gstreamermm: Gst::Pad Class Reference

gstreamermm 0.10.10

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# Gst::Pad Class Reference

A class that represents objects contained by elements that allows links to other elements. More...

Inheritance diagram for Gst::Pad:
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Collaboration diagram for Gst::Pad:
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List of all members.

## Public Types
typedef sigc::slot< void, const Glib::RefPtr< Gst::Pad > &, bool > | SlotBlock
| For example, void on_block(const Glib::RefPtr<Gst::Pad>& pad, bool blocked);.
typedef sigc::slot< bool, const Glib::RefPtr< Gst::Pad > &, const Glib::RefPtr < Gst::MiniObject >& > | SlotData
| For example, bool on_have_data(const Glib::RefPtr<Gst::Pad>& pad, const Glib::RefPtr<Gst::MiniObjec>& data);.
## Public Member Functions
virtual | ~Pad ()
GstPad* | gobj ()
| Provides access to the underlying C GObject.
const GstPad* | gobj () const
| Provides access to the underlying C GObject.
GstPad* | gobj_copy ()
| Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.
PadDirection | get_direction () const
| Gets the direction of the pad.
Glib::RefPtr< Gst::Element > | get_parent_element ()
| Gets the parent of pad, cast to a Gst::Element.
Glib::RefPtr< const Gst::Element > | get_parent_element () const
| Gets the parent of pad, cast to a Gst::Element.
Glib::RefPtr< Gst::PadTemplate > | get_pad_template ()
| Gets the template for pad.
Glib::RefPtr< const Gst::PadTemplate > | get_pad_template () const
| Gets the template for pad.
PadLinkReturn | link (const Glib::RefPtr< Gst::Pad >& sink_pad)
| Links the source pad and the sink pad.
bool | unlink (const Glib::RefPtr< Gst::Pad >& sink_pad)
| Unlinks the source pad from the sink pad.
bool | is_linked () const
| Checks if a pad is linked to another pad or not.
bool | can_link (const Glib::RefPtr< const Gst::Pad >& other_pad) const
| Checks if the source pad and the sink pad are compatible so they can be linked.
Glib::RefPtr< Gst::Caps > | get_caps ()
| Gets the capabilities this pad can produce or consume.
Glib::RefPtr< const Gst::Caps > | get_caps () const
| Gets the capabilities this pad can produce or consume.
Glib::RefPtr< Gst::Caps > | get_allowed_caps ()
| Gets the capabilities of the allowed media types that can flow through pad and its peer.
Glib::RefPtr< const Gst::Caps > | get_allowed_caps () const
| Gets the capabilities of the allowed media types that can flow through pad and its peer.
Glib::RefPtr< Gst::Caps > | get_negotiated_caps ()
| Gets the capabilities of the media type that currently flows through pad and its peer.
Glib::RefPtr< const Gst::Caps > | get_negotiated_caps () const
| Gets the capabilities of the media type that currently flows through pad and its peer.
Glib::RefPtr< const Gst::Caps > | get_pad_template_caps () const
| Gets the capabilities for pad's template.
bool | set_caps (const Glib::RefPtr< Gst::Caps >& caps)
| Sets the capabilities of this pad.
Glib::RefPtr< Gst::Pad > | get_peer ()
| Gets the peer of pad.
Glib::RefPtr< const Gst::Pad > | get_peer () const
| Gets the peer of pad.
Glib::RefPtr< Gst::Caps > | peer_get_caps ()
| Gets the capabilities of the peer connected to this pad.
Glib::RefPtr< const Gst::Caps > | peer_get_caps () const
| Gets the capabilities of the peer connected to this pad.
void | use_fixed_caps ()
| A helper function you can use that sets the gst_pad_get_fixed_caps_func as the getcaps function for the pad.
bool | is_active () const
| Query if a pad is active.
bool | set_blocked (bool blocked=true)
| Blocks or unblocks the dataflow on a pad.
bool | set_blocked_async (const SlotBlock& slot, bool blocked=true)
| Blocks or unblocks the dataflow on a pad asynchronously.
bool | is_blocked () const
| Checks if the pad is blocked or not.
bool | is_blocking () const
| Checks if the pad is blocking or not.
gulong | add_data_probe (const SlotData& slot)
| Adds a "data probe" to a pad.
gulong | add_buffer_probe (const SlotData& slot)
| Adds a probe that will be called for all buffers passing through a pad.
gulong | add_event_probe (const SlotData& slot)
| Adds a probe that will be called for all events passing through a pad.
void | remove_data_probe (guint handler_id)
| Removes a data probe from pad.
void | remove_buffer_probe (guint handler_id)
| Removes a buffer probe from pad.
void | remove_event_probe (guint handler_id)
| Removes an event probe from pad.
FlowReturn | alloc_buffer (guint64 offset, int size, const Glib::RefPtr< Gst::Caps >& caps, Glib::RefPtr< Gst::Buffer >& buf)
| Allocates a new, empty buffer optimized to push to pad pad.
FlowReturn | alloc_buffer_and_set_caps (guint64 offset, int size, const Glib::RefPtr< Gst::Caps >& caps, Glib::RefPtr< Gst::Buffer >& buf)
| In addition to the function alloc_buffer(), this function automatically calls set_caps() when the caps of the newly allocated buffer are different from the pad caps.
FlowReturn | get_range (guint64 offset, guint size, Glib::RefPtr< Gst::Buffer >& buffer)
| When pad is flushing this function returns Gst::FLOW_WRONG_STATE immediatly.
bool | accept_caps (const Glib::RefPtr< const Gst::Caps >& caps) const
| Check if the given pad accepts the caps.
Glib::RefPtr< Gst::Caps > | proxy_getcaps ()
| Calls get_allowed_caps() for every other pad belonging to the same element as pad, and returns the intersection of the results.
Glib::RefPtr< const Gst::Caps > | proxy_getcaps () const
| Calls get_allowed_caps() for every other pad belonging to the same element as pad, and returns the intersection of the results.
bool | proxy_setcaps (const Glib::RefPtr< Gst::Caps >& caps)
| Calls set_caps() for every other pad belonging to the same element as pad.
void | fixate_caps (const Glib::RefPtr< Gst::Caps >& caps)
| Fixate a caps on the given pad.
bool | peer_accept_caps (const Glib::RefPtr< const Gst::Caps >& caps) const
| Check if the peer of pad accepts caps.
FlowReturn | push (const Glib::RefPtr< Gst::Buffer >& buffer)
| Pushes a buffer to the peer of the pad.
bool | push_event (const Glib::RefPtr< Gst::Event >& event)
| Sends the event to the peer of the pad.
bool | check_pull_range () const
| Checks if a pull_range() can be performed on the peer source pad.
FlowReturn | pull_range (guint64 offset, guint size, Glib::RefPtr< Gst::Buffer >& buffer)
| Pulls a buffer from the peer pad.
bool | activate_pull (bool active=true)
| Activates or deactivates the given pad in pull mode via dispatching to the pad's activatepullfunc.
bool | activate_push (bool active=true)
| Activates or deactivates the given pad in push mode via dispatching to the pad's activatepushfunc.
bool | send_event (const Glib::RefPtr< Gst::Event >& event)
| Sends the event to the pad.
bool | event_default (const Glib::RefPtr< Gst::Event >& event)
| Invokes the default event handler for the given pad.
bool | query (const Glib::RefPtr< Gst::Query >& query) const
| Dispatches a query to a pad.
bool | peer_query (const Glib::RefPtr< Gst::Query >& query) const
| Performs query() on the peer of pad.
bool | query_default (const Glib::RefPtr< Gst::Query >& query) const
| Invokes the default query handler for the given pad.
bool | query_position (Format& format, gint64& position) const
| Queries a pad for the stream position.
bool | query_position (Format& format) const
| Queries a pad for the stream position parsing only the format.
bool | query_duration (Format& format, gint64& duration) const
| Queries a pad for the total stream duration.
bool | query_duration (Format& format) const
| Queries a pad for the total stream duration parsing only the format.
bool | query_convert (Format src_format, gint64 src_value, Format& dst_format, gint64& dst_value) const
| Queries a pad to convert src_val in src_format to dest_format.
bool | query_peer_position (Format& format, gint64& position) const
| Queries the peer of a given sink pad for the stream position.
bool | query_peer_position (Format& format) const
| Queries the peer of a given sink pad for the stream position parsing only the format.
bool | query_peer_duration (Format& format, gint64& duration) const
| Queries the peer pad of a given sink pad for the total stream duration.
bool | query_peer_duration (Format& format) const
| Queries the peer pad of a given sink pad for the total stream duration.
bool | query_peer_convert (Format src_format, gint64 src_value, Format& dst_format, gint64& dst_value) const
| Queries the peer pad of a given sink pad to convert src_val in src_format to dest_format.
Glib::ArrayHandle< QueryType > | get_query_types () const
| Get an array of supported queries that can be performed on this pad.
Glib::ArrayHandle< QueryType > | get_query_types_default () const
| Invoke the default dispatcher for the query types on the pad.
Gst::Iterator< Gst::Pad > | iterate_internal_links ()
| Gets an iterator for the pads to which the given pad is linked to inside of the parent element.
Gst::Iterator< const Gst::Pad > | iterate_internal_links () const
| Gets an iterator for the pads to which the given pad is linked to inside of the parent element.
Gst::Iterator< Gst::Pad > | iterate_internal_links_default ()
| Iterate the list of pads to which the given pad is linked to inside of the parent element.
Gst::Iterator< const Gst::Pad > | iterate_internal_links_default () const
| Iterate the list of pads to which the given pad is linked to inside of the parent element.
Glib::ListHandle< Glib::RefPtr < Gst::Pad > > | get_internal_links ()
| Gets a list of pads to which the given pad is linked to inside of the parent element.
Glib::ListHandle< Glib::RefPtr < const Gst::Pad > > | get_internal_links () const
| Gets a list of pads to which the given pad is linked to inside of the parent element.
Glib::ListHandle< Glib::RefPtr < Gst::Pad > > | get_internal_links_default ()
| Gets a list of pads to which the given pad is linked to inside of the parent element.
Glib::ListHandle< Glib::RefPtr < const Gst::Pad > > | get_internal_links_default () const
| Gets a list of pads to which the given pad is linked to inside of the parent element.
FlowReturn | chain (const Glib::RefPtr< Gst::Buffer >& buffer)
bool | pause_task ()
| Pause the task of pad.
bool | stop_task ()
| Stop the task of pad.
bool | set_active (bool active=true)
| Activates or deactivates the given pad.
Glib::SignalProxy1< void, const Glib::RefPtr< Gst::Pad >& > | signal_linked ()
| Signals that a pad has been linked to the peer pad.
Glib::SignalProxy0< void > | signal_request_link ()
| Signals that a pad connection has been requested.
Glib::SignalProxy1< void, const Glib::RefPtr< Gst::Pad >& > | signal_unlinked ()
| Signals that a pad has been unlinked from the peer pad.
Glib::PropertyProxy_ReadOnly < Glib::RefPtr< Gst::Caps > > | property_caps () const
| The capabilities of the pad.
Glib::PropertyProxy_ReadOnly < PadDirection > | property_direction () const
| The direction of the pad.
Glib::PropertyProxy< PadTemplate > | property_template ()
| The GstPadTemplate of this pad.
Glib::PropertyProxy_ReadOnly < PadTemplate > | property_template () const
| The GstPadTemplate of this pad.
## Static Public Member Functions
static Glib::RefPtr< Pad > | create (const Glib::ustring& name, PadDirection dir)
| Creates a new pad with the given name in the given direction.
static Glib::RefPtr< Pad > | create (PadDirection dir)
| Creates a new pad with a guaranteed unique name (across all pads) in the given direction.
static Glib::RefPtr< Pad > | create (const Glib::RefPtr< const Gst::PadTemplate >& pad_template)
| Creates a new pad with the given name from the given template.
static Glib::RefPtr< Pad > | create (const Glib::RefPtr< const Gst::PadTemplate >& pad_template, const Glib::ustring& name)
| Creates a new pad with a guaranteed unique name (across all pads) from the given template.
## Protected Member Functions
| Pad (const Glib::ustring& name, PadDirection direction)
| Constructs a Pad given a name and a direction.
| Pad (PadDirection direction)
| Constructs a Pad given a direction without specifying a name.
| Pad (const Glib::RefPtr< const Gst::PadTemplate >& templ, const Glib::ustring& name)
| Constructs a Pad from a PadTemplate with the specified name.
| Pad (const Glib::RefPtr< const Gst::PadTemplate >& templ)
| Constructs a Pad from a PadTemplate without specifying a name.
virtual void | on_linked (const Glib::RefPtr< Gst::Pad >& peer_pad)
virtual void | on_request_link ()
virtual void | on_unlinked (const Glib::RefPtr< Gst::Pad >& peer_pad)
## Related Functions
(Note that these are not member functions.)
Glib::RefPtr< Gst::Pad > | wrap (GstPad* object, bool take_copy=false)
| A Glib::wrap() method for this object.

## Detailed Description

A class that represents objects contained by elements that allows links to other elements.

A Gst::Element is linked to other elements via "pads", which are extremely light-weight generic link points. After two pads are retrieved from an element with Element::get_pad(), the pads can be link with link(). (For quick links, you can also use Element::link(), which will make the obvious link for you if it's straightforward.)

