gstreamermm: Gst::Caps Class Reference

A class that describes sets of media formats. More...

Inheritance diagram for Gst::Caps:
Collaboration diagram for Gst::Caps:

Public Member Functions

void reference () const
 Increment the reference count for this object. More...

 
void unreference () const
 Decrement the reference count for this object. More...

 
GstCaps* gobj ()
 Provides access to the underlying C instance. More...

 
const GstCaps* gobj () const
 Provides access to the underlying C instance. More...

 
GstCaps* gobj_copy () const
 Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs. More...

 
Glib::RefPtr< Gst::Capscopy () const
 
Glib::RefPtr< Gst::Capscopy_nth (guint nth) const
 Creates a new Gst::Caps and appends a copy of the nth structure contained in caps. More...

 
void append (Glib::RefPtr< Gst::Caps >& caps)
 Appends the structures contained in caps to this object. More...

 
Glib::RefPtr< Gst::Capsmerge (Glib::RefPtr< Gst::Caps >& caps)
 Appends the structures contained in caps to an object if they are not yet expressed by this object. More...

 
void append_structure (const Structure& structure)
 Appends a structure to caps. More...

 
void append_structure (const Structure& structure, const CapsFeatures& features)
 Appends a structure to caps. More...

 
Glib::RefPtr< Gst::Capsmerge_structure (const Structure& structure)
 Appends a structure to caps if its not already expressed by caps. More...

 
Glib::RefPtr< Gst::Capsmerge_structure (const Structure& structure, const CapsFeatures& features)
 Appends a structure to caps if its not already expressed by caps. More...

 
const Structure get_structure (guint idx) const
 Finds the structure in caps that has the index idx, and returns it. More...

 
void remove_structure (guint idx)
 removes the stucture with the given index from the list of structures contained in caps. More...

 
guint size () const
 Gets the number of structures contained in caps. More...

 
Structure steal_structure (guint index)
 Retrieves the structure with the given index from the list of structures contained in caps. More...

 
void set_simple (const Glib::ustring& name, const Glib::ValueBase& value)
 Sets fields in a simple Gst::Caps. More...

 
template<class DataType >
void set_simple (const Glib::ustring& name, const DataType& data)
 Sets fields in a simple Gst::Caps. More...

 
void set_simple (const Glib::ustring& name, const char* data)
 Sets fields in a simple Gst::Caps. More...

 
void set_value (const Glib::ustring& field, const Glib::ValueBase& value)
 Sets the given field on all structures of caps to the given value. More...

 
template<class DataType >
void set_value (const Glib::ustring& name, const DataType& data)
 Sets the given field on all structures to the given value. More...

 
bool is_any () const
 Determines if caps represents any media format. More...

 
bool empty () const
 Determines if caps represents no media formats. More...

 
bool is_fixed () const
 Fixed Gst::Caps describe exactly one format, that is, they have exactly one structure, and each field in the structure describes a fixed type. More...

 
bool equals (const Glib::RefPtr< const Gst::Caps >& other_caps) const
 Checks if the given caps represent the same set of caps. More...

 
bool equals_fixed (const Glib::RefPtr< const Gst::Caps >& other_caps) const
 Tests if two Gst::Caps are equal. More...

 
bool is_always_compatible (const Glib::RefPtr< const Gst::Caps >& other_caps) const
 A given Gst::Caps structure is always compatible with another if every media format that is in the first is also contained in the second. More...

 
bool is_subset (const Glib::RefPtr< const Gst::Caps >& superset_caps) const
 Checks if all caps represented by subset are also represented by superset. More...

 
bool can_intersect (const Glib::RefPtr< const Gst::Caps >& caps2) const
 Tries intersecting caps1 and caps2 and reports whether the result would not be empty. More...

 
Glib::RefPtr< Gst::Capsget_intersect (const Glib::RefPtr< const Gst::Caps >& other_caps) const
 Creates a new Gst::Caps that contains all the formats that are common to both caps1 and caps2. More...

 
Glib::RefPtr< Gst::Capsget_intersect (const Glib::RefPtr< const Gst::Caps >& other_caps, CapsIntersectMode p2) const
 Creates a new Gst::Caps that contains all the formats that are common to both caps1 and caps2, the order is defined by the Gst::CapsIntersectMode used. More...

