gstreamer/docs/gst/tmpl/gstpad.sgml
Thomas Vander Stichele 8ce827c406 move check stuff to its own library to be used by other modules
Original commit message from CVS:
move check stuff to its own library to be used by other modules
2005-08-20 12:14:28 +00:00

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16 KiB
Text

<!-- ##### SECTION Title ##### -->
GstPad
<!-- ##### SECTION Short_Description ##### -->
Object contained by elements that allows links to other elements
<!-- ##### SECTION Long_Description ##### -->
<para>
A #GstElement is linked to other elements via "pads", which are extremely
light-weight generic link points.
After two pads are retrieved from an element with gst_element_get_pad(),
the pads can be link with gst_pad_link(). (For quick links,
you can also use gst_element_link(), which will make the obvious
link for you if it's straightforward.)
</para>
<para>
Pads are typically created from a #GstPadTemplate with
gst_pad_new_from_template().
</para>
<para>
Pads have #GstCaps attached to it to describe the media type they
are capable of dealing with.
gst_pad_get_caps() and gst_pad_try_set_caps() are used to
manipulate the caps of the pads.
Pads created from a pad template cannot set capabilities that are
incompatible with the pad template capabilities.
</para>
<para>
Pads without pad templates can be created with gst_pad_new(),
which takes a direction and a name as an argument. If the name is NULL,
then a guaranteed unique name will be assigned to it.
</para>
<para>
gst_pad_get_parent() will retrieve the #GstElement that owns the pad.
</para>
<para>
A #GstElement creating a pad will typically 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 in a buffer.
gst_pad_select() and gst_pad_selectv() are used by plugins to wait for the
first incoming buffer or event on any of the given set of pads.
</para>
<para>
To send a #GstEvent on a pad, use gst_pad_send_event().
</para>
<para>
Last reviewed on December 13th, 2002 (0.5.0.1)
</para>
<!-- ##### SECTION See_Also ##### -->
<para>
#GstPadTemplate, #GstElement, #GstEvent
</para>
<!-- ##### SECTION Stability_Level ##### -->
<!-- ##### STRUCT GstPad ##### -->
<para>
</para>
@stream_rec_lock:
@task:
@preroll_lock:
@preroll_cond:
@block_cond:
@block_callback:
@block_data:
@caps:
@getcapsfunc:
@setcapsfunc:
@acceptcapsfunc:
@fixatecapsfunc:
@activatefunc:
@activatepushfunc:
@activatepullfunc:
@linkfunc:
@unlinkfunc:
@peer:
@sched_private:
@chainfunc:
@checkgetrangefunc:
@getrangefunc:
@eventfunc:
@mode:
@querytypefunc:
@queryfunc:
@intlinkfunc:
@bufferallocfunc:
@do_buffer_signals:
@do_event_signals:
<!-- ##### SIGNAL GstPad::have-data ##### -->
<para>
</para>
@gstpad: the object which received the signal.
@arg1:
@Returns:
<!-- ##### SIGNAL GstPad::linked ##### -->
<para>
</para>
@gstpad: the object which received the signal.
@arg1:
<!-- ##### SIGNAL GstPad::request-link ##### -->
<para>
</para>
@gstpad: the object which received the signal.
<!-- ##### SIGNAL GstPad::unlinked ##### -->
<para>
</para>
@gstpad: the object which received the signal.
@arg1:
<!-- ##### ARG GstPad:caps ##### -->
<para>
</para>
<!-- ##### ARG GstPad:direction ##### -->
<para>
</para>
<!-- ##### ARG GstPad:template ##### -->
<para>
</para>
<!-- ##### MACRO GST_PAD_LINK_FAILED ##### -->
<para>
Macro to test if the given #GstPadLinkReturn value indicates a
failed negotiation step (REFUSED/DELAYED).
</para>
@ret: the #GstPadLinkReturn value
<!-- ##### MACRO GST_PAD_LINK_SUCCESSFUL ##### -->
<para>
Macro to test if the given #GstPadLinkReturn value indicates a
successfull negotiation step (OK/DONE).
</para>
@ret: the #GstPadLinkReturn value
<!-- ##### USER_FUNCTION GstPadActivateFunction ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### USER_FUNCTION GstPadActivateModeFunction ##### -->
<para>
</para>
@pad:
@active:
@Returns:
<!-- ##### USER_FUNCTION GstPadBlockCallback ##### -->
<para>
</para>
@pad:
@blocked:
@user_data:
<!-- ##### USER_FUNCTION GstPadChainFunction ##### -->
<para>
A function that will be called when chaining buffers.
</para>
@pad: the #GstPad that performed the chain.
@buffer:
@Returns:
<!-- # Unused Parameters # -->
@data:
@buf: the #GstBuffer that is chained.
<!-- ##### USER_FUNCTION GstPadEventFunction ##### -->
<para>
Function signature to handle an event for the pad.
</para>
@pad: the #GstPad to handle the event.
@event: the #GstEvent to handle.
@Returns: TRUE if the pad could handle the event.
<!-- ##### USER_FUNCTION GstPadCheckGetRangeFunction ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### USER_FUNCTION GstPadGetRangeFunction ##### -->
<para>
</para>
@pad:
@offset:
@length:
@buffer:
@Returns:
<!-- ##### USER_FUNCTION GstPadQueryFunction ##### -->
<para>
The signature of the query function.
</para>
@pad: the #GstPad to query.
@query:
@Returns: TRUE if the query could be performed.
<!-- # Unused Parameters # -->
@type: the #GstPadQueryType.
@format: a pointer to the target #GstFormat.
@value: a pointer to the target value.
<!-- ##### USER_FUNCTION GstPadIntLinkFunction ##### -->
<para>
The signature of the internal pad link function.
</para>
@pad: The #GstPad to query.
@Returns: a newly allocated #GList of pads that are linked to
the given pad on the inside of the parent element.
The caller must call g_list_free() on it after use.
<!-- ##### USER_FUNCTION GstPadQueryTypeFunction ##### -->
<para>
The signature of the query types function.
</para>
@pad: a #GstPad to query
@Returns: an array of query types
<!-- ##### USER_FUNCTION GstPadLinkFunction ##### -->
<para>
Function signature to handle a new link on the pad.
</para>
@pad: the #GstPad that is linked.
@peer:
@Returns: the result of the link with the specified caps.
<!-- # Unused Parameters # -->
@caps: the peer's #GstCaps.
<!-- ##### USER_FUNCTION GstPadUnlinkFunction ##### -->
<para>
</para>
@pad:
<!-- ##### USER_FUNCTION GstPadAcceptCapsFunction ##### -->
<para>
</para>
@pad:
@caps:
@Returns:
<!-- ##### USER_FUNCTION GstPadFixateCapsFunction ##### -->
<para>
</para>
@pad:
@caps:
<!-- ##### USER_FUNCTION GstPadGetCapsFunction ##### -->
<para>
Returns a copy of the capabilities of the specified pad. By default this
function will return the pad template capabilities, but can optionally
be overridden.
</para>
@pad: the #GstPad to get the capabilities of.
@Returns: a newly allocated copy #GstCaps of the pad.
<!-- # Unused Parameters # -->
@caps: the peer's #GstCaps, can be used to filter the capabilities.
<!-- ##### USER_FUNCTION GstPadSetCapsFunction ##### -->
<para>
</para>
@pad:
@caps:
@Returns:
<!-- ##### USER_FUNCTION GstPadBufferAllocFunction ##### -->
<para>
</para>
@pad:
@offset:
@size:
@caps:
@buf:
@Returns:
<!-- ##### USER_FUNCTION GstPadDispatcherFunction ##### -->
<para>
A dispatcher function is called for all internally linked pads, see
gst_pad_dispatcher().
</para>
@pad: the #GstPad that is dispatched.
@data: the gpointer to optional user data.
@Returns: TRUE if the dispatching procedure has to be stopped.
<!-- ##### ENUM GstPadDirection ##### -->
<para>
The direction of a pad.
</para>
@GST_PAD_UNKNOWN: direction is unknown.
@GST_PAD_SRC: the pad is a source pad.
@GST_PAD_SINK: the pad is a sink pad.
<!-- ##### ENUM GstPadFlags ##### -->
<para>
</para>
@GST_PAD_BLOCKED:
@GST_PAD_FLUSHING:
@GST_PAD_IN_GETCAPS:
@GST_PAD_IN_SETCAPS:
@GST_PAD_FLAG_LAST:
<!-- ##### ENUM GstPadLinkReturn ##### -->
<para>
The result of a pad link.
</para>
@GST_PAD_LINK_OK: the link succeeded.