Pads are typically created from a Gst::PadTemplate with the create() method that takes a Gst::PadTemplate.

Pads have Gst::Caps attached to it to describe the media type they are capable of dealing with. get_caps() and 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 create(), which takes a direction and a name as an argument.

get_parent_element() will retrieve the Gst::Element that owns the pad.

A Gst::Element creating a pad will typically use the underlying C API to register callbacks for various events on the pads.

Elements will use push() and pull_range() to push out or pull in a buffer.

To send a Gst::Event on a pad, use send_event() and push_event().

Last reviewed on 2006-07-06 (0.10.9)

## Member Typedef Documentation

typedef sigc::slot<void, const Glib::RefPtr<Gst::Pad>&, bool> Gst::Pad::SlotBlock

For example, void on_block(const Glib::RefPtr<Gst::Pad>& pad, bool blocked);.

typedef sigc::slot< bool, const Glib::RefPtr<Gst::Pad>&, const Glib::RefPtr<Gst::MiniObject>& > Gst::Pad::SlotData

For example, bool on_have_data(const Glib::RefPtr<Gst::Pad>& pad, const Glib::RefPtr<Gst::MiniObjec>& data);.

The data method should return true to keep the data in the pipeline, false to drop it (throw it away).

## Constructor & Destructor Documentation

virtual Gst::Pad::~Pad | ( |  | ) | `[virtual]`

Gst::Pad::Pad | ( | const Glib::ustring & | name,
|  | PadDirection | direction
| ) |  | `[explicit, protected]`

Constructs a Pad given a name and a direction.

Parameters:

  name | The desired name of the pad.
  direction | The desired direction of the pad.

Gst::Pad::Pad | ( | PadDirection | direction | ) | `[explicit, protected]`

Constructs a Pad given a direction without specifying a name.

A unique name will be assigned to the pad.

Parameters:

  direction | the direction of the pad.

Gst::Pad::Pad | ( | const Glib::RefPtr< const Gst::PadTemplate >& | templ,
|  | const Glib::ustring & | name
| ) |  | `[protected]`

Constructs a Pad from a PadTemplate with the specified name.

Parameters:

  templ | The PadTemplate.
  name | The desired name of the pad.

Exceptions:

  std::runtime_error | if construction fails.

Gst::Pad::Pad | ( | const Glib::RefPtr< const Gst::PadTemplate >& | templ | ) | `[explicit, protected]`

Constructs a Pad from a PadTemplate without specifying a name.

A unique name will ge assigned to the pad.

Parameters:

  templ | The PadTemplate.

Exceptions:

  std::runtime_error | if construction fails.

## Member Function Documentation

bool Gst::Pad::accept_caps | ( | const Glib::RefPtr< const Gst::Caps >& | caps | ) | const

Check if the given pad accepts the caps.

Parameters:

  caps | A Gst::Caps to check on the pad.

Returns:
  `true` if the pad can accept the caps.

bool Gst::Pad::activate_pull | ( | bool | active = `true` | ) |

Activates or deactivates the given pad in pull mode via dispatching to the pad's activatepullfunc.

For use from within pad activation functions only. When called on sink pads, will first proxy the call to the peer pad, which is expected to activate its internally linked pads from within its activate_pull function.

If you don't know what this is, you probably don't want to call it.

Parameters:

  active | Whether or not the pad should be active.

Returns:
  `true` if the operation was successful.

MT safe.

bool Gst::Pad::activate_push | ( | bool | active = `true` | ) |

Activates or deactivates the given pad in push mode via dispatching to the pad's activatepushfunc.

For use from within pad activation functions only.

If you don't know what this is, you probably don't want to call it.

Parameters:

  active | Whether the pad should be active or not.

Returns:
  `true` if the operation was successful.

MT safe.

gulong Gst::Pad::add_buffer_probe | ( | const SlotData & | slot | ) |

Adds a probe that will be called for all buffers passing through a pad.

See add_data_probe() for more information.

Parameters:

  slot | The slot to call when buffers are passed over pad.

Returns:
  The handler id.

gulong Gst::Pad::add_data_probe | ( | const SlotData & | slot | ) |

Adds a "data probe" to a pad.

The slot will be called whenever data passes through a pad. In this case data means both events and buffers. The probe will be called with the data as an argument. Note that the data will have a reference count greater than 1, so it will be immutable -- you must not change it.

For source pads, the probe will be called after the blocking function, if any (see set_blocked_async()), but before looking up the peer to chain to. For sink pads, the probe function will be called before configuring the sink with new caps, if any, and before calling the pad's chain function.

Your data probe should return true to let the data continue to flow, or false to drop it. Dropping data is rarely useful, but occasionally comes in handy with events.

To remove a probe, use the appropriate function, such as remove_data_probe().

Parameters:

  slot | The slot to call when data is passed over pad (note: slot is not copied because it is connected to a signal).

Returns:
  The handler id which may be used to remove the connection later.

gulong Gst::Pad::add_event_probe | ( | const SlotData & | slot | ) |

Adds a probe that will be called for all events passing through a pad.

See add_data_probe() for more information.

Parameters:

  slot | The slot to call when events are passed over pad.

Returns:
  The handler id.

FlowReturn Gst::Pad::alloc_buffer | ( | guint64 | offset,
|  | int | size,
|  | const Glib::RefPtr< Gst::Caps >& | caps,
|  | Glib::RefPtr< Gst::Buffer >& | buf
| ) |  |

Allocates a new, empty buffer optimized to push to pad pad.

This function only works if pad is a source pad and has a peer.

A new, empty Gst::Buffer will be put in the buf argument. You need to check the caps of the buffer after performing this function and renegotiate to the format if needed.

Parameters:

  offset | The offset of the new buffer in the stream.
  size | The size of the new buffer.
  caps | The caps of the new buffer.
  buf | An uninitialized Glib::RefPtr<> in which to store the new Gst::Buffer.

Returns:
  A result code indicating success of the operation. Any result code other than Gst::FLOW_OK is an error and buf should not be used. An error can occur if the pad is not connected or when the downstream peer elements cannot provide an acceptable buffer. MT safe.

FlowReturn Gst::Pad::alloc_buffer_and_set_caps | ( | guint64 | offset,
|  | int | size,
|  | const Glib::RefPtr< Gst::Caps >& | caps,
|  | Glib::RefPtr< Gst::Buffer >& | buf
| ) |  |

In addition to the function alloc_buffer(), this function automatically calls set_caps() when the caps of the newly allocated buffer are different from the pad caps.

Again, the pad must be a source pad.

