GstGhostPad

GstGhostPad — Pseudo link pads

Functions

Types and Values

struct GstProxyPad
struct GstGhostPad

Object Hierarchy

    GObject
    ╰── GInitiallyUnowned
        ╰── GstObject
            ╰── GstPad
                ├── GstProxyPad
                   ╰── GstGhostPad
                ╰── GstProxyPad
                    ╰── GstGhostPad

Includes

#include <gst/gst.h>

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)

Functions

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.

Parameters

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.

Parameters

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.

Parameters

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 .

Parameters

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.

Parameters

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.

Parameters

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).

Parameters

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.

Parameters

pad

the GstPad to activate or deactivate.

 

parent

the parent of pad or NULL.

[allow-none]

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.

Parameters

pad

the GstPad to activate or deactivate.

 

parent

the parent of pad or NULL.

[allow-none]

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.

Parameters

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.

Parameters

pad

the GstPad to get the internal links of.

 

parent

the parent of pad or NULL.

[allow-none]

Returns

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


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.

Parameters

pad

a sink GstPad, returns GST_FLOW_ERROR if not.

 

parent

the parent of pad or NULL.

[allow-none]

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.

Parameters

pad

a sink GstPad, returns GST_FLOW_ERROR if not.

 

parent

the parent of pad or NULL.

[allow-none]

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);

returns GST_FLOW_ERROR if NULL.

Invoke the default getrange function of the proxy pad.

Parameters

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,.

[out callee-allocates]

Returns

a GstFlowReturn from the pad.

Types and Values

struct GstProxyPad

struct GstProxyPad;

struct GstGhostPad

struct GstGhostPad;

Opaque GstGhostPad structure.

See Also

GstPad