Struct CapabilityDescriptor 

pub struct CapabilityDescriptor {
    pub output_memory: MemoryDomainKind,
    pub acceleration: Acceleration,
    pub rank: i16,
}

What an element offers the auto-plug search beyond its pad templates: the signals used to choose among several elements that satisfy the same caps.

This generalizes a bare output-memory tag, the principled alternative to a flat global rank. A single integer cannot express that the best element is context-dependent (a hardware decoder that keeps frames on the GPU beats a faster one that forces a PCIe download when the consumer is GPU-resident), so score ranks a candidate against a SelectionContext; the numeric rank is only the deterministic tiebreaker among otherwise-equal candidates (the explicit-override knob GStreamer’s rank gets right). All-default descriptors score equally, so registration order decides, leaving a plain pipeline’s selection unchanged.

Fields

output_memory: MemoryDomainKind

The memory feature the source pad emits (a decodebin caps feature, GStreamer’s memory:CUDAMemory analog). Caps geometry / format is in the pad templates; the memory domain is not, so it rides here. Matching the consumer’s domain avoids a copy / download (e.g. pick NvDec -> Cuda).

acceleration: Acceleration

Hardware vs software path.

rank: i16

Deterministic tiebreaker among candidates of equal score (higher wins); default 0. Use it to order otherwise-equivalent backends (e.g. two ffmpeg codecs), or as an operator override, not as the primary selector.

Implementations

impl CapabilityDescriptor

pub fn score(&self, ctx: &SelectionContext) -> i32

Score this candidate against what the search wants; higher is tried first. Memory-domain match dominates (it removes a download, the structural win), then a hardware preference, then the explicit rank.

Trait Implementations

impl Clone for CapabilityDescriptor

fn clone(&self) -> CapabilityDescriptor

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for CapabilityDescriptor

impl Debug for CapabilityDescriptor

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for CapabilityDescriptor

fn default() -> Self

Returns the “default value” for a type.

impl Eq for CapabilityDescriptor

impl PartialEq for CapabilityDescriptor

fn eq(&self, other: &CapabilityDescriptor) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for CapabilityDescriptor