GstGhostPad

GstGhostPad — Pseudo link pads

Synopsis

#include <gst/gst.h>

struct              GstProxyPad;
struct              GstGhostPad;
GstPad *            gst_ghost_pad_new                   (const gchar *name,
                                                         GstPad *target);
GstPad *            gst_ghost_pad_new_no_target         (const gchar *name,
                                                         GstPadDirection dir);
GstPad *            gst_ghost_pad_new_from_template     (const gchar *name,
                                                         GstPad *target,
                                                         GstPadTemplate *templ);
GstPad *            gst_ghost_pad_new_no_target_from_template
                                                        (const gchar *name,
                                                         GstPadTemplate *templ);
gboolean            gst_ghost_pad_set_target            (GstGhostPad *gpad,
                                                         GstPad *newtarget);
GstPad *            gst_ghost_pad_get_target            (GstGhostPad *gpad);
gboolean            gst_ghost_pad_construct             (GstGhostPad *gpad);
gboolean            gst_ghost_pad_activate_mode_default (GstPad *pad,
                                                         GstObject *parent,
                                                         GstPadMode mode,
                                                         gboolean active);
gboolean            gst_ghost_pad_internal_activate_mode_default
                                                        (GstPad *pad,
                                                         GstObject *parent,
                                                         GstPadMode mode,
                                                         gboolean active);
GstProxyPad *       gst_proxy_pad_get_internal          (GstProxyPad *pad);
GstIterator *       gst_proxy_pad_iterate_internal_links_default
                                                        (GstPad *pad,
                                                         GstObject *parent);
GstFlowReturn       gst_proxy_pad_chain_default         (GstPad *pad,
                                                         GstObject *parent,
                                                         GstBuffer *buffer);
GstFlowReturn       gst_proxy_pad_chain_list_default    (GstPad *pad,
                                                         GstObject *parent,
                                                         GstBufferList *list);
GstFlowReturn       gst_proxy_pad_getrange_default      (GstPad *pad,
                                                         GstObject *parent,
                                                         guint64 offset,
                                                         guint size,
                                                         GstBuffer **buffer);

Object Hierarchy

  GObject
   +----GInitiallyUnowned
         +----GstObject
               +----GstPad
                     +----GstProxyPad
                           +----GstGhostPad

  GObject
   +----GInitiallyUnowned
         +----GstObject
               +----GstPad
                     +----GstProxyPad
                           +----GstGhostPad

Description

GhostPads are useful when organizing pipelines with GstBin like elements. The idea here is to create hierarchical element graphs. The bin element contains a sub-graph. Now one would like to treat the bin-element like any other GstElement. This is where GhostPads come into play. A GhostPad acts as a proxy for another pad. Thus the bin can have sink and source ghost-pads that are associated with sink and source pads of the child elements.

If the target pad is known at creation time, gst_ghost_pad_new() is the function to use to get a ghost-pad. Otherwise one can use gst_ghost_pad_new_no_target() to create the ghost-pad and use gst_ghost_pad_set_target() to establish the association later on.

Note that GhostPads add overhead to the data processing of a pipeline.

Last reviewed on 2005-11-18 (0.9.5)

Details

struct GstProxyPad

struct GstProxyPad;

struct GstGhostPad

struct GstGhostPad;

Opaque GstGhostPad structure.

gst_ghost_pad_new ()

GstPad *            gst_ghost_pad_new                   (const gchar *name,
                                                         GstPad *target);

Create a new ghostpad with target as the target. The direction will be taken from the target pad. target must be unlinked.

Will ref the target.

name :

 the name of the new pad, or NULL to assign a default name. [allow-none]

target :

 the pad to ghost. [transfer none]

Returns :

 a new GstPad, or NULL in case of an error. [transfer floating]

gst_ghost_pad_new_no_target ()

GstPad *            gst_ghost_pad_new_no_target         (const gchar *name,
                                                         GstPadDirection dir);

Create a new ghostpad without a target with the given direction. A target can be set on the ghostpad later with the gst_ghost_pad_set_target() function.

The created ghostpad will not have a padtemplate.

name :

 the name of the new pad, or NULL to assign a default name. [allow-none]

dir :

 the direction of the ghostpad

Returns :

 a new GstPad, or NULL in case of an error. [transfer full]

gst_ghost_pad_new_from_template ()

GstPad *            gst_ghost_pad_new_from_template     (const gchar *name,
                                                         GstPad *target,
                                                         GstPadTemplate *templ);

Create a new ghostpad with target as the target. The direction will be taken from the target pad. The template used on the ghostpad will be template.

Will ref the target.

name :

 the name of the new pad, or NULL to assign a default name. [allow-none]

target :

 the pad to ghost. [transfer none]

templ :

 the GstPadTemplate to use on the ghostpad. [transfer none]

Returns :

 a new GstPad, or NULL in case of an error. [transfer full]

gst_ghost_pad_new_no_target_from_template ()

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

Create a new ghostpad based on templ, without setting a target. The direction will be taken from the templ.

name :

 the name of the new pad, or NULL to assign a default name. [allow-none]

templ :

 the GstPadTemplate to create the ghostpad from. [transfer none]

Returns :

 a new GstPad, or NULL in case of an error. [transfer full]

gst_ghost_pad_set_target ()

gboolean            gst_ghost_pad_set_target            (GstGhostPad *gpad,
                                                         GstPad *newtarget);

Set the new target of the ghostpad gpad. Any existing target is unlinked and links to the new target are established. if newtarget is NULL the target will be cleared.

gpad :

 the GstGhostPad

newtarget :

 the new pad target. [transfer none][allow-none]

Returns :

 TRUE if the new target could be set. This function can return FALSE when the internal pads could not be linked. [transfer full]

gst_ghost_pad_get_target ()

GstPad *            gst_ghost_pad_get_target            (GstGhostPad *gpad);

Get the target pad of gpad. Unref target pad after usage.

gpad :

 the GstGhostPad

Returns :

 the target GstPad, can be NULL if the ghostpad has no target set. Unref target pad after usage. [transfer full]

gst_ghost_pad_construct ()

gboolean            gst_ghost_pad_construct             (GstGhostPad *gpad);

Finish initialization of a newly allocated ghost pad.

This function is most useful in language bindings and when subclassing GstGhostPad; plugin and application developers normally will not call this function. Call this function directly after a call to g_object_new (GST_TYPE_GHOST_PAD, "direction", dir, ..., NULL).

gpad :

 the newly allocated ghost pad

Returns :

 TRUE if the construction succeeds, FALSE otherwise.

gst_ghost_pad_activate_mode_default ()

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

Invoke the default activate mode function of a ghost pad.

pad :

 the GstPad to activate or deactivate.

parent :

 the parent of pad or NULL

mode :

 the requested activation mode

active :

 whether the pad should be active or not.

Returns :

 TRUE if the operation was successful.

gst_ghost_pad_internal_activate_mode_default ()

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

Invoke the default activate mode function of a proxy pad that is owned by a ghost pad.

pad :

 the GstPad to activate or deactivate.

parent :

 the parent of pad or NULL

mode :

 the requested activation mode

active :

 whether the pad should be active or not.

Returns :

 TRUE if the operation was successful.

gst_proxy_pad_get_internal ()

GstProxyPad *       gst_proxy_pad_get_internal          (GstProxyPad *pad);

Get the internal pad of pad. Unref target pad after usage.

The internal pad of a GstGhostPad is the internally used pad of opposite direction, which is used to link to the target.

pad :

 the GstProxyPad

Returns :

 the target GstProxyPad, can be NULL. Unref target pad after usage. [transfer full]

gst_proxy_pad_iterate_internal_links_default ()

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

Invoke the default iterate internal links function of the proxy pad.

pad :

 the GstPad to get the internal links of.

parent :

 the parent of pad or NULL

Returns :

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

gst_proxy_pad_chain_default ()

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

Invoke the default chain function of the proxy pad.

pad :

 a sink GstPad, returns GST_FLOW_ERROR if not.

parent :

 the parent of pad or NULL

buffer :

 the GstBuffer to send, return GST_FLOW_ERROR if not. [transfer full]

Returns :

 a GstFlowReturn from the pad.

gst_proxy_pad_chain_list_default ()

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

Invoke the default chain list function of the proxy pad.

pad :

 a sink GstPad, returns GST_FLOW_ERROR if not.

parent :

 the parent of pad or NULL

list :

 the GstBufferList to send, return GST_FLOW_ERROR if not. [transfer full]

Returns :

 a GstFlowReturn from the pad.

gst_proxy_pad_getrange_default ()

GstFlowReturn       gst_proxy_pad_getrange_default      (GstPad *pad,
                                                         GstObject *parent,
                                                         guint64 offset,
                                                         guint size,
                                                         GstBuffer **buffer);

Invoke the default getrange function of the proxy pad.

pad :

 a src GstPad, returns GST_FLOW_ERROR if not.

parent :

 the parent of pad

offset :

 The start offset of the buffer

size :

 The length of the buffer

buffer :

 a pointer to hold the GstBuffer, returns GST_FLOW_ERROR if NULL. [out callee-allocates]

Returns :

 a GstFlowReturn from the pad.

See Also

GstPad
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