GstPad

GstPad — Object contained by elements that allows links to other elements

Functions

const gchar * gst_pad_link_get_name ()
#define GST_PAD_LINK_FAILED()
#define GST_PAD_LINK_SUCCESSFUL()
const gchar * gst_flow_get_name ()
GQuark gst_flow_to_quark ()
const gchar * gst_pad_mode_get_name ()
GstFlowReturn gst_pad_store_sticky_event ()
#define gst_pad_get_name()
GstPadDirection gst_pad_get_direction ()
#define gst_pad_get_parent()
GstElement * gst_pad_get_parent_element ()
GstPadTemplate * gst_pad_get_pad_template ()
GstPadLinkReturn gst_pad_link ()
GstPadLinkReturn gst_pad_link_full ()
gboolean gst_pad_unlink ()
gboolean gst_pad_is_linked ()
gboolean gst_pad_can_link ()
GstCaps * gst_pad_get_allowed_caps ()
GstCaps * gst_pad_get_current_caps ()
GstCaps * gst_pad_get_pad_template_caps ()
GstPad * gst_pad_get_peer ()
void gst_pad_use_fixed_caps ()
gboolean gst_pad_has_current_caps ()
GstEvent * gst_pad_get_sticky_event ()
gboolean (*GstPadStickyEventsForeachFunction) ()
void gst_pad_sticky_events_foreach ()
gboolean gst_pad_is_active ()
GstFlowReturn gst_pad_get_last_flow_return ()
#define GST_PAD_PROBE_INFO_TYPE()
#define GST_PAD_PROBE_INFO_ID()
#define GST_PAD_PROBE_INFO_DATA()
#define GST_PAD_PROBE_INFO_BUFFER()
#define GST_PAD_PROBE_INFO_BUFFER_LIST()
#define GST_PAD_PROBE_INFO_EVENT()
#define GST_PAD_PROBE_INFO_QUERY()
GstBuffer * gst_pad_probe_info_get_buffer ()
GstBufferList * gst_pad_probe_info_get_buffer_list ()
GstEvent * gst_pad_probe_info_get_event ()
GstQuery * gst_pad_probe_info_get_query ()
#define GST_PAD_PROBE_INFO_OFFSET()
#define GST_PAD_PROBE_INFO_SIZE()
GstPadProbeReturn (*GstPadProbeCallback) ()
gulong gst_pad_add_probe ()
void gst_pad_remove_probe ()
gboolean gst_pad_is_blocked ()
gboolean gst_pad_is_blocking ()
gint64 gst_pad_get_offset ()
void gst_pad_set_offset ()
GstPad * gst_pad_new ()
GstPad * gst_pad_new_from_template ()
GstPad * gst_pad_new_from_static_template ()
#define gst_pad_set_chain_function()
void gst_pad_set_chain_function_full ()
GstFlowReturn (*GstPadChainFunction) ()
#define gst_pad_set_chain_list_function()
void gst_pad_set_chain_list_function_full ()
GstFlowReturn (*GstPadChainListFunction) ()
GstFlowReturn gst_pad_get_range ()
#define gst_pad_set_getrange_function()
void gst_pad_set_getrange_function_full ()
GstFlowReturn (*GstPadGetRangeFunction) ()
#define gst_pad_set_event_function()
void gst_pad_set_event_function_full ()
gboolean (*GstPadEventFunction) ()
#define gst_pad_set_link_function()
void gst_pad_set_link_function_full ()
GstPadLinkReturn (*GstPadLinkFunction) ()
#define gst_pad_set_unlink_function()
void gst_pad_set_unlink_function_full ()
void (*GstPadUnlinkFunction) ()
gboolean gst_pad_proxy_query_caps ()
gboolean gst_pad_proxy_query_accept_caps ()
#define gst_pad_set_activate_function()
void gst_pad_set_activate_function_full ()
gboolean (*GstPadActivateFunction) ()
#define gst_pad_set_activatemode_function()
void gst_pad_set_activatemode_function_full ()
gboolean (*GstPadActivateModeFunction) ()
gboolean gst_pad_needs_reconfigure ()
gboolean gst_pad_check_reconfigure ()
void gst_pad_mark_reconfigure ()
GstFlowReturn gst_pad_push ()
gboolean gst_pad_push_event ()
GstFlowReturn gst_pad_push_list ()
GstFlowReturn gst_pad_pull_range ()
gboolean gst_pad_activate_mode ()
gboolean gst_pad_send_event ()
gboolean gst_pad_event_default ()
gboolean gst_pad_query ()
gboolean gst_pad_peer_query ()
gboolean gst_pad_query_default ()
gboolean gst_pad_query_position ()
gboolean gst_pad_query_duration ()
gboolean gst_pad_query_convert ()
gboolean gst_pad_query_accept_caps ()
GstCaps * gst_pad_query_caps ()
gboolean gst_pad_peer_query_position ()
gboolean gst_pad_peer_query_duration ()
gboolean gst_pad_peer_query_convert ()
gboolean gst_pad_peer_query_accept_caps ()
GstCaps * gst_pad_peer_query_caps ()
#define gst_pad_set_query_function()
void gst_pad_set_query_function_full ()
gboolean (*GstPadQueryFunction) ()
#define gst_pad_set_iterate_internal_links_function()
void gst_pad_set_iterate_internal_links_function_full ()
GstIterator * (*GstPadIterIntLinkFunction) ()
GstIterator * gst_pad_iterate_internal_links ()
GstIterator * gst_pad_iterate_internal_links_default ()
void gst_pad_set_element_private ()
gpointer gst_pad_get_element_private ()
gchar * gst_pad_create_stream_id ()
gchar * gst_pad_create_stream_id_printf ()
gchar * gst_pad_create_stream_id_printf_valist ()
gchar * gst_pad_get_stream_id ()
gboolean (*GstPadForwardFunction) ()
gboolean gst_pad_forward ()
GstFlowReturn gst_pad_chain ()
GstFlowReturn gst_pad_chain_list ()
gboolean gst_pad_start_task ()
gboolean gst_pad_pause_task ()
gboolean gst_pad_stop_task ()
gboolean gst_pad_set_active ()
#define GST_PAD_GET_STREAM_LOCK()
#define GST_PAD_STREAM_LOCK()
#define GST_PAD_STREAM_TRYLOCK()
#define GST_PAD_STREAM_UNLOCK()
#define GST_PAD_NAME()
#define GST_PAD_PARENT()
#define GST_PAD_ELEMENT_PRIVATE()
#define GST_PAD_PAD_TEMPLATE()
#define GST_PAD_DIRECTION()
#define GST_PAD_LAST_FLOW_RETURN()
#define GST_PAD_TASK()
#define GST_PAD_MODE()
#define GST_PAD_ACTIVATEFUNC()
#define GST_PAD_ACTIVATEMODEFUNC()
#define GST_PAD_CHAINFUNC()
#define GST_PAD_CHAINLISTFUNC()
#define GST_PAD_EVENTFUNC()
#define GST_PAD_GETRANGEFUNC()
#define GST_PAD_QUERYFUNC()
#define GST_PAD_ITERINTLINKFUNC()
#define GST_PAD_PEER()
#define GST_PAD_LINKFUNC()
#define GST_PAD_UNLINKFUNC()
#define GST_PAD_IS_LINKED()
#define GST_PAD_IS_SRC()
#define GST_PAD_IS_SINK()
#define GST_PAD_IS_ACTIVE()
#define GST_PAD_IS_BLOCKED()
#define GST_PAD_IS_BLOCKING()
#define GST_PAD_IS_FLUSHING()
#define GST_PAD_SET_FLUSHING()
#define GST_PAD_UNSET_FLUSHING()
#define GST_PAD_IS_EOS()
#define GST_PAD_NEEDS_RECONFIGURE()
#define GST_PAD_HAS_PENDING_EVENTS()
#define GST_PAD_IS_FIXED_CAPS()
#define GST_PAD_NEEDS_PARENT()
#define GST_PAD_IS_PROXY_CAPS()
#define GST_PAD_SET_PROXY_CAPS()
#define GST_PAD_UNSET_PROXY_CAPS()
#define GST_PAD_IS_PROXY_ALLOCATION()
#define GST_PAD_SET_PROXY_ALLOCATION()
#define GST_PAD_UNSET_PROXY_ALLOCATION()
#define GST_PAD_SET_PROXY_SCHEDULING()
#define GST_PAD_UNSET_PROXY_SCHEDULING()
#define GST_PAD_IS_PROXY_SCHEDULING()
#define GST_PAD_IS_ACCEPT_INTERSECT()
#define GST_PAD_SET_ACCEPT_INTERSECT()
#define GST_PAD_UNSET_ACCEPT_INTERSECT()

Properties

GstCaps * caps Read
GstPadDirection direction Read / Write / Construct Only
GstPadTemplate * template Read / Write

Signals

void linked Run Last
void unlinked Run Last

Types and Values

Object Hierarchy

    GObject
    ╰── GInitiallyUnowned
        ╰── GstObject
            ╰── GstPad
                ╰── GstProxyPad

Includes

#include <gst/gst.h>

Description

A GstElement is linked to other elements via "pads", which are extremely light-weight generic link points.

Pads have a GstPadDirection, source pads produce data, sink pads consume data.

Pads are typically created from a GstPadTemplate with gst_pad_new_from_template() and are then added to a GstElement. This usually happens when the element is created but it can also happen dynamically based on the data that the element is processing or based on the pads that the application requests.

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.

A GstElement creating a pad will typically use the various gst_pad_set_*_function() calls to register callbacks for events, queries or dataflow on the pads.

gst_pad_get_parent() will retrieve the GstElement that owns the pad.

After two pads are retrieved from an element by gst_element_get_static_pad(), the pads can be linked 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.). Pads can be unlinked again with gst_pad_unlink(). gst_pad_get_peer() can be used to check what the pad is linked to.

Before dataflow is possible on the pads, they need to be activated with gst_pad_set_active().

gst_pad_query() and gst_pad_peer_query() can be used to query various properties of the pad and the stream.

To send a GstEvent on a pad, use gst_pad_send_event() and gst_pad_push_event(). Some events will be sticky on the pad, meaning that after they pass on the pad they can be queried later with gst_pad_get_sticky_event() and gst_pad_sticky_events_foreach(). gst_pad_get_current_caps() and gst_pad_has_current_caps() are convenience functions to query the current sticky CAPS event on a pad.

GstElements will use gst_pad_push() and gst_pad_pull_range() to push out or pull in a buffer.

The dataflow, events and queries that happen on a pad can be monitored with probes that can be installed with gst_pad_add_probe(). gst_pad_is_blocked() can be used to check if a block probe is installed on the pad. gst_pad_is_blocking() checks if the blocking probe is currently blocking the pad. gst_pad_remove_probe() is used to remove a previously installed probe and unblock blocking probes if any.

Pad have an offset that can be retrieved with gst_pad_get_offset(). This offset will be applied to the running_time of all data passing over the pad. gst_pad_set_offset() can be used to change the offset.

Convenience functions exist to start, pause and stop the task on a pad with gst_pad_start_task(), gst_pad_pause_task() and gst_pad_stop_task() respectively.

Functions

gst_pad_link_get_name ()

const gchar *
gst_pad_link_get_name (GstPadLinkReturn ret);

Gets a string representing the given pad-link return.

Parameters

ret

a GstPadLinkReturn to get the name of.

 

Returns

a static string with the name of the pad-link return.

Since 1.4


GST_PAD_LINK_FAILED()

#define GST_PAD_LINK_FAILED(ret) ((ret) < GST_PAD_LINK_OK)

Macro to test if the given GstPadLinkReturn value indicates a failed link step.

