Struct Settings 

#[non_exhaustive]
pub struct Settings {
    pub threads: u32,
    pub apply_grain: bool,
    pub frame_size_limit: u32,
    pub all_layers: bool,
    pub operating_point: u8,
    pub output_invisible_frames: bool,
    pub inloop_filters: InloopFilters,
    pub decode_frame_type: DecodeFrameType,
    pub max_frame_delay: u32,
    pub strict_std_compliance: bool,
    pub cpu_level: CpuLevel,
}

Decoder configuration settings

Use Settings::default() or struct update syntax (Settings { threads: 4, ..Default::default() }) to construct. New fields may be added in minor releases.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

threads: u32

Number of threads for decoding

• 0 = auto-detect (enables frame threading for better performance but asynchronous behavior)
• 1 = single-threaded (default, simpler synchronous behavior)
• 2+ = multi-threaded with frame threading

With frame threading enabled (threads >= 2 or threads == 0), decode() may return None even when complete frame data is provided, as frames are processed asynchronously. Call decode() or flush() multiple times to drain buffered frames.

Note: Multithreading requires the unchecked feature. Without it, the decoder silently falls back to single-threaded to prevent runtime panics from DisjointMut overlap detection on stride gap bytes.

apply_grain: bool

Apply film grain synthesis during decoding

frame_size_limit: u32

Maximum frame size in total pixels, i.e. width * height (0 = unlimited)

Default: 35,389,440 (8K UHD: 8192 × 4320). Set to 0 to disable the limit. Frames exceeding this limit are rejected during OBU parsing with Err(InvalidData).

all_layers: bool

Decode all layers or just the selected operating point

operating_point: u8

Operating point to decode (0-31)

output_invisible_frames: bool

Output invisible frames (frames not meant for display)

inloop_filters: InloopFilters

Inloop filters to apply during decoding

decode_frame_type: DecodeFrameType

Which frame types to decode

max_frame_delay: u32

Maximum number of frames in flight for frame threading.

• 0 = auto (default, derived from thread count: min(sqrt(threads), 8))
• 1 = no frame threading (tile parallelism only — ideal for still images)
• 2+ = up to N frames decoded in parallel

For still image formats (AVIF, HEIC), set this to 1 to get tile-level parallelism without frame threading overhead or async decode behavior.

strict_std_compliance: bool

Enforce strict standard compliance

cpu_level: CpuLevel

CPU feature level for SIMD dispatch.

Controls which instruction sets the decoder is allowed to use. Default is CpuLevel::Native (use all detected features).

Set to a lower level to force the decoder through a specific code path, e.g. CpuLevel::Scalar to test the pure-Rust fallback.

Trait Implementations

impl Clone for Settings

fn clone(&self) -> Settings

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Settings

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

Formats the value using the given formatter.

impl Default for Settings

fn default() -> Self

Returns the “default value” for a type.