollfd pfds[1] = {
1950  *          { .fd = pipefd, .events = POLLIN },
1951  *      };
1952  *      // Wait until there are possibly new mpv events.
1953  *      poll(pfds, 1, -1);
1954  *      if (pfds[0].revents & POLLIN) {
1955  *          // Empty the pipe. Doing this before calling mpv_wait_event()
1956  *          // ensures that no wakeups are missed. It's not so important to
1957  *          // make sure the pipe is really empty (it will just cause some
1958  *          // additional wakeups in unlikely corner cases).
1959  *          char unused[256];
1960  *          read(pipefd, unused, sizeof(unused));
1961  *          while (1) {
1962  *              mpv_event *ev = mpv_wait_event(mpv, 0);
1963  *              // If MPV_EVENT_NONE is received, the event queue is empty.
1964  *              if (ev->event_id == MPV_EVENT_NONE)
1965  *                  break;
1966  *              // Process the event.
1967  *              ...
1968  *          }
1969  *      }
1970  *  }
1971  *
1972  * @deprecated this function will be removed in the future. If you need this
1973  *             functionality, use mpv_set_wakeup_callback(), create a pipe
1974  *             manually, and call write() on your pipe in the callback.
1975  *
1976  * @return A UNIX FD of the read end of the wakeup pipe, or -1 on error.
1977  *         On MS Windows/MinGW, this will always return -1.
1978  */
1979 int mpv_get_wakeup_pipe (mpv_handle* ctx);
1980 
1981 /**
1982  * @deprecated use render.h
1983  */
1984 enum mpv_sub_api
1985 {
1986     /**
1987      * For using mpv's OpenGL renderer on an external OpenGL context.
1988      * mpv_get_sub_api(MPV_SUB_API_OPENGL_CB) returns mpv_opengl_cb_context*.
1989      * This context can be used with mpv_opengl_cb_* functions.
1990      * Will return NULL if unavailable (if OpenGL support was not compiled in).
1991      * See opengl_cb.h for details.
1992      *
1993      * @deprecated use render.h
1994      */
1995     MPV_SUB_API_OPENGL_CB = 1
1996 }
1997 
1998 /**
1999  * This is used for additional APIs that are not strictly part of the core API.
2000  * See the individual mpv_sub_api member values.
2001  *
2002  * @deprecated use render.h
2003  */
2004 void* mpv_get_sub_api (mpv_handle* ctx, mpv_sub_api sub_api);
2005