1 <!-- ##### SECTION Title ##### -->
4 <!-- ##### SECTION Short_Description ##### -->
5 Object contained by elements that allows links to other elements
7 <!-- ##### SECTION Long_Description ##### -->
9 A #GstElement is linked to other elements via "pads", which are extremely
10 light-weight generic link points.
11 After two pads are retrieved from an element with gst_element_get_pad(),
12 the pads can be link with gst_pad_link(). (For quick links,
13 you can also use gst_element_link(), which will make the obvious
14 link for you if it's straightforward.)
17 Pads are typically created from a #GstPadTemplate with
18 gst_pad_new_from_template().
21 Pads have #GstCaps attached to it to describe the media type they
22 are capable of dealing with.
23 gst_pad_get_caps() and gst_pad_try_set_caps() are used to
24 manipulate the caps of the pads.
25 Pads created from a pad template cannot set capabilities that are
26 incompatible with the pad template capabilities.
29 Pads without pad templates can be created with gst_pad_new(),
30 which takes a direction and a name as an argument. If the name is NULL,
31 then a guaranteed unique name will be assigned to it.
34 gst_pad_get_parent() will retrieve the #GstElement that owns the pad.
37 A #GstElement creating a pad will typically use the various
38 gst_pad_set_*_function() calls to register callbacks for various events
42 GstElements will use gst_pad_push() and gst_pad_pull() to push out
44 gst_pad_select() and gst_pad_selectv() are used by plugins to wait for the
45 first incoming buffer or event on any of the given set of pads.
48 To send a #GstEvent on a pad, use gst_pad_send_event().
52 Last reviewed on December 13th, 2002 (0.5.0.1)
55 <!-- ##### SECTION See_Also ##### -->
57 #GstPadTemplate, #GstElement, #GstEvent
60 <!-- ##### MACRO GST_IS_PAD_FAST ##### -->
68 <!-- ##### MACRO GST_PAD_CLASS ##### -->
76 <!-- ##### MACRO GST_TYPE_REAL_PAD ##### -->
83 <!-- ##### MACRO GST_IS_REAL_PAD ##### -->
91 <!-- ##### MACRO GST_IS_REAL_PAD_FAST ##### -->
99 <!-- ##### MACRO GST_IS_REAL_PAD_CLASS ##### -->
105 <!-- # Unused Parameters # -->
109 <!-- ##### MACRO GST_REAL_PAD ##### -->
117 <!-- ##### MACRO GST_REAL_PAD_CLASS ##### -->
125 <!-- ##### MACRO GST_TYPE_GHOST_PAD ##### -->
132 <!-- ##### MACRO GST_IS_GHOST_PAD ##### -->
140 <!-- ##### MACRO GST_IS_GHOST_PAD_FAST ##### -->
148 <!-- ##### MACRO GST_IS_GHOST_PAD_CLASS ##### -->
154 <!-- # Unused Parameters # -->
158 <!-- ##### MACRO GST_GHOST_PAD ##### -->
166 <!-- ##### MACRO GST_GHOST_PAD_CLASS ##### -->
174 <!-- ##### STRUCT GstStaticPadTemplate ##### -->
184 <!-- ##### STRUCT GstPadLink ##### -->
190 <!-- ##### ENUM GstPadLinkReturn ##### -->
192 The result of a pad link.
195 @GST_PAD_LINK_REFUSED: the link was refused.
196 @GST_PAD_LINK_DELAYED: the link was delayed, probably because the
197 element needs more specific pad capabilitiess.
198 @GST_PAD_LINK_OK: the link succeeded.
199 @GST_PAD_LINK_DONE: the link succeeded,
200 any more attempts are not needed.
202 <!-- ##### MACRO GST_PAD_LINK_FAILED ##### -->
210 <!-- ##### MACRO GST_PAD_LINK_SUCCESSFUL ##### -->
218 <!-- ##### MACRO GST_PAD_QUERY_TYPE_FUNCTION ##### -->
220 A convenience macro to construct query type functions
223 @functionname: the name of the function
224 @...: query types, 0 to mark the last element
227 <!-- ##### MACRO GST_PAD_FORMATS_FUNCTION ##### -->
229 Convenience function to define an array of formats that can be used
230 as #GstPadGetFormatsFunction.
