Expand description
Low-level bit writers and entropy coders shared by the gamut codecs.
The pieces here are the encoder-side mirror of the parsing processes defined in the AV1
Bitstream & Decoding Process Specification (references/av1/av1-spec.pdf):
BitWriter— most-significant-bit-first fixed-width fields (f(n)) and byte alignment, used by the AV1 uncompressed sequence/frame headers (AV1 §4, §8.1).write_leb128/leb128_len— unsigned LEB128 used for OBU sizes (AV1 §4.10.5, Annex B).SymbolEncoder— the AV1 multi-symbol arithmetic (range) coder, derived by inverting the symbol decoder of AV1 §8.2. It is the entropy back-end for coded tile data.
The forward-looking ANS / Huffman coders named in the workspace plan (for AV2 / JPEG XL) are not implemented yet; they will join this crate behind their own modules.
Structs§
- BitWriter
- A most-significant-bit-first bit writer.
- Symbol
Encoder - Encoder for the AV1 symbol (range) coder.
Functions§
- leb128_
len - Returns the number of bytes the minimal unsigned LEB128 encoding of
valueoccupies. - write_
leb128 - Appends the minimal unsigned LEB128 encoding of
valuetoout.