*
* \li pa_channel_map_init_mono() - Create a channel map with only mono audio.
* \li pa_channel_map_init_stereo() - Create a standard stereo mapping.
- * \li pa_channel_map_init_auto() - Create a standard channel map for up to
- * six channels.
+ * \li pa_channel_map_init_auto() - Create a standard channel map for a specific number of channels
+ * \li pa_channel_map_init_extend() - Similar to
+ * pa_channel_map_init_auto() but synthesize a channel map if noone
+ * predefined one is known for the specified number of channels.
*
* \section conv_sec Convenience Functions
*
* \section overv_sec Overview
*
* The asynchronous API is the native interface to the PulseAudio library.
- * It allows full access to all available functions. This also means that
+ * It allows full access to all available functionality. This however means that
* it is rather complex and can take some time to fully master.
*
* \section mainloop_sec Main Loop Abstraction
* implementation where all of PulseAudio's
* internal handling runs in a separate
* thread.
- * \li \subpage glib-mainloop - A wrapper around GLIB's main loop. Available
- * for both GLIB 1.2 and GLIB 2.x.
+ * \li \subpage glib-mainloop - A wrapper around GLib's main loop.
*
* UNIX signals may be hooked to a main loop using the functions from
* \ref mainloop-signal.h. These rely only on the main loop abstraction
PA_STREAM_START_MUTED = 4096, /**< Create in muted state. \since 0.9.11 */
-
PA_STREAM_ADJUST_LATENCY = 8192, /**< Try to adjust the latency of
* the sink/source based on the
* requested buffer metrics and
* adjust buffer metrics
- * accordingly. \since 0.9.11 */
+ * accordingly. See pa_buffer_attr \since 0.9.11 */
} pa_stream_flags_t;
/** Playback and record buffer metrics */
typedef struct pa_buffer_attr {
uint32_t maxlength; /**< Maximum length of the
- * buffer. Setting this to 0 will
+ * buffer. Setting this to (uint32_t) -1 will
* initialize this to the maximum value
* supported by server, which is
* recommended. */
uint32_t tlength; /**< Playback only: target length of the
* buffer. The server tries to assure
* that at least tlength bytes are always
- * available in the buffer. It is
- * recommended to set this to 0, which
- * will initialize this to a value that
- * is deemed sensible by the
+ * available in the per-stream
+ * server-side playback buffer. It is
+ * recommended to set this to (uint32_t)
+ * -1, which will initialize this to a
+ * value that is deemed sensible by the
* server. However, this value will
* default to something like 2s, i.e. for
* applications that have specific
* latency requirements this value should
* be set to the maximum latency that the
- * application can deal with. */
+ * application can deal with. When
+ * PA_STREAM_ADJUST_LATENCY is not set
+ * this value will influence only the
+ * per-stream playback buffer size. When
+ * PA_STREAM_ADJUST_LATENCY is set the
+ * overall latency of the sink plus the
+ * playback buffer size is configured to
+ * this value. Set
+ * PA_STREAM_ADJUST_LATENCY if you are
+ * interested in adjusting the overall
+ * latency. Don't set it if you are
+ * interested in configuring the
+ * server-sider per-stream playback
+ * buffer size. */
uint32_t prebuf; /**< Playback only: pre-buffering. The
* server does not start with playback
* before at least prebug bytes are
* available in the buffer. It is
- * recommended to set this to 0, which
- * will initialize this to the same value
- * as tlength, whatever that may be. */
+ * recommended to set this to (uint32_t)
+ * -1, which will initialize this to the
+ * same value as tlength, whatever that
+ * may be. Initialize to 0 to enable
+ * manual start/stop control of the
+ * stream. This means that playback will
+ * not stop on underrun and playback will
+ * not start automatically. Instead
+ * pa_stream_corked() needs to be called
+ * explicitly. If you set this value to 0
+ * you should also set
+ * PA_STREAM_START_CORKED. */
uint32_t minreq; /**< Playback only: minimum request. The
* server does not request less than
* minreq bytes from the client, instead
* waits until the buffer is free enough
* to request more bytes at once. It is
- * recommended to set this to 0, which
- * will initialize this to a value that
- * is deemed sensible by the server. */
+ * recommended to set this to (uint32_t)
+ * -1, which will initialize this to a
+ * value that is deemed sensible by the
+ * server. This should be set to a value
+ * that gives PulseAudio enough time to
+ * move the data from the per-stream
+ * playback buffer into the hardware
+ * playback buffer. */
uint32_t fragsize; /**< Recording only: fragment size. The
* server sends data in blocks of
* fragsize bytes size. Large values
* deminish interactivity with other
* operations on the connection context
* but decrease control overhead. It is
- * recommended to set this to 0, which