233 @functionname: The name of the function
234 @...: comma separated list of formats, 0 to mark the end
237 <!-- ##### MACRO GST_PAD_EVENT_MASK_FUNCTION ##### -->
239 Convenience function to define an array of event masks that can be used
240 as #GstPadGetEventMaskFunction.
243 @functionname: The name of the function
244 @...: comma separated list of event maks, { 0, } to mark the end
247 <!-- ##### USER_FUNCTION GstPadChainFunction ##### -->
249 A function that will be called when chaining buffers.
252 @pad: the #GstPad that performed the chain.
254 <!-- # Unused Parameters # -->
255 @buf: the #GstBuffer that is chained.
258 <!-- ##### USER_FUNCTION GstPadGetFunction ##### -->
260 A function that will be called when pulling a buffer.
263 @pad: the #GstPad to get a buffer from.
264 @Returns: the #GstBuffer pulled.
267 <!-- ##### USER_FUNCTION GstPadEventFunction ##### -->
269 Function signature to handle an event for the pad.
272 @pad: the #GstPad to handle the event.
273 @event: the #GstEvent to handle.
274 @Returns: TRUE if the pad could handle the event.
277 <!-- ##### USER_FUNCTION GstPadConvertFunction ##### -->
279 The signature of a convert function.
282 @pad: the #GstPad to perform the convert on.
283 @src_format: the source #GstFormat of the conversion.
284 @src_value: the source value of the conversion.
285 @dest_format: a pointer to the destination #GstFormat.
286 @dest_value: a pointer to the destination value.
287 @Returns: TRUE if the conversion could be performed.
290 <!-- ##### USER_FUNCTION GstPadQueryFunction ##### -->
292 The signature of the query function.
295 @pad: the #GstPad to query.
296 @type: the #GstPadQueryType.
297 @format: a pointer to the target #GstFormat.
298 @value: a pointer to the target value.
299 @Returns: TRUE if the query could be performed.
302 <!-- ##### USER_FUNCTION GstPadIntLinkFunction ##### -->
304 The signature of the internal pad link function.
307 @pad: The #GstPad to query.
308 @Returns: a newly allocated #GList of pads that are linked to
309 the given pad on the inside of the parent element.
310 The caller must call g_list_free() on it after use.
313 <!-- ##### USER_FUNCTION GstPadFormatsFunction ##### -->
315 The signature of the formats function.
318 @pad: a #GstPad to query
319 @Returns: an array of formats
322 <!-- ##### USER_FUNCTION GstPadEventMaskFunction ##### -->
324 The signature of the eventmask function.
327 @pad: the #GstPad to query
328 @Returns: an array of event masks
331 <!-- ##### USER_FUNCTION GstPadQueryTypeFunction ##### -->
333 The signature of the query types function.
336 @pad: a #GstPad to query
337 @Returns: an array of query types
340 <!-- ##### USER_FUNCTION GstPadLinkFunction ##### -->
342 Function signature to handle a new link on the pad.
345 @pad: the #GstPad that is linked.
346 @caps: the peer's #GstCaps.
347 @Returns: the result of the link with the specified caps.
350 <!-- ##### USER_FUNCTION GstPadUnlinkFunction ##### -->
358 <!-- ##### USER_FUNCTION GstPadGetCapsFunction ##### -->
360 Returns the capabilities of the specified pad. By default this function
361 will return the pad template capabilities, but can optionally be overridden.
364 @pad: the #GstPad to get the capabilities of.
365 @Returns: the #GstCaps of the pad.
366 <!-- # Unused Parameters # -->
367 @caps: the peer's #GstCaps, can be used to filter the capabilities.
370 <!-- ##### USER_FUNCTION GstPadFixateFunction ##### -->
380 <!-- ##### USER_FUNCTION GstPadBufferAllocFunction ##### -->
391 <!-- ##### USER_FUNCTION GstPadDispatcherFunction ##### -->
393 A dispatcher function is called for all internally linked pads, see
394 gst_pad_dispatcher().
397 @pad: the #GstPad that is dispatched.
398 @data: the gpointer to optional user data.
399 @Returns: TRUE if the dispatching procedure has to be stopped.
402 <!-- ##### ENUM GstPadDirection ##### -->
404 The direction of a pad.
407 @GST_PAD_UNKNOWN: direction is unknown.
408 @GST_PAD_SRC: the pad is a source pad.
