gamut-av1

gamut-av1 is a pure-Rust AV1 image encoder. AVIF relies on AV1 intra-frame coding, so this crate is usable standalone as well as through gamut-avif.

If you want a complete .avif file, use gamut-avif. Reach for this crate when you need the raw AV1 still bitstream itself — to embed in your own container or build another AV1-based format. It operates on Planar8 planes and emits an AV1 temporal unit, not a container.

Goals

Part of the gamut workspace, this crate exists to provide AV1 still-image encoding that is:

Memory-safe on hostile input. #![forbid(unsafe_code)] across the whole encode path, deleting the memory-corruption bug class that has repeatedly bitten the C AV1 codecs.
Clean-slate from the spec. Implemented directly from the AV1 Bitstream & Decoding Process Specification (../../references/av1/) rather than wrapping libaom, so it is auditable and forkable. Modules mirror the spec: headers = OBU framing + sequence/frame headers (§5.3/§5.5/§5.9), tile = partition/prediction/coefficient coding (§5.11), cdf = default CDF + scan + context tables (§9.2/§9.4/§8.3.2).
Decoder-verified. Output is checked bit-exact against real decoders (dav1d, libavif), linked from vendored third_party/ submodules — never from system-installed binaries.
Buildable anywhere cargo is. No C, no nasm — cross-compiles cleanly (wasm32, aarch64, musl).

It builds on gamut-color (pixel formats / CICP), gamut-dsp (the Walsh–Hadamard transform), and gamut-bitstream (bit writer + AV1 symbol coder).

Usage

use gamut_av1::encode_still_lossless_identity;
use gamut_color::Planar8;

// 8-bit interleaved RGB -> identity 4:4:4 planes -> lossless AV1 keyframe.
let (width, height) = (64u32, 64u32);
let rgb = vec![0u8; (width * height * 3) as usize];
let planes = Planar8::from_rgb8_identity(&rgb, width, height).expect("valid input");

let still = encode_still_lossless_identity(&planes).expect("encode");
// `still.obus` is the AV1 temporal unit; `still.config` carries the sequence-header
// values that `gamut-avif` mirrors into the `av1C`/`colr` boxes.
std::fs::write("out.obu", &still.obus).unwrap();

Status

Today (milestone M0) the encoder implements a single, narrow path: a lossless all-intra keyframe — seq_profile = 1 (8-bit 4:4:4), identity matrix coefficients, full range, single tile, 64×64 superblocks, DC_PRED, and the forced TX_4X4 Walsh–Hadamard transform, with static default CDFs (disable_cdf_update = 1). It produces the AV1 temporal unit that gamut-avif wraps in an AVIF still image.

The wider AV1 surface — lossy DCT/ADST, more intra modes, in-loop filters, inter coding for image sequences — is tracked row by row in gamut-avif/STATUS.md.

Roadmap

M1: lossy intra (DCT/ADST + quantization), adaptive CDFs, more intra prediction modes.
Later: in-loop filters, multi-tile, and inter coding for animated AVIF.

License