Caps

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

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

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

A gstreamer.Caps 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 gstreamer.Caps is fixed when it has no properties with ranges or lists. Use Caps.isFixed 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 gstreamer.Caps / gstreamer.Structure serialization into string has limited support for nested gstreamer.Caps / gstreamer.Structure fields. It can only support one level of nesting. Using more levels will lead to unexpected behavior when using serialization features, such as Caps.toString or Value.serialize and their counterparts.

class Caps {

GstCaps* gstCaps;

protected

bool ownedRef;

GstCaps* getCapsStruct(bool transferOwnership);

void* getStruct();

this(GstCaps* gstCaps, bool ownedRef);

static Caps newAny();

static GType getType();

this(string mediaType);

this(Structure structure, void* varArgs);

void append(Caps caps2);

void appendStructure(Structure structure);

void appendStructureFull(Structure structure, CapsFeatures features);

bool canIntersect(Caps caps2);

Caps copyNth(uint nth);

void filterAndMapInPlace(GstCapsFilterMapFunc func, void* userData);

Caps fixate();

bool foreach_(GstCapsForeachFunc func, void* userData);

CapsFeatures getFeatures(uint index);

uint getSize();

Structure getStructure(uint index);

Caps intersect(Caps caps2);

Caps intersectFull(Caps caps2, GstCapsIntersectMode mode);

bool isAlwaysCompatible(Caps caps2);

bool isAny();

bool isEmpty();

bool isEqual(Caps caps2);

bool isEqualFixed(Caps caps2);

bool isFixed();

bool isStrictlyEqual(Caps caps2);

bool isSubset(Caps superset);

bool isSubsetStructure(Structure structure);

bool isSubsetStructureFull(Structure structure, CapsFeatures features);

bool mapInPlace(GstCapsMapFunc func, void* userData);

Caps merge(Caps caps2);

Caps mergeStructure(Structure structure);

Caps mergeStructureFull(Structure structure, CapsFeatures features);

Caps normalize();

void removeStructure(uint idx);

void setFeatures(uint index, CapsFeatures features);

void setFeaturesSimple(CapsFeatures features);

void setSimpleValist(string field, void* varargs);

void setValue(string field, Value value);

Caps simplify();

Structure stealStructure(uint index);

Caps subtract(Caps subtrahend);

string toString();

Caps truncate();

static Caps fromString(string string_);

}

Constructors

this this(GstCaps* gstCaps, bool ownedRef): Sets our main struct and passes it to the parent class.
this this(): Creates a new gstreamer.Caps that is empty. That is, the returned gstreamer.Caps contains no media formats. The gstreamer.Caps is guaranteed to be writable. Caller is responsible for unreffing the returned caps.
this this(string mediaType): Creates a new gstreamer.Caps that contains one gstreamer.Structure with name media_type. Caller is responsible for unreffing the returned caps.
this this(Structure structure, void* varArgs): Creates a new gstreamer.Caps and adds all the structures listed as arguments. The list must be NULL-terminated. The structures are not copied; the returned gstreamer.Caps 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
copy Caps copy(): Creates a new gstreamer.Caps as a copy of the old caps. The new caps will have a refcount of 1, owned by the caller. The structures are copied as well.
copyNth Caps copyNth(uint nth): Creates a new gstreamer.Caps and appends a copy of the nth structure contained in caps.
filterAndMapInPlace void filterAndMapInPlace(GstCapsFilterMapFunc func, void* userData): Calls the provided function once for each structure and caps feature in the gstreamer.Caps In contrast to Caps.foreach, the function may modify the structure and features. In contrast to Caps.filterAndMapInPlace, the structure and features are removed from the caps if FALSE is returned from the function. The caps must be mutable.
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 Structure.fixate.
foreach_ bool foreach_(GstCapsForeachFunc func, void* userData): Calls the provided function once for each structure and caps feature in the gstreamer.Caps The function must not modify the fields. Also see Caps.mapInPlace and Caps.filterAndMapInPlace.
getCapsStruct GstCaps* getCapsStruct(bool transferOwnership): 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 gstreamer.Caps 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 gstreamer.Caps 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 gstreamer.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.
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 gstreamer.Caps are equal. This function only works on fixed gstreamer.Caps
isFixed bool isFixed(): Fixed gstreamer.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.
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 Caps.isSubset for more information.
isSubsetStructureFull bool isSubsetStructureFull(Structure structure, CapsFeatures features): Checks if structure is a subset of caps. See Caps.isSubset for more information.
mapInPlace bool mapInPlace(GstCapsMapFunc func, void* userData): Calls the provided function once for each structure and caps feature in the gstreamer.Caps In contrast to Caps.foreach, the function may modify but not delete the structures and features. The caps must be mutable.
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 gstreamer.Caps 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 gstreamer.CapsFeatures features for the structure at index.
setFeaturesSimple void setFeaturesSimple(CapsFeatures features): Sets the gstreamer.CapsFeatures features for all the structures of caps.
setSimpleValist void setSimpleValist(string field, void* varargs): Sets fields in a gstreamer.Caps The arguments must be passed in the same manner as 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 Structure.setValue 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. > This function does not work reliably if optional properties for caps > are included on one caps and omitted on the other.
toString string toString(): Converts caps to a string representation. This string representation can be converted back to a gstreamer.Caps by Caps.fromString.
truncate Caps truncate(): Discard all but the first structure from caps. Useful when fixating.

Static functions

fromString Caps fromString(string string_): 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

gstreamer Caps classes

Caps