Parameters

ret

the GstPadLinkReturn value

 

GST_PAD_LINK_SUCCESSFUL()

#define GST_PAD_LINK_SUCCESSFUL(ret) ((ret) >= GST_PAD_LINK_OK)

Macro to test if the given GstPadLinkReturn value indicates a successful link step.

Parameters

ret

the GstPadLinkReturn value

 

gst_flow_get_name ()

const gchar *
gst_flow_get_name (GstFlowReturn ret);

Gets a string representing the given flow return.

Parameters

ret

a GstFlowReturn to get the name of.

 

Returns

a static string with the name of the flow return.


gst_flow_to_quark ()

GQuark
gst_flow_to_quark (GstFlowReturn ret);

Get the unique quark for the given GstFlowReturn.

Parameters

ret

a GstFlowReturn to get the quark of.

 

Returns

the quark associated with the flow return or 0 if an invalid return was specified.


gst_pad_mode_get_name ()

const gchar *
gst_pad_mode_get_name (GstPadMode mode);

Return the name of a pad mode, for use in debug messages mostly.

Parameters

mode

the pad mode

 

Returns

short mnemonic for pad mode mode


gst_pad_store_sticky_event ()

GstFlowReturn
gst_pad_store_sticky_event (GstPad *pad,
                            GstEvent *event);

Store the sticky event on pad

Parameters

pad

a GstPad

 

event

a GstEvent

 

Returns

GST_FLOW_OK on success, GST_FLOW_FLUSHING when the pad was flushing or GST_FLOW_EOS when the pad was EOS.

Since 1.2


gst_pad_get_name()

#define gst_pad_get_name(pad) gst_object_get_name (GST_OBJECT_CAST (pad))

Get a copy of the name of the pad. g_free() after usage.

MT safe.

Parameters

pad

the pad to get the name from

 

gst_pad_get_direction ()

GstPadDirection
gst_pad_get_direction (GstPad *pad);

Gets the direction of the pad. The direction of the pad is decided at construction time so this function does not take the LOCK.

Parameters

pad

a GstPad to get the direction of.

 

Returns

the GstPadDirection of the pad.

MT safe.


gst_pad_get_parent()

#define gst_pad_get_parent(pad) gst_object_get_parent (GST_OBJECT_CAST (pad))

Get the parent of pad . This function increases the refcount of the parent object so you should gst_object_unref() it after usage. Can return NULL if the pad did not have a parent.

MT safe.

Parameters

pad

the pad to get the parent of

 

Returns

the parent.

[nullable]


gst_pad_get_parent_element ()

GstElement *
gst_pad_get_parent_element (GstPad *pad);

Gets the parent of pad , cast to a GstElement. If a pad has no parent or its parent is not an element, return NULL.

Parameters

pad

a pad

 

Returns

the parent of the pad. The caller has a reference on the parent, so unref when you're finished with it.

MT safe.

[transfer full][nullable]


gst_pad_get_pad_template ()

GstPadTemplate *
gst_pad_get_pad_template (GstPad *pad);

Gets the template for pad .

Parameters

pad

a GstPad.

 

Returns

the GstPadTemplate from which this pad was instantiated, or NULL if this pad has no template. Unref after usage.

[transfer full][nullable]


gst_pad_link ()

GstPadLinkReturn
gst_pad_link (GstPad *srcpad,
              GstPad *sinkpad);

Links the source pad and the sink pad.

Parameters

srcpad

the source GstPad to link.

 

sinkpad

the sink GstPad to link.

 

Returns

A result code indicating if the connection worked or what went wrong.

MT Safe.


gst_pad_link_full ()

GstPadLinkReturn
gst_pad_link_full (GstPad *srcpad,
                   GstPad *sinkpad,
                   GstPadLinkCheck flags);

Links the source pad and the sink pad.

This variant of gst_pad_link provides a more granular control on the checks being done when linking. While providing some considerable speedups the caller of this method must be aware that wrong usage of those flags can cause severe issues. Refer to the documentation of GstPadLinkCheck for more information.

MT Safe.

Parameters

srcpad

the source GstPad to link.

 

sinkpad

the sink GstPad to link.

 

flags

the checks to validate when linking

 

Returns

A result code indicating if the connection worked or what went wrong.


gst_pad_unlink ()

gboolean
gst_pad_unlink (GstPad *srcpad,
                GstPad *sinkpad);

Unlinks the source pad from the sink pad. Will emit the “unlinked” signal on both pads.

Parameters

srcpad

the source GstPad to unlink.

 

sinkpad

the sink GstPad to unlink.

 

Returns

TRUE if the pads were unlinked. This function returns FALSE if the pads were not linked together.

MT safe.


gst_pad_is_linked ()

gboolean
gst_pad_is_linked (GstPad *pad);

Checks if a pad is linked to another pad or not.

Parameters

pad

pad to check

 

Returns

TRUE if the pad is linked, FALSE otherwise.

MT safe.


gst_pad_can_link ()

gboolean
gst_pad_can_link (GstPad *srcpad,
                  GstPad *sinkpad);

Checks if the source pad and the sink pad are compatible so they can be linked.

Parameters

srcpad

the source GstPad.

 

sinkpad

the sink GstPad.

 

Returns

TRUE if the pads can be linked.


gst_pad_get_allowed_caps ()

GstCaps *
gst_pad_get_allowed_caps (GstPad *pad);

Gets the capabilities of the allowed media types that can flow through pad and its peer.

The allowed capabilities is calculated as the intersection of the results of calling gst_pad_query_caps() on pad and its peer. The caller owns a reference on the resulting caps.

Parameters

pad

a GstPad.

 

Returns

the allowed GstCaps of the pad link. Unref the caps when you no longer need it. This function returns NULL when pad has no peer.

MT safe.

[transfer full][nullable]


gst_pad_get_current_caps ()

GstCaps *
gst_pad_get_current_caps (GstPad *pad);

Gets the capabilities currently configured on pad with the last GST_EVENT_CAPS event.

Parameters

pad

a GstPad to get the current capabilities of.

 

Returns

the current caps of the pad with incremented ref-count.


gst_pad_get_pad_template_caps ()

GstCaps *
gst_pad_get_pad_template_caps (GstPad *pad);

Gets the capabilities for pad 's template.

Parameters

pad

a GstPad to get the template capabilities from.

 

Returns

the GstCaps of this pad template. Unref after usage.

[transfer full]


gst_pad_get_peer ()

GstPad *
gst_pad_get_peer (GstPad *pad);

Gets the peer of pad . This function refs the peer pad so you need to unref it after use.

Parameters

pad

a GstPad to get the peer of.

 

Returns

the peer GstPad. Unref after usage.

MT safe.

[transfer full]


gst_pad_use_fixed_caps ()

void
gst_pad_use_fixed_caps (GstPad *pad);

A helper function you can use that sets the FIXED_CAPS flag This way the default CAPS query will always return the negotiated caps or in case the pad is not negotiated, the padtemplate caps.

The negotiated caps are the caps of the last CAPS event that passed on the pad. Use this function on a pad that, once it negotiated to a CAPS, cannot be renegotiated to something else.

Parameters

pad

the pad to use

 

gst_pad_has_current_caps ()

gboolean
gst_pad_has_current_caps (GstPad *pad);

Check if pad has caps set on it with a GST_EVENT_CAPS event.

Parameters

pad

a GstPad to check

 

Returns

TRUE when pad has caps associated with it.


gst_pad_get_sticky_event ()

GstEvent *
gst_pad_get_sticky_event (GstPad *pad,
                          GstEventType event_type,
                          guint idx);

Returns a new reference of the sticky event of type event_type from the event.

Parameters

pad

the GstPad to get the event from.

 

event_type

the GstEventType that should be retrieved.

 

idx

the index of the event

 

Returns

a GstEvent of type event_type or NULL when no event of event_type was on pad . Unref after usage.

[transfer full][nullable]


GstPadStickyEventsForeachFunction ()

gboolean
(*GstPadStickyEventsForeachFunction) (GstPad *pad,
                                      GstEvent **event,
                                      gpointer user_data);

Callback used by gst_pad_sticky_events_foreach().

When this function returns TRUE, the next event will be returned. When FALSE is returned, gst_pad_sticky_events_foreach() will return.

When event is set to NULL, the item will be removed from the list of sticky events. event can be replaced by assigning a new reference to it. This function is responsible for unreffing the old event when removing or modifying.

Parameters

pad

the GstPad.

 

event

a sticky GstEvent.

[allow-none]

user_data

the gpointer to optional user data.

 

Returns

TRUE if the iteration should continue


gst_pad_sticky_events_foreach ()

void
gst_pad_sticky_events_foreach (GstPad *pad,
                               GstPadStickyEventsForeachFunction foreach_func,
                               gpointer user_data);

Iterates all sticky events on pad and calls foreach_func for every event. If foreach_func returns FALSE the iteration is immediately stopped.

Parameters

pad

the GstPad that should be used for iteration.

 

foreach_func

the GstPadStickyEventsForeachFunction that should be called for every event.

[scope call]

user_data

the optional user data.

[closure]

gst_pad_is_active ()

gboolean
gst_pad_is_active (GstPad *pad);

Query if a pad is active

Parameters

pad

the GstPad to query

 

Returns

TRUE if the pad is active.

MT safe.


gst_pad_get_last_flow_return ()

GstFlowReturn
gst_pad_get_last_flow_return (GstPad *pad);

Gets the GstFlowReturn return from the last data passed by this pad.

Parameters

pad

the GstPad

 

Since 1.4


GST_PAD_PROBE_INFO_TYPE()

#define GST_PAD_PROBE_INFO_TYPE(d)         ((d)->type)

GST_PAD_PROBE_INFO_ID()

#define GST_PAD_PROBE_INFO_ID(d)           ((d)->id)

GST_PAD_PROBE_INFO_DATA()

#define GST_PAD_PROBE_INFO_DATA(d)         ((d)->data)

GST_PAD_PROBE_INFO_BUFFER()

#define GST_PAD_PROBE_INFO_BUFFER(d)       GST_BUFFER_CAST(GST_PAD_PROBE_INFO_DATA(d))

GST_PAD_PROBE_INFO_BUFFER_LIST()

#define GST_PAD_PROBE_INFO_BUFFER_LIST(d)  GST_BUFFER_LIST_CAST(GST_PAD_PROBE_INFO_DATA(d))

GST_PAD_PROBE_INFO_EVENT()

#define GST_PAD_PROBE_INFO_EVENT(d)        GST_EVENT_CAST(GST_PAD_PROBE_INFO_DATA(d))

GST_PAD_PROBE_INFO_QUERY()

#define GST_PAD_PROBE_INFO_QUERY(d)        GST_QUERY_CAST(GST_PAD_PROBE_INFO_DATA(d))

gst_pad_probe_info_get_buffer ()

GstBuffer *
gst_pad_probe_info_get_buffer (GstPadProbeInfo *info);

Parameters

info

a GstPadProbeInfo

 

Returns

The GstBuffer from the probe.

[transfer none]


gst_pad_probe_info_get_buffer_list ()

GstBufferList *
gst_pad_probe_info_get_buffer_list (GstPadProbeInfo *info);

gst_pad_probe_info_get_event ()

GstEvent *
gst_pad_probe_info_get_event (GstPadProbeInfo *info);

Parameters

info

a GstPadProbeInfo

 

Returns

The GstEvent from the probe.

[transfer none]


gst_pad_probe_info_get_query ()

GstQuery *
gst_pad_probe_info_get_query (GstPadProbeInfo *info);

Parameters

info

a GstPadProbeInfo

 

Returns

The GstQuery from the probe.

[transfer none]


GST_PAD_PROBE_INFO_OFFSET()

#define GST_PAD_PROBE_INFO_OFFSET(d)       ((d)->offset)

GST_PAD_PROBE_INFO_SIZE()

#define GST_PAD_PROBE_INFO_SIZE(d)         ((d)->size)

GstPadProbeCallback ()

GstPadProbeReturn
(*GstPadProbeCallback) (GstPad *pad,
                        GstPadProbeInfo *info,
                        gpointer user_data);

Callback used by gst_pad_add_probe(). Gets called to notify about the current blocking type.

The callback is allowed to modify the data pointer in info .

Parameters

pad

the GstPad that is blocked

 

info

GstPadProbeInfo

 

user_data

the gpointer to optional user data.

 

Returns

a GstPadProbeReturn


gst_pad_add_probe ()

gulong
gst_pad_add_probe (GstPad *pad,
                   GstPadProbeType mask,
                   GstPadProbeCallback callback,
                   gpointer user_data,
                   GDestroyNotify destroy_data);

Be notified of different states of pads. The provided callback is called for every state that matches mask .

Parameters

pad

the GstPad to add the probe to

 

mask

the probe mask

 

callback

GstPadProbeCallback that will be called with notifications of the pad state

 

user_data

user data passed to the callback.

[closure]

destroy_data

GDestroyNotify for user_data

 

Returns

an id or 0 if no probe is pending. The id can be used to remove the probe with gst_pad_remove_probe(). When using GST_PAD_PROBE_TYPE_IDLE it can happend that the probe can be run immediately and if the probe returns GST_PAD_PROBE_REMOVE this functions returns 0.

MT safe.


gst_pad_remove_probe ()

void
gst_pad_remove_probe (GstPad *pad,
                      gulong id);

Remove the probe with id from pad .

MT safe.

Parameters

pad

the GstPad with the probe

 

id

the probe id to remove

 

gst_pad_is_blocked ()

gboolean
gst_pad_is_blocked (GstPad *pad);

Checks if the pad is blocked or not. This function returns the last requested state of the pad. It is not certain that the pad is actually blocking at this point (see gst_pad_is_blocking()).

Parameters

pad

the GstPad to query

 

Returns

TRUE if the pad is blocked.

MT safe.


gst_pad_is_blocking ()

gboolean
gst_pad_is_blocking (GstPad *pad);

Checks if the pad is blocking or not. This is a guaranteed state of whether the pad is actually blocking on a GstBuffer or a GstEvent.

Parameters

pad

the GstPad to query

 

Returns

TRUE if the pad is blocking.

MT safe.


gst_pad_get_offset ()

gint64
gst_pad_get_offset (GstPad *pad);

Get the offset applied to the running time of pad . pad has to be a source pad.

Parameters

pad

a GstPad

 

Returns

the offset.


gst_pad_set_offset ()

void
gst_pad_set_offset (GstPad *pad,
                    gint64 offset);

Set the offset that will be applied to the running time of pad .

Parameters

pad

a GstPad

 

offset

the offset

 

gst_pad_new ()

GstPad *
gst_pad_new (const gchar *name,
             GstPadDirection direction);

Creates a new pad with the given name in the given direction. If name is NULL, a guaranteed unique name (across all pads) will be assigned. This function makes a copy of the name so you can safely free the name.

Parameters

name

the name of the new pad.

[allow-none]

direction

the GstPadDirection of the pad.

 

Returns

a new GstPad, or NULL in case of an error.

MT safe.

[transfer floating][nullable]


gst_pad_new_from_template ()

GstPad *
gst_pad_new_from_template (GstPadTemplate *templ,
                           const gchar *name);

Creates a new pad with the given name from the given template. If name is NULL, a guaranteed unique name (across all pads) will be assigned. This function makes a copy of the name so you can safely free the name.

Parameters

templ

the pad template to use

 

name

the name of the element.

[allow-none]

Returns

a new GstPad, or NULL in case of an error.

[transfer floating][nullable]


gst_pad_new_from_static_template ()

GstPad *
gst_pad_new_from_static_template (GstStaticPadTemplate *templ,
                                  const gchar *name);

Creates a new pad with the given name from the given static template. If name is NULL, a guaranteed unique name (across all pads) will be assigned. This function makes a copy of the name so you can safely free the name.

Parameters

templ

the GstStaticPadTemplate to use

 

name

the name of the element

 

Returns

a new GstPad, or NULL in case of an error.

[transfer floating][nullable]


gst_pad_set_chain_function()

#define gst_pad_set_chain_function(p,f)         gst_pad_set_chain_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_chain_function_full() with NULL for the user_data and notify.

Parameters

p

a sink GstPad.

 

f

the GstPadChainFunction to set.

 

gst_pad_set_chain_function_full ()

void
gst_pad_set_chain_function_full (GstPad *pad,
                                 GstPadChainFunction chain,
                                 gpointer user_data,
                                 GDestroyNotify notify);

Sets the given chain function for the pad. The chain function is called to process a GstBuffer input buffer. see GstPadChainFunction for more details.

Parameters

pad

a sink GstPad.

 

chain

the GstPadChainFunction to set.

 

user_data

user_data passed to notify

 

notify

notify called when chain will not be used anymore.

 

GstPadChainFunction ()

GstFlowReturn
(*GstPadChainFunction) (GstPad *pad,
                        GstObject *parent,
                        GstBuffer *buffer);

A function that will be called on sinkpads when chaining buffers. The function typically processes the data contained in the buffer and either consumes the data or passes it on to the internally linked pad(s).

The implementer of this function receives a refcount to buffer and should gst_buffer_unref() when the buffer is no longer needed.

When a chain function detects an error in the data stream, it must post an error on the bus and return an appropriate GstFlowReturn value.

Parameters

pad

the sink GstPad that performed the chain.

 

parent

the parent of pad . If the GST_PAD_FLAG_NEED_PARENT flag is set, parent is guaranteed to be not-NULL and remain valid during the execution of this function.

[allow-none]

buffer

the GstBuffer that is chained, not NULL.

 

Returns

GST_FLOW_OK for success


gst_pad_set_chain_list_function()

#define gst_pad_set_chain_list_function(p,f)    gst_pad_set_chain_list_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_chain_list_function_full() with NULL for the user_data and notify.

Parameters

p

a sink GstPad.

 

f

the GstPadChainListFunction to set.

 

gst_pad_set_chain_list_function_full ()

void
gst_pad_set_chain_list_function_full (GstPad *pad,
                                      GstPadChainListFunction chainlist,
                                      gpointer user_data,
                                      GDestroyNotify notify);

Sets the given chain list function for the pad. The chainlist function is called to process a GstBufferList input buffer list. See GstPadChainListFunction for more details.

Parameters

pad

a sink GstPad.

 

chainlist

the GstPadChainListFunction to set.

 

user_data

user_data passed to notify

 

notify

notify called when chainlist will not be used anymore.

 

GstPadChainListFunction ()

GstFlowReturn
(*GstPadChainListFunction) (GstPad *pad,
                            GstObject *parent,
                            GstBufferList *list);

A function that will be called on sinkpads when chaining buffer lists. The function typically processes the data contained in the buffer list and either consumes the data or passes it on to the internally linked pad(s).

The implementer of this function receives a refcount to list and should gst_buffer_list_unref() when the list is no longer needed.

When a chainlist function detects an error in the data stream, it must post an error on the bus and return an appropriate GstFlowReturn value.

Parameters

pad

the sink GstPad that performed the chain.

 

parent

the parent of pad . If the GST_PAD_FLAG_NEED_PARENT flag is set, parent is guaranteed to be not-NULL and remain valid during the execution of this function.

[allow-none]

list

the GstBufferList that is chained, not NULL.

 

Returns

GST_FLOW_OK for success


gst_pad_get_range ()

GstFlowReturn
gst_pad_get_range (GstPad *pad,
                   guint64 offset,
                   guint size,
                   GstBuffer **buffer);

When pad is flushing this function returns GST_FLOW_FLUSHING immediately and buffer is NULL.

Calls the getrange function of pad , see GstPadGetRangeFunction for a description of a getrange function. If pad has no getrange function installed (see gst_pad_set_getrange_function()) this function returns GST_FLOW_NOT_SUPPORTED.

If buffer points to a variable holding NULL, a valid new GstBuffer will be placed in buffer when this function returns GST_FLOW_OK. The new buffer must be freed with gst_buffer_unref() after usage.

When buffer points to a variable that points to a valid GstBuffer, the buffer will be filled with the result data when this function returns GST_FLOW_OK. If the provided buffer is larger than size , only size bytes will be filled in the result buffer and its size will be updated accordingly.

Note that less than size bytes can be returned in buffer when, for example, an EOS condition is near or when buffer is not large enough to hold size bytes. The caller should check the result buffer size to get the result size.

When this function returns any other result value than GST_FLOW_OK, buffer will be unchanged.

This is a lowlevel function. Usually gst_pad_pull_range() is used.

Parameters

pad

a src GstPad, returns GST_FLOW_ERROR if not.

 

offset

The start offset of the buffer

 

size

The length of the buffer

 

buffer

a pointer to hold the GstBuffer, returns GST_FLOW_ERROR if NULL.

[out callee-allocates]

Returns

a GstFlowReturn from the pad.

MT safe.


gst_pad_set_getrange_function()

#define gst_pad_set_getrange_function(p,f)      gst_pad_set_getrange_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_getrange_function_full() with NULL for the user_data and notify.

Parameters

p

a source GstPad.

 

f

the GstPadGetRangeFunction to set.

 

gst_pad_set_getrange_function_full ()

void
gst_pad_set_getrange_function_full (GstPad *pad,
                                    GstPadGetRangeFunction get,
                                    gpointer user_data,
                                    GDestroyNotify notify);

Sets the given getrange function for the pad. The getrange function is called to produce a new GstBuffer to start the processing pipeline. see GstPadGetRangeFunction for a description of the getrange function.

Parameters

pad

a source GstPad.

 

get

the GstPadGetRangeFunction to set.

 

user_data

user_data passed to notify

 

notify

notify called when get will not be used anymore.

 

GstPadGetRangeFunction ()

GstFlowReturn
(*GstPadGetRangeFunction) (GstPad *pad,
                           GstObject *parent,
                           guint64 offset,
                           guint length,
                           GstBuffer **buffer);

This function will be called on source pads when a peer element request a buffer at the specified offset and length . If this function returns GST_FLOW_OK, the result buffer will be stored in buffer . The contents of buffer is invalid for any other return value.

This function is installed on a source pad with gst_pad_set_getrange_function() and can only be called on source pads after they are successfully activated with gst_pad_activate_mode() with the GST_PAD_MODE_PULL.

offset and length are always given in byte units. offset must normally be a value between 0 and the length in bytes of the data available on pad . The length (duration in bytes) can be retrieved with a GST_QUERY_DURATION or with a GST_QUERY_SEEKING.

Any offset larger or equal than the length will make the function return GST_FLOW_EOS, which corresponds to EOS. In this case buffer does not contain a valid buffer.

The buffer size of buffer will only be smaller than length when offset is near the end of the stream. In all other cases, the size of buffer must be exactly the requested size.

It is allowed to call this function with a 0 length and valid offset , in which case buffer will contain a 0-sized buffer and the function returns GST_FLOW_OK.

When this function is called with a -1 offset , the sequentially next buffer of length length in the stream is returned.

When this function is called with a -1 length , a buffer with a default optimal length is returned in buffer . The length might depend on the value of offset .

Parameters

pad

the src GstPad to perform the getrange on.

 

parent

the parent of pad . If the GST_PAD_FLAG_NEED_PARENT flag is set, parent is guaranteed to be not-NULL and remain valid during the execution of this function.

[allow-none]

offset

the offset of the range

 

length

the length of the range

 

buffer

a memory location to hold the result buffer, cannot be NULL.

 

Returns

GST_FLOW_OK for success and a valid buffer in buffer . Any other return value leaves buffer undefined.


gst_pad_set_event_function()

#define gst_pad_set_event_function(p,f)         gst_pad_set_event_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_event_function_full() with NULL for the user_data and notify.

Parameters

p

a GstPad of either direction.

 

f

the GstPadEventFunction to set.

 

gst_pad_set_event_function_full ()

void
gst_pad_set_event_function_full (GstPad *pad,
                                 GstPadEventFunction event,
                                 gpointer user_data,
                                 GDestroyNotify notify);

Sets the given event handler for the pad.

Parameters

pad

a GstPad of either direction.

 

event

the GstPadEventFunction to set.

 

user_data

user_data passed to notify

 

notify

notify called when event will not be used anymore.

 

GstPadEventFunction ()

gboolean
(*GstPadEventFunction) (GstPad *pad,
                        GstObject *parent,
                        GstEvent *event);

Function signature to handle an event for the pad.

Parameters

pad

the GstPad to handle the event.

 

parent

the parent of pad . If the GST_PAD_FLAG_NEED_PARENT flag is set, parent is guaranteed to be not-NULL and remain valid during the execution of this function.

[allow-none]

event

the GstEvent to handle.

 

Returns

TRUE if the pad could handle the event.


gst_pad_set_link_function()

#define gst_pad_set_link_function(p,f)          gst_pad_set_link_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_link_function_full() with NULL for the user_data and notify.

Parameters

p

a GstPad.

 

f

the GstPadLinkFunction to set.

 

gst_pad_set_link_function_full ()

void
gst_pad_set_link_function_full (GstPad *pad,
                                GstPadLinkFunction link,
                                gpointer user_data,
                                GDestroyNotify notify);

Sets the given link function for the pad. It will be called when the pad is linked with another pad.

The return value GST_PAD_LINK_OK should be used when the connection can be made.

The return value GST_PAD_LINK_REFUSED should be used when the connection cannot be made for some reason.

If link is installed on a source pad, it should call the GstPadLinkFunction of the peer sink pad, if present.

Parameters

pad

a GstPad.

 

link

the GstPadLinkFunction to set.

 

user_data

user_data passed to notify

 

notify

notify called when link will not be used anymore.

 

GstPadLinkFunction ()

GstPadLinkReturn
(*GstPadLinkFunction) (GstPad *pad,
                       GstObject *parent,
                       GstPad *peer);

Function signature to handle a new link on the pad.

Parameters

pad

the GstPad that is linked.

 

parent

the parent of pad . If the GST_PAD_FLAG_NEED_PARENT flag is set, parent is guaranteed to be not-NULL and remain valid during the execution of this function.

[allow-none]

peer

the peer GstPad of the link

 

Returns

the result of the link with the specified peer.


gst_pad_set_unlink_function()

#define gst_pad_set_unlink_function(p,f)        gst_pad_set_unlink_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_unlink_function_full() with NULL for the user_data and notify.

Parameters

p

a GstPad.

 

f

the GstPadUnlinkFunction to set.

 

gst_pad_set_unlink_function_full ()

void
gst_pad_set_unlink_function_full (GstPad *pad,
                                  GstPadUnlinkFunction unlink,
                                  gpointer user_data,
                                  GDestroyNotify notify);

Sets the given unlink function for the pad. It will be called when the pad is unlinked.

Parameters

pad

a GstPad.

 

unlink

the GstPadUnlinkFunction to set.

 

user_data

user_data passed to notify

 

notify

notify called when unlink will not be used anymore.

 

GstPadUnlinkFunction ()

void
(*GstPadUnlinkFunction) (GstPad *pad,
                         GstObject *parent);

Function signature to handle a unlinking the pad prom its peer.

Parameters

pad

the GstPad that is linked.

 

parent

the parent of pad . If the GST_PAD_FLAG_NEED_PARENT flag is set, parent is guaranteed to be not-NULL and remain valid during the execution of this function.

[allow-none]

gst_pad_proxy_query_caps ()

gboolean
gst_pad_proxy_query_caps (GstPad *pad,
                          GstQuery *query);

Calls gst_pad_query_caps() for all internally linked pads of pad and returns the intersection of the results.

This function is useful as a default caps query function for an element that can handle any stream format, but requires all its pads to have the same caps. Two such elements are tee and adder.

Parameters

pad

a GstPad to proxy.

 

query

a CAPS GstQuery.

 

Returns

TRUE if query could be executed


gst_pad_proxy_query_accept_caps ()

gboolean
gst_pad_proxy_query_accept_caps (GstPad *pad,
                                 GstQuery *query);

Checks if all internally linked pads of pad accepts the caps in query and returns the intersection of the results.

This function is useful as a default accept caps query function for an element that can handle any stream format, but requires caps that are acceptable for all opposite pads.

Parameters

pad

a GstPad to proxy.

 

query

an ACCEPT_CAPS GstQuery.

 

Returns

TRUE if query could be executed


gst_pad_set_activate_function()

#define gst_pad_set_activate_function(p,f)      gst_pad_set_activate_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_activate_function_full() with NULL for the user_data and notify.

Parameters

p

a GstPad.

 

f

the GstPadActivateFunction to set.

 

gst_pad_set_activate_function_full ()

void
gst_pad_set_activate_function_full (GstPad *pad,
                                    GstPadActivateFunction activate,
                                    gpointer user_data,
                                    GDestroyNotify notify);

Sets the given activate function for pad . The activate function will dispatch to gst_pad_activate_mode() to perform the actual activation. Only makes sense to set on sink pads.

Call this function if your sink pad can start a pull-based task.

Parameters

pad

a GstPad.

 

activate

the GstPadActivateFunction to set.

 

user_data

user_data passed to notify

 

notify

notify called when activate will not be used anymore.

 

GstPadActivateFunction ()

gboolean
(*GstPadActivateFunction) (GstPad *pad,
                           GstObject *parent);

This function is called when the pad is activated during the element READY to PAUSED state change. By default this function will call the activate function that puts the pad in push mode but elements can override this function to activate the pad in pull mode if they wish.

Parameters

pad

a GstPad

 

parent

the parent of pad

 

Returns

TRUE if the pad could be activated.


gst_pad_set_activatemode_function()

#define gst_pad_set_activatemode_function(p,f)  gst_pad_set_activatemode_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_activatemode_function_full() with NULL for the user_data and notify.

Parameters

p

a GstPad.

 

f

the GstPadActivateModeFunction to set.

 

gst_pad_set_activatemode_function_full ()

void
gst_pad_set_activatemode_function_full
                               (GstPad *pad,
                                GstPadActivateModeFunction activatemode,
                                gpointer user_data,
                                GDestroyNotify notify);

Sets the given activate_mode function for the pad. An activate_mode function prepares the element for data passing.

Parameters

pad

a GstPad.

 

activatemode

the GstPadActivateModeFunction to set.

 

user_data

user_data passed to notify

 

notify

notify called when activatemode will not be used anymore.

 

GstPadActivateModeFunction ()

gboolean
(*GstPadActivateModeFunction) (GstPad *pad,
                               GstObject *parent,
                               GstPadMode mode,
                               gboolean active);

The prototype of the push and pull activate functions.

Parameters

pad

a GstPad

 

parent

the parent of pad

 

mode

the requested activation mode of pad

 

active

activate or deactivate the pad.

 

Returns

TRUE if the pad could be activated or deactivated.


gst_pad_needs_reconfigure ()

gboolean
gst_pad_needs_reconfigure (GstPad *pad);

Check the GST_PAD_FLAG_NEED_RECONFIGURE flag on pad and return TRUE if the flag was set.

Parameters

pad

the GstPad to check

 

Returns

TRUE is the GST_PAD_FLAG_NEED_RECONFIGURE flag is set on pad .


gst_pad_check_reconfigure ()

gboolean
gst_pad_check_reconfigure (GstPad *pad);

Check and clear the GST_PAD_FLAG_NEED_RECONFIGURE flag on pad and return TRUE if the flag was set.

Parameters

pad

the GstPad to check

 

Returns

TRUE is the GST_PAD_FLAG_NEED_RECONFIGURE flag was set on pad .


gst_pad_mark_reconfigure ()

void
gst_pad_mark_reconfigure (GstPad *pad);

Mark a pad for needing reconfiguration. The next call to gst_pad_check_reconfigure() will return TRUE after this call.

Parameters

pad

the GstPad to mark

 

gst_pad_push ()

GstFlowReturn
gst_pad_push (GstPad *pad,
              GstBuffer *buffer);

Pushes a buffer to the peer of pad .

This function will call installed block probes before triggering any installed data probes.

The function proceeds calling gst_pad_chain() on the peer pad and returns the value from that function. If pad has no peer, GST_FLOW_NOT_LINKED will be returned.

In all cases, success or failure, the caller loses its reference to buffer after calling this function.

Parameters

pad

a source GstPad, returns GST_FLOW_ERROR if not.

 

buffer

the GstBuffer to push returns GST_FLOW_ERROR if not.

[transfer full]

Returns

a GstFlowReturn from the peer pad.

MT safe.


gst_pad_push_event ()

gboolean
gst_pad_push_event (GstPad *pad,
                    GstEvent *event);

Sends the event to the peer of the given pad. This function is mainly used by elements to send events to their peer elements.

This function takes ownership of the provided event so you should gst_event_ref() it if you want to reuse the event after this call.

Parameters

pad

a GstPad to push the event to.

 

event

the GstEvent to send to the pad.

[transfer full]

Returns

TRUE if the event was handled.

MT safe.


gst_pad_push_list ()

GstFlowReturn
gst_pad_push_list (GstPad *pad,
                   GstBufferList *list);

Pushes a buffer list to the peer of pad .

This function will call installed block probes before triggering any installed data probes.

The function proceeds calling the chain function on the peer pad and returns the value from that function. If pad has no peer, GST_FLOW_NOT_LINKED will be returned. If the peer pad does not have any installed chainlist function every group buffer of the list will be merged into a normal GstBuffer and chained via gst_pad_chain().

In all cases, success or failure, the caller loses its reference to list after calling this function.

Parameters

pad

a source GstPad, returns GST_FLOW_ERROR if not.

 

list

the GstBufferList to push returns GST_FLOW_ERROR if not.

[transfer full]

Returns

a GstFlowReturn from the peer pad.

MT safe.


gst_pad_pull_range ()

GstFlowReturn
gst_pad_pull_range (GstPad *pad,
                    guint64 offset,
                    guint size,
                    GstBuffer **buffer);

Pulls a buffer from the peer pad or fills up a provided buffer.

This function will first trigger the pad block signal if it was installed.

When pad is not linked GST_FLOW_NOT_LINKED is returned else this function returns the result of gst_pad_get_range() on the peer pad. See gst_pad_get_range() for a list of return values and for the semantics of the arguments of this function.

If buffer points to a variable holding NULL, a valid new GstBuffer will be placed in buffer when this function returns GST_FLOW_OK. The new buffer must be freed with gst_buffer_unref() after usage. When this function returns any other result value, buffer will still point to NULL.

When buffer points to a variable that points to a valid GstBuffer, the buffer will be filled with the result data when this function returns GST_FLOW_OK. When this function returns any other result value, buffer will be unchanged. If the provided buffer is larger than size , only size bytes will be filled in the result buffer and its size will be updated accordingly.

Note that less than size bytes can be returned in buffer when, for example, an EOS condition is near or when buffer is not large enough to hold size bytes. The caller should check the result buffer size to get the result size.

Parameters

pad

a sink GstPad, returns GST_FLOW_ERROR if not.

 

offset

The start offset of the buffer

 

size

The length of the buffer

 

buffer

a pointer to hold the GstBuffer, returns GST_FLOW_ERROR if NULL.

[out callee-allocates]

Returns

a GstFlowReturn from the peer pad.

MT safe.


gst_pad_activate_mode ()

gboolean
gst_pad_activate_mode (GstPad *pad,
                       GstPadMode mode,
                       gboolean active);

Activates or deactivates the given pad in mode via dispatching to the pad's activatemodefunc. For use from within pad activation functions only.

If you don't know what this is, you probably don't want to call it.

Parameters

pad

the GstPad to activate or deactivate.

 

mode

the requested activation mode

 

active

whether or not the pad should be active.

 

Returns

TRUE if the operation was successful.

MT safe.


gst_pad_send_event ()

gboolean
gst_pad_send_event (GstPad *pad,
                    GstEvent *event);

Sends the event to the pad. This function can be used by applications to send events in the pipeline.

If pad is a source pad, event should be an upstream event. If pad is a sink pad, event should be a downstream event. For example, you would not send a GST_EVENT_EOS on a src pad; EOS events only propagate downstream. Furthermore, some downstream events have to be serialized with data flow, like EOS, while some can travel out-of-band, like GST_EVENT_FLUSH_START. If the event needs to be serialized with data flow, this function will take the pad's stream lock while calling its event function.

To find out whether an event type is upstream, downstream, or downstream and serialized, see GstEventTypeFlags, gst_event_type_get_flags(), GST_EVENT_IS_UPSTREAM, GST_EVENT_IS_DOWNSTREAM, and GST_EVENT_IS_SERIALIZED. Note that in practice that an application or plugin doesn't need to bother itself with this information; the core handles all necessary locks and checks.

This function takes ownership of the provided event so you should gst_event_ref() it if you want to reuse the event after this call.

Parameters

pad

a GstPad to send the event to.

 

event

the GstEvent to send to the pad.

[transfer full]

Returns

TRUE if the event was handled.


gst_pad_event_default ()

gboolean
gst_pad_event_default (GstPad *pad,
                       GstObject *parent,
                       GstEvent *event);

Invokes the default event handler for the given pad.

The EOS event will pause the task associated with pad before it is forwarded to all internally linked pads,

The the event is sent to all pads internally linked to pad . This function takes ownership of event .

Parameters

pad

a GstPad to call the default event handler on.

 

parent

the parent of pad or NULL.

[allow-none]

event

the GstEvent to handle.

[transfer full]

Returns

TRUE if the event was sent successfully.


gst_pad_query ()

gboolean
gst_pad_query (GstPad *pad,
               GstQuery *query);

Dispatches a query to a pad. The query should have been allocated by the caller via one of the type-specific allocation functions. The element that the pad belongs to is responsible for filling the query with an appropriate response, which should then be parsed with a type-specific query parsing function.

Again, the caller is responsible for both the allocation and deallocation of the query structure.

Please also note that some queries might need a running pipeline to work.

Parameters

pad

a GstPad to invoke the default query on.

 

query

the GstQuery to perform.

[transfer none]

Returns

TRUE if the query could be performed.


gst_pad_peer_query ()

gboolean
gst_pad_peer_query (GstPad *pad,
                    GstQuery *query);

Performs gst_pad_query() on the peer of pad .

The caller is responsible for both the allocation and deallocation of the query structure.

Parameters

pad

a GstPad to invoke the peer query on.

 

query

the GstQuery to perform.

[transfer none]

Returns

TRUE if the query could be performed. This function returns FALSE if pad has no peer.


gst_pad_query_default ()

gboolean
gst_pad_query_default (GstPad *pad,
                       GstObject *parent,
                       GstQuery *query);

Invokes the default query handler for the given pad. The query is sent to all pads internally linked to pad . Note that if there are many possible sink pads that are internally linked to pad , only one will be sent the query. Multi-sinkpad elements should implement custom query handlers.

Parameters

pad

a GstPad to call the default query handler on.

 

parent

the parent of pad or NULL.

[allow-none]

query

the GstQuery to handle.

[transfer none]

Returns

TRUE if the query was performed successfully.


gst_pad_query_position ()

gboolean
gst_pad_query_position (GstPad *pad,
                        GstFormat format,
                        gint64 *cur);

Queries a pad for the stream position.

Parameters

pad

a GstPad to invoke the position query on.

 

format

the GstFormat requested

 

cur

A location in which to store the current position, or NULL.

[out][allow-none]

Returns

TRUE if the query could be performed.


gst_pad_query_duration ()

gboolean
gst_pad_query_duration (GstPad *pad,
                        GstFormat format,
                        gint64 *duration);

Queries a pad for the total stream duration.

Parameters

pad

a GstPad to invoke the duration query on.

 

format

the GstFormat requested

 

duration

a location in which to store the total duration, or NULL.

[out][allow-none]

Returns

TRUE if the query could be performed.


gst_pad_query_convert ()

gboolean
gst_pad_query_convert (GstPad *pad,
                       GstFormat src_format,
                       gint64 src_val,
                       GstFormat dest_format,
                       gint64 *dest_val);

Queries a pad to convert src_val in src_format to dest_format .

Parameters

pad

a GstPad to invoke the convert query on.

 

src_format

a GstFormat to convert from.

 

src_val

a value to convert.

 

dest_format

the GstFormat to convert to.

 

dest_val

a pointer to the result.

[out]

Returns

TRUE if the query could be performed.


gst_pad_query_accept_caps ()

gboolean
gst_pad_query_accept_caps (GstPad *pad,
                           GstCaps *caps);

Check if the given pad accepts the caps.

Parameters

pad

a GstPad to check

 

caps

a GstCaps to check on the pad

 

Returns

TRUE if the pad can accept the caps.


gst_pad_query_caps ()

GstCaps *
gst_pad_query_caps (GstPad *pad,
                    GstCaps *filter);

Gets the capabilities this pad can produce or consume. Note that this method doesn't necessarily return the caps set by sending a gst_event_new_caps() - use gst_pad_get_current_caps() for that instead. gst_pad_query_caps returns all possible caps a pad can operate with, using the pad's CAPS query function, If the query fails, this function will return filter , if not NULL, otherwise ANY.

When called on sinkpads filter contains the caps that upstream could produce in the order preferred by upstream. When called on srcpads filter contains the caps accepted by downstream in the preferred order. filter might be NULL but if it is not NULL the returned caps will be a subset of filter .

Note that this function does not return writable GstCaps, use gst_caps_make_writable() before modifying the caps.

Parameters

pad

a GstPad to get the capabilities of.

 

filter

suggested GstCaps, or NULL.

[allow-none]

Returns

the caps of the pad with incremented ref-count.

[transfer full]


gst_pad_peer_query_position ()

gboolean
gst_pad_peer_query_position (GstPad *pad,
                             GstFormat format,
                             gint64 *cur);

Queries the peer of a given sink pad for the stream position.

Parameters

pad

a GstPad on whose peer to invoke the position query on. Must be a sink pad.

 

format

the GstFormat requested

 

cur

a location in which to store the current position, or NULL.

[out][allow-none]

Returns

TRUE if the query could be performed.


gst_pad_peer_query_duration ()

gboolean
gst_pad_peer_query_duration (GstPad *pad,
                             GstFormat format,
                             gint64 *duration);

Queries the peer pad of a given sink pad for the total stream duration.

Parameters

pad

a GstPad on whose peer pad to invoke the duration query on. Must be a sink pad.

 

format

the GstFormat requested

 

duration

a location in which to store the total duration, or NULL.

[out][allow-none]

Returns

TRUE if the query could be performed.


gst_pad_peer_query_convert ()

gboolean
gst_pad_peer_query_convert (GstPad *pad,
                            GstFormat src_format,
                            gint64 src_val,
                            GstFormat dest_format,
                            gint64 *dest_val);

Queries the peer pad of a given sink pad to convert src_val in src_format to dest_format .

Parameters

pad

a GstPad, on whose peer pad to invoke the convert query on. Must be a sink pad.

 

src_format

a GstFormat to convert from.

 

src_val

a value to convert.

 

dest_format

the GstFormat to convert to.

 

dest_val

a pointer to the result.

[out]

Returns

TRUE if the query could be performed.


gst_pad_peer_query_accept_caps ()

gboolean
gst_pad_peer_query_accept_caps (GstPad *pad,
                                GstCaps *caps);

Check if the peer of pad accepts caps . If pad has no peer, this function returns TRUE.

Parameters

pad

a GstPad to check the peer of

 

caps

a GstCaps to check on the pad

 

Returns

TRUE if the peer of pad can accept the caps or pad has no peer.


gst_pad_peer_query_caps ()

GstCaps *
gst_pad_peer_query_caps (GstPad *pad,
                         GstCaps *filter);

Gets the capabilities of the peer connected to this pad. Similar to gst_pad_query_caps().

When called on srcpads filter contains the caps that upstream could produce in the order preferred by upstream. When called on sinkpads filter contains the caps accepted by downstream in the preferred order. filter might be NULL but if it is not NULL the returned caps will be a subset of filter .

Parameters

pad

a GstPad to get the capabilities of.

 

filter

a GstCaps filter, or NULL.

[allow-none]

Returns

the caps of the peer pad with incremented ref-count. When there is no peer pad, this function returns filter or, when filter is NULL, ANY caps.


gst_pad_set_query_function()

#define gst_pad_set_query_function(p,f)   gst_pad_set_query_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_query_function_full() with NULL for the user_data and notify.

Parameters

p

a GstPad of either direction.

 

f

the GstPadQueryFunction to set.

 

gst_pad_set_query_function_full ()

void
gst_pad_set_query_function_full (GstPad *pad,
                                 GstPadQueryFunction query,
                                 gpointer user_data,
                                 GDestroyNotify notify);

Set the given query function for the pad.

Parameters

pad

a GstPad of either direction.

 

query

the GstPadQueryFunction to set.

 

user_data

user_data passed to notify

 

notify

notify called when query will not be used anymore.

 

GstPadQueryFunction ()

gboolean
(*GstPadQueryFunction) (GstPad *pad,
                        GstObject *parent,
                        GstQuery *query);

The signature of the query function.

Parameters

pad

the GstPad to query.

 

parent

the parent of pad . If the GST_PAD_FLAG_NEED_PARENT flag is set, parent is guaranteed to be not-NULL and remain valid during the execution of this function.

[allow-none]

query

the GstQuery object to execute

 

Returns

TRUE if the query could be performed.


gst_pad_set_iterate_internal_links_function()

#define gst_pad_set_iterate_internal_links_function(p,f) gst_pad_set_iterate_internal_links_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_iterate_internal_links_function_full() with NULL for the user_data and notify.

Parameters

p

a GstPad of either direction.

 

f

the GstPadIterIntLinkFunction to set.

 

gst_pad_set_iterate_internal_links_function_full ()

void
gst_pad_set_iterate_internal_links_function_full
                               (GstPad *pad,
                                GstPadIterIntLinkFunction iterintlink,
                                gpointer user_data,
                                GDestroyNotify notify);

Sets the given internal link iterator function for the pad.

Parameters

pad

a GstPad of either direction.

 

iterintlink

the GstPadIterIntLinkFunction to set.

 

user_data

user_data passed to notify

 

notify

notify called when iterintlink will not be used anymore.

 

GstPadIterIntLinkFunction ()

GstIterator *
(*GstPadIterIntLinkFunction) (GstPad *pad,
                              GstObject *parent);

The signature of the internal pad link iterator function.

Parameters

pad

The GstPad to query.

 

parent

the parent of pad . If the GST_PAD_FLAG_NEED_PARENT flag is set, parent is guaranteed to be not-NULL and remain valid during the execution of this function.

[allow-none]

Returns

a new GstIterator that will iterate over all pads that are linked to the given pad on the inside of the parent element.

the caller must call gst_iterator_free() after usage.


gst_pad_iterate_internal_links ()

GstIterator *
gst_pad_iterate_internal_links (GstPad *pad);

Gets an iterator for the pads to which the given pad is linked to inside of the parent element.

Each GstPad element yielded by the iterator will have its refcount increased, so unref after use.

Free-function: gst_iterator_free

Parameters

pad

the GstPad to get the internal links of.

 

Returns

a new GstIterator of GstPad or NULL when the pad does not have an iterator function configured. Use gst_iterator_free() after usage.

[transfer full][nullable]


gst_pad_iterate_internal_links_default ()

GstIterator *
gst_pad_iterate_internal_links_default
                               (GstPad *pad,
                                GstObject *parent);

Iterate the list of pads to which the given pad is linked to inside of the parent element. This is the default handler, and thus returns an iterator of all of the pads inside the parent element with opposite direction.

The caller must free this iterator after use with gst_iterator_free().

Parameters

pad

the GstPad to get the internal links of.

 

parent

the parent of pad or NULL.

[allow-none]

Returns

a GstIterator of GstPad, or NULL if pad has no parent. Unref each returned pad with gst_object_unref().

[nullable]


gst_pad_set_element_private ()

void
gst_pad_set_element_private (GstPad *pad,
                             gpointer priv);

Set the given private data gpointer on the pad. This function can only be used by the element that owns the pad. No locking is performed in this function.

Parameters

pad

the GstPad to set the private data of.

 

priv

The private data to attach to the pad.

 

gst_pad_get_element_private ()

gpointer
gst_pad_get_element_private (GstPad *pad);

Gets the private data of a pad. No locking is performed in this function.

Parameters

pad

the GstPad to get the private data of.

 

Returns

a gpointer to the private data.

[transfer none]


gst_pad_create_stream_id ()

gchar *
gst_pad_create_stream_id (GstPad *pad,
                          GstElement *parent,
                          const gchar *stream_id);

Creates a stream-id for the source GstPad pad by combining the upstream information with the optional stream_id of the stream of pad . pad must have a parent GstElement and which must have zero or one sinkpad. stream_id can only be NULL if the parent element of pad has only a single source pad.

This function generates an unique stream-id by getting the upstream stream-start event stream ID and appending stream_id to it. If the element has no sinkpad it will generate an upstream stream-id by doing an URI query on the element and in the worst case just uses a random number. Source elements that don't implement the URI handler interface should ideally generate a unique, deterministic stream-id manually instead.

Since stream IDs are sorted alphabetically, any numbers in the stream ID should be printed with a fixed number of characters, preceded by 0's, such as by using the format %03u instead of %u.

Parameters

pad

A source GstPad

 

parent

Parent GstElement of pad

 

stream_id

The stream-id.

[allow-none]

Returns

A stream-id for pad . g_free() after usage.


gst_pad_create_stream_id_printf ()

gchar *
gst_pad_create_stream_id_printf (GstPad *pad,
                                 GstElement *parent,
                                 const gchar *stream_id,
                                 ...);

Creates a stream-id for the source GstPad pad by combining the upstream information with the optional stream_id of the stream of pad . pad must have a parent GstElement and which must have zero or one sinkpad. stream_id can only be NULL if the parent element of pad has only a single source pad.

This function generates an unique stream-id by getting the upstream stream-start event stream ID and appending stream_id to it. If the element has no sinkpad it will generate an upstream stream-id by doing an URI query on the element and in the worst case just uses a random number. Source elements that don't implement the URI handler interface should ideally generate a unique, deterministic stream-id manually instead.

Parameters

pad

A source GstPad

 

parent

Parent GstElement of pad

 

stream_id

The stream-id.

[allow-none]

...

parameters for the stream_id format string

 

Returns

A stream-id for pad . g_free() after usage.


gst_pad_create_stream_id_printf_valist ()

gchar *
gst_pad_create_stream_id_printf_valist
                               (GstPad *pad,
                                GstElement *parent,
                                const gchar *stream_id,
                                va_list var_args);

Creates a stream-id for the source GstPad pad by combining the upstream information with the optional stream_id of the stream of pad . pad must have a parent GstElement and which must have zero or one sinkpad. stream_id can only be NULL if the parent element of pad has only a single source pad.

This function generates an unique stream-id by getting the upstream stream-start event stream ID and appending stream_id to it. If the element has no sinkpad it will generate an upstream stream-id by doing an URI query on the element and in the worst case just uses a random number. Source elements that don't implement the URI handler interface should ideally generate a unique, deterministic stream-id manually instead.

Parameters

pad

A source GstPad

 

parent

Parent GstElement of pad

 

stream_id

The stream-id.

[allow-none]

var_args

parameters for the stream_id format string

 

Returns

A stream-id for pad . g_free() after usage.


gst_pad_get_stream_id ()

gchar *
gst_pad_get_stream_id (GstPad *pad);

Returns the current stream-id for the pad , or NULL if none has been set yet, i.e. the pad has not received a stream-start event yet.

This is a convenience wrapper around gst_pad_get_sticky_event() and gst_event_parse_stream_start().

The returned stream-id string should be treated as an opaque string, its contents should not be interpreted.

Parameters

pad

A source GstPad

 

Returns

a newly-allocated copy of the stream-id for pad , or NULL. g_free() the returned string when no longer needed.

[nullable]

Since 1.2


GstPadForwardFunction ()

gboolean
(*GstPadForwardFunction) (GstPad *pad,
                          gpointer user_data);

A forward function is called for all internally linked pads, see gst_pad_forward().

Parameters

pad

the GstPad that is forwarded.

 

user_data

the gpointer to optional user data.

 

Returns

TRUE if the dispatching procedure has to be stopped.


gst_pad_forward ()

gboolean
gst_pad_forward (GstPad *pad,
                 GstPadForwardFunction forward,
                 gpointer user_data);

Calls forward for all internally linked pads of pad . This function deals with dynamically changing internal pads and will make sure that the forward function is only called once for each pad.

When forward returns TRUE, no further pads will be processed.

Parameters

pad

a GstPad

 

forward

a GstPadForwardFunction.

[scope call]

user_data

user data passed to forward

 

Returns

TRUE if one of the dispatcher functions returned TRUE.


gst_pad_chain ()

GstFlowReturn
gst_pad_chain (GstPad *pad,
               GstBuffer *buffer);

Chain a buffer to pad .

The function returns GST_FLOW_FLUSHING if the pad was flushing.

If the buffer type is not acceptable for pad (as negotiated with a preceding GST_EVENT_CAPS event), this function returns GST_FLOW_NOT_NEGOTIATED.

The function proceeds calling the chain function installed on pad (see gst_pad_set_chain_function()) and the return value of that function is returned to the caller. GST_FLOW_NOT_SUPPORTED is returned if pad has no chain function.

In all cases, success or failure, the caller loses its reference to buffer after calling this function.

Parameters

pad

a sink GstPad, returns GST_FLOW_ERROR if not.

 

buffer

the GstBuffer to send, return GST_FLOW_ERROR if not.

[transfer full]

Returns

a GstFlowReturn from the pad.

MT safe.


gst_pad_chain_list ()

GstFlowReturn
gst_pad_chain_list (GstPad *pad,
                    GstBufferList *list);

Chain a bufferlist to pad .

The function returns GST_FLOW_FLUSHING if the pad was flushing.

If pad was not negotiated properly with a CAPS event, this function returns GST_FLOW_NOT_NEGOTIATED.

The function proceeds calling the chainlist function installed on pad (see gst_pad_set_chain_list_function()) and the return value of that function is returned to the caller. GST_FLOW_NOT_SUPPORTED is returned if pad has no chainlist function.

In all cases, success or failure, the caller loses its reference to list after calling this function.

MT safe.

Parameters

pad

a sink GstPad, returns GST_FLOW_ERROR if not.

 

list

the GstBufferList to send, return GST_FLOW_ERROR if not.

[transfer full]

Returns

a GstFlowReturn from the pad.


gst_pad_start_task ()

gboolean
gst_pad_start_task (GstPad *pad,
                    GstTaskFunction func,
                    gpointer user_data,
                    GDestroyNotify notify);

Starts a task that repeatedly calls func with user_data . This function is mostly used in pad activation functions to start the dataflow. The GST_PAD_STREAM_LOCK of pad will automatically be acquired before func is called.

Parameters

pad

the GstPad to start the task of

 

func

the task function to call

 

user_data

user data passed to the task function

 

notify

called when user_data is no longer referenced

 

Returns

a TRUE if the task could be started.


gst_pad_pause_task ()

gboolean
gst_pad_pause_task (GstPad *pad);

Pause the task of pad . This function will also wait until the function executed by the task is finished if this function is not called from the task function.

Parameters

pad

the GstPad to pause the task of

 

Returns

a TRUE if the task could be paused or FALSE when the pad has no task.


gst_pad_stop_task ()

gboolean
gst_pad_stop_task (GstPad *pad);

Stop the task of pad . This function will also make sure that the function executed by the task will effectively stop if not called from the GstTaskFunction.

This function will deadlock if called from the GstTaskFunction of the task. Use gst_task_pause() instead.

Regardless of whether the pad has a task, the stream lock is acquired and released so as to ensure that streaming through this pad has finished.

Parameters

pad

the GstPad to stop the task of

 

Returns

a TRUE if the task could be stopped or FALSE on error.


gst_pad_set_active ()

gboolean
gst_pad_set_active (GstPad *pad,
                    gboolean active);

Activates or deactivates the given pad. Normally called from within core state change functions.

If active , makes sure the pad is active. If it is already active, either in push or pull mode, just return. Otherwise dispatches to the pad's activate function to perform the actual activation.

If not active , calls gst_pad_activate_mode() with the pad's current mode and a FALSE argument.

Parameters

pad

the GstPad to activate or deactivate.

 

active

whether or not the pad should be active.

 

Returns

TRUE if the operation was successful.

MT safe.


GST_PAD_GET_STREAM_LOCK()

#define GST_PAD_GET_STREAM_LOCK(pad)    (&(GST_PAD_CAST(pad)->stream_rec_lock))

Get the stream lock of pad . The stream lock is protecting the resources used in the data processing functions of pad . Accessor macro, use GST_PAD_STREAM_LOCK() and GST_PAD_STREAM_UNLOCK() instead to take/release the pad's stream lock.

Parameters

pad

a GstPad

 

GST_PAD_STREAM_LOCK()

#define GST_PAD_STREAM_LOCK(pad)        g_rec_mutex_lock(GST_PAD_GET_STREAM_LOCK(pad))

Take the pad's stream lock. The stream lock is recursive and will be taken when buffers or serialized downstream events are pushed on a pad.

Parameters

pad

a GstPad

 

GST_PAD_STREAM_TRYLOCK()

#define GST_PAD_STREAM_TRYLOCK(pad)     g_rec_mutex_trylock(GST_PAD_GET_STREAM_LOCK(pad))

Try to take the pad's stream lock, and return TRUE if the lock could be taken, and otherwise FALSE.

Parameters

pad

a GstPad

 

GST_PAD_STREAM_UNLOCK()

#define GST_PAD_STREAM_UNLOCK(pad)      g_rec_mutex_unlock(GST_PAD_GET_STREAM_LOCK(pad))

Release the pad's stream lock.

Parameters

pad

a GstPad

 

GST_PAD_NAME()

#define GST_PAD_NAME(pad)		(GST_OBJECT_NAME(pad))

Get name of the given pad. No locking is performed in this function, use gst_pad_get_name() instead.

Parameters

pad

a GstPad

 

GST_PAD_PARENT()

#define GST_PAD_PARENT(pad)		(GST_ELEMENT_CAST(GST_OBJECT_PARENT(pad)))

Get the pad parent. No locking is performed in this function, use gst_pad_get_parent() instead.

Parameters

pad

a GstPad

 

GST_PAD_ELEMENT_PRIVATE()

#define GST_PAD_ELEMENT_PRIVATE(pad)    (GST_PAD_CAST(pad)->element_private)

Get the private data of pad , which is usually some pad- or stream-specific structure created by the element and set on the pad when creating it. No locking is performed in this function.

