Caps

Caps (capabilities) are lightweight refcounted objects describing media types. They are composed of an array of #GstStructure.

Caps are exposed on #GstPadTemplate to describe all possible types a given pad can handle. They are also stored in the #GstRegistry along with a description of the #GstElement.

Caps are exposed on the element pads using the gst_pad_query_caps() pad function. This function describes the possible types that the pad can handle or produce at runtime.

A #GstCaps can be constructed with the following code fragment: |[ GstCaps *caps = gst_caps_new_simple ("video/x-raw", "format", G_TYPE_STRING, "I420", "framerate", GST_TYPE_FRACTION, 25, 1, "pixel-aspect-ratio", GST_TYPE_FRACTION, 1, 1, "width", G_TYPE_INT, 320, "height", G_TYPE_INT, 240, NULL); ]|

A #GstCaps is fixed when it has no properties with ranges or lists. Use gst_caps_is_fixed() to test for fixed caps. Fixed caps can be used in a caps event to notify downstream elements of the current media type.

Various methods exist to work with the media types such as subtracting or intersecting.

Be aware that the current #GstCaps / #GstStructure serialization into string has limited support for nested #GstCaps / #GstStructure fields. It can only support one level of nesting. Using more levels will lead to unexpected behavior when using serialization features, such as gst_caps_to_string() or gst_value_serialize() and their counterparts.

Constructors

this
this(GstCaps* gstCaps)

Sets our main struct and passes it to the parent class.

this
this()

Creates a new #GstCaps that is empty. That is, the returned #GstCaps contains no media formats. The #GstCaps is guaranteed to be writable. Caller is responsible for unreffing the returned caps.

this
this(string mediaType)

Creates a new #GstCaps that contains one #GstStructure with name @media_type. Caller is responsible for unreffing the returned caps.

this
this(Structure structure, void* varArgs)

Creates a new #GstCaps and adds all the structures listed as arguments. The list must be %NULL-terminated. The structures are not copied; the returned #GstCaps owns the structures.

Members

Functions

append
void append(Caps caps2)

Appends the structures contained in @caps2 to @caps1. The structures in @caps2 are not copied -- they are transferred to @caps1, and then @caps2 is freed. If either caps is ANY, the resulting caps will be ANY.

appendStructure
void appendStructure(Structure structure)

Appends @structure to @caps. The structure is not copied; @caps becomes the owner of @structure.

appendStructureFull
void appendStructureFull(Structure structure, CapsFeatures features)

Appends @structure with @features to @caps. The structure is not copied; @caps becomes the owner of @structure.

canIntersect
bool canIntersect(Caps caps2)

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

copyNth
Caps copyNth(uint nth)

Creates a new #GstCaps and appends a copy of the nth structure contained in @caps.

fixate
Caps fixate()

Modifies the given @caps into a representation with only fixed values. First the caps will be truncated and then the first structure will be fixated with gst_structure_fixate().

getCapsStruct
GstCaps* getCapsStruct()

Get the main Gtk struct

getFeatures
CapsFeatures getFeatures(uint index)

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

getSize
uint getSize()

Gets the number of structures contained in @caps.

getStruct
void* getStruct()

the main Gtk struct as a void*

getStructure
Structure getStructure(uint index)

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

intersect
Caps intersect(Caps caps2)

Creates a new #GstCaps that contains all the formats that are common to both @caps1 and @caps2. Defaults to %GST_CAPS_INTERSECT_ZIG_ZAG mode.

intersectFull
Caps intersectFull(Caps caps2, GstCapsIntersectMode mode)

Creates a new #GstCaps that contains all the formats that are common to both @caps1 and @caps2, the order is defined by the #GstCapsIntersectMode used.

isAlwaysCompatible
bool isAlwaysCompatible(Caps caps2)

A given #GstCaps 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.

isAny
bool isAny()

Determines if @caps represents any media format.

isEmpty
bool isEmpty()

Determines if @caps represents no media formats.

isEqual
bool isEqual(Caps caps2)

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

isEqualFixed
bool isEqualFixed(Caps caps2)

Tests if two #GstCaps are equal. This function only works on fixed #GstCaps.

isFixed
bool isFixed()

Fixed #GstCaps 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.

isStrictlyEqual
bool isStrictlyEqual(Caps caps2)

Checks if the given caps are exactly the same set of caps.

isSubset
bool isSubset(Caps superset)

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

isSubsetStructure
bool isSubsetStructure(Structure structure)

Checks if @structure is a subset of @caps. See gst_caps_is_subset() for more information.

isSubsetStructureFull
bool isSubsetStructureFull(Structure structure, CapsFeatures features)

Checks if @structure is a subset of @caps. See gst_caps_is_subset() for more information.

merge
Caps merge(Caps caps2)

Appends the structures contained in @caps2 to @caps1 if they are not yet expressed by @caps1. The structures in @caps2 are not copied -- they are transferred to a writable copy of @caps1, and then @caps2 is freed. If either caps is ANY, the resulting caps will be ANY.

mergeStructure
Caps mergeStructure(Structure structure)

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

mergeStructureFull
Caps mergeStructureFull(Structure structure, CapsFeatures features)

Appends @structure with @features to @caps if its not already expressed by @caps.

normalize
Caps normalize()

Returns a #GstCaps that represents the same set of formats as @caps, but contains no lists. Each list is expanded into separate @GstStructures.

removeStructure
void removeStructure(uint idx)

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

setFeatures
void setFeatures(uint index, CapsFeatures features)

Sets the #GstCapsFeatures @features for the structure at @index.

setSimpleValist
void setSimpleValist(string field, void* varargs)

Sets fields in a #GstCaps. The arguments must be passed in the same manner as gst_structure_set(), and be %NULL-terminated.

setValue
void setValue(string field, Value 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.

simplify
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.

stealStructure
Structure stealStructure(uint 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.

subtract
Caps subtract(Caps subtrahend)

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>

toString
string toString()

Converts @caps to a string representation. This string representation can be converted back to a #GstCaps by gst_caps_from_string().

truncate
Caps truncate()

Discard all but the first structure from @caps. Useful when fixating.

Static functions

fromString
Caps fromString(string str)

Converts @caps from a string representation.

getType
GType getType()
newAny
Caps newAny()

Creates a new GstCaps that indicates that it is compatible with any media format.

Variables

gstCaps
GstCaps* gstCaps;

the main Gtk struct

Meta