Enum Sampling 

#[non_exhaustive]
pub enum Sampling {
    All,
    EveryNth(u64),
    EverySec(f64),
    KeyframesOnly,
    UniformN(u32),
}

How to select which decoded frames are exported.

Index-based modes (All, EveryNth) count delivered decoder output; time-based modes (EverySec) float their grid on the first delivered frame and compare presentation timestamps.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

All

Every decoded frame (the default).

EveryNth(u64)

Every n-th decoded frame, starting with the first (n >= 1).

EverySec(f64)

Starting from the first delivered frame, the first frame at or after each subsequent k * seconds boundary (k = 1, 2, …). No synthesis: sparse sources yield fewer frames, and each source frame is selected at most once.

KeyframesOnly

Only frames flagged as keyframes. Pins the decoder option skip_frame=nokey for a decode-time fast path, plus a key-flag check as a belt for codecs that ignore the hint.

UniformN(u32)

Exactly n frames (fewer only when a lower max_frames cap wins), sampled uniformly by presentation time over the (trimmed) duration — the standard VLM/CLIP primitive. Short inputs pad by repeating the nearest displayed frame; each repeat keeps that frame’s pts_us. Requires a resolvable duration (see duration_hint_us).

Cost model: the strategy is a single sequential decode of the (trimmed) input — there is no seek-per-target fast path. Frames that lose the grid race are dropped pre-filtergraph and pay no scaling, but once the grid completes the remaining tail (~1/(2n) of the span) passes through the graph — and is scaled — solely to keep the encoder-side termination path fed.

Trait Implementations

impl Clone for Sampling

fn clone(&self) -> Sampling

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Sampling

impl Debug for Sampling

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

Formats the value using the given formatter.

impl PartialEq for Sampling

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Sampling