Parameters:

  offset | The offset of the new buffer in the stream.
  size | The size of the new buffer.
  caps | The caps of the new buffer.
  buf | An uninitialized Glib::RefPtr<> in which to store the new Gst::Buffer.

Returns:
  A result code indicating success of the operation. Any result code other than Gst::FLOW_OK is an error and buf should not be used. An error can occur if the pad is not connected or when the downstream peer elements cannot provide an acceptable buffer. MT safe.

bool Gst::Pad::can_link | ( | const Glib::RefPtr< const Gst::Pad >& | other_pad | ) | const

Checks if the source pad and the sink pad are compatible so they can be linked.

Parameters:

  sinkpad | The sink Gst::Pad.

Returns:
  `true` if the pads can be linked.

FlowReturn Gst::Pad::chain | ( | const Glib::RefPtr< Gst::Buffer >& | buffer | ) |

bool Gst::Pad::check_pull_range | ( |  | ) | const

Checks if a pull_range() can be performed on the peer source pad.

This function is used by plugins that want to check if they can use random access on the peer source pad.

The peer sourcepad can implement a custom Gst::PadCheckGetRangeFunction if it needs to perform some logic to determine if pull_range is possible.

Returns:
  A `bool` with the result.

MT safe.

static Glib::RefPtr<Pad> Gst::Pad::create | ( | PadDirection | dir | ) | `[static]`

Creates a new pad with a guaranteed unique name (across all pads) in the given direction.

Parameters:

  direction | The GstPadDirection of the pad.

Returns:
  A new Gst::Pad, or a null RefPtr<> in case of an error. MT safe.

static Glib::RefPtr<Pad> Gst::Pad::create | ( | const Glib::ustring & | name,
|  | PadDirection | dir
| ) |  | `[static]`

Creates a new pad with the given name in the given direction.

Parameters:

  name | The name of the new pad.
  direction | The GstPadDirection of the pad.

Returns:
  A new Gst::Pad, or a null RefPtr<> in case of an error. MT safe.

static Glib::RefPtr<Pad> Gst::Pad::create | ( | const Glib::RefPtr< const Gst::PadTemplate >& | pad_template | ) | `[static]`

Creates a new pad with the given name from the given template.

Parameters:

  templ | The pad template to use.
  name | The name of the element.

Returns:
  A new Gst::Pad, or a null RefPtr<> in case of an error.

Exceptions:

  std::runtime_error | if construction fails.

static Glib::RefPtr<Pad> Gst::Pad::create | ( | const Glib::RefPtr< const Gst::PadTemplate >& | pad_template,
|  | const Glib::ustring & | name
| ) |  | `[static]`

Creates a new pad with a guaranteed unique name (across all pads) from the given template.

Parameters:

  templ | The pad template to use.

Returns:
  A new Gst::Pad, or a null RefPtr<> in case of an error.

Exceptions:

  std::runtime_error | if construction fails.

bool Gst::Pad::event_default | ( | const Glib::RefPtr< Gst::Event >& | event | ) |

Invokes the default event handler for the given pad.

End-of-stream and discontinuity events are handled specially, and then the event is sent to all pads internally linked to pad. Note that if there are many possible sink pads that are internally linked to pad, only one will be sent an event. Multi-sinkpad elements should implement custom event handlers.

Parameters:

  event | The Gst::Event to handle.

Returns:
  `true` if the event was sent succesfully.

void Gst::Pad::fixate_caps | ( | const Glib::RefPtr< Gst::Caps >& | caps | ) |

Fixate a caps on the given pad.

Modifies the caps in place, so you should make sure that the caps are actually writable (see Gst::Caps::make_writable()).

Parameters:

  caps | The Gst::Caps to fixate.

Glib::RefPtr<Gst::Caps> Gst::Pad::get_allowed_caps | ( |  | ) |

Gets the capabilities of the allowed media types that can flow through pad and its peer.

The allowed capabilities is calculated as the intersection of the results of calling get_caps() on pad and its peer. The caller owns a reference on the resulting caps.

Returns:
  The allowed Gst::Caps of the pad link. Unref the caps when you no longer need it. This function returns `0` when pad has no peer.

MT safe.

Glib::RefPtr<const Gst::Caps> Gst::Pad::get_allowed_caps | ( |  | ) | const

Gets the capabilities of the allowed media types that can flow through pad and its peer.

The allowed capabilities is calculated as the intersection of the results of calling get_caps() on pad and its peer. The caller owns a reference on the resulting caps.

Returns:
  The allowed Gst::Caps of the pad link. Unref the caps when you no longer need it. This function returns `0` when pad has no peer.

MT safe.

Glib::RefPtr<Gst::Caps> Gst::Pad::get_caps | ( |  | ) |

Gets the capabilities this pad can produce or consume.

Note that this method doesn't necessarily return the caps set by set_caps() - use GST_PAD_CAPS() for that instead. gst_pad_get_caps returns all possible caps a pad can operate with, using the pad's get_caps function; this returns the pad template caps if not explicitly set.

Returns:
  A newly allocated copy of the Gst::Caps of this pad

MT safe.

Glib::RefPtr<const Gst::Caps> Gst::Pad::get_caps | ( |  | ) | const

Gets the capabilities this pad can produce or consume.

Note that this method doesn't necessarily return the caps set by set_caps() - use GST_PAD_CAPS() for that instead. gst_pad_get_caps returns all possible caps a pad can operate with, using the pad's get_caps function; this returns the pad template caps if not explicitly set.

Returns:
  A newly allocated copy of the Gst::Caps of this pad

MT safe.

PadDirection Gst::Pad::get_direction | ( |  | ) | const

Gets the direction of the pad.

The direction of the pad is decided at construction time so this function does not take the LOCK.

Returns:
  The Gst::PadDirection of the pad.

MT safe.

Glib::ListHandle< Glib::RefPtr<Gst::Pad> > Gst::Pad::get_internal_links | ( |  | ) |

Gets a list of pads to which the given pad is linked to inside of the parent element.

The caller must free this list after use.

Not MT safe.

Deprecated: This function does not ref the pads in the list so that they could become invalid by the time the application accesses them. It's also possible that the list changes while handling the pads, which the caller of this function is unable to know. Use the thread-safe iterate_internal_links() instead.

Returns:
  A newly allocated List of pads, free with Glib::list_free().

Glib::ListHandle< Glib::RefPtr<const Gst::Pad> > Gst::Pad::get_internal_links | ( |  | ) | const

Gets a list of pads to which the given pad is linked to inside of the parent element.

The caller must free this list after use.

Not MT safe.

Deprecated: This function does not ref the pads in the list so that they could become invalid by the time the application accesses them. It's also possible that the list changes while handling the pads, which the caller of this function is unable to know. Use the thread-safe iterate_internal_links() instead.

Returns:
  A newly allocated List of pads, free with Glib::list_free().

Glib::ListHandle< Glib::RefPtr<const Gst::Pad> > Gst::Pad::get_internal_links_default | ( |  | ) | const

Gets a list of pads to which the given pad is linked to inside of the parent element.

This is the default handler, and thus returns a list of all of the pads inside the parent element with opposite direction.

The caller must free this list after use with Glib::list_free().

Deprecated: This function does not ref the pads in the list so that they could become invalid by the time the application accesses them. It's also possible that the list changes while handling the pads, which the caller of this function is unable to know. Use the thread-safe iterate_internal_links_default() instead.

Returns:
  A newly allocated List of pads, or `0` if the pad has no parent.

Not MT safe.

Glib::ListHandle< Glib::RefPtr<Gst::Pad> > Gst::Pad::get_internal_links_default | ( |  | ) |

Gets a list of pads to which the given pad is linked to inside of the parent element.

This is the default handler, and thus returns a list of all of the pads inside the parent element with opposite direction.

The caller must free this list after use with Glib::list_free().

Deprecated: This function does not ref the pads in the list so that they could become invalid by the time the application accesses them. It's also possible that the list changes while handling the pads, which the caller of this function is unable to know. Use the thread-safe iterate_internal_links_default() instead.

Returns:
  A newly allocated List of pads, or `0` if the pad has no parent.

Not MT safe.

Glib::RefPtr<Gst::Caps> Gst::Pad::get_negotiated_caps | ( |  | ) |

Gets the capabilities of the media type that currently flows through pad and its peer.

This function can be used on both src and sinkpads. Note that srcpads are always negotiated before sinkpads so it is possible that the negotiated caps on the srcpad do not match the negotiated caps of the peer.

Returns:
  The negotiated Gst::Caps of the pad link. Unref the caps when you no longer need it. This function returns `0` when the pad has no peer or is not negotiated yet.

MT safe.

Glib::RefPtr<const Gst::Caps> Gst::Pad::get_negotiated_caps | ( |  | ) | const

Gets the capabilities of the media type that currently flows through pad and its peer.

This function can be used on both src and sinkpads. Note that srcpads are always negotiated before sinkpads so it is possible that the negotiated caps on the srcpad do not match the negotiated caps of the peer.

Returns:
  The negotiated Gst::Caps of the pad link. Unref the caps when you no longer need it. This function returns `0` when the pad has no peer or is not negotiated yet.

MT safe.

Glib::RefPtr<Gst::PadTemplate> Gst::Pad::get_pad_template | ( |  | ) |

Gets the template for pad.

Returns:
  The Gst::PadTemplate from which this pad was instantiated, or `0` if this pad has no template.

FIXME: currently returns an unrefcounted padtemplate.

Glib::RefPtr<const Gst::PadTemplate> Gst::Pad::get_pad_template | ( |  | ) | const

Gets the template for pad.

Returns:
  The Gst::PadTemplate from which this pad was instantiated, or `0` if this pad has no template.

FIXME: currently returns an unrefcounted padtemplate.

Glib::RefPtr<const Gst::Caps> Gst::Pad::get_pad_template_caps | ( |  | ) | const

Gets the capabilities for pad's template.

Returns:
  The Gst::Caps of this pad template.

Glib::RefPtr<Gst::Element> Gst::Pad::get_parent_element | ( |  | ) |

Gets the parent of pad, cast to a Gst::Element.

If a pad has no parent or its parent is not an element, return `0`.

Returns:
  The parent of the pad. The caller has a reference on the parent, so unref when you're finished with it.

MT safe.

Glib::RefPtr<const Gst::Element> Gst::Pad::get_parent_element | ( |  | ) | const

Gets the parent of pad, cast to a Gst::Element.

If a pad has no parent or its parent is not an element, return `0`.

Returns:
  The parent of the pad. The caller has a reference on the parent, so unref when you're finished with it.

MT safe.

Glib::RefPtr<Gst::Pad> Gst::Pad::get_peer | ( |  | ) |

Gets the peer of pad.

This function refs the peer pad so you need to unref it after use.

Returns:
  The peer Gst::Pad. Unref after usage.

MT safe.

Glib::RefPtr<const Gst::Pad> Gst::Pad::get_peer | ( |  | ) | const

Gets the peer of pad.

This function refs the peer pad so you need to unref it after use.

Returns:
  The peer Gst::Pad. Unref after usage.

MT safe.

Glib::ArrayHandle<QueryType> Gst::Pad::get_query_types | ( |  | ) | const

Get an array of supported queries that can be performed on this pad.

Returns:
  A zero-terminated array of Gst::QueryType.

Glib::ArrayHandle<QueryType> Gst::Pad::get_query_types_default | ( |  | ) | const

Invoke the default dispatcher for the query types on the pad.

Returns:
  A zero-terminated array of Gst::QueryType, or `0` if none of the internally-linked pads has a query types function.

FlowReturn Gst::Pad::get_range | ( | guint64 | offset,
|  | guint | size,
|  | Glib::RefPtr< Gst::Buffer >& | buffer
| ) |  |

When pad is flushing this function returns Gst::FLOW_WRONG_STATE immediatly.

Calls the getrange function of pad. If pad has no getrange function installed this function returns Gst::FLOW_NOT_SUPPORTED.

This is a lowlevel function. Usually pull_range() is used. This function is designed to be used with a source pad only.

Parameters:

  offset | The start offset of the buffer.
  size | The length of the buffer.
  buffer | An unitialized Glib::RefPtr<> in which to store the Gst::Buffer.

Returns:
  A Gst::FlowReturn from the pad (Gst::FLOW_NOT_SUPPORTED if pad is not a source pad). MT safe.

const GstPad* Gst::Pad::gobj | ( |  | ) | const`[inline]`

Provides access to the underlying C GObject.

Reimplemented from Gst::Object.

Reimplemented in Gst::GhostPad.

GstPad* Gst::Pad::gobj | ( |  | ) | `[inline]`

Provides access to the underlying C GObject.

Reimplemented from Gst::Object.

Reimplemented in Gst::GhostPad.

GstPad* Gst::Pad::gobj_copy | ( |  | ) |

Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.

Reimplemented from Gst::Object.

Reimplemented in Gst::GhostPad.

bool Gst::Pad::is_active | ( |  | ) | const

Query if a pad is active.

Returns:
  `true` if the pad is active.

MT safe.

bool Gst::Pad::is_blocked | ( |  | ) | const

Checks if the pad is blocked or not.

This function returns the last requested state of the pad. It is not certain that the pad is actually blocking at this point (see is_blocking()).

Returns:
  `true` if the pad is blocked.

MT safe.

bool Gst::Pad::is_blocking | ( |  | ) | const

Checks if the pad is blocking or not.

This is a guaranteed state of whether the pad is actually blocking on a Gst::Buffer or a Gst::Event.

Returns:
  `true` if the pad is blocking.

MT safe.

bool Gst::Pad::is_linked | ( |  | ) | const

Checks if a pad is linked to another pad or not.

Returns:
  `true` if the pad is linked, `false` otherwise.

MT safe.

Gst::Iterator<Gst::Pad> Gst::Pad::iterate_internal_links | ( |  | ) |

Gets an iterator for the pads to which the given pad is linked to inside of the parent element.

Each Gst::Pad element yielded by the iterator will have its refcount increased, so unref after use.

Free-function: gst_iterator_free

Returns:
  A new Gst::Iterator of Gst::Pad or `0` when the pad does not have an iterator function configured. Use Gst::Iterator::free() after usage.

Gst::Iterator<const Gst::Pad> Gst::Pad::iterate_internal_links | ( |  | ) | const

Gets an iterator for the pads to which the given pad is linked to inside of the parent element.

Each Gst::Pad element yielded by the iterator will have its refcount increased, so unref after use.

Free-function: gst_iterator_free

Returns:
  A new Gst::Iterator of Gst::Pad or `0` when the pad does not have an iterator function configured. Use Gst::Iterator::free() after usage.

Gst::Iterator<Gst::Pad> Gst::Pad::iterate_internal_links_default | ( |  | ) |

Iterate the list of pads to which the given pad is linked to inside of the parent element.

This is the default handler, and thus returns an iterator of all of the pads inside the parent element with opposite direction.

The caller must free this iterator after use with Gst::Iterator::free().

Returns:
  A Gst::Iterator of Gst::Pad, or `0` if pad has no parent. Unref each returned pad with Gst::Object::unref().

Gst::Iterator<const Gst::Pad> Gst::Pad::iterate_internal_links_default | ( |  | ) | const

Iterate the list of pads to which the given pad is linked to inside of the parent element.

This is the default handler, and thus returns an iterator of all of the pads inside the parent element with opposite direction.

The caller must free this iterator after use with Gst::Iterator::free().

Returns:
  A Gst::Iterator of Gst::Pad, or `0` if pad has no parent. Unref each returned pad with Gst::Object::unref().

PadLinkReturn Gst::Pad::link | ( | const Glib::RefPtr< Gst::Pad >& | sink_pad | ) |

Links the source pad and the sink pad.

Parameters:

  sinkpad | The sink Gst::Pad to link.

Returns:
  A result code indicating if the connection worked or what went wrong.

MT Safe.

virtual void Gst::Pad::on_linked | ( | const Glib::RefPtr< Gst::Pad >& | peer_pad | ) | `[protected, virtual]`

virtual void Gst::Pad::on_request_link | ( |  | ) | `[protected, virtual]`

virtual void Gst::Pad::on_unlinked | ( | const Glib::RefPtr< Gst::Pad >& | peer_pad | ) | `[protected, virtual]`

bool Gst::Pad::pause_task | ( |  | ) |

Pause the task of pad.

This function will also wait until the function executed by the task is finished if this function is not called from the task function.

Returns:
  A `true` if the task could be paused or `false` when the pad has no task.

bool Gst::Pad::peer_accept_caps | ( | const Glib::RefPtr< const Gst::Caps >& | caps | ) | const

Check if the peer of pad accepts caps.

If pad has no peer, this function returns `true`.

Parameters:

  caps | A Gst::Caps to check on the pad.

Returns:
  `true` if the peer of pad can accept the caps or pad has no peer.

Glib::RefPtr<Gst::Caps> Gst::Pad::peer_get_caps | ( |  | ) |

Gets the capabilities of the peer connected to this pad.

Similar to get_caps().

Returns:
  A newly allocated copy of the Gst::Caps of the peer pad. Use Gst::Caps::unref() to get rid of it. This function returns `0` if there is no peer pad.

Glib::RefPtr<const Gst::Caps> Gst::Pad::peer_get_caps | ( |  | ) | const

Gets the capabilities of the peer connected to this pad.

Similar to get_caps().

Returns:
  A newly allocated copy of the Gst::Caps of the peer pad. Use Gst::Caps::unref() to get rid of it. This function returns `0` if there is no peer pad.

bool Gst::Pad::peer_query | ( | const Glib::RefPtr< Gst::Query >& | query | ) | const

Performs query() on the peer of pad.

The caller is responsible for both the allocation and deallocation of the query structure.

Parameters:

  query | The Gst::Query to perform.

Returns:
  `true` if the query could be performed. This function returns `false` if pad has no peer.

Glib::PropertyProxy_ReadOnly< Glib::RefPtr<Gst::Caps> > Gst::Pad::property_caps | ( |  | ) | const

The capabilities of the pad.

You rarely need to use properties because there are get_ and set_ methods for almost all of them.

Returns:
  A PropertyProxy that allows you to get or set the property of the value, or receive notification when the value of the property changes.

Glib::PropertyProxy_ReadOnly<PadDirection> Gst::Pad::property_direction | ( |  | ) | const

The direction of the pad.

You rarely need to use properties because there are get_ and set_ methods for almost all of them.

Returns:
  A PropertyProxy that allows you to get or set the property of the value, or receive notification when the value of the property changes.

Glib::PropertyProxy_ReadOnly<PadTemplate> Gst::Pad::property_template | ( |  | ) | const

The GstPadTemplate of this pad.

You rarely need to use properties because there are get_ and set_ methods for almost all of them.

Returns:
  A PropertyProxy that allows you to get or set the property of the value, or receive notification when the value of the property changes.

Glib::PropertyProxy<PadTemplate> Gst::Pad::property_template | ( |  | ) |

The GstPadTemplate of this pad.

You rarely need to use properties because there are get_ and set_ methods for almost all of them.

Returns:
  A PropertyProxy that allows you to get or set the property of the value, or receive notification when the value of the property changes.

Glib::RefPtr<const Gst::Caps> Gst::Pad::proxy_getcaps | ( |  | ) | const

Calls get_allowed_caps() for every other pad belonging to the same element as pad, and returns the intersection of the results.

This function is useful as a default getcaps function for an element that can handle any stream format, but requires all its pads to have the same caps. Two such elements are tee and adder.

Free-function: gst_caps_unref

Returns:
  The intersection of the other pads' allowed caps.

Glib::RefPtr<Gst::Caps> Gst::Pad::proxy_getcaps | ( |  | ) |

Calls get_allowed_caps() for every other pad belonging to the same element as pad, and returns the intersection of the results.

This function is useful as a default getcaps function for an element that can handle any stream format, but requires all its pads to have the same caps. Two such elements are tee and adder.

Free-function: gst_caps_unref

Returns:
  The intersection of the other pads' allowed caps.

bool Gst::Pad::proxy_setcaps | ( | const Glib::RefPtr< Gst::Caps >& | caps | ) |

Calls set_caps() for every other pad belonging to the same element as pad.

If set_caps() fails on any pad, the proxy setcaps fails. May be used only during negotiation.

Parameters:

  caps | The Gst::Caps to link with.

Returns:
  `true` if sucessful.

FlowReturn Gst::Pad::pull_range | ( | guint64 | offset,
|  | guint | size,
|  | Glib::RefPtr< Gst::Buffer >& | buffer
| ) |  |

Pulls a buffer from the peer pad.

This function will first trigger the pad block signal if it was installed. This method works only on sink pads.

When pad is not linked Gst::FLOW_NOT_LINKED is returned else this function returns the result of get_range() on the peer pad.

buffer's caps must either be unset or the same as what is already configured on pad. Renegotiation within a running pull-mode pipeline is not supported.

Parameters:

  offset | The start offset of the buffer.
  size | The length of the buffer.
  buffer | An uninitialized Glib::RefPtr<> in which to hold the Gst::Buffer.

Returns:
  A Gst::FlowReturn from the peer pad (Gst::FLOW_ERROR if pad is not a sink pad). When this function returns Gst::FLOW_OK, buffer will contain a valid Gst::Buffer. buffer may not be used when any other return value than Gst::FLOW_OK is returned. MT safe.

FlowReturn Gst::Pad::push | ( | const Glib::RefPtr< Gst::Buffer >& | buffer | ) |

Pushes a buffer to the peer of the pad.

The pad must be a source pad, otherwise this method returns Gst::FLOW_ERROR.

This function will call an installed pad block before triggering any installed pad probes.

If the caps on buffer are different from the currently configured caps on pad, this function will call any installed setcaps function on pad (see the C API gst_pad_set_setcaps_function()). In case of failure to renegotiate the new format, this function returns Gst::FLOW_NOT_NEGOTIATED.

The function proceeds calling chain() on the peer pad and returns the value from that function. If pad has no peer, Gst::FLOW_NOT_LINKED will be returned.

Parameters:

  buffer | The Gst::Buffer to push.

Returns:
  A Gst::FlowReturn from the peer pad. MT safe.

bool Gst::Pad::push_event | ( | const Glib::RefPtr< Gst::Event >& | event | ) |

Sends the event to the peer of the pad.

This function is mainly used by elements to send events to their peer elements.

Parameters:

  event | The GstEvent to send to the pad.

Returns:
  true if the event was handled. MT safe.

bool Gst::Pad::query | ( | const Glib::RefPtr< Gst::Query >& | query | ) | const

Dispatches a query to a pad.

The query should have been allocated by the caller via one of the type-specific allocation functions. The element that the pad belongs to is responsible for filling the query with an appropriate response, which should then be parsed with a type-specific query parsing function.

Again, the caller is responsible for both the allocation and deallocation of the query structure.

Please also note that some queries might need a running pipeline to work.

Parameters:

  query | The Gst::Query to perform.

Returns:
  `true` if the query could be performed.

bool Gst::Pad::query_convert | ( | Format | src_format,
|  | gint64 | src_value,
|  | Format& | dst_format,
|  | gint64 & | dst_value
| ) |  | const

Queries a pad to convert src_val in src_format to dest_format.

Parameters:

  src_format | A Gst::Format to convert from.
  src_val | A value to convert.
  dest_format | A pointer to the Gst::Format to convert to.
  dest_val | A pointer to the result.

Returns:
  `true` if the query could be performed.

bool Gst::Pad::query_default | ( | const Glib::RefPtr< Gst::Query >& | query | ) | const

Invokes the default query handler for the given pad.

The query is sent to all pads internally linked to pad. Note that if there are many possible sink pads that are internally linked to pad, only one will be sent the query. Multi-sinkpad elements should implement custom query handlers.

Parameters:

  query | The Gst::Query to handle.

Returns:
  `true` if the query was performed succesfully.

bool Gst::Pad::query_duration | ( | Format& | format | ) | const

Queries a pad for the total stream duration parsing only the format.

Parameters:

  format | A reference to the Gst::Format asked for. On return contains the GstFormat used.

Returns:
  true if the query could be performed.

bool Gst::Pad::query_duration | ( | Format& | format,
|  | gint64 & | duration
| ) |  | const

Queries a pad for the total stream duration.

Parameters:

  format | A pointer to the Gst::Format asked for. On return contains the Gst::Format used.
  duration | A location in which to store the total duration, or `0`.

Returns:
  `true` if the query could be performed.

bool Gst::Pad::query_peer_convert | ( | Format | src_format,
|  | gint64 | src_value,
|  | Format& | dst_format,
|  | gint64 & | dst_value
| ) |  | const

Queries the peer pad of a given sink pad to convert src_val in src_format to dest_format.

Parameters:

  src_format | A Gst::Format to convert from.
  src_val | A value to convert.
  dest_format | A pointer to the Gst::Format to convert to.
  dest_val | A pointer to the result.

Returns:
  `true` if the query could be performed.

bool Gst::Pad::query_peer_duration | ( | Format& | format,
|  | gint64 & | duration
| ) |  | const

Queries the peer pad of a given sink pad for the total stream duration.

Parameters:

  format | A pointer to the Gst::Format asked for. On return contains the Gst::Format used.
  duration | A location in which to store the total duration, or `0`.

Returns:
  `true` if the query could be performed.

bool Gst::Pad::query_peer_duration | ( | Format& | format | ) | const

Queries the peer pad of a given sink pad for the total stream duration.

Parameters:

  format | A reference to the Gst::Format asked for. On return contains the Gst::Format used.

Returns:
  true if the query could be performed.

bool Gst::Pad::query_peer_position | ( | Format& | format,
|  | gint64 & | position
| ) |  | const

Queries the peer of a given sink pad for the stream position.

Parameters:

  format | A pointer to the Gst::Format asked for. On return contains the Gst::Format used.
  cur | A location in which to store the current position, or `0`.

Returns:
  `true` if the query could be performed.

bool Gst::Pad::query_peer_position | ( | Format& | format | ) | const

Queries the peer of a given sink pad for the stream position parsing only the format.

Parameters:

  format | A reference to the Gst::Format asked for. On return contains the Gst::Format used.

Returns:
  true if the query could be performed.

bool Gst::Pad::query_position | ( | Format& | format | ) | const

Queries a pad for the stream position parsing only the format.

Parameters:

  format | A reference to the Gst::Format asked for. On return contains the Gst::Format used.

Returns:
  true if the query could be performed.

bool Gst::Pad::query_position | ( | Format& | format,
|  | gint64 & | position
| ) |  | const

Queries a pad for the stream position.

Parameters:

  format | A pointer to the Gst::Format asked for. On return contains the Gst::Format used.
  cur | A location in which to store the current position, or `0`.

Returns:
  `true` if the query could be performed.

void Gst::Pad::remove_buffer_probe | ( | guint | handler_id | ) |

Removes a buffer probe from pad.

Parameters:

  handler_id | Handler id returned from gst_pad_add_buffer_probe.

void Gst::Pad::remove_data_probe | ( | guint | handler_id | ) |

Removes a data probe from pad.

Parameters:

  handler_id | Handler id returned from gst_pad_add_data_probe.

void Gst::Pad::remove_event_probe | ( | guint | handler_id | ) |

Removes an event probe from pad.

Parameters:

  handler_id | Handler id returned from gst_pad_add_event_probe.

bool Gst::Pad::send_event | ( | const Glib::RefPtr< Gst::Event >& | event | ) |

Sends the event to the pad.

This function can be used by applications to send events in the pipeline.

If the pad is a source pad, event should be an upstream event. If the pad is a sink pad, the event should be a downstream event. For example, you would not send a Gst::EVENT_EOS on a src pad; EOS events only propagate downstream. Furthermore, some downstream events have to be serialized with data flow, like EOS, while some can travel out-of-band, like Gst::EVENT_FLUSH_START. If the event needs to be serialized with data flow, this function will take the pad's stream lock while calling its event function.

To find out whether an event type is upstream, downstream, or downstream and serialized, see Gst::EventTypeFlags, Gst::Enums::get_flags(), is_upstream(), Gst::Event::is_downstream(), and Gst::Event::is_serialized(). Note that in practice that an application or plugin doesn't need to bother itself with this information; the core handles all necessary locks and checks.

Parameters:

  event | The Gst::Event to send to the pad.

Returns:
  true if the event was handled.

bool Gst::Pad::set_active | ( | bool | active = `true` | ) |

Activates or deactivates the given pad.

Normally called from within core state change functions.

If active, makes sure the pad is active. If it is already active, either in push or pull mode, just return. Otherwise dispatches to the pad's activate function to perform the actual activation.

If not active, checks the pad's current mode and calls activate_push() or activate_pull(), as appropriate, with a `false` argument.

Parameters:

  active | Whether or not the pad should be active.

Returns:
  #`true` if the operation was successful.

MT safe.

bool Gst::Pad::set_blocked | ( | bool | blocked = `true` | ) |

Blocks or unblocks the dataflow on a pad.

This function is a shortcut for set_blocked_async() with a `0` callback.

<note> Pad blocks are only possible for source pads in push mode and sink pads in pull mode. </note>

Parameters:

  blocked | Boolean indicating we should block or unblock.

Returns:
  `true` if the pad could be blocked. This function can fail if the wrong parameters were passed or the pad was already in the requested state.

MT safe.

bool Gst::Pad::set_blocked_async | ( | const SlotBlock & | slot,
|  | bool | blocked = `true`
| ) |  |

Blocks or unblocks the dataflow on a pad asynchronously.

The provided slot is called when the operation succeeds; this happens right before the next attempt at pushing a buffer on the pad.

This can take a while as the pad can only become blocked when real dataflow is happening. When the pipeline is stalled, for example in PAUSED, this can take an indeterminate amount of time. Be careful with this blocking call as it might not return for reasons stated above.

Parameters:

  slot | SlotBlock that will be called when the operation succeeds.
  blocked | boolean indicating whether the pad should be blocked or unblocked.

Returns:
  true if the pad could be blocked. This function can fail if the pad was already in the requested state. MT safe.

bool Gst::Pad::set_caps | ( | const Glib::RefPtr< Gst::Caps >& | caps | ) |

Sets the capabilities of this pad.

The caps must be fixed. Any previous caps on the pad will be unreffed. This function refs the caps so you should unref if as soon as you don't need it anymore. It is possible to set `0` caps, which will make the pad unnegotiated again.

Parameters:

  caps | A Gst::Caps to set.

Returns:
  `true` if the caps could be set. `false` if the caps were not fixed or bad parameters were provided to this function.

MT safe.

Glib::SignalProxy1< void,const Glib::RefPtr<Gst::Pad>& > Gst::Pad::signal_linked | ( |  | ) |

Signals that a pad has been linked to the peer pad.

Prototype:
  `void on_my_linked(const Glib::RefPtr<Gst::Pad>& peer_pad)`

Glib::SignalProxy0< void > Gst::Pad::signal_request_link | ( |  | ) |

Signals that a pad connection has been requested.

Prototype:
  `void on_my_request_link()`

Glib::SignalProxy1< void,const Glib::RefPtr<Gst::Pad>& > Gst::Pad::signal_unlinked | ( |  | ) |

Signals that a pad has been unlinked from the peer pad.

Prototype:
  `void on_my_unlinked(const Glib::RefPtr<Gst::Pad>& peer_pad)`

bool Gst::Pad::stop_task | ( |  | ) |

Stop the task of pad.

This function will also make sure that the function executed by the task will effectively stop if not called from the GstTaskFunction.

This function will deadlock if called from the GstTaskFunction of the task. Use Gst::Task::pause() instead.

Regardless of whether the pad has a task, the stream lock is acquired and released so as to ensure that streaming through this pad has finished.

Returns:
  A `true` if the task could be stopped or `false` on error.

bool Gst::Pad::unlink | ( | const Glib::RefPtr< Gst::Pad >& | sink_pad | ) |

Unlinks the source pad from the sink pad.

Will emit the Gst::Pad::unlinked signal on both pads.

Parameters:

  sinkpad | The sink Gst::Pad to unlink.

Returns:
  `true` if the pads were unlinked. This function returns `false` if the pads were not linked together.

MT safe.

void Gst::Pad::use_fixed_caps | ( |  | ) |

A helper function you can use that sets the gst_pad_get_fixed_caps_func as the getcaps function for the pad.

This way the function will always return the negotiated caps or in case the pad is not negotiated, the padtemplate caps.

Use this function on a pad that, once set_caps() has been called on it, cannot be renegotiated to something else.

## Friends And Related Function Documentation

Glib::RefPtr< Gst::Pad > wrap | ( | GstPad * | object,
|  | bool | take_copy = `false`
| ) |  | `[related]`

A Glib::wrap() method for this object.

Parameters:

  object | The C instance.
  take_copy | False if the result should take ownership of the C instance. True if it should take a new copy or ref.

Returns:
  A C++ instance that wraps this C instance.

The documentation for this class was generated from the following file:

- gstreamermm/pad.h