409 @GST_PAD_SINK: the pad is a sink pad.
411 <!-- ##### ENUM GstPadFlags ##### -->
416 @GST_PAD_DISABLED: the pad is disabled.
417 @GST_PAD_NEGOTIATING:
418 @GST_PAD_FLAG_LAST: subclasses can use this number to enumerate their flags.
420 <!-- ##### MACRO GST_PAD_NAME ##### -->
422 Gets the name of the pad.
425 @pad: a #GstPad to get the name of.
426 @Returns: the pad's name.
429 <!-- ##### MACRO GST_PAD_PARENT ##### -->
431 Gets the parent element of this pad.
434 @pad: a #GstPad to get the parent of.
435 @Returns: the parent #GstElement of this pad.
438 <!-- ##### MACRO GST_PAD_ELEMENT_PRIVATE ##### -->
440 Gets the private data set by the element that owns the pad.
443 @pad: a #GstPad to get the private data of.
444 #Returns: a gpointer to the private data.
447 <!-- ##### MACRO GST_PAD_PAD_TEMPLATE ##### -->
449 Gets the pad template that was used to create this pad.
452 @pad: a #GstPad to get the pad template of.
453 #Returns: the #GstPadTemplate used to create the pad, or NULL if none was
457 <!-- ##### MACRO GST_RPAD_DIRECTION ##### -->
459 Get the direction of the real pad.
462 @pad: the realpad to query.
465 <!-- ##### MACRO GST_RPAD_CAPS ##### -->
467 Get the caps of the real pad.
470 @pad: the real pad to query.
473 <!-- ##### MACRO GST_RPAD_APPFILTER ##### -->
475 Get the application filter for this pad
478 @pad: the pad to query
481 <!-- ##### MACRO GST_RPAD_PEER ##### -->
483 Get the peer element of the real pad.
486 @pad: the real pad to query.
489 <!-- ##### MACRO GST_RPAD_CHAINFUNC ##### -->
491 Get the chain function of the real pad.
494 @pad: the real pad to query.
497 <!-- ##### MACRO GST_RPAD_CHAINHANDLER ##### -->
499 Get the eventhandler function from the real pad.
502 @pad: the real pad to query.
505 <!-- ##### MACRO GST_RPAD_GETFUNC ##### -->
507 Get get getfunction of the real pad.
510 @pad: the real pad to query.
513 <!-- ##### MACRO GST_RPAD_GETHANDLER ##### -->
515 Get the gethandler function of this real pad.
518 @pad: the real pad to query.
521 <!-- ##### MACRO GST_RPAD_EVENTFUNC ##### -->
523 Get the event function of this real pad.
526 @pad: the real pad to query.
529 <!-- ##### MACRO GST_RPAD_EVENTHANDLER ##### -->
531 Get the eventhandler function of this real pad.
534 @pad: the real pad to query.
537 <!-- ##### MACRO GST_RPAD_CONVERTFUNC ##### -->
539 Get the convert function of this pad
542 @pad: the pad to query
545 <!-- ##### MACRO GST_RPAD_QUERYFUNC ##### -->
547 Get the query function of this pad
550 @pad: the pad to query
553 <!-- ##### MACRO GST_RPAD_INTLINKFUNC ##### -->
555 Get the internal link function of this pad
558 @pad: the pad to query
561 <!-- ##### MACRO GST_RPAD_FORMATSFUNC ##### -->
563 Get the formats function of this pad
566 @pad: the pad to query
569 <!-- ##### MACRO GST_RPAD_QUERYTYPEFUNC ##### -->
571 Get the query types function of this pad
574 @pad: the pad to query
577 <!-- ##### MACRO GST_RPAD_EVENTMASKFUNC ##### -->
579 Get the event mask function of this pad
582 @pad: the pad to query
585 <!-- ##### MACRO GST_RPAD_LINKFUNC ##### -->
587 Get the link function of the pad
590 @pad: the pad to query
593 <!-- ##### MACRO GST_RPAD_UNLINKFUNC ##### -->
601 <!-- ##### MACRO GST_RPAD_GETCAPSFUNC ##### -->
603 Get the getcaps function of this pad
606 @pad: the pad to query
609 <!-- ##### MACRO GST_RPAD_FIXATEFUNC ##### -->
617 <!-- ##### MACRO GST_RPAD_BUFFERALLOCFUNC ##### -->
625 <!-- ##### MACRO GST_RPAD_LINK ##### -->
633 <!-- ##### MACRO GST_RPAD_EXPLICIT_CAPS ##### -->
641 <!-- ##### MACRO GST_GPAD_REALPAD ##### -->
643 Get the real pad of this ghost pad.
646 @pad: the real pad to query.
649 <!-- ##### MACRO GST_PAD_REALIZE ##### -->
651 Returns the real pad of this pad.
654 @pad: a #GstPad to realize.
655 @Returns: the actual #GstPad.
658 <!-- ##### MACRO GST_PAD_DIRECTION ##### -->
660 Gets the pad's direction.
663 @pad: a #GstPad to get the direction of.
664 @Returns: the #GstPadDirection of the pad.
667 <!-- ##### MACRO GST_PAD_CAPS ##### -->
669 Gets the capabilities of a pad.
672 @pad: a #GstPad to get the capabilities of.
673 @Returns: the #GstCaps of the pad.
676 <!-- ##### MACRO GST_PAD_PEER ##### -->
678 Gets the peer pad of this pad. The peer pad is the pad on to which the parent
679 element is linked through this pad.
682 @pad: a #GstPad to get the peer pad of.
683 @Returns: the peer #GstPad.
686 <!-- ##### MACRO GST_PAD_IS_LINKED ##### -->
688 Checks if the pad is linked.
691 @pad: a #GstPad to check.
694 <!-- ##### MACRO GST_PAD_IS_ACTIVE ##### -->
696 Checks if the pad is active.
699 @pad: a #GstPad to check
702 <!-- ##### MACRO GST_PAD_IS_NEGOTIATING ##### -->
710 <!-- ##### MACRO GST_PAD_IS_USABLE ##### -->
712 Checks if a pad is usable. A usable pad is both linked and active.
715 @pad: a #GstPad to check
718 <!-- ##### MACRO GST_PAD_CAN_PULL ##### -->
720 Checks if buffers can be pulled from this buffer.
723 @pad: a #GstPad to check on if a buffer can be pulled from it.
726 <!-- ##### MACRO GST_PAD_IS_SRC ##### -->
728 Checks if the pad is a source pad.
731 @pad: a #GstPad to check.
734 <!-- ##### MACRO GST_PAD_IS_SINK ##### -->
736 Checks if the pad is a sink pad.
739 @pad: a #GstPad to check.
742 <!-- ##### MACRO GST_TYPE_PAD_TEMPLATE ##### -->
749 <!-- ##### MACRO GST_PAD_TEMPLATE ##### -->
757 <!-- ##### MACRO GST_PAD_TEMPLATE_CLASS ##### -->
765 <!-- ##### MACRO GST_IS_PAD_TEMPLATE ##### -->
773 <!-- ##### MACRO GST_IS_PAD_TEMPLATE_CLASS ##### -->
779 <!-- # Unused Parameters # -->
783 <!-- ##### ENUM GstPadPresence ##### -->
785 Indicates when this pad will become available.
788 @GST_PAD_ALWAYS: the pad is always available
789 @GST_PAD_SOMETIMES: the pad will become available depending on the media stream
790 @GST_PAD_REQUEST: th pad is only available on request with
791 gst_element_request_pad_by_name() or gst_element_request_compatible_pad().
793 <!-- ##### MACRO GST_PAD_TEMPLATE_NAME_TEMPLATE ##### -->
795 Get the nametemplate of the padtemplate.
798 @templ: the template to query
801 <!-- ##### MACRO GST_PAD_TEMPLATE_DIRECTION ##### -->
803 Get the direction of the padtemplate.
806 @templ: the template to query
809 <!-- ##### MACRO GST_PAD_TEMPLATE_PRESENCE ##### -->
811 Get the presence of the padtemplate.
814 @templ: the template to query
817 <!-- ##### MACRO GST_PAD_TEMPLATE_CAPS ##### -->
819 Get a handle to the padtemplate #GstCaps
822 @templ: the template to query
825 <!-- ##### ENUM GstPadTemplateFlags ##### -->
827 Flags for the padtemplate
830 @GST_PAD_TEMPLATE_FIXED: The padtemplate has no variable properties
831 @GST_PAD_TEMPLATE_FLAG_LAST: first flag that can be used by subclasses.