@GST_PAD_LINK_WRONG_HIERARCHY:
@GST_PAD_LINK_WAS_LINKED:
@GST_PAD_LINK_WRONG_DIRECTION:
@GST_PAD_LINK_NOFORMAT:
@GST_PAD_LINK_NOSCHED:
@GST_PAD_LINK_REFUSED: the link was refused.
<!-- ##### ENUM GstPadPresence ##### -->
<para>
Indicates when this pad will become available.
</para>
@GST_PAD_ALWAYS: the pad is always available
@GST_PAD_SOMETIMES: the pad will become available depending on the media stream
@GST_PAD_REQUEST: the pad is only available on request with
gst_element_request_pad_by_name() or gst_element_request_compatible_pad().
<!-- ##### FUNCTION gst_pad_new ##### -->
<para>
</para>
@name:
@direction:
@Returns:
<!-- ##### FUNCTION gst_pad_new_from_template ##### -->
<para>
</para>
@templ:
@name:
@Returns:
<!-- ##### MACRO gst_pad_get_name ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_get_direction ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### MACRO gst_pad_get_parent ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_get_parent_element ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_set_active ##### -->
<para>
</para>
@pad:
@active:
@Returns:
<!-- # Unused Parameters # -->
@mode:
<!-- ##### FUNCTION gst_pad_is_active ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_set_blocked ##### -->
<para>
</para>
@pad:
@blocked:
@Returns:
<!-- ##### FUNCTION gst_pad_set_blocked_async ##### -->
<para>
</para>
@pad:
@blocked:
@callback:
@user_data:
@Returns:
<!-- ##### FUNCTION gst_pad_is_blocked ##### -->
<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_get_pad_template ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_set_bufferalloc_function ##### -->
<para>
</para>
@pad:
@bufalloc:
<!-- # Unused Parameters # -->
@bufferalloc:
<!-- ##### FUNCTION gst_pad_alloc_buffer ##### -->
<para>
</para>
@pad:
@offset:
@size:
@caps:
@buf:
@Returns:
<!-- ##### FUNCTION gst_pad_set_chain_function ##### -->
<para>
</para>
@pad:
@chain:
<!-- ##### FUNCTION gst_pad_chain ##### -->
<para>
</para>
@pad:
@buffer:
@Returns:
<!-- ##### FUNCTION gst_pad_set_checkgetrange_function ##### -->
<para>
</para>
@pad:
@check:
<!-- ##### FUNCTION gst_pad_set_getrange_function ##### -->
<para>
</para>
@pad:
@get:
<!-- ##### FUNCTION gst_pad_get_range ##### -->
<para>
</para>
@pad:
@offset:
@size:
@buffer:
@Returns:
<!-- ##### FUNCTION gst_pad_set_event_function ##### -->
<para>
</para>
@pad:
@event:
<!-- ##### FUNCTION gst_pad_set_unlink_function ##### -->
<para>
</para>
@pad:
@unlink:
<!-- ##### FUNCTION gst_pad_set_activate_function ##### -->
<para>
</para>
@pad:
@activate:
<!-- ##### FUNCTION gst_pad_set_activatepull_function ##### -->
<para>
</para>
@pad:
@activatepull:
<!-- ##### FUNCTION gst_pad_start_task ##### -->
<para>
</para>
@pad:
@func:
@data:
@Returns:
<!-- ##### FUNCTION gst_pad_pause_task ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_stop_task ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_link ##### -->
<para>
</para>
@srcpad:
@sinkpad:
@Returns:
<!-- ##### FUNCTION gst_pad_unlink ##### -->
<para>
</para>
@srcpad:
@sinkpad:
@Returns:
<!-- ##### FUNCTION gst_pad_is_linked ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_set_link_function ##### -->
<para>
</para>
@pad:
@link:
<!-- ##### FUNCTION gst_pad_can_link ##### -->
<para>
</para>
@srcpad:
@sinkpad:
@Returns:
<!-- ##### FUNCTION gst_pad_accept_caps ##### -->
<para>
</para>
@pad:
@caps:
@Returns:
<!-- ##### FUNCTION gst_pad_get_negotiated_caps ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_get_caps ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_set_caps ##### -->
<para>
</para>
@pad:
@caps:
@Returns:
<!-- ##### FUNCTION gst_pad_get_pad_template_caps ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_set_acceptcaps_function ##### -->
<para>
</para>
@pad:
@acceptcaps:
<!-- ##### FUNCTION gst_pad_set_getcaps_function ##### -->
<para>
</para>
@pad:
@getcaps:
<!-- ##### FUNCTION gst_pad_set_setcaps_function ##### -->
<para>
</para>
@pad:
@setcaps:
<!-- ##### FUNCTION gst_pad_proxy_getcaps ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_proxy_setcaps ##### -->
<para>
</para>
@pad:
@caps:
@Returns:
<!-- ##### FUNCTION gst_pad_get_allowed_caps ##### -->
<para>
</para>
@srcpad:
@Returns:
<!-- # Unused Parameters # -->
@pad:
<!-- ##### FUNCTION gst_pad_get_fixed_caps_func ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_get_peer ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_peer_get_caps ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_peer_accept_caps ##### -->
<para>
</para>
@pad:
@caps:
@Returns:
<!-- ##### FUNCTION gst_pad_use_fixed_caps ##### -->
<para>
</para>
@pad:
<!-- ##### FUNCTION gst_pad_fixate_caps ##### -->
<para>
</para>
@pad:
@caps:
<!-- ##### FUNCTION gst_pad_set_fixatecaps_function ##### -->
<para>
</para>
@pad:
@fixatecaps:
<!-- ##### FUNCTION gst_pad_set_activatepush_function ##### -->
<para>
</para>
@pad:
@activatepush:
<!-- ##### FUNCTION gst_pad_push ##### -->
<para>
</para>
@pad:
@buffer:
@Returns:
<!-- # Unused Parameters # -->
@data:
@buf:
<!-- ##### FUNCTION gst_pad_push_event ##### -->
<para>
</para>
@pad:
@event:
@Returns:
<!-- ##### FUNCTION gst_pad_check_pull_range ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_pull_range ##### -->
<para>
</para>
@pad:
@offset:
@size:
@buffer:
@Returns:
<!-- ##### FUNCTION gst_pad_activate_pull ##### -->
<para>
</para>
@pad:
@active:
@Returns:
<!-- ##### FUNCTION gst_pad_activate_push ##### -->
<para>
</para>
@pad:
@active:
@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_query_function ##### -->
<para>
</para>
@pad:
@query:
<!-- ##### FUNCTION gst_pad_set_query_type_function ##### -->
<para>
</para>
@pad:
@type_func:
<!-- ##### FUNCTION gst_pad_get_query_types ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_get_query_types_default ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_query ##### -->
<para>
</para>
@pad:
@query:
@Returns:
<!-- # Unused Parameters # -->
@type:
@format:
@value:
<!-- ##### FUNCTION gst_pad_query_default ##### -->
<para>
</para>
@pad:
@query:
@Returns:
<!-- # Unused Parameters # -->
@type:
@format:
@value:
<!-- ##### FUNCTION gst_pad_query_position ##### -->
<para>
</para>
@pad:
@format:
@cur:
@end:
@Returns:
<!-- ##### FUNCTION gst_pad_query_convert ##### -->
<para>
</para>
@pad:
@src_format:
@src_val:
@dest_fmt:
@dest_val:
@Returns:
<!-- ##### FUNCTION gst_pad_set_internal_link_function ##### -->
<para>
</para>
@pad:
@intlink:
<!-- ##### FUNCTION gst_pad_get_internal_links ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_get_internal_links_default ##### -->
<para>
</para>
@pad:
@Returns:
<!-- ##### FUNCTION gst_pad_dispatcher ##### -->
<para>
</para>
@pad:
@dispatch:
@data:
@Returns:
<!-- ##### FUNCTION gst_pad_load_and_link ##### -->
<para>
</para>
@self:
@parent:
<!-- ##### FUNCTION gst_pad_add_data_probe ##### -->
<para>
</para>
@pad:
@handler:
@data:
@Returns:
<!-- ##### FUNCTION gst_pad_add_buffer_probe ##### -->
<para>
</para>
@pad:
@handler:
@data:
@Returns:
<!-- ##### FUNCTION gst_pad_add_event_probe ##### -->
<para>
</para>
@pad:
@handler:
@data:
@Returns:
<!-- ##### FUNCTION gst_pad_remove_data_probe ##### -->
<para>
</para>
@pad:
@handler:
@data:
<!-- ##### FUNCTION gst_pad_remove_buffer_probe ##### -->
<para>
</para>
@pad:
@handler:
@data:
<!-- ##### FUNCTION gst_pad_remove_event_probe ##### -->
<para>
</para>
@pad:
@handler:
@data: