GstPad
The connection between Elements
A #GstElement is connected to other elements via "pads", which are extremely
light-weight generic connections points.
After two pads are retrieved from an element with gst_element_get_pad(),
the pads can be connected with gst_pad_connect(). (For quick connections,
you can also use gst_element_connect(), which will make the obvious
connection for you if it's straightforward).
Pads are typically created from a #GstPadTemplate with
gst_pad_new_from_template().
Pads have #GstCaps attached to it to describe the media type they
are capable of dealing with.
gst_pad_get_caps() and gst_pad_try_set_caps() are used to
manipulate the caps of the pads.
Pads created from a pad template cannot set capabilities that are
incompatible with the pad template capabilities.
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.
gst_pad_get_parent() will retrieve the #GstElement that owns the pad.
A #GstElement creating a pad will typically use the various
gst_pad_set_*_function() calls to register callbacks for various events
on the pads.
GstElements will use gst_pad_push() and gst_pad_pull() to push out
or pull in a buffer.
The gst_pad_pullregion() function can be used to request for a buffer
with a specific offset (in time or in bytes).
gst_pad_select() and gst_pad_selectv() are used by plugins to wait for the
first incoming buffer or event on any of the given set of pads.
To send a #GstEvent on a pad, use gst_pad_send_event().
Last reviewed on September 1st, 2002 (0.4.0.1)
#GstPadTemplate, #GstElement, #GstEvent
Gets the name of the pad.
@pad: a #GstPad to get the name of.
@Returns: the pad's name.
Gets the private data set by the element that owns the pad.
@pad: a #GstPad to get the private data of.
#Returns: a gpointer to the private data.
Gets the parent element of this pad.
@pad: a #GstPad to get the parent of.
@Returns: the parent #GstElement of this pad.
Gets the pad template that was used to create this pad.
@pad: a #GstPad to get the pad template of.
#Returns: the #GstPadTemplate used to create the pad, or NULL if none was
used.
Returns the real pad of this pad.
@pad: a #GstPad to realize.
@Returns: the actual #GstPad.
Gets the pad's direction.
@pad: a #GstPad to get the direction of.
@Returns: the #GstPadDirection of the pad.
Gets the capabilities of a pad.
@pad: a #GstPad to get the capabilities of.
@Returns: the #GstCaps of the pad.
Gets the peer pad of this pad. The peer pad is the pad on to which the parent
element is connected through this pad.
@pad: a #GstPad to get the peer pad of.
@Returns: the peer #GstPad.
Checks if buffers can be pulled from this buffer.
@pad: a #GstPad to check on if a buffer can be pulled from it.
Checks if the pad is a sink pad.
@pad: a #GstPad to check.
Checks if the pad is a source pad.
@pad: a #GstPad to check.
Checks if the pad is connected.
@pad: a #GstPad to check.
A function that will be called when chaining buffers.
@pad: the #GstPad that performed the chain.
@buf: the #GstBuffer that is chained.
A function that will be called when pulling a buffer.
@pad: the #GstPad to get a buffer from.
@Returns: the #GstBuffer pulled.
A function that will be called when a buffer pool is requested
from this pad.
@pad: the #GstPad to which the buffer pool is associated.
@Returns: the #GstBufferPool associated with this pad.
Returns the capabilities of the specified pad. By default this function
will return the pad template capabilities, but can optionally be overridden.
@pad: the #GstPad to get the capabilities of.
@caps: the peer's #GstCaps, can be used to filter the capabilities.
@Returns: the #GstCaps of the pad.
Function signature to handle an event for the pad.
@pad: the #GstPad to handle the event.
@event: the #GstEvent to handle.
@Returns: TRUE if the pad could handle the event.
Function signature to handle a new connection on the pad.
@pad: the #GstPad that is connected.
@caps: the peer's #GstCaps.
@Returns: the result of the connection with the specified caps.
The result of a pad connection.
@GST_PAD_CONNECT_REFUSED: the connection was refused.
@GST_PAD_CONNECT_DELAYED: the connection was delayed, probably because the
element needs more specific pad capabilitiess.
@GST_PAD_CONNECT_OK: the connection succeeded.
@GST_PAD_CONNECT_DONE: the connection succeeded,
any more attempts are not needed.
The signature of a convert function.
@pad: the #GstPad to perform the convert on.
@src_format: the source #GstFormat of the conversion.
@src_value: the source value of the conversion.
@dest_format: a pointer to the destination #GstFormat.
@dest_value: a pointer to the destination value.
@Returns: TRUE if the conversion could be performed.
A dispatcher function is called for all internally connected pads, see
gst_pad_dispatcher().
@pad: the #GstPad that is dispatched.
@data: the gpointer to optional user data.
@Returns: TRUE if the dispatching procedure has to be stopped.
The signature of the internal pad connection function.
@pad: The #GstPad to query.
@Returns: a newly allocated #GList of pads that are connected to
the given pad on the inside of the parent element.
The caller must call g_list_free() on it after use.
The different supported query types.
@GST_PAD_QUERY_NONE:
@GST_PAD_QUERY_TOTAL: Query the total stream time.
@GST_PAD_QUERY_POSITION: Query the current stream position.
@GST_PAD_QUERY_LATENCY: Query the latency on the pad.
@GST_PAD_QUERY_JITTER: Query the average jitter beteen optimal processing
and current processing.
@GST_PAD_QUERY_START:
@GST_PAD_QUERY_SEGMENT_END: Query the end position of the currently
executing segment.
@GST_PAD_QUERY_RATE:
The signature of the query function.
@pad: the #GstPad to query.
@type: the #GstPadQueryType.
@format: a pointer to the target #GstFormat.
@value: a pointer to the target value.
@Returns: TRUE if the query could be performed.
The direction of a pad.
@GST_PAD_UNKNOWN: direction is unknown.
@GST_PAD_SRC: the pad is a source pad.
@GST_PAD_SINK: the pad is a sink pad.
Flags for the pad.
@GST_PAD_DISABLED: the pad is disabled.
@GST_PAD_EOS: the pad is in end of stream state.
@GST_PAD_FLAG_LAST: subclasses can use this number to enumerate their flags.
@name:
@direction:
@Returns:
@type:
@name:
@direction:
@Returns:
@type:
@templ:
@name:
@Returns:
Destroy the pad.
@pad: the pad to destroy
@templ:
@name:
@Returns:
@temp:
@pad:
@Returns:
@pad:
@chain:
@pad:
@get:
@pad:
@bufpool:
@pad:
@connect:
@pad:
@getcaps:
@pad:
@caps:
@Returns:
@pad:
@Returns:
@srcpad:
@sinkpad:
@Returns:
@pad:
@name:
@pad:
@Returns:
@pad:
@priv:
@pad:
@Returns:
@pad:
@parent:
@pad:
@Returns:
@pad:
@Returns:
@pad:
@Returns:
@pad:
@ghostpad:
@pad:
@ghostpad:
@pad:
@Returns:
@pad:
@Returns:
@srcpad:
@sinkpad:
@Returns:
@srcpad:
@sinkpad:
@filtercaps:
@Returns:
@srcpad:
@sinkpad:
@filtercaps:
@Returns:
@pad:
@srcpad:
@sinkpad:
@filtercaps:
@Returns:
@pad:
@srcpad:
@sinkpad:
@srcpad:
@sinkpad:
@Returns:
@srcpad:
@sinkpad:
@filtercaps:
@Returns:
@pad:
@buf:
@buffer:
@pad:
@Returns:
@pad:
@Returns:
@self:
@parent:
@element:
@elements:
@pad:
@caps:
@Returns:
@pad:
@Returns:
@pad:
@Returns:
@pad:
@Returns:
@pad:
@Returns:
@srcpad:
@sinkpad:
@Returns:
@padlist:
@Returns:
@pad:
@Varargs:
@Returns:
@pad:
@dispatch:
@data:
@Returns:
@pad:
@event:
@Returns:
@pad:
@event:
@Returns:
@pad:
@event:
@pad:
@convert:
@pad:
@src_format:
@src_value:
@dest_format:
@dest_value:
@Returns:
@pad:
@src_format:
@src_value:
@dest_format:
@dest_value:
@Returns:
@pad:
@Returns:
@pad:
@Returns:
@pad:
@intconn:
@pad:
@query:
@pad:
@type:
@format:
@value:
@Returns:
@pad:
@type:
@format:
@value:
@Returns:
@pad:
@caps:
@filter:
@appfilter:
@getcapsfunc:
@direction:
@connectfunc:
@peer:
@sched_private:
@chainfunc:
@chainhandler:
@getfunc:
@gethandler:
@eventfunc:
@eventhandler:
@eventmaskfunc:
@ghostpads:
@convertfunc:
@queryfunc:
@formatsfunc:
@querytypefunc:
@intconnfunc:
@bufferpoolfunc:
Get the direction of the real pad.
@pad: the realpad to query.
Get the caps of the real pad.
@pad: the real pad to query.
Get the peer element of the real pad.
@pad: the real pad to query.
Get the chain function of the real pad.
@pad: the real pad to query.
Get the filter from the pad
@pad: the pad to query
Get the application filter for this pad
@pad: the pad to query
Get get getfunction of the real pad.
@pad: the real pad to query.
Get the bufferpoolfunction from the real pad.
@pad: the real pad to query.
Get the eventhandler function from the real pad.
@pad: the real pad to query.
Get the event function of this real pad.
@pad: the real pad to query.
Get the eventhandler function of this real pad.
@pad: the real pad to query.
Get the gethandler function of this real pad.
@pad: the real pad to query.
Get the connect function of the pad
@pad: the pad to query
Get the getcaps function of this pad
@pad: the pad to query
Get the convert function of this pad
@pad: the pad to query
Get the internal connection function of this pad
@pad: the pad to query
Get the query function of this pad
@pad: the pad to query
Get the real pad of this ghost pad.
@pad: the real pad to query.
@name:
@pad:
@Returns: