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Functions
RBPlayer * | rb_player_new () |
gboolean | rb_player_open () |
gboolean | rb_player_opened () |
gboolean | rb_player_close () |
gboolean | rb_player_play () |
void | rb_player_pause () |
gboolean | rb_player_playing () |
void | rb_player_set_volume () |
float | rb_player_get_volume () |
gboolean | rb_player_seekable () |
void | rb_player_set_time () |
gint64 | rb_player_get_time () |
gboolean | rb_player_multiple_open () |
Signals
void | buffering | Run Last |
void | eos | No Recursion |
void | error | No Recursion |
void | event | Has Details |
void | image | Run Last |
void | info | Run Last |
void | playing-stream | Run Last |
void | redirect | Run Last |
void | tick | Run Last |
void | volume-changed | Run Last |
Description
This is the interface implemented by the rhythmbox playback backends. It allows the caller to control playback (open, play, pause, close), seek (set_time), control volume (get_volume, set_volume) and receive playback state information (get_time, various signals).
The playback interface allows for multiple streams to be playing (or at least open) concurrently. The caller associates some data with each stream it opens (rb_player_open), which is included in the paramters with each signal emitted. The caller should not assume that the new stream is playing immediately upon returning from rb_player_play. Instead, it should use the 'playing-stream' signal to determine that.
The player implementation should emit signals for metadata extracted from the stream using the 'info' signal
While playing, the player implementation should emit 'tick' signals frequently enough to update an elapsed/remaining time display consistently. The duration value included in tick signal emissions is used to prepare the next stream before the current stream reaches EOS, so it should be updated for each emission to account for variable bitrate streams that produce inaccurate duration estimates early on.
When playing a stream from the network, the player can report buffering status using the 'buffering' signal. The value included in the signal indicates the percentage of the buffer that has been filled.
The 'event' signal can be used to communicate events from the player to the application. For GStreamer-based player implementations, events are triggered by elements in the pipeline posting application messages. The name of the message becomes the name of the event.
Functions
rb_player_new ()
RBPlayer * rb_player_new (gboolean want_crossfade
,GError **error
);
Creates a new player object.
rb_player_open ()
gboolean rb_player_open (RBPlayer *player
,const char *uri
,gpointer stream_data
,GDestroyNotify stream_data_destroy
,GError **error
);
Prepares a stream for playback. Depending on the player implementation, this may stop any existing stream being played. The stream preparation process may continue asynchronously, in which case errors may be reported from rb_player_play or using the 'error' signal.
Parameters
player |
a RBPlayer |
|
uri |
URI to open |
|
stream_data |
arbitrary data to associate with the stream |
|
stream_data_destroy |
function to call to destroy the stream data |
|
error |
returns error information |
rb_player_opened ()
gboolean
rb_player_opened (RBPlayer *player
);
Determines whether a stream has been prepared for playback.
rb_player_close ()
gboolean rb_player_close (RBPlayer *player
,const char *uri
,GError **error
);
If a URI is specified, this will close the stream corresponding
to that URI and free any resources related resources. If uri
is NULL, this will close all streams.
If no streams remain open after this call, the audio device will be released.
Parameters
player |
a RBPlayer |
|
uri |
optionally, the URI of the stream to close |
|
error |
returns error information |
rb_player_play ()
gboolean rb_player_play (RBPlayer *player
,RBPlayerPlayType play_type
,gint64 crossfade
,GError **error
);
Starts playback of the most recently opened stream.
if play_type
is RB_PLAYER_PLAY_CROSSFADE, the player
may attempt to crossfade the new stream with any existing
streams. If it does this, the it will use crossfade
as the
duration of the fade.
If play_type
is RB_PLAYER_PLAY_AFTER_EOS, the player may
attempt to start the stream immediately after the current
playing stream reaches EOS. This may or may not result in
the phenomemon known as 'gapless playback'.
If play_type
is RB_PLAYER_PLAY_REPLACE, the player will stop any
existing stream before starting the new stream. It may do
this anyway, regardless of the value of play_type
.
The 'playing-stream' signal will be emitted when the new stream is actually playing. This may be before or after control returns to the caller.
Parameters
player |
a RBPlayer |
|
play_type |
requested playback start type |
|
crossfade |
requested crossfade duration (nanoseconds) |
|
error |
returns error information |
rb_player_pause ()
void
rb_player_pause (RBPlayer *player
);
Pauses playback of the most recently started stream. Any streams being faded out may continue until the fade is complete.
rb_player_playing ()
gboolean
rb_player_playing (RBPlayer *player
);
Determines whether the player is currently playing a stream. A stream is playing if it's not paused or being faded out.
rb_player_set_volume ()
void rb_player_set_volume (RBPlayer *player
,float volume
);
Adjusts the output volume level. This affects all streams. The player may use a hardware volume control to implement this volume adjustment.
rb_player_get_volume ()
float
rb_player_get_volume (RBPlayer *player
);
Returns the current volume level, between 0.0 and 1.0.
rb_player_seekable ()
gboolean
rb_player_seekable (RBPlayer *player
);
Determines whether seeking is supported for the current stream.
rb_player_set_time ()
void rb_player_set_time (RBPlayer *player
,gint64 newtime
);
Attempts to seek in the current stream. The player may ignore this if the stream is not seekable. The seek may take place asynchronously.
rb_player_get_time ()
gint64
rb_player_get_time (RBPlayer *player
);
Returns the current playback for the current stream in nanoseconds.
Types and Values
struct RBPlayerIface
struct RBPlayerIface { GTypeInterface g_iface; /* virtual functions */ gboolean (*open) (RBPlayer *player, const char *uri, gpointer stream_data, GDestroyNotify stream_data_destroy, GError **error); gboolean (*opened) (RBPlayer *player); gboolean (*close) (RBPlayer *player, const char *uri, GError **error); gboolean (*play) (RBPlayer *player, RBPlayerPlayType play_type, gint64 crossfade, GError **error); void (*pause) (RBPlayer *player); gboolean (*playing) (RBPlayer *player); void (*set_volume) (RBPlayer *player, float volume); float (*get_volume) (RBPlayer *player); gboolean (*seekable) (RBPlayer *player); void (*set_time) (RBPlayer *player, gint64 newtime); gint64 (*get_time) (RBPlayer *player); gboolean (*multiple_open) (RBPlayer *player); /* signals */ void (*playing_stream) (RBPlayer *player, gpointer stream_data); void (*eos) (RBPlayer *player, gpointer stream_data, gboolean early); void (*info) (RBPlayer *player, gpointer stream_data, RBMetaDataField field, GValue *value); void (*buffering) (RBPlayer *player, gpointer stream_data, guint progress); void (*error) (RBPlayer *player, gpointer stream_data, GError *error); void (*tick) (RBPlayer *player, gpointer stream_data, gint64 elapsed, gint64 duration); void (*event) (RBPlayer *player, gpointer stream_data, gpointer data); void (*volume_changed) (RBPlayer *player, float volume); void (*image) (RBPlayer *player, gpointer stream_data, GdkPixbuf *image); void (*redirect) (RBPlayer *player, gpointer stream_data, const gchar *uri); };
Signal Details
The “buffering”
signal
void user_function (RBPlayer *player, gpointer stream_data, guint progress, gpointer user_data)
The 'buffering' signal is emitted while a stream is paused so that a buffer can be filled. The progress value typically varies from 0 to 100, and once it reaches 100, playback resumes.
Parameters
player |
the RBPlayer |
|
stream_data |
the data associated with the buffering stream |
|
progress |
buffering percentage |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run Last
The “eos”
signal
void user_function (RBPlayer *player, gpointer stream_data, gboolean early, gpointer user_data)
The 'eos' signal is emitted when a stream finishes, or in some cases, when it
is about to finish (with early
set to TRUE
) to allow for a new track to be
played immediately afterwards.
Flags: No Recursion
The “error”
signal
void user_function (RBPlayer *player, gpointer stream_data, gpointer error, gpointer user_data)
The 'error' signal is emitted when an error is encountered while opening or playing a stream.
Parameters
player |
the RBPlayer |
|
stream_data |
the data associated with the stream |
|
error |
description of the error |
|
user_data |
user data set when the signal handler was connected. |
Flags: No Recursion
The “event”
signal
void user_function (RBPlayer *player, gpointer stream_data, gpointer data, gpointer user_data)
The 'event' signal provides a means for custom GStreamer elements to communicate events back to the rest of the application. The GStreamer element posts an application message on the GStreamer bus, which is translated into an event signal with the detail of the signal set to the name of the structure found in the message.
Parameters
player |
the RBPlayer |
|
stream_data |
data associated with the stream |
|
data |
event data |
|
user_data |
user data set when the signal handler was connected. |
Flags: Has Details
The “image”
signal
void user_function (RBPlayer *player, gpointer stream_data, GdkPixbuf *image, gpointer user_data)
The 'image' signal is emitted to provide access to images extracted from the stream.
Parameters
player |
the RBPlayer |
|
stream_data |
data associated with the stream |
|
image |
the image extracted from the stream |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run Last
The “info”
signal
void user_function (RBPlayer *player, gpointer stream_data, gint field, GValue *value, gpointer user_data)
The 'info' signal is emitted when a metadata value is found in the stream.
Parameters
player |
the RBPlayer |
|
stream_data |
the data associated with the stream |
|
field |
the RBMetaDataField corresponding to the stream info |
|
value |
the value of the stream info field |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run Last
The “playing-stream”
signal
void user_function (RBPlayer *player, gpointer stream_data, gpointer user_data)
The 'playing-stream' signal is emitted when the main playing stream changes. It should be used to update the UI to show the new stream. It can either be emitted before or after rb_player_play returns, depending on the player backend.
Parameters
player |
the RBPlayer |
|
stream_data |
data associated with the stream |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run Last
The “redirect”
signal
void user_function (RBPlayer *player, gpointer stream_data, gchar *uri, gpointer user_data)
The 'redirect' signal is emitted to indicate when a stream has change URI.
Parameters
player |
the RBPlayer |
|
stream_data |
data associated with the stream |
|
uri |
URI to redirect to |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run Last
The “tick”
signal
void user_function (RBPlayer *player, gpointer stream_data, gint64 elapsed, gint64 duration, gpointer user_data)
The 'tick' signal is emitted repeatedly while the stream is playing. Signal handlers can use this to update UI and to prepare new streams for crossfade or gapless playback.
Parameters
player |
the RBPlayer |
|
stream_data |
the data associated with the stream |
|
elapsed |
playback position in the stream (in nanoseconds) |
|
duration |
current estimate of the duration of the stream (in nanoseconds) |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run Last
The “volume-changed”
signal
void user_function (RBPlayer *player, gfloat volume, gpointer user_data)
The 'volume-changed' signal is emitted when the output stream volume is changed externally.
Parameters
player |
the RBPlayer |
|
volume |
the new volume level |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run Last