 
Glib::RefPtr< Gst::Capsget_normal () const
 Returns a Gst::Caps that represents the same set of formats as caps, but contains no lists. More...

 
Glib::RefPtr< Gst::Capssimplify ()
 Converts the given caps into a representation that represents the same set of formats, but in a simpler form. More...

 
Glib::ustring to_string () const
 Converts caps to a string representation. More...

 
Glib::RefPtr< Gst::Capsget_difference (const Glib::RefPtr< const Gst::Caps >& subtrahend_caps) const
 Subtracts the subtrahend from the minuend. More...

 
Glib::RefPtr< Gst::Capscreate_writable ()
 Returns a writable copy of . More...

 
Glib::RefPtr< Gst::Capstruncate ()
 Discard all but the first structure from caps. More...

 
CapsFeatures get_features (guint index) const
 Finds the features in caps that has the index index , and returns it. More...

 
void set_features (guint index, const CapsFeatures& features)
 Sets the Gst::CapsFeatures for the structure at index. More...

 
- Public Member Functions inherited from Gst::MiniObject
void reference () const
 Increment the reference count for this object. More...

 
void unreference () const
 Decrement the reference count for this object. More...

 
GstMiniObject* gobj ()
 Provides access to the underlying C instance. More...

 
const GstMiniObject* gobj () const
 Provides access to the underlying C instance. More...

 
GstMiniObject* gobj_copy () const
 Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs. More...

 
 ~MiniObject ()
 
guint get_flags () const
 
void set_flags (const guint& value)
 
gint get_refcount () const
 
gint get_lockstate () const
 
bool lock (LockFlags flags)
 Lock the mini-object with the specified access mode in flags. More...

 
void unlock (LockFlags flags)
 Unlock the mini-object with the specified access mode in flags. More...

 
bool is_writable () const
 If mini_object has the LOCKABLE flag set, check if the current EXCLUSIVE lock on object is the only one, this means that changes to the object will not be visible to any other object. More...

 
Glib::RefPtr< MiniObjectcreate_writable ()
 Checks if a mini-object is writable. More...

 
void set_qdata (GQuark quark, QuarkData* data)
 This sets an opaque, named pointer on a miniobject. More...

 
QuarkDataget_qdata (GQuark quark) const
 This function gets back user data pointers stored via set_qdata(). More...

 
QuarkDatasteal_qdata (GQuark quark)
 This function gets back user data pointers stored via set_qdata() and removes the data from object without invoking its destroy() function (if any was set). More...

 
void add_finalize_notifier (const SlotFinalizer& slot)
 Adds notifier when mini object is finalized. More...

 
void remove_finalize_notifier ()
 Remove finalize notifier. More...

 

Static Public Member Functions

static Glib::RefPtr< Capscreate ()
 
static Glib::RefPtr< Gst::Capscreate_any ()
 Creates a new Gst::Caps that indicates that it is compatible with any media format. More...

 
static Glib::RefPtr< Gst::Capscreate_simple (const Glib::ustring& media_type)
 Creates a new Gst::Caps that contains one Gst::Structure. More...

 
static Glib::RefPtr< Gst::Capscreate (const Structure& first_struct)
 Creates a new Gst::Caps and adds the given Gst::Structure. More...

 
static Glib::RefPtr< Gst::Capscreate_from_string (const Glib::ustring&string)
 Converts caps from a string representation. More...

 

Protected Member Functions

 Caps ()
 
void operator delete (void*, std::size_t)
 
- Protected Member Functions inherited from Gst::MiniObject
 MiniObject ()
 
void operator delete (void*, std::size_t)
 

Related Functions

(Note that these are not member functions.)

Glib::RefPtr< Gst::Capswrap (GstCaps* object, bool take_copy=false)
 A Glib::wrap() method for this object. More...

 

Additional Inherited Members

- Public Types inherited from Gst::MiniObject
typedef sigc::slot< void > SlotFinalizer
 

Detailed Description

A class that describes sets of media formats.

Caps (capabilities) are lightweight objects describing media formats. They are composed of an array of Gst::Structure.

Caps are exposed on Gst::PadTemplate to describe all possible types a given pad can handle. They are also stored in the Gst::Registry along with a description of the Gst::Element.

Caps are exposed on the element pads using the Gst::Pad::get_caps() method. This method describes the possible types that the pad can handle or produce at runtime.

Caps are also attached to buffers to describe to content of the data pointed to by the buffer with Gst::Buffer::set_caps(). Gst::Caps attached to a Gst::Buffer allow for format negotiation upstream and downstream.

A Gst::Caps can be constructed with the following code fragment:

caps->set_simple("format", Gst::Fourcc('I', '4', '2', '0'));
caps->set_simple("framerate", Gst::Fraction(25, 1));
caps->set_simple("pixel-aspect-ratio", Gst::Fraction(1, 1));
caps->set_simple("width", 320);
caps->set_simple("height", 240);

Constructor & Destructor Documentation

Gst::Caps::Caps ( )
protected

Member Function Documentation

void Gst::Caps::append ( Glib::RefPtr< Gst::Caps >&  caps)

Appends the structures contained in caps to this object.

The structures in caps are not copied – they are transferred to this object, and then caps is freed. If either caps is ANY, the resulting caps will be ANY.

Parameters
capsThe Gst::Caps to append.
void Gst::Caps::append_structure ( const Structure structure)

Appends a structure to caps.

Parameters
structureThe Gst::Structure to append.
void Gst::Caps::append_structure ( const Structure structure,
const CapsFeatures features 
)

Appends a structure to caps.

Parameters
structureThe Gst::Structure to append.
featuresThe Gst::CapsFeatures to append.
bool Gst::Caps::can_intersect ( const Glib::RefPtr< const Gst::Caps >&  caps2) const

Tries intersecting caps1 and caps2 and reports whether the result would not be empty.

Parameters
caps2A Gst::Caps to intersect.
Returns
true if intersection would be not empty.
Glib::RefPtr<Gst::Caps> Gst::Caps::copy ( ) const
Glib::RefPtr<Gst::Caps> Gst::Caps::copy_nth ( guint  nth) const

Creates a new Gst::Caps and appends a copy of the nth structure contained in caps.

Parameters
nthThe nth structure to copy.
Returns
The new Gst::Caps.
static Glib::RefPtr<Caps> Gst::Caps::create ( )
static
static Glib::RefPtr<Gst::Caps> Gst::Caps::create ( const Structure first_struct)
static

Creates a new Gst::Caps and adds the given Gst::Structure.

Use append_structure() to add additional structures.

Parameters
first_structThe first structure to add.
Returns
Returns the new Gst::Caps.
static Glib::RefPtr<Gst::Caps> Gst::Caps::create_any ( )
static

Creates a new Gst::Caps that indicates that it is compatible with any media format.

Returns
The new Gst::Caps.
static Glib::RefPtr<Gst::Caps> Gst::Caps::create_from_string ( const Glib::ustring string)
static

Converts caps from a string representation.

Parameters
stringA string to convert to Gst::Caps.
Returns
A newly allocated Gst::Caps.
static Glib::RefPtr<Gst::Caps> Gst::Caps::create_simple ( const Glib::ustring media_type)
static

Creates a new Gst::Caps that contains one Gst::Structure.

Parameters
media_typeThe media type of the structure.
Returns
The new Gst::Caps.
Glib::RefPtr<Gst::Caps> Gst::Caps::create_writable ( )

Returns a writable copy of .

If there is only one reference count on Gst::Caps object , the caller must be the owner, and so this function will return the caps object unchanged. If on the other hand there is more than one reference on the object, a new caps object will be returned.

Returns
A buffer (possibly the same pointer) that is writable.
bool Gst::Caps::empty ( ) const

Determines if caps represents no media formats.

Returns
true if caps represents no formats.
bool Gst::Caps::equals ( const Glib::RefPtr< const Gst::Caps >&  other_caps) const

Checks if the given caps represent the same set of caps.

Parameters
caps2Another Gst::Caps.
Returns
true if both caps are equal.
bool Gst::Caps::equals_fixed ( const Glib::RefPtr< const Gst::Caps >&  other_caps) const

Tests if two Gst::Caps are equal.

This function only works on fixed Gst::Caps.

Parameters
caps2The Gst::Caps to test.
Returns
true if the arguments represent the same format.
Glib::RefPtr<Gst::Caps> Gst::Caps::get_difference ( const Glib::RefPtr< const Gst::Caps >&  subtrahend_caps) const

Subtracts the subtrahend from the minuend.

<note>This function does not work reliably if optional properties for caps are included on one caps and omitted on the other.</note>

Parameters
subtrahendGst::Caps to subtract.
Returns
The resulting caps.
CapsFeatures Gst::Caps::get_features ( guint  index) const

Finds the features in caps that has the index index , and returns it.

Parameters
indexthe index of the structure.
Returns
The new Gst::CapsFeatures corresponding to index.
Glib::RefPtr<Gst::Caps> Gst::Caps::get_intersect ( const Glib::RefPtr< const Gst::Caps >&  other_caps) const

Creates a new Gst::Caps that contains all the formats that are common to both caps1 and caps2.

Defaults to Gst::CAPS_INTERSECT_ZIG_ZAG mode.

Parameters
caps2A Gst::Caps to intersect.
Returns
The new Gst::Caps.
Glib::RefPtr<Gst::Caps> Gst::Caps::get_intersect ( const Glib::RefPtr< const Gst::Caps >&  other_caps,
CapsIntersectMode  p2 
) const

Creates a new Gst::Caps that contains all the formats that are common to both caps1 and caps2, the order is defined by the Gst::CapsIntersectMode used.

Parameters
caps2A Gst::Caps to intersect.
modeThe intersection algorithm/mode to use.
Returns
The new Gst::Caps.
Glib::RefPtr<Gst::Caps> Gst::Caps::get_normal ( ) const

Returns a Gst::Caps that represents the same set of formats as caps, but contains no lists.

Each list is expanded into separate GstStructures.

This function takes ownership of caps.

Returns
The normalized Gst::Caps.
const Structure Gst::Caps::get_structure ( guint  idx) const

Finds the structure in caps that has the index idx, and returns it.

Parameters
indexThe index of the structure.
Returns
The Gst::Structure corresponding to index.
GstCaps* Gst::Caps::gobj ( )

Provides access to the underlying C instance.

const GstCaps* Gst::Caps::gobj ( ) const

Provides access to the underlying C instance.

GstCaps* Gst::Caps::gobj_copy ( ) const

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

bool Gst::Caps::is_always_compatible ( const Glib::RefPtr< const Gst::Caps >&  other_caps) const

A given Gst::Caps structure is always compatible with another if every media format that is in the first is also contained in the second.

That is, caps1 is a subset of caps2.

Parameters
caps2The Gst::Caps to test.
Returns
true if caps1 is a subset of caps2.
bool Gst::Caps::is_any ( ) const

Determines if caps represents any media format.

Returns
true if caps represents any format.
bool Gst::Caps::is_fixed ( ) const

Fixed Gst::Caps describe exactly one format, that is, they have exactly one structure, and each field in the structure describes a fixed type.

Examples of non-fixed types are GST_TYPE_INT_RANGE and GST_TYPE_LIST.

Returns
true if caps is fixed.
bool Gst::Caps::is_subset ( const Glib::RefPtr< const Gst::Caps >&  superset_caps) const

Checks if all caps represented by subset are also represented by superset.

Parameters
supersetA potentially greater Gst::Caps.
Returns
true if subset is a subset of superset.
Glib::RefPtr<Gst::Caps> Gst::Caps::merge ( Glib::RefPtr< Gst::Caps >&  caps)

Appends the structures contained in caps to an object if they are not yet expressed by this object.

The structures in caps are not copied – they are transferred to a writable copy of this object, and then caps is freed. If either caps is ANY, the resulting caps will be ANY.

Parameters
capsThe Gst::Caps to merge in.
Returns
The merged caps.
Glib::RefPtr<Gst::Caps> Gst::Caps::merge_structure ( const Structure structure)

Appends a structure to caps if its not already expressed by caps.

Parameters
structureThe Gst::Structure to merge.
Glib::RefPtr<Gst::Caps> Gst::Caps::merge_structure ( const Structure structure,
const CapsFeatures features 
)

Appends a structure to caps if its not already expressed by caps.

Parameters
structureThe Gst::Structure to merge.
featuresThe Gst::CapsFeatures to merge.
void Gst::Caps::operator delete ( void *  ,
std::size_t   
)
protected
void Gst::Caps::reference ( ) const

Increment the reference count for this object.

You should never need to do this manually - use the object via a RefPtr instead.

void Gst::Caps::remove_structure ( guint  idx)

removes the stucture with the given index from the list of structures contained in caps.

Parameters
idxIndex of the structure to remove.
void Gst::Caps::set_features ( guint  index,
const CapsFeatures features 
)

Sets the Gst::CapsFeatures for the structure at index.

Parameters
indexThe index of the structure.
featuresThe Gst::CapsFeatures to set.
void Gst::Caps::set_simple ( const Glib::ustring name,
const Glib::ValueBase value 
)

Sets fields in a simple Gst::Caps.

A simple Gst::Caps is one that only has one structure. This method, like the Gst::Structure::set_field() methods, translates certain GTypes to GStreamer specific GTypes for functional compatibility.

Parameters
nameField to set.
valueThe value which the field should be set to.
template <class DataType >
void Gst::Caps::set_simple ( const Glib::ustring name,
const DataType &  data 
)

Sets fields in a simple Gst::Caps.

A simple Gst::Caps is one that only has one structure. This method, like the Gst::Structure::set_field() methods, translates certain GTypes to GStreamer specific GTypes for functional compatibility.

Parameters
nameField to set.
dataA value which the field should be set to (this can be any supported C++ type).
void Gst::Caps::set_simple ( const Glib::ustring name,
const char *  data 
)

Sets fields in a simple Gst::Caps.

A simple Gst::Caps is one that only has one structure.

Parameters
nameField to set.
dataA C string (const char*) which the field should be set to.
void Gst::Caps::set_value ( const Glib::ustring field,
const Glib::ValueBase value 
)

Sets the given field on all structures of caps to the given value.

This is a convenience function for calling Gst::Structure::set_value() on all structures of caps.

Parameters
fieldName of the field to set.
valueValue to set the field to.
template <class DataType >
void Gst::Caps::set_value ( const Glib::ustring name,
const DataType &  data 
)

Sets the given field on all structures to the given value.

This is a convenience function for calling Gst::Structure::set_value() on all structures.

Parameters
nameField to set.
dataA value which the field should be set to (this can be any supported C++ type).
Glib::RefPtr<Gst::Caps> Gst::Caps::simplify ( )

Converts the given caps into a representation that represents the same set of formats, but in a simpler form.

Component structures that are identical are merged. Component structures that have values that can be merged are also merged.

This method does not preserve the original order of caps.

Returns
The simplified caps.
guint Gst::Caps::size ( ) const

Gets the number of structures contained in caps.

Returns
The number of structures that caps contains.
Structure Gst::Caps::steal_structure ( guint  index)

Retrieves the structure with the given index from the list of structures contained in caps.

The caller becomes the owner of the returned structure.

Parameters
indexIndex of the structure to retrieve.
Returns
A pointer to the Gst::Structure corresponding to index.
Glib::ustring Gst::Caps::to_string ( ) const

Converts caps to a string representation.

This string representation can be converted back to a Gst::Caps by from_string().

For debugging purposes its easier to do something like this:

[C example ellipted] This prints the caps in human readable form.

Returns
A newly allocated string representing caps.
Glib::RefPtr<Gst::Caps> Gst::Caps::truncate ( )

Discard all but the first structure from caps.

Useful when fixating.

Returns
Truncated caps.
void Gst::Caps::unreference ( ) const

Decrement the reference count for this object.

You should never need to do this manually - use the object via a RefPtr instead.

Friends And Related Function Documentation

Glib::RefPtr< Gst::Caps > wrap ( GstCaps *  object,
bool  take_copy = false 
)
related

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

Parameters
objectThe C instance.
take_copyFalse 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/caps.h