Class 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 fields 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 until 1.20 the #GstCaps / #GstStructure serialization into string had limited support for nested #GstCaps / #GstStructure fields. It could only support one level of nesting. Using more levels would lead to unexpected behavior when using serialization features, such as gst_caps_to_string() or gst_value_serialize() and their counterparts.

record

Hierarchy

Caps

Constructors

constructor

new Caps(): Gst.Caps

Returns Gst.Caps

Properties

mini_object

mini_object: Gst.MiniObject

the parent type

field

Static name

name: string

Methods

append

append(caps2: Gst.Caps): void

- Defined in @types/Gjs/Gst-1.0.d.ts:16120
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.

Parameters
- caps2: Gst.Caps
  
  the #GstCaps to append
Returns void

append_structure

append_structure(structure: Gst.Structure): void

- Defined in @types/Gjs/Gst-1.0.d.ts:16126
Appends structure to caps. The structure is not copied; caps becomes the owner of structure.

Parameters
- structure: Gst.Structure
  
  the #GstStructure to append
Returns void

append_structure_full

append_structure_full(structure: Gst.Structure, features: CapsFeatures): void

- Defined in @types/Gjs/Gst-1.0.d.ts:16133
Appends structure with features to caps. The structure is not copied; caps becomes the owner of structure.

Parameters
- structure: Gst.Structure
  
  the #GstStructure to append
- features: CapsFeatures
  
  the #GstCapsFeatures to append
Returns void

can_intersect

can_intersect(caps2: Gst.Caps): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16139
Tries intersecting caps1 and caps2 and reports whether the result would not be empty

Parameters
- caps2: Gst.Caps
  
  a #GstCaps to intersect
Returns boolean

copy

copy(): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16148
Creates a new #GstCaps 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.

Note that this function is the semantic equivalent of a gst_caps_ref() followed by a gst_caps_make_writable(). If you only want to hold on to a reference to the data, you should use gst_caps_ref().

Returns Gst.Caps

copy_nth

copy_nth(nth: number): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16154
Creates a new #GstCaps and appends a copy of the nth structure contained in caps.

Parameters
- nth: number
  
  the nth structure to copy
Returns Gst.Caps

filter_and_map_in_place

filter_and_map_in_place(func: CapsFilterMapFunc): void

- Defined in @types/Gjs/Gst-1.0.d.ts:16164
Calls the provided function once for each structure and caps feature in the #GstCaps. In contrast to gst_caps_foreach(), the function may modify the structure and features. In contrast to gst_caps_filter_and_map_in_place(), the structure and features are removed from the caps if %FALSE is returned from the function. The caps must be mutable.

Parameters
- func: CapsFilterMapFunc
  
  a function to call for each field
Returns void

fixate

fixate(): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16180
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().

This function takes ownership of caps and will call gst_caps_make_writable() on it so you must not use caps afterwards unless you keep an additional reference to it with gst_caps_ref().

Note that it is not guaranteed that the returned caps have exactly one structure. If caps are empty caps then the returned caps will be the empty too and contain no structure at all.

Calling this function with ANY caps is not allowed.

Returns Gst.Caps

foreach

foreach(func: CapsForeachFunc): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16187
Calls the provided function once for each structure and caps feature in the #GstCaps. The function must not modify the fields. Also see gst_caps_map_in_place() and gst_caps_filter_and_map_in_place().

Parameters
- func: CapsForeachFunc
  
  a function to call for each field
Returns boolean

get_features

get_features(index: number): CapsFeatures

- Defined in @types/Gjs/Gst-1.0.d.ts:16201
Finds the features in caps at index, and returns it.

WARNING: This function takes a const GstCaps *, but returns a non-const GstCapsFeatures *. This is for programming convenience -- the caller should be aware that features inside a constant #GstCaps should not be modified. However, if you know the caps are writable, either because you have just copied them or made them writable with gst_caps_make_writable(), you may modify the features returned in the usual way, e.g. with functions like gst_caps_features_add().

Parameters
- index: number
  
  the index of the structure
Returns CapsFeatures

get_size

get_size(): number

- Defined in @types/Gjs/Gst-1.0.d.ts:16205
Gets the number of structures contained in caps.

Returns number

get_structure

get_structure(index: number): Gst.Structure

- Defined in @types/Gjs/Gst-1.0.d.ts:16219
Finds the structure in caps at index, and returns it.

WARNING: This function takes a const GstCaps *, but returns a non-const GstStructure *. This is for programming convenience -- the caller should be aware that structures inside a constant #GstCaps should not be modified. However, if you know the caps are writable, either because you have just copied them or made them writable with gst_caps_make_writable(), you may modify the structure returned in the usual way, e.g. with functions like gst_structure_set().

