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gstreamer/docs/gst/tmpl/gstpad.sgml
Thomas Vander Stichele d2af387684 review of gstbuffer documentation small doc fixes 
Original commit message from CVS:
* review of gstbuffer documentation
* small doc fixes
2002-04-17 12:28:32 +00:00

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<!-- ##### 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 GstPadGetRegionFunction ##### -->
<para>
The function that will be called when pulling a region buffer.
You can specify which buffer to get using an offset/length pair or
a start/stop timecode pair.
</para>
@pad: the pad to get a buffer from
@type: the type of region to get (time or offset based)
@offset: the offset of the region to get
@len: the length of the region to get
@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.
<!-- ##### ENUM GstRegionType ##### -->
<para>
the region types for #gst_pad_pullregion.
</para>
@GST_REGION_VOID:
@GST_REGION_OFFSET_LEN: an offet/length pair
@GST_REGION_TIME_LEN: a time start/length pair
<!-- ##### USER_FUNCTION GstPadPullRegionFunction ##### -->
<para>
The function that will be called when pulling a region buffer.
You can specify which buffer to get using an offset/length pair or
a start/stop timecode pair.
</para>
@pad: the pad to get a buffer from
@type: the type of region to get (time or offset based)
@offset: the offset of the region to get
@len: the length of the region to get
@Returns: a #GstBuffer
<!-- ##### 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>
</para>
@GST_PAD_CONNECT_REFUSED:
@GST_PAD_CONNECT_DELAYED:
@GST_PAD_CONNECT_OK:
@GST_PAD_CONNECT_DONE:
<!-- ##### 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:
<!-- ##### 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_getregion_function ##### -->
<para>
</para>
@pad:
@getregion:
<!-- ##### 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_sched ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_set_sched ##### -->
<para>
</para>
@pad:
@sched:
<!-- ##### FUNCTION gst_pad_unset_sched ##### -->
<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_pullregion ##### -->
<para>
</para>
@pad:
@type:
@offset:
@len:
@Returns:
<!-- # Unused Parameters # -->
@size:
<!-- ##### 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_send_event ##### -->
<para>
</para>
@pad:
@event:
@Returns:
<!-- ##### FUNCTION gst_pad_event_default ##### -->
<para>
</para>
@pad:
@event:
<!-- ##### FUNCTION gst_pad_set_event_function ##### -->
<para>
</para>
@pad:
@event:
<!-- ##### STRUCT GstRealPad ##### -->
<para>
</para>
@pad:
@caps:
@filter:
@appfilter:
@direction:
@sched:
@sched_private:
@peer:
@bufpen:
@regiontype:
@offset:
@len:
@chainfunc:
@chainhandler:
@getfunc:
@gethandler:
@eventfunc:
@eventhandler:
@getregionfunc:
@pullregionfunc:
@getcapsfunc:
@connectfunc:
@bufferpoolfunc:
@ghostpads:
<!-- ##### MACRO GST_RPAD_LEN ##### -->
<para>
Get the length of the region that is being pulled.
</para>
@pad: the real pad to query.
<!-- ##### MACRO GST_RPAD_OFFSET ##### -->
<para>
Get the offset of the region that is being pulled.
</para>
@pad: the real pad to query.
<!-- ##### MACRO GST_RPAD_SCHED ##### -->
<para>
Get the scheduler of this real pad.
</para>
@pad: the real pad to query.
<!-- ##### MACRO GST_RPAD_REGIONTYPE ##### -->
<para>
Get the type of the region that is being pulled.
</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_GETREGIONFUNC ##### -->
<para>
Get the getregion function of the real pad.
</para>
@pad: the real pad to query.
<!-- ##### MACRO GST_RPAD_PULLREGIONFUNC ##### -->
<para>
Get the pullregion function 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_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:
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