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GStreamer 0.9 Core Reference Manual | ![]() |
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GstBinGstBin — Base class for elements that contain other elements |
#include <gst/gst.h> GstBin; enum GstBinFlags; #define GST_BIN_CHILDREN (bin) #define GST_BIN_CHILDREN_COOKIE (bin) #define GST_BIN_NUMCHILDREN (bin) GstElement* gst_bin_new (const gchar *name); gboolean gst_bin_add (GstBin *bin, GstElement *element); gboolean gst_bin_remove (GstBin *bin, GstElement *element); GstElement* gst_bin_get_by_name (GstBin *bin, const gchar *name); GstElement* gst_bin_get_by_name_recurse_up (GstBin *bin, const gchar *name); GstElement* gst_bin_get_by_interface (GstBin *bin, GType interface); GstIterator* gst_bin_iterate_elements (GstBin *bin); GstIterator* gst_bin_iterate_recurse (GstBin *bin); GstIterator* gst_bin_iterate_sinks (GstBin *bin); GstIterator* gst_bin_iterate_sorted (GstBin *bin); GstIterator* gst_bin_iterate_all_by_interface (GstBin *bin, GType interface); void gst_bin_add_many (GstBin *bin, GstElement *element_1, ...); void gst_bin_remove_many (GstBin *bin, GstElement *element_1, ...);
"element-added" void user_function (GstBin *bin, GstElement *element, gpointer user_data); "element-removed" void user_function (GstBin *bin, GstElement *element, gpointer user_data);
GstBin is the simplest of the container elements, allowing elements to become children of itself. Pads from the child elements can be ghosted to the bin, making the bin itself look transparently like any other element, allowing for deep nesting of predefined sub-pipelines.
A new GstBin is created with gst_bin_new()
. Use a GstPipeline instead if you
want to create a toplevel bin because a normal bin doesn't have a bus or
handle clock distribution of its own.
After the bin has been created you will typically add elements to it with
gst_bin_add()
. You can remove elements with gst_bin_remove()
.
An element can be retrieved from a bin with gst_bin_get_by_name()
, using the
elements name. gst_bin_get_by_name_recurse_up()
is mainly used for internal
purposes and will query the parent bins when the element is not found in the
current bin.
An iterator of elements in a bin can be retrieved with
gst_bin_iterate_elements()
. Various other iterators exist to retrieve the
elements in a bin.
The "element_added" signal is fired whenever a new element is added to the bin. Likewise the "element_removed" signal is fired whenever an element is removed from the bin.
gst_object_unref()
is used to destroy the bin.
typedef struct { /* our children, subclass are supposed to update these * fields to reflect their state with _iterate_*() */ gint numchildren; GList *children; guint32 children_cookie; GstBus *child_bus; /* Bus we set on our children */ GList *messages; /* list of queued messages */ gboolean polling; gboolean state_dirty; gboolean clock_dirty; GstClock *provided_clock; } GstBin;
typedef enum { /* padding */ GST_BIN_FLAG_LAST = (GST_ELEMENT_FLAG_LAST << 5) } GstBinFlags;
GstBinFlags are a set of flags specific to bins. Most are set/used
internally. They can be checked using the GST_OBJECT_FLAG_IS_SET()
macro,
and (un)set using GST_OBJECT_FLAG_SET()
and GST_OBJECT_FLAG_UNSET()
.
GST_BIN_FLAG_LAST |
the last enum in the series of flags for bins. Derived classes can use this as first value in a list of flags. |
#define GST_BIN_CHILDREN(bin) (GST_BIN_CAST(bin)->children)
Gets the list with children a bin manages.
bin : |
the bin to get the list with children from |
#define GST_BIN_CHILDREN_COOKIE(bin) (GST_BIN_CAST(bin)->children_cookie)
Gets the children cookie that watches the children list.
bin : |
the bin to get the children cookie from |
#define GST_BIN_NUMCHILDREN(bin) (GST_BIN_CAST(bin)->numchildren)
Gets the number of children a bin manages.
bin : |
the bin to get the number of children from |
GstElement* gst_bin_new (const gchar *name);
Create a new bin with given name.
name : |
name of new bin |
Returns : | new bin |
gboolean gst_bin_add (GstBin *bin, GstElement *element);
Adds the given element to the bin. Sets the element's parent, and thus takes ownership of the element. An element can only be added to one bin.
If the element's pads are linked to other pads, the pads will be unlinked before the element is added to the bin.
MT safe.
bin : |
GstBin to add element to |
element : |
GstElement to add to bin |
Returns : | TRUE if the element could be added, FALSE on wrong parameters or the bin does not want to accept the element. |
gboolean gst_bin_remove (GstBin *bin, GstElement *element);
Remove the element from its associated bin, unparenting it as well.
Unparenting the element means that the element will be dereferenced,
so if the bin holds the only reference to the element, the element
will be freed in the process of removing it from the bin. If you
want the element to still exist after removing, you need to call
gst_object_ref()
before removing it from the bin.
If the element's pads are linked to other pads, the pads will be unlinked before the element is removed from the bin.
MT safe.
bin : |
GstBin to remove element from |
element : |
GstElement to remove |
Returns : | TRUE if the element could be removed, FALSE on wrong parameters or the bin does not want to remove the element. |
GstElement* gst_bin_get_by_name (GstBin *bin, const gchar *name);
Get the element with the given name from this bin. This function recurses into subbins.
MT safe.
bin : |
Gstbin to search |
name : |
the element name to search for |
Returns : | the element with the given name. Returns NULL if the element is not found or when bad parameters were given. Unref after use. |
GstElement* gst_bin_get_by_name_recurse_up (GstBin *bin, const gchar *name);
MT safe.
Get the element with the given name from this bin. If the element is not found, a recursion is performed on the parent bin.
bin : |
Gstbin to search |
name : |
the element name to search for |
Returns : | the element with the given name or NULL when the element was not found or bad parameters were given. Unref after use. |
GstElement* gst_bin_get_by_interface (GstBin *bin, GType interface);
Looks for the first element inside the bin that implements the given
interface. If such an element is found, it returns the element. You can
cast this element to the given interface afterwards.
If you want all elements that implement the interface, use
gst_bin_iterate_all_by_interface()
. The function recurses inside bins.
MT safe.
bin : |
bin to find element in |
interface : |
interface to be implemented by interface |
Returns : | An GstElement inside the bin implementing the interface. Unref after use. |
GstIterator* gst_bin_iterate_elements (GstBin *bin);
Get an iterator for the elements in this bin. Each element will have its refcount increased, so unref after use.
MT safe.
bin : |
Gstbin to iterate the elements of |
Returns : | a GstIterator of GstElements. gst_iterator_free after use. returns NULL when passing bad parameters. |
GstIterator* gst_bin_iterate_recurse (GstBin *bin);
Get an iterator for the elements in this bin. Each element will have its refcount increased, so unref after use. This iterator recurses into GstBin children.
MT safe.
bin : |
Gstbin to iterate the elements of |
Returns : | a GstIterator of GstElements. gst_iterator_free after use. returns NULL when passing bad parameters. |
GstIterator* gst_bin_iterate_sinks (GstBin *bin);
Get an iterator for the sink elements in this bin. Each element will have its refcount increased, so unref after use.
The sink elements are those with the GST_ELEMENT_IS_SINK flag set.
MT safe.
bin : |
Gstbin to iterate on |
Returns : | a GstIterator of GstElements. gst_iterator_free after use. |
GstIterator* gst_bin_iterate_sorted (GstBin *bin);
Get an iterator for the elements in this bin in topologically sorted order. This means that the elements are returned from the most downstream elements (sinks) to the sources.
This function is used internally to perform the state changes of the bin elements.
Each element will have its refcount increased, so unref after use.
MT safe.
bin : |
Gstbin to iterate on |
Returns : | a GstIterator of GstElements. gst_iterator_free after use. |
GstIterator* gst_bin_iterate_all_by_interface (GstBin *bin, GType interface);
Looks for all elements inside the bin that implements the given interface. You can safely cast all returned elements to the given interface. The function recurses bins inside bins. The iterator will return a series of GstElement that should be unreffed after use.
MT safe.
bin : |
bin to find elements in |
interface : |
interface to be implemented by interface |
Returns : | A GstIterator for the elements inside the bin implementing the given interface. |
void gst_bin_add_many (GstBin *bin, GstElement *element_1, ...);
Adds a NULL-terminated list of elements to a bin. This function is
equivalent to calling gst_bin_add()
for each member of the list.
bin : |
the bin to add the elements to |
element_1 : |
the first element to add to the bin |
... : |
additional elements to add to the bin |
void gst_bin_remove_many (GstBin *bin, GstElement *element_1, ...);
Remove a list of elements from a bin. This function is equivalent
to calling gst_bin_remove()
with each member of the list.
bin : |
the bin to remove the elements from |
element_1 : |
the first element to remove from the bin |
... : |
NULL-terminated list of elements to remove from the bin |
void user_function (GstBin *bin, GstElement *element, gpointer user_data);
Will be emitted if a new element was removed/added to this bin.
bin : |
the object which emitted the signal. |
element : |
the element that was added to the bin |
user_data : |
user data set when the signal handler was connected. |
void user_function (GstBin *bin, GstElement *element, gpointer user_data);
Will be emitted if an element was removed from this bin.
bin : |
the object which emitted the signal. |
element : |
the element that was removed from the bin |
user_data : |
user data set when the signal handler was connected. |
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