GstPad
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.
GstPad
GObject ╰──GInitiallyUnowned ╰──GstObject ╰──GstPad ╰──GstProxyPad
The GstPad structure. Use the functions to update the variables.
Members
object
(GstObject)
–
element_private
(gpointer)
–
private data owned by the parent element
padtemplate
(GstPadTemplate *)
–
padtemplate for this pad
direction
(GstPadDirection)
–
the direction of the pad, cannot change after creating the pad.
ABI._gst_reserved
(gpointer *)
–
ABI.abi.last_flowret
(GstFlowReturn)
–
ABI.abi.eventfullfunc
(GstPadEventFullFunction)
–
Class structure
Constructors
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
(
[allow-none])
–
the name of the new pad.
direction
–
the GstPadDirection of the pad.
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.
a new GstPad.
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
(
[allow-none])
–
the name of the pad
a new GstPad.
Methods
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.
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.
Probes are called in groups: First GST_PAD_PROBE_TYPE_BLOCK probes are called, then others, then finally GST_PAD_PROBE_TYPE_IDLE. The only exception here are GST_PAD_PROBE_TYPE_IDLE probes that are called immediately if the pad is already idle while calling gst_pad_add_probe. In each of the groups, probes are called in the order in which they were added.
Parameters:
pad
–
the GstPad to add the probe to
mask
–
the probe mask
callback
(
[closure])
–
GstPadProbeCallback that will be called with notifications of the pad state
user_data
–
user data passed to the callback
destroy_data
–
GDestroyNotify for user_data
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 happen that the probe can be run immediately and if the probe returns GST_PAD_PROBE_REMOVE this functions returns 0.
MT safe.
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
(
[transfer: full])
–
the GstBuffer to send, return GST_FLOW_ERROR if not.
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
(
[transfer: full])
–
the GstBufferList to send, return GST_FLOW_ERROR if not.
a GstFlowReturn from the pad.
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
(
[nullable])
–
The stream-id
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
(
[nullable])
–
The stream-id
...
–
parameters for the stream_id format string
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
(
[nullable])
–
The stream-id
var_args
–
parameters for the stream_id format string
A stream-id for pad. g_free after usage.
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 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
(
[allow-none])
–
the parent of pad or NULL
event
(
[transfer: full])
–
the GstEvent to handle.
TRUE if the event was sent successfully.
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.
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.
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.
the current caps of the pad with incremented ref-count or NULL when pad has no caps. Unref after usage.
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.
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_get_pad_template
GstPadTemplate * gst_pad_get_pad_template (GstPad * pad)
Gets the template for pad.
Parameters:
pad
–
a GstPad.
the GstPadTemplate from which this pad was instantiated, or NULL if this pad has no template. Unref after usage.
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
the parent of the pad. The caller has a reference on the parent, so unref when you're finished with it.
MT safe.
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
(
[out])
–
a pointer to hold the GstBuffer, returns GST_FLOW_ERROR if NULL.
gst_pad_get_single_internal_link
GstPad * gst_pad_get_single_internal_link (GstPad * pad)
If there is a single internal link of the given pad, this function will return it. Otherwise, it will return NULL.
Parameters:
pad
–
the GstPad to get the internal link of.
a GstPad, or NULL if pad has none or more than one internal links. Unref returned pad with gst_object_unref.
Since : 1.18
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
gst_pad_get_stream
GstStream * gst_pad_get_stream (GstPad * pad)
Returns the current GstStream 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.
Parameters:
pad
–
A source GstPad
Since : 1.10
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
Since : 1.2
gst_pad_get_task_state
GstTaskState gst_pad_get_task_state (GstPad * pad)
Get pad task state. If no task is currently set, GST_TASK_STOPPED is returned.
Parameters:
pad
–
the GstPad to get task state from
The current state of pad's task.
Since : 1.12
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
TRUE when pad has caps associated with it.
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
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.
a new GstIterator of GstPad or NULL when the pad does not have an iterator function configured. Use gst_iterator_free after usage.
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
(
[allow-none])
–
the parent of pad or NULL
a GstIterator of GstPad, or NULL if pad has no parent. Unref each returned pad with gst_object_unref.
gst_pad_link
GstPadLinkReturn gst_pad_link (GstPad * srcpad, GstPad * sinkpad)
Links the source pad and the sink pad.
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
A result code indicating if the connection worked or what went wrong.
gst_pad_link_maybe_ghosting
gboolean gst_pad_link_maybe_ghosting (GstPad * src, GstPad * sink)
Links src to sink, creating any GstGhostPad's in between as necessary.
This is a convenience function to save having to create and add intermediate GstGhostPad's as required for linking across GstBin boundaries.
If src or sink pads don't have parent elements or do not share a common ancestor, the link will fail.
whether the link succeeded.
Since : 1.10
gst_pad_link_maybe_ghosting_full
gboolean gst_pad_link_maybe_ghosting_full (GstPad * src, GstPad * sink, GstPadLinkCheck flags)
Links src to sink, creating any GstGhostPad's in between as necessary.
This is a convenience function to save having to create and add intermediate GstGhostPad's as required for linking across GstBin boundaries.
If src or sink pads don't have parent elements or do not share a common ancestor, the link will fail.
Calling gst_pad_link_maybe_ghosting_full with flags == GST_PAD_LINK_CHECK_DEFAULT is the recommended way of linking pads with safety checks applied.
whether the link succeeded.
Since : 1.10
gst_pad_mark_reconfigure
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_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
(
[transfer: none])
–
the GstQuery to perform.
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.
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_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
(
[out])
–
a pointer to the result.
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
(
[out][optional])
–
a location in which to store the total duration, or NULL.
TRUE if the query could be performed.
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
(
[out][optional])
–
a location in which to store the current position, or NULL.
TRUE if the query could be performed.
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.
TRUE if query could be executed
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.
TRUE if query could be executed
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
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
(
[transfer: full])
–
the GstBuffer to push returns GST_FLOW_ERROR if not.
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
(
[transfer: full])
–
the GstEvent to send to the pad.
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
(
[transfer: full])
–
the GstBufferList to push returns GST_FLOW_ERROR if not.
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
(
[transfer: none])
–
the GstQuery to perform.
TRUE if the query could be performed.
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.
the caps of the pad with incremented ref-count.
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
(
[out])
–
a pointer to the result.
TRUE if the query could be performed.
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
(
[allow-none])
–
the parent of pad or NULL
query
(
[transfer: none])
–
the GstQuery to handle.
TRUE if the query was performed successfully.
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
(
[out][optional])
–
a location in which to store the total duration, or NULL.
TRUE if the query could be performed.
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
(
[out][optional])
–
A location in which to store the current position, or NULL.
TRUE if the query could be performed.
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
(
[transfer: full])
–
the GstEvent to send to the pad.
TRUE if the event was handled.
gst_pad_set_activate_function_full
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.
gst_pad_set_activatemode_function_full
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.
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.
gst_pad_set_chain_function_full
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.
gst_pad_set_chain_list_function_full
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.
gst_pad_set_element_private
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_set_event_full_function_full
gst_pad_set_event_full_function_full (GstPad * pad, GstPadEventFullFunction event, gpointer user_data, GDestroyNotify notify)
Sets the given event handler for the pad.
Parameters:
pad
–
a GstPad of either direction.
event
–
the GstPadEventFullFunction to set.
user_data
–
user_data passed to notify
notify
–
notify called when event will not be used anymore.
Since : 1.8
gst_pad_set_event_function_full
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.
gst_pad_set_getrange_function_full
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.
gst_pad_set_iterate_internal_links_function_full
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.
gst_pad_set_link_function_full
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.
gst_pad_set_query_function_full
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.
gst_pad_set_unlink_function_full
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.
Note that the pad's lock is already held when the unlink function is called, so most pad functions cannot be called from within the callback.
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.
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
a TRUE if the task could be started.
gst_pad_sticky_events_foreach
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
(
[scope call][closure])
–
the GstPadStickyEventsForeachFunction that should be called for every event.
user_data
–
the optional user data.
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
gst_pad_store_sticky_event
GstFlowReturn gst_pad_store_sticky_event (GstPad * pad, GstEvent * event)
Store the sticky event on pad
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_use_fixed_caps
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
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.
a static string with the name of the pad-link return.
Since : 1.4
Signals
Properties
offset
“offset” gint64
The offset that will be applied to the running time of the pad.
Flags : Read / Write
Since : 1.6
Virtual Methods
GstPadProbeInfo
Info passed in the GstPadProbeCallback.
Members
type
(GstPadProbeType)
–
the current probe type
id
(gulong)
–
the id of the probe
data
(gpointer)
–
type specific data, check the type field to know the datatype. This field can be NULL.
offset
(guint64)
–
offset of pull probe, this field is valid when type contains GST_PAD_PROBE_TYPE_PULL
size
(guint)
–
size of pull probe, this field is valid when type contains GST_PAD_PROBE_TYPE_PULL
ABI._gst_reserved
(gpointer *)
–
ABI.abi.flow_ret
(GstFlowReturn)
–
Methods
gst_pad_probe_info_get_buffer
GstBuffer * gst_pad_probe_info_get_buffer (GstPadProbeInfo * info)
Parameters:
info
–
The GstBuffer from the probe
gst_pad_probe_info_get_buffer_list
GstBufferList * gst_pad_probe_info_get_buffer_list (GstPadProbeInfo * info)
Parameters:
info
–
The GstBufferList from the probe
gst_pad_probe_info_get_event
GstEvent * gst_pad_probe_info_get_event (GstPadProbeInfo * info)
Parameters:
info
–
The GstEvent from the probe
gst_pad_probe_info_get_query
GstQuery * gst_pad_probe_info_get_query (GstPadProbeInfo * info)
Parameters:
info
–
The GstQuery from the probe
Functions
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.
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.
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
short mnemonic for pad mode mode
Function Macros
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_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_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_EVENTFULLFUNC
#define GST_PAD_EVENTFULLFUNC(pad) (GST_PAD_CAST(pad)->ABI.abi.eventfullfunc)
Get the GstPadEventFullFunction 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
Since : 1.8
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_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_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_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 if 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_IS_ACCEPT_TEMPLATE
#define GST_PAD_IS_ACCEPT_TEMPLATE(pad) (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_ACCEPT_TEMPLATE))
Check if the pad's accept caps operation will use the pad template caps. The default accept-caps will do a query caps to get the caps, which might be querying downstream causing unnecessary overhead. It is recommended to implement a proper accept-caps query handler or to use this flag to prevent recursive accept-caps handling.
Parameters:
pad
–
a GstPad
Since : 1.6
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_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_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_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_IS_LINKED
#define GST_PAD_IS_LINKED(pad) (GST_PAD_PEER(pad) != NULL)
Parameters:
pad
–
a GstPad
TRUE if the pad is linked to another pad. Use gst_pad_is_linked instead.
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_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_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_ITERINTLINKFUNC
#define GST_PAD_ITERINTLINKFUNC(pad) (GST_PAD_CAST(pad)->iterintlinkfunc)
Get the GstPadIterIntLinkFunction from the given pad.
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_LINKFUNC
#define GST_PAD_LINKFUNC(pad) (GST_PAD_CAST(pad)->linkfunc)
Get the GstPadLinkFunction for the given pad.
Parameters:
pad
–
a GstPad
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_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_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_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_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_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_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_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_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_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_SET_ACCEPT_TEMPLATE
#define GST_PAD_SET_ACCEPT_TEMPLATE(pad) (GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_ACCEPT_TEMPLATE))
Set pad to by default use the pad template caps to compare with the accept caps instead of using a caps query result.
Parameters:
pad
–
a GstPad
Since : 1.6
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_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_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_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_STREAM_AUTO_LOCK
#define GST_PAD_STREAM_AUTO_LOCK(pad, var) g_autoptr(GRecMutexLocker) G_GNUC_UNUSED var = g_rec_mutex_locker_new(GST_PAD_GET_STREAM_LOCK(pad))
Declare a GRecMutexLocker variable with g_autoptr and lock the pad. The recursive mutex will be unlocked automatically when leaving the scope.
{
GST_PAD_STREAM_AUTO_LOCK (pad, locker);
gst_pad_push_event(pad, event1);
if (cond) {
// No need to unlock
return;
}
// Unlock before end of scope
g_clear_pointer (&locker, g_rec_mutex_locker_free);
gst_pad_push_event(pad, event2);
}
Since : 1.24.0
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_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_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_UNLINKFUNC
#define GST_PAD_UNLINKFUNC(pad) (GST_PAD_CAST(pad)->unlinkfunc)
Get the GstPadUnlinkFunction from the given pad.
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
GST_PAD_UNSET_ACCEPT_TEMPLATE
#define GST_PAD_UNSET_ACCEPT_TEMPLATE(pad) (GST_OBJECT_FLAG_UNSET (pad, GST_PAD_FLAG_ACCEPT_TEMPLATE))
Unset accept template flag.
Parameters:
pad
–
a GstPad
Since : 1.6
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_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_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_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_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_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
the parent
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.
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.
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.
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.
gst_pad_set_event_full_function
#define gst_pad_set_event_full_function(p,f) gst_pad_set_event_full_function_full((p),(f),NULL,NULL)
Calls gst_pad_set_event_full_function_full with NULL for the user_data and notify.
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.
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.
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.
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.
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.
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.
Enumerations
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
(102)
–
Pre-defined custom success code.
GST_FLOW_CUSTOM_SUCCESS_1
(101)
–
Pre-defined custom success code (define your custom success code to this to avoid compiler warnings).
GST_FLOW_CUSTOM_SUCCESS
(100)
–
Elements can use values starting from this (and higher) to define custom success codes.
GST_FLOW_OK
(0)
–
Data passing was ok.
GST_FLOW_NOT_LINKED
(-1)
–
Pad is not linked.
GST_FLOW_FLUSHING
(-2)
–
Pad is flushing.
GST_FLOW_EOS
(-3)
–
Pad is EOS.
GST_FLOW_NOT_NEGOTIATED
(-4)
–
Pad is not negotiated.
GST_FLOW_ERROR
(-5)
–
Some (fatal) error occurred. Element generating this error should post an error message using GST_ELEMENT_ERROR with more details.
GST_FLOW_NOT_SUPPORTED
(-6)
–
This operation is not supported.
GST_FLOW_CUSTOM_ERROR
(-100)
–
Elements can use values starting from this (and lower) to define custom error codes.
GST_FLOW_CUSTOM_ERROR_1
(-101)
–
Pre-defined custom error code (define your custom error code to this to avoid compiler warnings).
GST_FLOW_CUSTOM_ERROR_2
(-102)
–
Pre-defined custom error code.
GstPadFlags
Pad state flags
Members
GST_PAD_FLAG_BLOCKED
(16)
–
is dataflow on a pad blocked
GST_PAD_FLAG_FLUSHING
(32)
–
is pad flushing
GST_PAD_FLAG_EOS
(64)
–
is pad in EOS state
GST_PAD_FLAG_BLOCKING
(128)
–
is pad currently blocking on a buffer or event
GST_PAD_FLAG_NEED_PARENT
(256)
–
ensure that there is a parent object before calling into the pad callbacks.
GST_PAD_FLAG_NEED_RECONFIGURE
(512)
–
the pad should be reconfigured/renegotiated. The flag has to be unset manually after reconfiguration happened.
GST_PAD_FLAG_PENDING_EVENTS
(1024)
–
the pad has pending events
GST_PAD_FLAG_FIXED_CAPS
(2048)
–
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
(4096)
–
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
(8192)
–
the default query handler will forward allocation queries to the internally linked pads instead of discarding them.
GST_PAD_FLAG_PROXY_SCHEDULING
(16384)
–
the default query handler will forward scheduling queries to the internally linked pads instead of discarding them.
GST_PAD_FLAG_ACCEPT_INTERSECT
(32768)
–
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_ACCEPT_TEMPLATE
(65536)
–
the default accept-caps handler will use the template pad caps instead of query caps to compare with the accept caps. Use this in combination with GST_PAD_FLAG_ACCEPT_INTERSECT. (Since: 1.6)
GST_PAD_FLAG_LAST
(1048576)
–
offset to define more flags
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
(0)
–
Don't check hierarchy or caps compatibility.
GST_PAD_LINK_CHECK_HIERARCHY
(1)
–
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
(2)
–
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
(4)
–
Check if the pads are compatible by comparing the caps returned by gst_pad_query_caps.
GST_PAD_LINK_CHECK_NO_RECONFIGURE
(8)
–
Disables pushing a reconfigure event when pads are linked.
GST_PAD_LINK_CHECK_DEFAULT
(5)
–
The default checks done when linking pads (i.e. the ones used by gst_pad_link).
GstPadLinkReturn
Result values from gst_pad_link and friends.
Members
GST_PAD_LINK_OK
(0)
–
link succeeded
GST_PAD_LINK_WRONG_HIERARCHY
(-1)
–
pads have no common grandparent
GST_PAD_LINK_WAS_LINKED
(-2)
–
pad was already linked
GST_PAD_LINK_WRONG_DIRECTION
(-3)
–
pads have wrong direction
GST_PAD_LINK_NOFORMAT
(-4)
–
pads do not have common format
GST_PAD_LINK_NOSCHED
(-5)
–
pads cannot cooperate in scheduling
GST_PAD_LINK_REFUSED
(-6)
–
refused for some reason
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
(0)
–
Pad will not handle dataflow
GST_PAD_MODE_PUSH
(1)
–
Pad handles dataflow in downstream push mode
GST_PAD_MODE_PULL
(2)
–
Pad handles dataflow in upstream pull mode
GstPadProbeReturn
Different return values for the GstPadProbeCallback.
Members
GST_PAD_PROBE_DROP
(0)
–
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, no other probes are called for this item and GST_FLOW_OK or TRUE is returned to the caller.
GST_PAD_PROBE_OK
(1)
–
normal probe return value. This leaves the probe in place, and defers decisions about dropping or passing data to other probes, if any. If there are no other probes, the default behaviour for the probe type applies ('block' for blocking probes, and 'pass' for non-blocking probes).
GST_PAD_PROBE_REMOVE
(2)
–
remove this probe, passing the data. For blocking probes this will cause data flow to unblock, unless there are also other blocking probes installed.
GST_PAD_PROBE_PASS
(3)
–
pass the data item in the block probe and block on the next item. Note, that if there are multiple pad probes installed and any probe returns PASS, the data will be passed.
GST_PAD_PROBE_HANDLED
(4)
–
Data has been handled in the probe and will not be forwarded further. For events and buffers this is the same behaviour as GST_PAD_PROBE_DROP (except that in this case you need to unref the buffer or event yourself). For queries it will also return TRUE to the caller. The probe can also modify the GstFlowReturn value by using the GST_PAD_PROBE_INFO_FLOW_RETURN() accessor. Note that the resulting query must contain valid entries. Since: 1.6
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
(0)
–
invalid probe type
GST_PAD_PROBE_TYPE_IDLE
(1)
–
probe idle pads and block while the callback is called
GST_PAD_PROBE_TYPE_BLOCK
(2)
–
probe and block pads
GST_PAD_PROBE_TYPE_BUFFER
(16)
–
probe buffers
GST_PAD_PROBE_TYPE_BUFFER_LIST
(32)
–
probe buffer lists
GST_PAD_PROBE_TYPE_EVENT_DOWNSTREAM
(64)
–
probe downstream events
GST_PAD_PROBE_TYPE_EVENT_UPSTREAM
(128)
–
probe upstream events
GST_PAD_PROBE_TYPE_EVENT_FLUSH
(256)
–
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
(512)
–
probe downstream queries
GST_PAD_PROBE_TYPE_QUERY_UPSTREAM
(1024)
–
probe upstream queries
GST_PAD_PROBE_TYPE_PUSH
(4096)
–
probe push
GST_PAD_PROBE_TYPE_PULL
(8192)
–
probe pull
GST_PAD_PROBE_TYPE_BLOCKING
(3)
–
probe and block at the next opportunity, at data flow or when idle
GST_PAD_PROBE_TYPE_DATA_DOWNSTREAM
(112)
–
probe downstream data (buffers, buffer lists, and events)
GST_PAD_PROBE_TYPE_DATA_UPSTREAM
(128)
–
probe upstream data (events)
GST_PAD_PROBE_TYPE_DATA_BOTH
(240)
–
probe upstream and downstream data (buffers, buffer lists, and events)