- * will initialize this to a value that
- * is deemed sensible by the
+ * recommended to set this to (uint32_t)
+ * -1, which will initialize this to a
+ * value that is deemed sensible by the
* server. However, this value will
* default to something like 2s, i.e. for
* applications that have specific
* latency requirements this value should
* be set to the maximum latency that the
- * application can deal with. */
+ * application can deal with. If
+ * PA_STREAM_ADJUST_LATENCY is set the
+ * overall source latency will be
+ * adjusted according to this value. If
+ * it is not set the source latency is
+ * left unmodified. */
} pa_buffer_attr;
/** Error values as used by pa_context_errno(). Use pa_strerror() to convert these values to human readable strings */
* PA_SEEK_RELATIVE_ON_READ
* instead. */
- pa_usec_t configured_sink_usec; /**< The static configured latency for
+ pa_usec_t configured_sink_usec; /**< The configured latency for
* the sink. \since 0.9.11 */
- pa_usec_t configured_source_usec; /**< The static configured latency for
+ pa_usec_t configured_source_usec; /**< The configured latency for
* the source. \since 0.9.11 */
int64_t since_underrun; /**< Bytes that were handed to the sink
*
* \subsection autoload_subsec Autoload Entries
*
- * Modules can be autoloaded as a result of a client requesting a certain
- * sink or source. This mapping between sink/source names and modules can be
+ * Modules can be autoloaded as a result of a client requesting a
+ * certain sink or source. Please note that autoloading is deprecated
+ * in 0.9.11. and is likely to be removed from the API in a later
+ * version. This mapping between sink/source names and modules can be
* queried from the server:
*
* \li By index - pa_context_get_autoload_info_by_index()
*
* New module autoloading rules can be added, and existing can be removed
* using pa_context_add_autoload() and pa_context_remove_autoload_by_index()
- * / pa_context_remove_autoload_by_name().
+ * / pa_context_remove_autoload_by_name(). Please note that autoloading is deprecated
+ * in 0.9.11. and is likely to be removed from the API in a later
+ * version.
*
* \subsection client_subsec Clients
*
* media.artist "Guns'N'Roses"
* media.language "de_DE"
* media.filename
- * media.icon
- * media.icon_name
+ * media.icon Binary blob containing PNG icon data
+ * media.icon_name Name from XDG icon naming spec
* media.role video, music, game, event, phone, production, filter, abstract, stream
- * event.id button-click, session-login
+ * event.id Name from XDG sound naming spec
+ * event.description "Button blabla clicked" for a11y
* event.mouse.x
* event.mouse.y
- * event.mouse.hpos
- * event.mouse.vpos
- * event.mouse.button
+ * event.mouse.hpos Float formatted as string in range 0..1
+ * event.mouse.vpos Float formatted as string in range 0..1
+ * event.mouse.button Button number following X11 ordering
* window.name
- * window.id
- * window.icon
- * window.icon_name
+ * window.id "org.gnome.rhytmbox.MainWindow"
+ * window.icon Binary blob containing PNG icon data
+ * window.icon_name Name from XDG icon naming spec
* window.x11.display
* window.x11.screen
* window.x11.monitor
* application.name "Rhythmbox Media Player"
* application.id "org.gnome.rhythmbox"
* application.version
- * application.icon
- * application.icon_name
+ * application.icon Binary blob containing PNG icon data
+ * application.icon_name Name from XDG icon naming spec
* application.language
* application.process.id
* application.process.binary
* application.process.user
* application.process.host
* device.string
- * device.api oss, alsa, sunaudio
+ * device.api oss, alsa, sunaudio
* device.description
* device.bus_path
* device.serial
* device.vendor_product_id
- * device.class sound, modem, monitor, filter, abstract
- * device.form_factor laptop-speakers, external-speakers, telephone, tv-capture, webcam-capture, microphone-capture, headset
- * device.connector isa, pci, usb, firewire, bluetooth
- * device.access_mode mmap, mmap_rewrite, serial
+ * device.class sound, modem, monitor, filter, abstract
+ * device.form_factor laptop-speakers, external-speakers, telephone, tv-capture, webcam-capture, microphone-capture, headset
+ * device.connector isa, pci, usb, firewire, bluetooth
+ * device.access_mode mmap, mmap_rewrite, serial
* device.master_device
* device.bufferin.buffer_size
* device.bufferin.fragment_size
#define PA_PROP_MEDIA_ICON_NAME "media.icon_name"
#define PA_PROP_MEDIA_ROLE "media.role"
#define PA_PROP_EVENT_ID "event.id"
+#define PA_PROP_EVENT_DESCRIPTION "event.description"
#define PA_PROP_EVENT_MOUSE_X "event.mouse.x"
#define PA_PROP_EVENT_MOUSE_Y "event.mouse.y"
#define PA_PROP_EVENT_MOUSE_HPOS "event.mouse.hpos"
*
* \section thread_sec Threads
*
- * The PulseAudio client libraries are not designed to be used in a
- * heavily threaded environment. They are however designed to be reentrant
- * safe.
+ * The PulseAudio client libraries are not designed to be directly
+ * thread-safe. They are however designed to be reentrant and
+ * threads-aware.
*
- * To use a the libraries in a threaded environment, you must assure that
+ * To use the libraries in a threaded environment, you must assure that
* all objects are only used in one thread at a time. Normally, this means
* that all objects belonging to a single context must be accessed from the
* same thread.
*
* The included main loop implementation is also not thread safe. Take care
- * to make sure event lists are not manipulated when any other code is
+ * to make sure event objects are not manipulated when any other code is
* using the main loop.
*
* \section pkgconfig pkg-config
* \li PA_SAMPLE_S32LE - Signed 32 bit integer PCM, little endian.
* \li PA_SAMPLE_S32BE - Signed 32 bit integer PCM, big endian.
*
- * The floating point sample formats have the range from -1 to 1.
+ * The floating point sample formats have the range from -1.0 to 1.0.
*
* The sample formats that are sensitive to endianness have convenience
* macros for native endian (NE), and reverse endian (RE).
*
* \subsection bufattr_subsec Buffer Attributes
*
- * Playback and record streams always have a server side buffer as
- * part of the data flow. The size of this buffer strikes a
- * compromise between low latency and sensitivity for buffer
+ * Playback and record streams always have a server-side buffer as
+ * part of the data flow. The size of this buffer needs to be chosen
+ * in a compromise between low latency and sensitivity for buffer
* overflows/underruns.
*
* The buffer metrics may be controlled by the application. They are
* described with a pa_buffer_attr structure which contains a number
* of fields:
*
- * \li maxlength - The absolute maximum number of bytes that can be stored in
- * the buffer. If this value is exceeded then data will be
- * lost.
- * \li tlength - The target length of a playback buffer. The server will only
- * send requests for more data as long as the buffer has less
- * than this number of bytes of data.
+ * \li maxlength - The absolute maximum number of bytes that can be
+ * stored in the buffer. If this value is exceeded
+ * then data will be lost. It is recommended to pass
+ * (uint32_t) -1 here which will cause the server to
+ * fill in the maximum possible value.
+ *
+ * \li tlength - The target fill level of the playback buffer. The
+ * server will only send requests for more data as long
+ * as the buffer has less than this number of bytes of
+ * data. If you pass (uint32_t) -1 (which is
+ * recommended) here the server will choose the longest
+ * target buffer fill level possible to minimize the
+ * number of necessary wakeups and maximize drop-out
+ * safety. This can exceed 2s of buffering. For
+ * low-latency applications or applications where
+ * latency matters you should pass a proper value here.
+ *
* \li prebuf - Number of bytes that need to be in the buffer before
- * playback will commence. Start of playback can be forced using
- * pa_stream_trigger() even though the prebuffer size hasn't been
- * reached. If a buffer underrun occurs, this prebuffering will be
- * again enabled. If the playback shall never stop in case of a buffer
- * underrun, this value should be set to 0. In that case the read
- * index of the output buffer overtakes the write index, and hence the
- * fill level of the buffer is negative.
- * \li minreq - Minimum free number of the bytes in the playback buffer before
- * the server will request more data.
- * \li fragsize - Maximum number of bytes that the server will push in one
- * chunk for record streams.
- *
- * The server side playback buffers are indexed by a write and a read
+ * playback will commence. Start of playback can be
+ * forced using pa_stream_trigger() even though the
+ * prebuffer size hasn't been reached. If a buffer
+ * underrun occurs, this prebuffering will be again
+ * enabled. If the playback shall never stop in case of a
+ * buffer underrun, this value should be set to 0. In
+ * that case the read index of the output buffer
+ * overtakes the write index, and hence the fill level of
+ * the buffer is negative. If you pass (uint32_t) -1 here
+ * (which is recommended) the server will choose the same
+ * value as tlength here.
+ *
+ * \li minreq - Minimum free number of the bytes in the playback
+ * buffer before the server will request more data. It is
+ * recommended to fill in (uint32_t) -1 here. This value
+ * influences how much time the sound server has to move
+ * data from the per-stream server-side playback buffer
+ * to the hardware playback buffer.
+ *
+ * \li fragsize - Maximum number of bytes that the server will push in
+ * one chunk for record streams. If you pass (uint32_t)
+ * -1 (which is recommended) here, the server will
+ * choose the longest fragment setting possible to
+ * minimize the number of necessary wakeups and
+ * maximize drop-out safety. This can exceed 2s of
+ * buffering. For low-latency applications or
+ * applications where latency matters you should pass a
+ * proper value here.
+ *
+ * If PA_STREAM_ADJUST_LATENCY is set, then the tlength/fragsize
+ * parameters will be interpreted slightly differently than described
+ * above when passed to pa_stream_connect_record() and
+ * pa_stream_connect_playback(): the overall latency that is comprised
+ * of both the server side playback buffer length, the hardware
+ * playback buffer length and additional latencies will be adjusted in
+ * a way that it matches tlength resp. fragsize. Set
+ * PA_STREAM_ADJUST_LATENCY if you want to control the overall
+ * playback latency for your stream. Unset it if you want to control
+ * only the latency induced by the server-side, rewritable playback
+ * buffer. The server will try to fulfill the clients latency requests
+ * as good as possible. However if the underlying hardware cannot
+ * change the hardware buffer length or only in a limited range, the
+ * actually resulting latency might be different from what the client
+ * requested. Thus, for synchronization clients always need to check
+ * the actual measured latency via pa_stream_get_latency() or a
+ * similar call, and not make any assumptions. about the latency
+ * available. The function pa_stream_get_buffer_attr() will always
+ * return the actual size of the server-side per-stream buffer in
+ * tlength/fragsize, regardless whether PA_STREAM_ADJUST_LATENCY is
+ * set or not.
+ *
+ * The server-side per-stream playback buffers are indexed by a write and a read
* index. The application writes to the write index and the sound
* device reads from the read index. The read index is increased
* monotonically, while the write index may be freely controlled by
* accordingly.
*
* The raw timing data in the pa_timing_info structure is usually hard
- * to deal with. Therefore a more simplistic interface is available:
+ * to deal with. Therefore a simpler interface is available:
* you can call pa_stream_get_time() or pa_stream_get_latency(). The
* former will return the current playback time of the hardware since
- * the stream has been started. The latter returns the time a sample
+ * the stream has been started. The latter returns the overall time a sample
* that you write now takes to be played by the hardware. These two
* functions base their calculations on the same data that is returned
* by pa_stream_get_timing_info(). Hence the same rules for keeping
/** Return a pointer to the stream's channel map. */
const pa_channel_map* pa_stream_get_channel_map(pa_stream *s);
-/** Return the buffer metrics of the stream. Only valid after the
- * stream has been connected successfuly and if the server is at least
- * PulseAudio 0.9. \since 0.9.0 */
+/** Return the per-stream server-side buffer metrics of the
+ * stream. Only valid after the stream has been connected successfuly
+ * and if the server is at least PulseAudio 0.9. This will return the
+ * actual configured buffering metrics, which may differ from what was
+ * requested during pa_stream_connect_record() or
+ * pa_stream_connect_playback(). This call will always return the
+ * actually per-stream server-side buffer metrics, regardless whether
+ * PA_STREAM_ADJUST_LATENCY is set or not. \since 0.9.0 */
const pa_buffer_attr* pa_stream_get_buffer_attr(pa_stream *s);
/** Change the buffer metrics of the stream during playback. The
* requested. The selected metrics may be queried with
* pa_stream_get_buffer_attr() as soon as the callback is called. Only
* valid after the stream has been connected successfully and if the
- * server is at least PulseAudio 0.9.8. \since 0.9.8 */
+ * server is at least PulseAudio 0.9.8. Please be aware of the
+ * slightly different semantics of the call depending whether
+ * PA_STREAM_ADJUST_LATENCY is set or not. \since 0.9.8 */
pa_operation *pa_stream_set_buffer_attr(pa_stream *s, const pa_buffer_attr *attr, pa_stream_success_cb_t cb, void *userdata);
/** Change the stream sampling rate during playback. You need to pass
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