Parameters

pad

a GstPad

 

GST_PAD_PAD_TEMPLATE()

#define GST_PAD_PAD_TEMPLATE(pad) (GST_PAD_CAST(pad)->padtemplate)

Get the pad GstPadTemplate. It describes the possible media types a pad or an element factory can handle.

Parameters

pad

a GstPad

 

GST_PAD_DIRECTION()

#define GST_PAD_DIRECTION(pad)		(GST_PAD_CAST(pad)->direction)

Get the GstPadDirection of the given pad . Accessor macro, use gst_pad_get_direction() instead.

Parameters

pad

a GstPad

 

GST_PAD_LAST_FLOW_RETURN()

#define GST_PAD_LAST_FLOW_RETURN(pad)   (GST_PAD_CAST(pad)->ABI.abi.last_flowret)

Gets the last flow return on this pad

Parameters

pad

a GstPad

 

Since 1.4


GST_PAD_TASK()

#define GST_PAD_TASK(pad)		(GST_PAD_CAST(pad)->task)

Get the GstTask of pad . Accessor macro used by GStreamer. Use the gst_pad_start_task(), gst_pad_stop_task() and gst_pad_pause_task() functions instead.

Parameters

pad

a GstPad

 

GST_PAD_MODE()

#define GST_PAD_MODE(pad)	        (GST_PAD_CAST(pad)->mode)

Get the GstPadMode of pad, which will be GST_PAD_MODE_NONE if the pad has not been activated yet, and otherwise either GST_PAD_MODE_PUSH or GST_PAD_MODE_PULL depending on which mode the pad was activated in.

Parameters

pad

a GstPad

 

GST_PAD_ACTIVATEFUNC()

#define GST_PAD_ACTIVATEFUNC(pad) (GST_PAD_CAST(pad)->activatefunc)

Get the GstPadActivateFunction from pad .

Parameters

pad

a GstPad

 

GST_PAD_ACTIVATEMODEFUNC()

#define GST_PAD_ACTIVATEMODEFUNC(pad) (GST_PAD_CAST(pad)->activatemodefunc)

Get the GstPadActivateModeFunction from the given pad .

Parameters

pad

a GstPad

 

GST_PAD_CHAINFUNC()

#define GST_PAD_CHAINFUNC(pad)		(GST_PAD_CAST(pad)->chainfunc)

Get the GstPadChainFunction from the given pad .

Parameters

pad

a GstPad

 

GST_PAD_CHAINLISTFUNC()

#define GST_PAD_CHAINLISTFUNC(pad)      (GST_PAD_CAST(pad)->chainlistfunc)

Get the GstPadChainListFunction from the given pad .

Parameters

pad

a GstPad

 

GST_PAD_EVENTFUNC()

#define GST_PAD_EVENTFUNC(pad)		(GST_PAD_CAST(pad)->eventfunc)

Get the GstPadEventFunction from the given pad , which is the function that handles events on the pad. You can use this to set your own event handling function on a pad after you create it. If your element derives from a base class, use the base class's virtual functions instead.

Parameters

pad

a GstPad

 

GST_PAD_GETRANGEFUNC()

#define GST_PAD_GETRANGEFUNC(pad) (GST_PAD_CAST(pad)->getrangefunc)

Get the GstPadGetRangeFunction from the given pad .

Parameters

pad

a GstPad

 

GST_PAD_QUERYFUNC()

#define GST_PAD_QUERYFUNC(pad)		(GST_PAD_CAST(pad)->queryfunc)

Get the GstPadQueryFunction from pad , which is the function that handles queries on the pad. You can use this to set your own query handling function on a pad after you create it. If your element derives from a base class, use the base class's virtual functions instead.

Parameters

pad

a GstPad

 

GST_PAD_ITERINTLINKFUNC()

#define GST_PAD_ITERINTLINKFUNC(pad)    (GST_PAD_CAST(pad)->iterintlinkfunc)

Get the GstPadIterIntLinkFunction from the given pad .

Parameters

pad

a GstPad

 

GST_PAD_PEER()

#define GST_PAD_PEER(pad)		(GST_PAD_CAST(pad)->peer)

Return the pad's peer member. This member is a pointer to the linked pad . No locking is performed in this function, use gst_pad_get_peer() instead.

Parameters

pad

a GstPad

 

GST_PAD_LINKFUNC()

#define GST_PAD_LINKFUNC(pad)		(GST_PAD_CAST(pad)->linkfunc)

Get the GstPadLinkFunction for the given pad .

Parameters

pad

a GstPad

 

GST_PAD_UNLINKFUNC()

#define GST_PAD_UNLINKFUNC(pad)		(GST_PAD_CAST(pad)->unlinkfunc)

Get the GstPadUnlinkFunction from the given pad .

Parameters

pad

a GstPad

 

GST_PAD_IS_LINKED()

#define GST_PAD_IS_LINKED(pad)		(GST_PAD_PEER(pad) != NULL)

Parameters

pad

a GstPad

 

Returns

TRUE if the pad is linked to another pad. Use gst_pad_is_linked() instead.


GST_PAD_IS_SRC()

#define GST_PAD_IS_SRC(pad)		(GST_PAD_DIRECTION(pad) == GST_PAD_SRC)

Parameters

pad

a GstPad

 

Returns

TRUE if the pad is a source pad (i.e. produces data).


GST_PAD_IS_SINK()

#define GST_PAD_IS_SINK(pad)		(GST_PAD_DIRECTION(pad) == GST_PAD_SINK)

Parameters

pad

a GstPad

 

Returns

TRUE if the pad is a sink pad (i.e. consumes data).


GST_PAD_IS_ACTIVE()

#define GST_PAD_IS_ACTIVE(pad)          (GST_PAD_MODE(pad) != GST_PAD_MODE_NONE)

Parameters

pad

a GstPad

 

Returns

TRUE if the pad has been activated.


GST_PAD_IS_BLOCKED()

#define GST_PAD_IS_BLOCKED(pad)		(GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_BLOCKED))

Check if the dataflow on a pad is blocked. Use gst_pad_is_blocked() instead.

Parameters

pad

a GstPad

 

GST_PAD_IS_BLOCKING()

#define GST_PAD_IS_BLOCKING(pad) (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_BLOCKING))

Check if the pad is currently blocking on a buffer or event. Use gst_pad_is_blocking() instead.

Parameters

pad

a GstPad

 

GST_PAD_IS_FLUSHING()

#define GST_PAD_IS_FLUSHING(pad) (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_FLUSHING))

Check if the given pad is flushing.

Parameters

pad

a GstPad

 

GST_PAD_SET_FLUSHING()

#define GST_PAD_SET_FLUSHING(pad) (GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_FLUSHING))

Set the given pad to flushing state, which means it will not accept any more events, queries or buffers, and return GST_FLOW_FLUSHING if any buffers are pushed on it. This usually happens when the pad is shut down or when a flushing seek happens. This is used inside GStreamer when flush start/stop events pass through pads, or when an element state is changed and pads are activated or deactivated.

Parameters

pad

a GstPad

 

GST_PAD_UNSET_FLUSHING()

#define GST_PAD_UNSET_FLUSHING(pad) (GST_OBJECT_FLAG_UNSET (pad, GST_PAD_FLAG_FLUSHING))

Unset the flushing flag.

Parameters

pad

a GstPad

 

GST_PAD_IS_EOS()

#define GST_PAD_IS_EOS(pad)	        (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_EOS))

Check if the pad is in EOS state.

Parameters

pad

a GstPad

 

GST_PAD_NEEDS_RECONFIGURE()

#define GST_PAD_NEEDS_RECONFIGURE(pad)  (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_NEED_RECONFIGURE))

Check if the pad should be reconfigured/renegotiated. The flag has to be unset manually after reconfiguration happened. Use gst_pad_needs_reconfigure() or gst_pad_check_reconfigure() instead.

Parameters

pad

a GstPad

 

GST_PAD_HAS_PENDING_EVENTS()

#define GST_PAD_HAS_PENDING_EVENTS(pad) (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_PENDING_EVENTS))

Check if the given pad has pending events. This is used internally by GStreamer.

Parameters

pad

a GstPad

 

GST_PAD_IS_FIXED_CAPS()

#define GST_PAD_IS_FIXED_CAPS(pad) (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_FIXED_CAPS))

Check if the given pad is using fixed caps, which means that once the caps are set on the pad , the caps query function will only return those caps. See gst_pad_use_fixed_caps().

Parameters

pad

a GstPad

 

GST_PAD_NEEDS_PARENT()

#define GST_PAD_NEEDS_PARENT(pad)       (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_NEED_PARENT))

Check if there is a parent object before calling into the pad callbacks. This is used internally by GStreamer.

Parameters

pad

a GstPad

 

GST_PAD_IS_PROXY_CAPS()

#define GST_PAD_IS_PROXY_CAPS(pad)      (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_PROXY_CAPS))

Check if the given pad is set to proxy caps. This means that the default event and query handler will forward all events and queries to the internally linked pads instead of discarding them.

Parameters

pad

a GstPad

 

GST_PAD_SET_PROXY_CAPS()

#define GST_PAD_SET_PROXY_CAPS(pad)     (GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_PROXY_CAPS))

Set pad to proxy caps, so that all caps-related events and queries are proxied down- or upstream to the other side of the element automatically. Set this if the element always outputs data in the exact same format as it receives as input. This is just for convenience to avoid implementing some standard event and query handling code in an element.

Parameters

pad

a GstPad

 

GST_PAD_UNSET_PROXY_CAPS()

#define GST_PAD_UNSET_PROXY_CAPS(pad)   (GST_OBJECT_FLAG_UNSET (pad, GST_PAD_FLAG_PROXY_CAPS))

Unset proxy caps flag.

Parameters

pad

a GstPad

 

GST_PAD_IS_PROXY_ALLOCATION()

#define GST_PAD_IS_PROXY_ALLOCATION(pad)    (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_PROXY_ALLOCATION))

Check if the given pad is set as proxy allocation which means that the default query handler will forward allocation queries to the internally linked pads instead of discarding them.

Parameters

pad

a GstPad

 

GST_PAD_SET_PROXY_ALLOCATION()

#define GST_PAD_SET_PROXY_ALLOCATION(pad)   (GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_PROXY_ALLOCATION))

Set pad to proxy allocation queries, which means that the default query handler will forward allocation queries to the internally linked pads instead of discarding them. Set this if the element always outputs data in the exact same format as it receives as input. This is just for convenience to avoid implementing some standard query handling code in an element.

Parameters

pad

a GstPad

 

GST_PAD_UNSET_PROXY_ALLOCATION()

#define GST_PAD_UNSET_PROXY_ALLOCATION(pad) (GST_OBJECT_FLAG_UNSET (pad, GST_PAD_FLAG_PROXY_ALLOCATION))

Unset proxy allocation flag.

Parameters

pad

a GstPad

 

GST_PAD_SET_PROXY_SCHEDULING()

#define GST_PAD_SET_PROXY_SCHEDULING(pad)   (GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_PROXY_SCHEDULING))

Set pad to proxy scheduling queries, which means that the default query handler will forward scheduling queries to the internally linked pads instead of discarding them. You will usually want to handle scheduling queries explicitly if your element supports multiple scheduling modes.

Parameters

pad

a GstPad

 

GST_PAD_UNSET_PROXY_SCHEDULING()

#define GST_PAD_UNSET_PROXY_SCHEDULING(pad) (GST_OBJECT_FLAG_UNSET (pad, GST_PAD_FLAG_PROXY_SCHEDULING))

Unset proxy scheduling flag.

Parameters

pad

a GstPad

 

GST_PAD_IS_PROXY_SCHEDULING()

#define GST_PAD_IS_PROXY_SCHEDULING(pad)    (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_PROXY_SCHEDULING))

Check if the given pad is set to proxy scheduling queries, which means that the default query handler will forward scheduling queries to the internally linked pads instead of discarding them.

Parameters

pad

a GstPad

 

GST_PAD_IS_ACCEPT_INTERSECT()

#define GST_PAD_IS_ACCEPT_INTERSECT(pad)    (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_ACCEPT_INTERSECT))

Check if the pad's accept intersect flag is set. The default accept-caps handler will check it the caps intersect the query-caps result instead of checking for a subset. This is interesting for parser elements that can accept incompletely specified caps.

Parameters

pad

a GstPad

 

GST_PAD_SET_ACCEPT_INTERSECT()

#define GST_PAD_SET_ACCEPT_INTERSECT(pad)   (GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_ACCEPT_INTERSECT))

Set pad to by default accept caps by intersecting the result instead of checking for a subset. This is interesting for parser elements that can accept incompletely specified caps.

Parameters

pad

a GstPad

 

GST_PAD_UNSET_ACCEPT_INTERSECT()

#define GST_PAD_UNSET_ACCEPT_INTERSECT(pad) (GST_OBJECT_FLAG_UNSET (pad, GST_PAD_FLAG_ACCEPT_INTERSECT))

Unset accept intersect flag.

Parameters

pad

a GstPad

 

Types and Values

struct GstPad

struct GstPad {
  gpointer                       element_private;

  GstPadTemplate                *padtemplate;

  GstPadDirection                direction;
};

The GstPad structure. Use the functions to update the variables.

Members

gpointer element_private;

private data owned by the parent element

 

GstPadTemplate *padtemplate;

padtemplate for this pad

 

GstPadDirection direction;

the direction of the pad, cannot change after creating the pad.

 

enum GstPadDirection

The direction of a pad.

Members

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

Pad state flags

Members

GST_PAD_FLAG_BLOCKED

is dataflow on a pad blocked

 

GST_PAD_FLAG_FLUSHING

is pad flushing

 

GST_PAD_FLAG_EOS

is pad in EOS state

 

GST_PAD_FLAG_BLOCKING

is pad currently blocking on a buffer or event

 

GST_PAD_FLAG_NEED_PARENT

ensure that there is a parent object before calling into the pad callbacks.

 

GST_PAD_FLAG_NEED_RECONFIGURE

the pad should be reconfigured/renegotiated. The flag has to be unset manually after reconfiguration happened.

 

GST_PAD_FLAG_PENDING_EVENTS

the pad has pending events

 

GST_PAD_FLAG_FIXED_CAPS

the pad is using fixed caps. This means that once the caps are set on the pad, the default caps query function will only return those caps.

 

GST_PAD_FLAG_PROXY_CAPS

the default event and query handler will forward all events and queries to the internally linked pads instead of discarding them.

 

GST_PAD_FLAG_PROXY_ALLOCATION

the default query handler will forward allocation queries to the internally linked pads instead of discarding them.

 

GST_PAD_FLAG_PROXY_SCHEDULING

the default query handler will forward scheduling queries to the internally linked pads instead of discarding them.

 

GST_PAD_FLAG_ACCEPT_INTERSECT

the default accept-caps handler will check it the caps intersect the query-caps result instead of checking for a subset. This is interesting for parsers that can accept incompletely specified caps.

 

GST_PAD_FLAG_LAST

offset to define more flags

 

enum GstPadLinkReturn

Result values from gst_pad_link and friends.

Members

GST_PAD_LINK_OK

link succeeded

 

GST_PAD_LINK_WRONG_HIERARCHY

pads have no common grandparent

 

GST_PAD_LINK_WAS_LINKED

pad was already linked

 

GST_PAD_LINK_WRONG_DIRECTION

pads have wrong direction

 

GST_PAD_LINK_NOFORMAT

pads do not have common format

 

GST_PAD_LINK_NOSCHED

pads cannot cooperate in scheduling

 

GST_PAD_LINK_REFUSED

refused for some reason

 

enum GstPadLinkCheck

The amount of checking to be done when linking pads. GST_PAD_LINK_CHECK_CAPS and GST_PAD_LINK_CHECK_TEMPLATE_CAPS are mutually exclusive. If both are specified, expensive but safe GST_PAD_LINK_CHECK_CAPS are performed.

Only disable some of the checks if you are 100% certain you know the link will not fail because of hierarchy/caps compatibility failures. If uncertain, use the default checks (GST_PAD_LINK_CHECK_DEFAULT) or the regular methods for linking the pads.

Members

GST_PAD_LINK_CHECK_NOTHING

Don't check hierarchy or caps compatibility.

 

GST_PAD_LINK_CHECK_HIERARCHY

Check the pads have same parents/grandparents. Could be omitted if it is already known that the two elements that own the pads are in the same bin.

 

GST_PAD_LINK_CHECK_TEMPLATE_CAPS

Check if the pads are compatible by using their template caps. This is much faster than GST_PAD_LINK_CHECK_CAPS , but would be unsafe e.g. if one pad has GST_CAPS_ANY.

 

GST_PAD_LINK_CHECK_CAPS

Check if the pads are compatible by comparing the caps returned by gst_pad_query_caps().

 

GST_PAD_LINK_CHECK_DEFAULT

The default checks done when linking pads (i.e. the ones used by gst_pad_link()).

 

enum GstFlowReturn

The result of passing data to a pad.

Note that the custom return values should not be exposed outside of the element scope.

Members

GST_FLOW_CUSTOM_SUCCESS_2

Pre-defined custom success code.

 

GST_FLOW_CUSTOM_SUCCESS_1

Pre-defined custom success code (define your custom success code to this to avoid compiler warnings).

 

GST_FLOW_CUSTOM_SUCCESS

Elements can use values starting from this (and higher) to define custom success codes.

 

GST_FLOW_OK

Data passing was ok.

 

GST_FLOW_NOT_LINKED

Pad is not linked.

 

GST_FLOW_FLUSHING

Pad is flushing.

 

GST_FLOW_EOS

Pad is EOS.

 

GST_FLOW_NOT_NEGOTIATED

Pad is not negotiated.

 

GST_FLOW_ERROR

Some (fatal) error occurred. Element generating this error should post an error message with more details.

 

GST_FLOW_NOT_SUPPORTED

This operation is not supported.

 

GST_FLOW_CUSTOM_ERROR

Elements can use values starting from this (and lower) to define custom error codes.

 

GST_FLOW_CUSTOM_ERROR_1

Pre-defined custom error code (define your custom error code to this to avoid compiler warnings).

 

GST_FLOW_CUSTOM_ERROR_2

Pre-defined custom error code.

 

enum GstPadMode

The status of a GstPad. After activating a pad, which usually happens when the parent element goes from READY to PAUSED, the GstPadMode defines if the pad operates in push or pull mode.

Members

GST_PAD_MODE_NONE

Pad will not handle dataflow

 

GST_PAD_MODE_PUSH

Pad handles dataflow in downstream push mode

 

GST_PAD_MODE_PULL

Pad handles dataflow in upstream pull mode

 

enum GstPadProbeReturn

Different return values for the GstPadProbeCallback.

Members

GST_PAD_PROBE_DROP

drop data in data probes. For push mode this means that the data item is not sent downstream. For pull mode, it means that the data item is not passed upstream. In both cases, this result code means that GST_FLOW_OK or TRUE is returned to the caller.

 

GST_PAD_PROBE_OK

normal probe return value

 

GST_PAD_PROBE_REMOVE

remove probe

 

GST_PAD_PROBE_PASS

pass the data item in the block probe and block on the next item

 

enum GstPadProbeType

The different probing types that can occur. When either one of GST_PAD_PROBE_TYPE_IDLE or GST_PAD_PROBE_TYPE_BLOCK is used, the probe will be a blocking probe.

Members

GST_PAD_PROBE_TYPE_INVALID

invalid probe type

 

GST_PAD_PROBE_TYPE_IDLE

probe idle pads and block

 

GST_PAD_PROBE_TYPE_BLOCK

probe and block pads

 

GST_PAD_PROBE_TYPE_BUFFER

probe buffers

 

GST_PAD_PROBE_TYPE_BUFFER_LIST

probe buffer lists

 

GST_PAD_PROBE_TYPE_EVENT_DOWNSTREAM

probe downstream events

 

GST_PAD_PROBE_TYPE_EVENT_UPSTREAM

probe upstream events

 

GST_PAD_PROBE_TYPE_EVENT_FLUSH

probe flush events. This probe has to be explicitly enabled and is not included in the @GST_PAD_PROBE_TYPE_EVENT_DOWNSTREAM or @GST_PAD_PROBE_TYPE_EVENT_UPSTREAM probe types.

 

GST_PAD_PROBE_TYPE_QUERY_DOWNSTREAM

probe downstream queries

 

GST_PAD_PROBE_TYPE_QUERY_UPSTREAM

probe upstream queries

 

GST_PAD_PROBE_TYPE_PUSH

probe push

 

GST_PAD_PROBE_TYPE_PULL

probe pull

 

GST_PAD_PROBE_TYPE_BLOCKING

probe and block at the next opportunity, at data flow or when idle

 

GST_PAD_PROBE_TYPE_DATA_DOWNSTREAM

probe downstream data (buffers, buffer lists, and events)

 

GST_PAD_PROBE_TYPE_DATA_UPSTREAM

probe upstream data (events)

 

GST_PAD_PROBE_TYPE_DATA_BOTH

probe upstream and downstream data (buffers, buffer lists, and events)

 

GST_PAD_PROBE_TYPE_BLOCK_DOWNSTREAM

probe and block downstream data (buffers, buffer lists, and events)

 

GST_PAD_PROBE_TYPE_BLOCK_UPSTREAM

probe and block upstream data (events)

 

GST_PAD_PROBE_TYPE_EVENT_BOTH

probe upstream and downstream events

 

GST_PAD_PROBE_TYPE_QUERY_BOTH

probe upstream and downstream queries

 

GST_PAD_PROBE_TYPE_ALL_BOTH

probe upstream events and queries and downstream buffers, buffer lists, events and queries

 

GST_PAD_PROBE_TYPE_SCHEDULING

probe push and pull

 

struct GstPadProbeInfo

struct GstPadProbeInfo {
  GstPadProbeType type;
  gulong id;
  gpointer data;
  guint64 offset;
  guint size;
};

Info passed in the GstPadProbeCallback.

Members

GstPadProbeType type;

the current probe type

 

gulong id;

the id of the probe

 

gpointer data;

type specific data, check the type field to know the datatype. This field can be NULL.

[allow-none]

guint64 offset;

offset of pull probe, this field is valid when type contains GST_PAD_PROBE_TYPE_PULL

 

guint size;

size of pull probe, this field is valid when type contains GST_PAD_PROBE_TYPE_PULL

 

Property Details

The “caps” property

  “caps”                     GstCaps *

The capabilities of the pad.

Flags: Read


The “direction” property

  “direction”                GstPadDirection

The direction of the pad.

Flags: Read / Write / Construct Only

Default value: GST_PAD_UNKNOWN


The “template” property

  “template”                 GstPadTemplate *

The GstPadTemplate of this pad.

Flags: Read / Write

Signal Details

The “linked” signal

void
user_function (GstPad  *pad,
               GstPad  *peer,
               gpointer user_data)

Signals that a pad has been linked to the peer pad.

Parameters

pad

the pad that emitted the signal

 

peer

the peer pad that has been connected

 

user_data

user data set when the signal handler was connected.

 

Flags: Run Last


The “unlinked” signal

void
user_function (GstPad  *pad,
               GstPad  *peer,
               gpointer user_data)

Signals that a pad has been unlinked from the peer pad.

Parameters

pad

the pad that emitted the signal

 

peer

the peer pad that has been disconnected

 

user_data

user data set when the signal handler was connected.

 

Flags: Run Last

See Also

GstPadTemplate, GstElement, GstEvent, GstQuery, GstBuffer