GST_PAD_PROBE_TYPE_BLOCK_DOWNSTREAM
(114)
–
probe and block downstream data (buffers, buffer lists, and events)
GST_PAD_PROBE_TYPE_BLOCK_UPSTREAM
(130)
–
probe and block upstream data (events)
GST_PAD_PROBE_TYPE_EVENT_BOTH
(192)
–
probe upstream and downstream events
GST_PAD_PROBE_TYPE_QUERY_BOTH
(1536)
–
probe upstream and downstream queries
GST_PAD_PROBE_TYPE_ALL_BOTH
(1776)
–
probe upstream events and queries and downstream buffers, buffer lists, events and queries
GST_PAD_PROBE_TYPE_SCHEDULING
(12288)
–
probe push and pull
Callbacks
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.
TRUE if the pad could be activated.
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.
TRUE if the pad could be activated or deactivated.
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
(
[allow-none])
–
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.
GST_FLOW_OK for success
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
(
[allow-none])
–
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.
list
(
[transfer: full])
–
the GstBufferList that is chained, not NULL.
GST_FLOW_OK for success
GstPadEventFullFunction
GstFlowReturn (*GstPadEventFullFunction) (GstPad * pad, GstObject * parent, GstEvent * event)
Function signature to handle an event for the pad.
This variant is for specific elements that will take into account the last downstream flow return (from a pad push), in which case they can return it.
Parameters:
pad
–
the GstPad to handle the event.
parent
(
[allow-none])
–
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.
event
(
[transfer: full])
–
the GstEvent to handle.
GST_FLOW_OK if the event was handled properly, or any other GstFlowReturn dependent on downstream state.
Since : 1.8
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
(
[allow-none])
–
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.
event
(
[transfer: full])
–
the GstEvent to handle.
TRUE if the pad could handle the event.
GstPadForwardFunction
gboolean (*GstPadForwardFunction) (GstPad * pad, gpointer user_data)
A forward function is called for all internally linked pads, see gst_pad_forward.
TRUE if the dispatching procedure has to be stopped.
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
(
[allow-none])
–
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.
offset
–
the offset of the range
length
–
the length of the range
buffer
–
a memory location to hold the result buffer, cannot be NULL.
GST_FLOW_OK for success and a valid buffer in buffer. Any other return value leaves buffer undefined.
GstPadIterIntLinkFunction
GstIterator * (*GstPadIterIntLinkFunction) (GstPad * pad, GstObject * parent)
The signature of the internal pad link iterator function.
Parameters:
pad
–
The GstPad to query.
parent
(
[allow-none])
–
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.
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.
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
(
[allow-none])
–
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.
peer
–
the peer GstPad of the link
the result of the link with the specified peer.
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.
GstPadQueryFunction
gboolean (*GstPadQueryFunction) (GstPad * pad, GstObject * parent, GstQuery * query)
The signature of the query function.
Parameters:
pad
–
the GstPad to query.
parent
(
[allow-none])
–
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.
query
–
the GstQuery object to execute
TRUE if the query could be performed.
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
(
[allow-none])
–
a sticky GstEvent.
user_data
–
the gpointer to optional user data.
TRUE if the iteration should continue
GstPadUnlinkFunction
(*GstPadUnlinkFunction) (GstPad * pad, GstObject * parent)
Function signature to handle a unlinking the pad prom its peer.
The pad's lock is already held when the unlink function is called, so most pad functions cannot be called from within the callback.
Parameters:
pad
–
the GstPad that is linked.
parent
(
[allow-none])
–
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.
The results of the search are