Media.Streaming.GStreamer.Core.Caps

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

Caps can be retrieved from an Element's Pads using the padGetCaps function. The returned Caps describes the possible types that the pad can handle or produce at runtime.

Caps are also attached to Buffers to describe the type of the contained data using the function bufferSetCaps. Caps attached to a buffer allow for format negotiation upstream and downstream.

Caps are fixed when they have no properties with ranges or lists. Use capsIsFixed to test for fixed caps. Only fixed caps may be set on a Pad or Buffer.

Types

data Caps

Instances

Eq Caps

capsNone :: Caps

A Caps that represents an undefined media type.

capsAny :: Caps

A Caps that represents all possible media types.

Caps Operations

capsSize

:: Caps	`caps` - a `Caps`
-> Word	the number of structures contained in the `Caps`
Get the number of structures contained in the `Caps`.

capsGetStructure

:: Caps	`caps` - a `Caps`
-> Word	`index` - the index of the `Structure`
-> Maybe Structure	the `Structure` at the given index, or Nothing if `index` is invalid
Get the `Structure` at the given index.

capsIsEmpty

:: Caps	`caps` - a `Caps`
-> Bool	True if `caps` is empty, otherwise False
Determine whether `caps` represents no media formats.

capsIsFixed

:: Caps	`caps` - a `Caps`
-> Bool	True if `caps` is fixed, otherwise False
Determine whether the `caps` is fixed; that is, if it has exactly one structure, and each field in the structure describes a fixed type.

capsIsEqual

:: Caps	`caps1` - the first `Caps`
-> Caps	`caps2` - the second `Caps`
-> Bool	True if both `Caps` represent the same set of capabilities.
Returns True if the caps represent the same set of capabilities. This function does not work reliably if optional properties for `Caps` are included on one `Caps` but omitted on the other.

capsIsEqualFixed

:: Caps	`caps1` - the first `Caps`
-> Caps	`caps2` - the second `Caps`
-> Bool	True if both `Caps` represent the same set of capabilities
Returns True if the caps are equal. The caps must both be fixed.

capsIsAlwaysCompatible

:: Caps	`caps1` - the first `Caps`
-> Caps	`caps2` - the second `Caps`
-> Bool	True if `caps1` is a subset of `caps2`, otherwise False
Returns True if every media format in the first caps is also contained by the second. That is, the first is a subset of the second.

capsIsSubset

:: Caps	`caps1` - the first `Caps`
-> Caps	`caps2` - the second `Caps`
-> Bool	True if `caps1` is a subset of `caps2`, otherwise False
Returns True if all caps represented by the first argument are also represented by the second. This function does not work reliably if optional properties for caps are included on one caps and omitted on the other.

capsIntersect

:: Caps	`caps1` - the first `Caps`
-> Caps	`caps2` - the second `Caps`
-> Caps	a new `Caps` containing all capabilities present in both `caps1` and `caps2`
Creates a new caps containing all the formats that are common to both of the caps.

capsUnion

:: Caps	`caps1` - the first `Caps`
-> Caps	`caps2` - the second `Caps`
-> Caps	a new `Caps` containing all capabilities present in either `caps1` and `caps2`
Creates a new caps containing all the formats that are common to either of the caps. If either of the structures are equivalient to `capsAny`, the result will be `capsAny`.

capsSubtract

:: Caps	`caps1` - the first `Caps`
-> Caps	`caps2` - the second `Caps`
-> Caps	a new `Caps` containing all capabilities present in `caps1` but not `caps2`
Creates a new caps containing all the formats that are in the first but not the second.

capsNormalize

:: Caps	`caps` - a `Caps`
-> Caps	the new, normalized `Caps`
Creates a new caps that represents the same set of formats as the argument, but that contains no lists.

capsFromString

:: String	`string` - the string representation of a `Caps`
-> Maybe Caps	the new `Caps`, or Nothing if `string` is invalid
Read a caps from a string.

capsToString

:: Caps	`caps` - a `Caps`
-> String	the string representation of `Caps`
Converts the argument to a string representation. The string can be converted back to a caps using `capsFromString`.

Caps Mutation

data CapsM a

A Monad for sequencing modifications to a Caps.

Instances

??? a => Functor (CapsM a)

??? a => Monad (CapsM a)

capsCreate

:: CapsM a	`mutate` - the mutating action
-> (Caps, a)	the new `Caps` and the action's result
Create a caps and mutate it according to the given action.

capsModify

:: Caps	`caps` - the `Caps` to modify
-> CapsM a	`mutate` - the mutating action
-> (Caps, a)	the new `Caps` and the action's result
Copy a caps and mutate it according to the given action.

capsAppendStructure

:: Structure	`structure` - the `Structure` to append to the current `Caps`
-> CapsM ()
Append the given structure to the current caps.

capsMergeStructure

:: Structure structure - the Structure to merge with the current Caps

-> CapsM ()

Append the structure to the current caps, if it is not already expressed by the caps.

Since 0.10.10.

capsRemoveStructure

:: Word	`idx` - the index of the `Structure` to remove
-> CapsM ()
Removes the structure at the given index from the current caps.

capsTruncate :: CapsM ()

Discard all but the first structure from the current caps.

Produced by Haddock version 0.8