833 <!-- ##### MACRO GST_PAD_TEMPLATE_IS_FIXED ##### -->
835 Check if the properties of the padtemplate are fixed
838 @templ: the template to query
841 <!-- ##### MACRO GST_STATIC_PAD_TEMPLATE ##### -->
852 <!-- ##### FUNCTION gst_real_pad_get_type ##### -->
860 <!-- ##### FUNCTION gst_ghost_pad_get_type ##### -->
868 <!-- ##### FUNCTION gst_pad_new ##### -->
878 <!-- ##### FUNCTION gst_pad_new_from_template ##### -->
888 <!-- ##### FUNCTION gst_pad_custom_new ##### -->
899 <!-- ##### FUNCTION gst_pad_custom_new_from_template ##### -->
910 <!-- ##### FUNCTION gst_pad_set_name ##### -->
919 <!-- ##### FUNCTION gst_pad_get_name ##### -->
928 <!-- ##### FUNCTION gst_pad_get_direction ##### -->
937 <!-- ##### FUNCTION gst_pad_set_active ##### -->
946 <!-- ##### FUNCTION gst_pad_is_active ##### -->
955 <!-- ##### FUNCTION gst_pad_set_element_private ##### -->
964 <!-- ##### FUNCTION gst_pad_get_element_private ##### -->
973 <!-- ##### FUNCTION gst_pad_set_parent ##### -->
982 <!-- ##### FUNCTION gst_pad_get_parent ##### -->
991 <!-- ##### FUNCTION gst_pad_get_real_parent ##### -->
1000 <!-- ##### FUNCTION gst_pad_get_scheduler ##### -->
1009 <!-- ##### FUNCTION gst_pad_add_ghost_pad ##### -->
1018 <!-- ##### FUNCTION gst_pad_remove_ghost_pad ##### -->
1027 <!-- ##### FUNCTION gst_pad_get_ghost_pad_list ##### -->
1036 <!-- ##### FUNCTION gst_pad_get_pad_template ##### -->
1045 <!-- ##### FUNCTION gst_pad_set_bufferalloc_function ##### -->
1052 <!-- # Unused Parameters # -->
1056 <!-- ##### FUNCTION gst_pad_alloc_buffer ##### -->
1067 <!-- ##### FUNCTION gst_pad_set_chain_function ##### -->
1076 <!-- ##### FUNCTION gst_pad_set_get_function ##### -->
1085 <!-- ##### FUNCTION gst_pad_set_event_function ##### -->
1094 <!-- ##### FUNCTION gst_pad_set_event_mask_function ##### -->
1103 <!-- ##### FUNCTION gst_pad_get_event_masks ##### -->
1112 <!-- ##### FUNCTION gst_pad_get_event_masks_default ##### -->
1121 <!-- ##### FUNCTION gst_pad_set_link_function ##### -->
1130 <!-- ##### FUNCTION gst_pad_can_link ##### -->
1140 <!-- ##### FUNCTION gst_pad_can_link_filtered ##### -->
1151 <!-- ##### FUNCTION gst_pad_set_unlink_function ##### -->
1160 <!-- ##### FUNCTION gst_pad_link ##### -->
1170 <!-- ##### FUNCTION gst_pad_link_filtered ##### -->
1181 <!-- ##### FUNCTION gst_pad_unlink ##### -->
1190 <!-- ##### FUNCTION gst_pad_is_linked ##### -->
1199 <!-- ##### FUNCTION gst_pad_get_peer ##### -->
1208 <!-- ##### FUNCTION gst_pad_get_negotiated_caps ##### -->
1217 <!-- ##### FUNCTION gst_pad_is_negotiated ##### -->
1226 <!-- ##### FUNCTION gst_pad_get_caps ##### -->
1235 <!-- ##### FUNCTION gst_pad_get_pad_template_caps ##### -->
1244 <!-- ##### FUNCTION gst_pad_try_set_caps ##### -->
1254 <!-- ##### FUNCTION gst_pad_try_set_caps_nonfixed ##### -->
1264 <!-- ##### FUNCTION gst_pad_check_compatibility ##### -->
1274 <!-- ##### FUNCTION gst_pad_set_getcaps_function ##### -->
1283 <!-- ##### FUNCTION gst_pad_set_fixate_function ##### -->
1292 <!-- ##### FUNCTION gst_pad_proxy_getcaps ##### -->
1301 <!-- ##### FUNCTION gst_pad_proxy_pad_link ##### -->
1311 <!-- ##### FUNCTION gst_pad_proxy_fixate ##### -->
1321 <!-- ##### FUNCTION gst_pad_proxy_link ##### -->
1331 <!-- ##### FUNCTION gst_pad_set_explicit_caps ##### -->
1341 <!-- ##### FUNCTION gst_pad_use_explicit_caps ##### -->
1349 <!-- ##### FUNCTION gst_pad_relink_filtered ##### -->
1360 <!-- ##### FUNCTION gst_pad_perform_negotiate ##### -->
1370 <!-- ##### FUNCTION gst_pad_renegotiate ##### -->
1379 <!-- ##### FUNCTION gst_pad_unnegotiate ##### -->
1387 <!-- ##### FUNCTION gst_pad_try_relink_filtered ##### -->
1398 <!-- ##### FUNCTION gst_pad_get_allowed_caps ##### -->
1407 <!-- ##### FUNCTION gst_pad_caps_change_notify ##### -->
1415 <!-- ##### FUNCTION gst_pad_recover_caps_error ##### -->
1425 <!-- ##### FUNCTION gst_pad_push ##### -->
1432 <!-- # Unused Parameters # -->
1436 <!-- ##### FUNCTION gst_pad_pull ##### -->
1445 <!-- ##### FUNCTION gst_pad_send_event ##### -->
1455 <!-- ##### FUNCTION gst_pad_event_default ##### -->
1465 <!-- ##### FUNCTION gst_pad_selectv ##### -->
1472 <!-- # Unused Parameters # -->
1477 <!-- ##### FUNCTION gst_pad_select ##### -->
1485 <!-- # Unused Parameters # -->
1489 <!-- ##### FUNCTION gst_pad_select_valist ##### -->
1499 <!-- ##### FUNCTION gst_pad_set_formats_function ##### -->
1508 <!-- ##### FUNCTION gst_pad_get_formats ##### -->
1517 <!-- ##### FUNCTION gst_pad_get_formats_default ##### -->
1526 <!-- ##### FUNCTION gst_pad_set_convert_function ##### -->
1535 <!-- ##### FUNCTION gst_pad_convert ##### -->
1548 <!-- ##### FUNCTION gst_pad_convert_default ##### -->
1561 <!-- ##### FUNCTION gst_pad_set_query_function ##### -->
1570 <!-- ##### FUNCTION gst_pad_set_query_type_function ##### -->
1579 <!-- ##### FUNCTION gst_pad_get_query_types ##### -->
1588 <!-- ##### FUNCTION gst_pad_get_query_types_default ##### -->
1597 <!-- ##### FUNCTION gst_pad_query ##### -->
1609 <!-- ##### FUNCTION gst_pad_query_default ##### -->
1621 <!-- ##### FUNCTION gst_pad_set_internal_link_function ##### -->
1630 <!-- ##### FUNCTION gst_pad_get_internal_links ##### -->
1639 <!-- ##### FUNCTION gst_pad_get_internal_links_default ##### -->
1648 <!-- ##### FUNCTION gst_pad_dispatcher ##### -->
1659 <!-- ##### MACRO gst_pad_add_probe ##### -->
1661 Adds the probe to the given pad
1664 @pad: The pad to add the probe to
1665 @probe: The probe to add to the pad
1668 <!-- ##### MACRO gst_pad_remove_probe ##### -->
1670 Remove the probe from the pad
1673 @pad: The pad to remove the probe of
1674 @probe: The probe to remove
1677 <!-- ##### FUNCTION gst_pad_load_and_link ##### -->
1686 <!-- ##### FUNCTION gst_ghost_pad_new ##### -->
1696 <!-- ##### FUNCTION gst_pad_template_get_type ##### -->
1704 <!-- ##### FUNCTION gst_pad_template_new ##### -->
1714 <!-- # Unused Parameters # -->
1718 <!-- ##### FUNCTION gst_static_pad_template_get ##### -->
1725 <!-- # Unused Parameters # -->
1729 <!-- ##### FUNCTION gst_pad_template_get_caps ##### -->
1738 <!-- ##### FUNCTION gst_pad_template_get_caps_by_name ##### -->
1748 <!-- ##### FUNCTION gst_ghost_pad_save_thyself ##### -->