gstreamer/docs/gst/tmpl/gstpad.sgml

<!-- ##### SECTION Title ##### -->
GstPad

<!-- ##### SECTION Short_Description ##### -->
The connection between Elements

<!-- ##### SECTION Long_Description ##### -->
<para>
#GstElement are connected to each other via "pads", which are extremely light-weight generic 
connections. After two pad are retrieved from an element with gst_element_get_pad(), the pads
can be connected with gst_pad_connect().
</para>
<para>
Pads are typically created from a #GstPadTemplate with gst_pad_new_from_template().
</para>
<para>
Pad have #GstCaps attached to it to describe the media type they
are capable of dealing with. gst_pad_get_caps() and gst_pad_set_caps() are used to
manipulate the caps of the pads. 
Pads created from a padtemplate cannot set capabilities that are incompatible with
the padtemplates capabilities.
</para>
<para>
Pads without padtemplates can be created with gst_pad_new() which takes a direction and
a name as an argument.
</para>
<para>
gst_pad_get_parent() will retrieve the #GstElement that owns the pad.
</para>
<para>
GstElements creating a pad will typicilally use the various gst_pad_set_*_function() calls
to register callbacks for various events on the pads.
</para>
<para>
GstElements will use gst_pad_push() and gst_pad_pull() to push out or pull a buffer in. The
gst_pad_pullregion() function can be used to request for a buffer with a specific offset (in
time or in bytes). gst_pad_select() and gst_pad_selectv() are use by plugins to wait on a set
of pads for a new #GstBuffer or #GstEvent.
</para>
<para>
To send an event on a pad, use gst_pad_send_event().
</para>

<!-- ##### SECTION See_Also ##### -->
<para>
#GstPadTemplate, #GstElement, #GstEvent
</para>

<!-- ##### MACRO GST_PAD_NAME ##### -->
<para>
Get the name of the pad.
</para>

@pad: the pad to query


<!-- ##### MACRO GST_PAD_ELEMENT_PRIVATE ##### -->
<para>
Get the private data set by the element that owns the pad.
</para>

@pad: the pad to query


<!-- ##### MACRO GST_PAD_PARENT ##### -->
<para>
Get the parent element of this pad.
</para>

@pad: the pad to query


<!-- ##### MACRO GST_PAD_PAD_TEMPLATE ##### -->
<para>
Get the padtemplate that was used to create this pad. NULL if no padtemplate
was used.
</para>

@pad: the pad to query


<!-- ##### MACRO GST_PAD_REALIZE ##### -->
<para>
Return the real pad of this pad.
</para>

@pad: the pad to query


<!-- ##### MACRO GST_PAD_DIRECTION ##### -->
<para>
Get the pad direction.
</para>

@pad: the pad to query


<!-- ##### MACRO GST_PAD_CAPS ##### -->
<para>
Get the capabilities of a pad.
</para>

@pad: the pad to query


<!-- ##### MACRO GST_PAD_PEER ##### -->
<para>
Get the peerpad of this pad.
</para>

@pad: the pad to query


<!-- ##### MACRO GST_PAD_CAN_PULL ##### -->
<para>
Can this pad be used to pull a buffer.
</para>

@pad: the pad to check


<!-- ##### MACRO GST_PAD_IS_SINK ##### -->
<para>
Check if the pad is a sinkpad.
</para>

@pad: the pad to query


<!-- ##### MACRO GST_PAD_IS_SRC ##### -->
<para>
Check if the pad is a srcpad.
</para>

@pad: the pad to query


<!-- ##### MACRO GST_PAD_IS_CONNECTED ##### -->
<para>
Checks if the pad is connected
</para>

@pad: the pad to query


<!-- ##### STRUCT GstPad ##### -->
<para>

</para>


<!-- ##### USER_FUNCTION GstPadChainFunction ##### -->
<para>
The function that will be called when chaining buffers.
</para>

@pad: the pad that performed the chain
@buf: the buffer that is chained


<!-- ##### USER_FUNCTION GstPadGetFunction ##### -->
<para>
The function that will be called when pulling a buffer.
</para>

@pad: the pad to get a buffer from
@Returns: a #GstBuffer


<!-- ##### USER_FUNCTION GstPadBufferPoolFunction ##### -->
<para>
The function that will be called when a bufferpool is requested
from this pad.
</para>

@pad: the pad with the bufferpool
@Returns: the GstBufferPool associated with this pad.


<!-- ##### USER_FUNCTION GstPadGetCapsFunction ##### -->
<para>
Return the caps of the specified pad. By default this function
will return the pad template caps but can optionally be overridden.
</para>

@pad: The pad to get the caps of
@caps: The peer caps, can be used to filter the caps.
@Returns: The caps of the pad.


<!-- ##### USER_FUNCTION GstPadEventFunction ##### -->
<para>
Function signature to handle an event for the pad.
</para>

@pad: The pad to handle the event
@event: The event to handle
@Returns: TRUE if the pad could handle the event.


<!-- ##### USER_FUNCTION GstPadConnectFunction ##### -->
<para>
Function signature to handle a new connection on the pad.
</para>

@pad: The pad that is connected.
@caps: The peer caps.
@Returns: the result of the connection with the specified caps.


<!-- ##### ENUM GstPadConnectReturn ##### -->
<para>
The result of a pad connection.
</para>

@GST_PAD_CONNECT_REFUSED: The connectino was refused
@GST_PAD_CONNECT_DELAYED: The connection was delayed, probably because the
                          element needs more specific pad caps.
@GST_PAD_CONNECT_OK: The connection succeeded.
@GST_PAD_CONNECT_DONE: The connection succeeded, any more attempts are not needed.

<!-- ##### USER_FUNCTION GstPadConvertFunction ##### -->
<para>
The signature of a convert function. 
</para>

@pad: The pad to perform the convert on
@src_format: The source format of the conversion
@src_value: The source value of the conversion
@dest_format: a pointer to the destination format
@dest_value: a pointer to the destination value
@Returns: TRUE if the conversion could be performed.


<!-- ##### USER_FUNCTION GstPadDispatcherFunction ##### -->
<para>
The dispatcher function is called for all internally connected pads, see 
gst_pad_dispatcher().
</para>

@pad: The pad that is dispatched
@data: User data
@Returns: TRUE if the dispatching procedure has to be stopped.


<!-- ##### USER_FUNCTION GstPadIntConnFunction ##### -->
<para>
The signature of the internal pad connection function
</para>

@pad: The pad to query
@Returns: a Glist of pads that connect to the requested pad internally to the
          parent element. g_list_free() after use.


<!-- ##### ENUM GstPadQueryType ##### -->
<para>
The different supported query types
</para>

@GST_PAD_QUERY_TOTAL: Query the total stream time
@GST_PAD_QUERY_POSITION: Query the current stream position
@GST_PAD_QUERY_LATENCY: Query the latency on the pad
@GST_PAD_QUERY_JITTER: Query the average jitter beteen optimal processing and current
                       processing.
@GST_PAD_QUERY_SEGMENT_END: Query the end position of the currently executing segment

<!-- ##### USER_FUNCTION GstPadQueryFunction ##### -->
<para>
The signature of query function
</para>

@pad: The pad to query
@type: The query type
@format: a pointer to the target format
@value: a pointer to the target value
@Returns: TRUE if the query could be performed


<!-- ##### ENUM GstPadDirection ##### -->
<para>
The direction this pad is.
</para>

@GST_PAD_UNKNOWN: direction is unknown
@GST_PAD_SRC: this is a source pad
@GST_PAD_SINK: this is a sink pad

<!-- ##### ENUM GstPadFlags ##### -->
<para>
Flags for the pad.
</para>

@GST_PAD_DISABLED: the pad is disabled
@GST_PAD_EOS: the pad is in end of stream state
@GST_PAD_FLAG_LAST: subclasses can use this number to enumerate their flags

<!-- ##### FUNCTION gst_pad_new ##### -->
<para>

</para>

@name: 
@direction: 
@Returns: 


<!-- ##### FUNCTION gst_pad_custom_new ##### -->
<para>

</para>

@type: 
@name: 
@direction: 
@Returns: 


<!-- ##### FUNCTION gst_pad_custom_new_from_template ##### -->
<para>

</para>

@type: 
@templ: 
@name: 
@Returns: 


<!-- ##### MACRO gst_pad_destroy ##### -->
<para>
Destroy the pad.
</para>

@pad: the pad to destroy


<!-- ##### FUNCTION gst_pad_new_from_template ##### -->
<para>

</para>

@templ: 
@name: 
@Returns: 
<!-- # Unused Parameters # -->
@temp: 


<!-- ##### FUNCTION gst_pad_get_direction ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_set_chain_function ##### -->
<para>

</para>

@pad: 
@chain: 


<!-- ##### FUNCTION gst_pad_set_get_function ##### -->
<para>

</para>

@pad: 
@get: 


<!-- ##### FUNCTION gst_pad_set_bufferpool_function ##### -->
<para>

</para>

@pad: 
@bufpool: 


<!-- ##### FUNCTION gst_pad_set_connect_function ##### -->
<para>

</para>

@pad: 
@connect: 


<!-- ##### FUNCTION gst_pad_set_getcaps_function ##### -->
<para>

</para>

@pad: 
@getcaps: 


<!-- ##### FUNCTION gst_pad_try_set_caps ##### -->
<para>

</para>

@pad: 
@caps: 
@Returns: 


<!-- ##### FUNCTION gst_pad_get_caps ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_check_compatibility ##### -->
<para>

</para>

@srcpad: 
@sinkpad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_set_name ##### -->
<para>

</para>

@pad: 
@name: 


<!-- ##### FUNCTION gst_pad_get_name ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_set_element_private ##### -->
<para>

</para>

@pad: 
@priv: 


<!-- ##### FUNCTION gst_pad_get_element_private ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_set_parent ##### -->
<para>

</para>

@pad: 
@parent: 


<!-- ##### FUNCTION gst_pad_get_parent ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_get_scheduler ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_set_scheduler ##### -->
<para>

</para>

@pad: 
@sched: 


<!-- ##### FUNCTION gst_pad_unset_scheduler ##### -->
<para>

</para>

@pad: 


<!-- ##### FUNCTION gst_pad_get_real_parent ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_add_ghost_pad ##### -->
<para>

</para>

@pad: 
@ghostpad: 


<!-- ##### FUNCTION gst_pad_remove_ghost_pad ##### -->
<para>

</para>

@pad: 
@ghostpad: 


<!-- ##### FUNCTION gst_pad_get_ghost_pad_list ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_get_peer ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_connect ##### -->
<para>

</para>

@srcpad: 
@sinkpad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_connect_filtered ##### -->
<para>

</para>

@srcpad: 
@sinkpad: 
@filtercaps: 
@Returns: 


<!-- ##### FUNCTION gst_pad_reconnect_filtered ##### -->
<para>

</para>

@srcpad: 
@sinkpad: 
@filtercaps: 
@Returns: 
<!-- # Unused Parameters # -->
@pad: 


<!-- ##### FUNCTION gst_pad_try_reconnect_filtered ##### -->
<para>

</para>

@srcpad: 
@sinkpad: 
@filtercaps: 
@Returns: 
<!-- # Unused Parameters # -->
@pad: 


<!-- ##### FUNCTION gst_pad_disconnect ##### -->
<para>

</para>

@srcpad: 
@sinkpad: 


<!-- ##### FUNCTION gst_pad_can_connect ##### -->
<para>

</para>

@srcpad: 
@sinkpad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_can_connect_filtered ##### -->
<para>

</para>

@srcpad: 
@sinkpad: 
@filtercaps: 
@Returns: 


<!-- ##### FUNCTION gst_pad_push ##### -->
<para>

</para>

@pad: 
@buf: 
<!-- # Unused Parameters # -->
@buffer: 


<!-- ##### FUNCTION gst_pad_pull ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_get_bufferpool ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_load_and_connect ##### -->
<para>

</para>

@self: 
@parent: 
<!-- # Unused Parameters # -->
@element: 
@elements: 


<!-- ##### FUNCTION gst_pad_proxy_connect ##### -->
<para>

</para>

@pad: 
@caps: 
@Returns: 


<!-- ##### FUNCTION gst_pad_get_pad_template ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_get_pad_template_caps ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_get_allowed_caps ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_recalc_allowed_caps ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_perform_negotiate ##### -->
<para>

</para>

@srcpad: 
@sinkpad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_ghost_save_thyself ##### -->
<para>

</para>

@pad: 
@bin: 
@parent: 
@Returns: 


<!-- ##### FUNCTION gst_pad_peek ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_select ##### -->
<para>

</para>

@padlist: 
@Returns: 


<!-- ##### FUNCTION gst_pad_selectv ##### -->
<para>

</para>

@pad: 
@Varargs: 
@Returns: 


<!-- ##### FUNCTION gst_pad_dispatcher ##### -->
<para>

</para>

@pad: 
@dispatch: 
@data: 
@Returns: 


<!-- ##### FUNCTION gst_pad_send_event ##### -->
<para>

</para>

@pad: 
@event: 
@Returns: 


<!-- ##### FUNCTION gst_pad_event_default ##### -->
<para>

</para>

@pad: 
@event: 
@Returns: 


<!-- ##### FUNCTION gst_pad_set_event_function ##### -->
<para>

</para>

@pad: 
@event: 


<!-- ##### FUNCTION gst_pad_set_convert_function ##### -->
<para>

</para>

@pad: 
@convert: 


<!-- ##### FUNCTION gst_pad_convert ##### -->
<para>

</para>

@pad: 
@src_format: 
@src_value: 
@dest_format: 
@dest_value: 
@Returns: 


<!-- ##### FUNCTION gst_pad_convert_default ##### -->
<para>

</para>

@pad: 
@src_format: 
@src_value: 
@dest_format: 
@dest_value: 
@Returns: 


<!-- ##### FUNCTION gst_pad_get_internal_connections ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_get_internal_connections_default ##### -->
<para>

</para>

@pad: 
@Returns: 


<!-- ##### FUNCTION gst_pad_set_internal_connection_function ##### -->
<para>

</para>

@pad: 
@intconn: 


<!-- ##### FUNCTION gst_pad_set_query_function ##### -->
<para>

</para>

@pad: 
@query: 


<!-- ##### FUNCTION gst_pad_query ##### -->
<para>

</para>

@pad: 
@type: 
@format: 
@value: 
@Returns: 


<!-- ##### FUNCTION gst_pad_query_default ##### -->
<para>

</para>

@pad: 
@type: 
@format: 
@value: 
@Returns: 


<!-- ##### STRUCT GstRealPad ##### -->
<para>

</para>

@pad: 
@caps: 
@filter: 
@appfilter: 
@direction: 
@sched: 
@sched_private: 
@peer: 
@bufpen: 
@chainfunc: 
@chainhandler: 
@getfunc: 
@gethandler: 
@eventfunc: 
@eventhandler: 
@convertfunc: 
@queryfunc: 
@intconnfunc: 
@getcapsfunc: 
@connectfunc: 
@bufferpoolfunc: 
@ghostpads: 

<!-- ##### MACRO GST_RPAD_SCHED ##### -->
<para>
Get the scheduler of this real pad.
</para>

@pad: the real pad to query.


<!-- ##### MACRO GST_RPAD_DIRECTION ##### -->
<para>
Get the direction of the real pad.
</para>

@pad: the realpad to query.


<!-- ##### MACRO GST_RPAD_CAPS ##### -->
<para>
Get the caps of the real pad.
</para>

@pad: the real pad to query.


<!-- ##### MACRO GST_RPAD_PEER ##### -->
<para>
Get the peer element of the real pad.
</para>

@pad: the real pad to query.


<!-- ##### MACRO GST_RPAD_BUFPEN ##### -->
<para>
Get the bufpen of the real pad.
</para>

@pad: the real pad to query.


<!-- ##### MACRO GST_RPAD_CHAINFUNC ##### -->
<para>
Get the chain function of the real pad.
</para>

@pad: the real pad to query.


<!-- ##### MACRO GST_RPAD_FILTER ##### -->
<para>
Get the filter from the pad
</para>

@pad: the pad to query


<!-- ##### MACRO GST_RPAD_APPFILTER ##### -->
<para>
Get the application filter for this pad
</para>

@pad: the pad to query


<!-- ##### MACRO GST_RPAD_GETFUNC ##### -->
<para>
Get get getfunction of the real pad.
</para>

@pad: the real pad to query.


<!-- ##### MACRO GST_RPAD_BUFFERPOOLFUNC ##### -->
<para>
Get the bufferpoolfunction from the real pad.
</para>

@pad: the real pad to query.


<!-- ##### MACRO GST_RPAD_CHAINHANDLER ##### -->
<para>
Get the eventhandler function from the real pad.
</para>

@pad: the real pad to query.


<!-- ##### MACRO GST_RPAD_EVENTFUNC ##### -->
<para>
Get the event function of this real pad.
</para>

@pad: the real pad to query.


<!-- ##### MACRO GST_RPAD_EVENTHANDLER ##### -->
<para>
Get the eventhandler function of this real pad.
</para>

@pad: the real pad to query.


<!-- ##### MACRO GST_RPAD_GETHANDLER ##### -->
<para>
Get the gethandler function of this real pad.
</para>

@pad: the real pad to query.


<!-- ##### MACRO GST_RPAD_CONNECTFUNC ##### -->
<para>
Get the connect function of the pad
</para>

@pad: the pad to query


<!-- ##### MACRO GST_RPAD_GETCAPSFUNC ##### -->
<para>
Get the getcaps function of this pad
</para>

@pad: the pad to query


<!-- ##### MACRO GST_RPAD_CONVERTFUNC ##### -->
<para>
Get the convert function of this pad
</para>

@pad: the pad to query


<!-- ##### MACRO GST_RPAD_INTCONNFUNC ##### -->
<para>
Get the internal connection function of this pad
</para>

@pad: the pad to query


<!-- ##### MACRO GST_RPAD_QUERYFUNC ##### -->
<para>
Get the query function of this pad
</para>

@pad: the pad to query


<!-- ##### MACRO GST_GPAD_REALPAD ##### -->
<para>
Get the real pad of this ghost pad.
</para>

@pad: the real pad to query.


<!-- ##### STRUCT GstGhostPad ##### -->
<para>

</para>


<!-- ##### FUNCTION gst_ghost_pad_new ##### -->
<para>

</para>

@name: 
@pad: 
@Returns: