292 lines
13 KiB
C++
292 lines
13 KiB
C++
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#ifndef foocontexthfoo
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#define foocontexthfoo
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/***
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This file is part of PulseAudio.
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Copyright 2004-2006 Lennart Poettering
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Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
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PulseAudio is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published
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by the Free Software Foundation; either version 2.1 of the License,
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or (at your option) any later version.
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PulseAudio is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
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***/
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#include <pulse/sample.h>
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#include <pulse/def.h>
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#include <pulse/mainloop-api.h>
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#include <pulse/cdecl.h>
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#include <pulse/operation.h>
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#include <pulse/proplist.h>
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#include <pulse/version.h>
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/** \page async Asynchronous API
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*
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* \section overv_sec Overview
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*
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* The asynchronous API is the native interface to the PulseAudio library.
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* It allows full access to all available functionality. This however means that
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* it is rather complex and can take some time to fully master.
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*
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* \section mainloop_sec Main Loop Abstraction
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*
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* The API is based around an asynchronous event loop, or main loop,
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* abstraction. This abstraction contains three basic elements:
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*
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* \li Deferred events - Events that will trigger as soon as possible. Note
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* that some implementations may block all other events
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* when a deferred event is active.
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* \li I/O events - Events that trigger on file descriptor activities.
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* \li Times events - Events that trigger after a fixed amount of time.
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*
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* The abstraction is represented as a number of function pointers in the
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* pa_mainloop_api structure.
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*
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* To actually be able to use these functions, an implementation needs to
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* be coupled to the abstraction. There are three of these shipped with
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* PulseAudio, but any other can be used with a minimal amount of work,
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* provided it supports the three basic events listed above.
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*
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* The implementations shipped with PulseAudio are:
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*
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* \li \subpage mainloop - A minimal but fast implementation based on poll().
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* \li \subpage threaded_mainloop - A special version of the previous
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* implementation where all of PulseAudio's
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* internal handling runs in a separate
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* thread.
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* \li \subpage glib-mainloop - A wrapper around GLib's main loop.
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*
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* UNIX signals may be hooked to a main loop using the functions from
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* \ref mainloop-signal.h. These rely only on the main loop abstraction
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* and can therefore be used with any of the implementations.
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*
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* \section refcnt_sec Reference Counting
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*
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* Almost all objects in PulseAudio are reference counted. What that means
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* is that you rarely malloc() or free() any objects. Instead you increase
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* and decrease their reference counts. Whenever an object's reference
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* count reaches zero, that object gets destroy and any resources it uses
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* get freed.
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*
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* The benefit of this design is that an application need not worry about
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* whether or not it needs to keep an object around in case the library is
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* using it internally. If it is, then it has made sure it has its own
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* reference to it.
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*
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* Whenever the library creates an object, it will have an initial
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* reference count of one. Most of the time, this single reference will be
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* sufficient for the application, so all required reference count
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* interaction will be a single call to the object's unref function.
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*
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* \section context_sec Context
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*
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* A context is the basic object for a connection to a PulseAudio server.
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* It multiplexes commands, data streams and events through a single
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* channel.
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*
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* There is no need for more than one context per application, unless
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* connections to multiple servers are needed.
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*
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* \subsection ops_subsec Operations
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*
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* All operations on the context are performed asynchronously. I.e. the
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* client will not wait for the server to complete the request. To keep
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* track of all these in-flight operations, the application is given a
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* pa_operation object for each asynchronous operation.
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*
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* There are only two actions (besides reference counting) that can be
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* performed on a pa_operation: querying its state with
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* pa_operation_get_state() and aborting it with pa_operation_cancel().
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*
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* A pa_operation object is reference counted, so an application must
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* make sure to unreference it, even if it has no intention of using it.
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*
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* \subsection conn_subsec Connecting
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*
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* A context must be connected to a server before any operation can be
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* issued. Calling pa_context_connect() will initiate the connection
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* procedure. Unlike most asynchronous operations, connecting does not
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* result in a pa_operation object. Instead, the application should
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* register a callback using pa_context_set_state_callback().
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*
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* \subsection disc_subsec Disconnecting
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*
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* When the sound support is no longer needed, the connection needs to be
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* closed using pa_context_disconnect(). This is an immediate function that
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* works synchronously.
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*
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* Since the context object has references to other objects it must be
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* disconnected after use or there is a high risk of memory leaks. If the
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* connection has terminated by itself, then there is no need to explicitly
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* disconnect the context using pa_context_disconnect().
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*
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* \section Functions
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*
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* The sound server's functionality can be divided into a number of
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* subsections:
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*
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* \li \subpage streams
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* \li \subpage scache
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* \li \subpage introspect
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* \li \subpage subscribe
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*/
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/** \file
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* Connection contexts for asynchronous communication with a
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* server. A pa_context object wraps a connection to a PulseAudio
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* server using its native protocol.