Parameters
- index: number
  
  the index of the structure
Returns Gst.Structure

intersect

intersect(caps2: Gst.Caps): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16225
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.

Parameters
- caps2: Gst.Caps
  
  a #GstCaps to intersect
Returns Gst.Caps

intersect_full

intersect_full(caps2: Gst.Caps, mode: CapsIntersectMode): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16233
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.

Parameters
- caps2: Gst.Caps
  
  a #GstCaps to intersect
- mode: CapsIntersectMode
  
  The intersection algorithm/mode to use
Returns Gst.Caps

is_always_compatible

is_always_compatible(caps2: Gst.Caps): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16240
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.

Parameters
- caps2: Gst.Caps
  
  the #GstCaps to test
Returns boolean

is_any

is_any(): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16244
Determines if caps represents any media format.

Returns boolean

is_empty

is_empty(): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16248
Determines if caps represents no media formats.

Returns boolean

is_equal

is_equal(caps2: Gst.Caps): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16253
Checks if the given caps represent the same set of caps.

Parameters
- caps2: Gst.Caps
  
  another #GstCaps
Returns boolean

is_equal_fixed

is_equal_fixed(caps2: Gst.Caps): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16259
Tests if two #GstCaps are equal. This function only works on fixed #GstCaps.

Parameters
- caps2: Gst.Caps
  
  the #GstCaps to test
Returns boolean

is_fixed

is_fixed(): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16265
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.

Returns boolean

is_strictly_equal

is_strictly_equal(caps2: Gst.Caps): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16270
Checks if the given caps are exactly the same set of caps.

Parameters
- caps2: Gst.Caps
  
  another #GstCaps
Returns boolean

is_subset

is_subset(superset: Gst.Caps): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16275
Checks if all caps represented by subset are also represented by superset.

Parameters
- superset: Gst.Caps
  
  a potentially greater #GstCaps
Returns boolean

is_subset_structure

is_subset_structure(structure: Gst.Structure): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16281
Checks if structure is a subset of caps. See gst_caps_is_subset() for more information.

Parameters
- structure: Gst.Structure
  
  a potential #GstStructure subset of caps
Returns boolean

is_subset_structure_full

is_subset_structure_full(structure: Gst.Structure, features: CapsFeatures): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16288
Checks if structure is a subset of caps. See gst_caps_is_subset() for more information.

Parameters
- structure: Gst.Structure
  
  a potential #GstStructure subset of caps
- features: CapsFeatures
  
  a #GstCapsFeatures for structure
Returns boolean

map_in_place

map_in_place(func: CapsMapFunc): boolean

- Defined in @types/Gjs/Gst-1.0.d.ts:16295
Calls the provided function once for each structure and caps feature in the #GstCaps. In contrast to gst_caps_foreach(), the function may modify but not delete the structures and features. The caps must be mutable.

Parameters
- func: CapsMapFunc
  
  a function to call for each field
Returns boolean

merge

merge(caps2: Gst.Caps): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16303
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.

Parameters
- caps2: Gst.Caps
  
  the #GstCaps to merge in
Returns Gst.Caps

merge_structure

merge_structure(structure: Gst.Structure): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16308
Appends structure to caps if it is not already expressed by caps.

Parameters
- structure: Gst.Structure
  
  the #GstStructure to merge
Returns Gst.Caps

merge_structure_full

merge_structure_full(structure: Gst.Structure, features: CapsFeatures): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16314
Appends structure with features to caps if its not already expressed by caps.

Parameters
- structure: Gst.Structure
  
  the #GstStructure to merge
- features: CapsFeatures
  
  the #GstCapsFeatures to merge
Returns Gst.Caps

normalize

normalize(): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16324
Returns a #GstCaps that represents the same set of formats as caps, but contains no lists. Each list is expanded into separate #GstStructure.

This function takes ownership of caps and will call gst_caps_make_writable() on it so you must not use caps afterwards unless you keep an additional reference to it with gst_caps_ref().

Returns Gst.Caps

remove_structure

remove_structure(idx: number): void

- Defined in @types/Gjs/Gst-1.0.d.ts:16330
Removes the structure with the given index from the list of structures contained in caps.

Parameters
- idx: number
  
  Index of the structure to remove
Returns void

serialize

serialize(flags: Gst.SerializeFlags): string

- Defined in @types/Gjs/Gst-1.0.d.ts:16343
Converts caps to a string representation. This string representation can be converted back to a #GstCaps by gst_caps_from_string().

This prints the caps in human readable form.

This version of the caps serialization function introduces support for nested structures and caps but the resulting strings won't be parsable with GStreamer prior to 1.20 unless #GST_SERIALIZE_FLAG_BACKWARD_COMPAT is passed as flag.

Parameters
- flags: Gst.SerializeFlags
  
  a #GstSerializeFlags
Returns string

set_features

set_features(index: number, features: CapsFeatures): void

- Defined in @types/Gjs/Gst-1.0.d.ts:16349
Sets the features for the structure at index.

Parameters
- index: number
  
  the index of the structure
- features: CapsFeatures
  
  the #GstCapsFeatures to set
Returns void

set_features_simple

set_features_simple(features: CapsFeatures): void

- Defined in @types/Gjs/Gst-1.0.d.ts:16354
Sets the features for all the structures of caps.

Parameters
- features: CapsFeatures
  
  the #GstCapsFeatures to set
Returns void

set_value

set_value(field: string, value: any): void

- Defined in @types/Gjs/Gst-1.0.d.ts:16362
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
- field: string
  
  name of the field to set
- value: any
  
  value to set the field to
Returns void

simplify

simplify(): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16375
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 function takes ownership of caps and will call gst_caps_make_writable() on it if necessary, so you must not use caps afterwards unless you keep an additional reference to it with gst_caps_ref().

This method does not preserve the original order of caps.

Returns Gst.Caps

steal_structure

steal_structure(index: number): Gst.Structure

- Defined in @types/Gjs/Gst-1.0.d.ts:16381
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
- index: number
  
  Index of the structure to retrieve
Returns Gst.Structure

subtract

subtract(subtrahend: Gst.Caps): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16388
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.

Parameters
- subtrahend: Gst.Caps
  
  #GstCaps to subtract
Returns Gst.Caps

to_string

to_string(): string

- Defined in @types/Gjs/Gst-1.0.d.ts:16404
Converts caps to a string representation. This string representation can be converted back to a #GstCaps by gst_caps_from_string().
For debugging purposes its easier to do something like this:
```
GST_LOG ("caps are %" GST_PTR_FORMAT, caps);
```
This prints the caps in human readable form.

The implementation of serialization up to 1.20 would lead to unexpected results when there were nested #GstCaps / #GstStructure deeper than one level.
Returns string

truncate

truncate(): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16417
Discards all but the first structure from caps. Useful when fixating.

This function takes ownership of caps and will call gst_caps_make_writable() on it if necessary, so you must not use caps afterwards unless you keep an additional reference to it with gst_caps_ref().

Note that it is not guaranteed that the returned caps have exactly one structure. If caps is any or empty caps then the returned caps will be the same and contain no structure at all.

Returns Gst.Caps

Static from_string

from_string(string: string): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16493
Converts caps from a string representation.

The implementation of serialization up to 1.20 would lead to unexpected results when there were nested #GstCaps / #GstStructure deeper than one level.

Parameters
- string: string
  
  a string to convert to #GstCaps
Returns Gst.Caps

Static new_any

new_any(): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16471
Creates a new #GstCaps that indicates that it is compatible with any media format.

Returns Gst.Caps

Static new_empty

new_empty(): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16478
Creates a new #GstCaps that is empty. That is, the returned #GstCaps contains no media formats. The #GstCaps is guaranteed to be writable.

Returns Gst.Caps

Static new_empty_simple

new_empty_simple(media_type: string): Gst.Caps

- Defined in @types/Gjs/Gst-1.0.d.ts:16485
Creates a new #GstCaps that contains one #GstStructure with name media_type.

Parameters
- media_type: string
  
  the media type of the structure
Returns Gst.Caps

Hierarchy

Index

Constructors

Properties

Methods

Constructors

constructor

Returns Gst.Caps

Properties

mini_object

Static name

Methods

append

Parameters

caps2: Gst.Caps

Returns void

append_structure

Parameters

structure: Gst.Structure

Returns void

append_structure_full

Parameters

structure: Gst.Structure

features: CapsFeatures

Returns void

can_intersect

Parameters

caps2: Gst.Caps

Returns boolean

copy

Returns Gst.Caps

copy_nth

Parameters

nth: number

Returns Gst.Caps

filter_and_map_in_place

Parameters

func: CapsFilterMapFunc

Returns void

fixate

Returns Gst.Caps

foreach

Parameters

func: CapsForeachFunc

Returns boolean

get_features

Parameters

index: number

Returns CapsFeatures

get_size

Returns number

get_structure

Parameters

index: number

Returns Gst.Structure

intersect

Parameters

caps2: Gst.Caps

Returns Gst.Caps

intersect_full

Parameters

caps2: Gst.Caps

mode: CapsIntersectMode

Returns Gst.Caps

is_always_compatible

Parameters

caps2: Gst.Caps

Returns boolean

is_any

Returns boolean

is_empty

Returns boolean

is_equal

Parameters

caps2: Gst.Caps

Returns boolean

is_equal_fixed

Parameters

caps2: Gst.Caps

Returns boolean