GStreamer 1.0 Core Reference Manual: GstGhostPad

## GstGhostPad GstGhostPad — Pseudo link pads |

## Functions

GstPad * | gst_ghost_pad_new ()
GstPad * | gst_ghost_pad_new_no_target ()
GstPad * | gst_ghost_pad_new_from_template ()
GstPad * | gst_ghost_pad_new_no_target_from_template ()
gboolean | gst_ghost_pad_set_target ()
GstPad * | gst_ghost_pad_get_target ()
gboolean | gst_ghost_pad_construct ()
gboolean | gst_ghost_pad_activate_mode_default ()
gboolean | gst_ghost_pad_internal_activate_mode_default ()
GstProxyPad * | gst_proxy_pad_get_internal ()
GstIterator * | gst_proxy_pad_iterate_internal_links_default ()
GstFlowReturn | gst_proxy_pad_chain_default ()
GstFlowReturn | gst_proxy_pad_chain_list_default ()
GstFlowReturn | gst_proxy_pad_getrange_default ()

## 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.

## 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][nullable]

### 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][nullable]

### 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][nullable]

### 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][nullable]

### 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][nullable]

### 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][nullable]

### 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()`.

[nullable]

### 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