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*
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* See also \subpage async
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*/
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PA_C_DECL_BEGIN
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/** An opaque connection context to a daemon */
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typedef struct pa_context pa_context;
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/** Generic notification callback prototype */
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typedef void (*pa_context_notify_cb_t)(pa_context *c, void *userdata);
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/** A generic callback for operation completion */
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typedef void (*pa_context_success_cb_t) (pa_context *c, int success, void *userdata);
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/** A callback for asynchronous meta/policy event messages. The set
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* of defined events can be extended at any time. Also, server modules
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* may introduce additional message types so make sure that your
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* callback function ignores messages it doesn't know. \since
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* 0.9.15 */
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typedef void (*pa_context_event_cb_t)(pa_context *c, const char *name, pa_proplist *p, void *userdata);
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/** Instantiate a new connection context with an abstract mainloop API
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* and an application name. It is recommended to use pa_context_new_with_proplist()
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* instead and specify some initial properties.*/
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pa_context *pa_context_new(pa_mainloop_api *mainloop, const char *name);
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/** Instantiate a new connection context with an abstract mainloop API
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* and an application name, and specify the initial client property
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* list. \since 0.9.11 */
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pa_context *pa_context_new_with_proplist(pa_mainloop_api *mainloop, const char *name, pa_proplist *proplist);
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/** Decrease the reference counter of the context by one */
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void pa_context_unref(pa_context *c);
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/** Increase the reference counter of the context by one */
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pa_context* pa_context_ref(pa_context *c);
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/** Set a callback function that is called whenever the context status changes */
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void pa_context_set_state_callback(pa_context *c, pa_context_notify_cb_t cb, void *userdata);
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/** Set a callback function that is called whenever a meta/policy
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* control event is received. \since 0.9.15 */
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void pa_context_set_event_callback(pa_context *p, pa_context_event_cb_t cb, void *userdata);
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/** Return the error number of the last failed operation */
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int pa_context_errno(pa_context *c);
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/** Return non-zero if some data is pending to be written to the connection */
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int pa_context_is_pending(pa_context *c);
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/** Return the current context status */
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pa_context_state_t pa_context_get_state(pa_context *c);
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/** Connect the context to the specified server. If server is NULL,
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connect to the default server. This routine may but will not always
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return synchronously on error. Use pa_context_set_state_callback() to
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be notified when the connection is established. If flags doesn't have
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PA_CONTEXT_NOAUTOSPAWN set and no specific server is specified or
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accessible a new daemon is spawned. If api is non-NULL, the functions
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specified in the structure are used when forking a new child
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process. */
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int pa_context_connect(pa_context *c, const char *server, pa_context_flags_t flags, const pa_spawn_api *api);
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/** Terminate the context connection immediately */
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void pa_context_disconnect(pa_context *c);
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/** Drain the context. If there is nothing to drain, the function returns NULL */
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pa_operation* pa_context_drain(pa_context *c, pa_context_notify_cb_t cb, void *userdata);
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/** Tell the daemon to exit. The returned operation is unlikely to
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* complete successfully, since the daemon probably died before
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* returning a success notification */
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pa_operation* pa_context_exit_daemon(pa_context *c, pa_context_success_cb_t cb, void *userdata);
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/** Set the name of the default sink. */
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pa_operation* pa_context_set_default_sink(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata);
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/** Set the name of the default source. */
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pa_operation* pa_context_set_default_source(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata);
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/** Returns 1 when the connection is to a local daemon. Returns negative when no connection has been made yet. */
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int pa_context_is_local(pa_context *c);
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/** Set a different application name for context on the server. */
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pa_operation* pa_context_set_name(pa_context *c, const char *name, pa_context_success_cb_t cb, void *userdata);
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/** Return the server name this context is connected to. */
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const char* pa_context_get_server(pa_context *c);
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/** Return the protocol version of the library. */
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uint32_t pa_context_get_protocol_version(pa_context *c);
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/** Return the protocol version of the connected server. */
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uint32_t pa_context_get_server_protocol_version(pa_context *c);
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/** Update the property list of the client, adding new entries. Please
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* note that it is highly recommended to set as much properties
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* initially via pa_context_new_with_proplist() as possible instead a
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* posteriori with this function, since that information may then be
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* used to route streams of the client to the right device. \since 0.9.11 */
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pa_operation *pa_context_proplist_update(pa_context *c, pa_update_mode_t mode, pa_proplist *p, pa_context_success_cb_t cb, void *userdata);
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/** Update the property list of the client, remove entries. \since 0.9.11 */
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pa_operation *pa_context_proplist_remove(pa_context *c, const char *const keys[], pa_context_success_cb_t cb, void *userdata);
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/** Return the client index this context is
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* identified in the server with. This is useful for usage with the
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* introspection functions, such as pa_context_get_client_info(). \since 0.9.11 */
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uint32_t pa_context_get_index(pa_context *s);
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/** Create a new timer event source for the specified time (wrapper
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* for mainloop->time_new). \since 0.9.16 */
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pa_time_event* pa_context_rttime_new(pa_context *c, pa_usec_t usec, pa_time_event_cb_t cb, void *userdata);
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/** Restart a running or expired timer event source (wrapper for
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* mainloop->time_restart). \since 0.9.16 */
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void pa_context_rttime_restart(pa_context *c, pa_time_event *e, pa_usec_t usec);
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/** Return the optimal block size for passing around audio buffers. It
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* is recommended to allocate buffers of the size returned here when
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* writing audio data to playback streams, if the latency constraints
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* permit this. It is not recommended writing larger blocks than this
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* because usually they will then be split up internally into chunks
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* of this size. It is not recommended writing smaller blocks than
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* this (unless required due to latency demands) because this
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* increases CPU usage. If ss is NULL you will be returned the
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* byte-exact tile size. If you pass a valid ss, then the tile size
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* will be rounded down to multiple of the frame size. This is
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* supposed to be used in a construct such as
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* pa_context_get_tile_size(pa_stream_get_context(s),
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* pa_stream_get_sample_spec(ss)); \since 0.9.20 */
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size_t pa_context_get_tile_size(pa_context *c, const pa_sample_spec *ss);
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/** Load the authentication cookie from a file. This function is primarily
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* meant for PulseAudio's own tunnel modules, which need to load the cookie
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* from a custom location. Applications don't usually need to care about the
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* cookie at all, but if it happens that you know what the authentication
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* cookie is and your application needs to load it from a non-standard
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* location, feel free to use this function. \since 5.0 */
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int pa_context_load_cookie_from_file(pa_context *c, const char *cookie_file_path);
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PA_C_DECL_END
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#endif
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