Struct SymbolEncoder 

pub struct SymbolEncoder { /* private fields */ }

Encoder for the AV1 symbol (range) coder.

Feed symbols with SymbolEncoder::encode_symbol (CDF-coded) and equiprobable bits with SymbolEncoder::encode_literal, then call SymbolEncoder::finish to flush and obtain the coded bytes. Those bytes are exactly what a decoder consumes via init_symbol(sz) (AV1 §8.2.2) where sz is the returned length.

Implementations

impl SymbolEncoder

pub fn new() -> Self

Creates an encoder with the initial range state of AV1’s symbol coder.

pub fn encode_symbol(&mut self, symbol: usize, cdf: &[u16])

Encodes symbol against a static cumulative cdf (cdf.len() symbols, cdf[last] == 32768).

Panics

Debug builds assert symbol < cdf.len() and the CDF normalisation invariants.

pub fn encode_symbol_adapt( &mut self, symbol: usize, cdf: &mut [u16], count: &mut u16, )

Encodes symbol against an adapting cumulative cdf, then applies the §8.2.6 CDF adaptation in place (disable_cdf_update = 0). count is the spec’s trailing cdf[N] adaptation counter (start it at 0 for a freshly initialised context); it is bumped here, up to a maximum of 32. A decoder must apply the identical §8.2.6 update (decode the symbol, then the same adaptation) with the same count so its CDF tracks the encoder’s exactly.

Panics

Debug builds assert symbol < cdf.len() and the CDF normalisation invariants.

pub fn encode_literal(&mut self, value: u32, n: u32)

Encodes the low n bits of value as equiprobable bits, most-significant bit first.

This is the inverse of the decoder’s read_literal(n) (AV1 §8.2.5), which itself calls read_bool() (§8.2.3) with the fixed CDF {1 << 14, 1 << 15}.

pub fn finish(self) -> Vec<u8>

Flushes the coder and returns the coded bytes. Mirrors od_ec_enc_done: it emits the minimum number of bits that decode correctly regardless of trailing padding, then resolves the buffered carries into a big-endian byte stream.

Trait Implementations

impl Clone for SymbolEncoder

fn clone(&self) -> SymbolEncoder

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SymbolEncoder

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

Formats the value using the given formatter.

impl Default for SymbolEncoder

fn default() -> Self

Returns the “default value” for a type.