gamut-isobmff

gamut-isobmff writes the ISO Base Media File Format (ISOBMFF) box structure that the AVIF — and later HEIC — containers are built from.

Goals

Part of the gamut workspace, this crate exists to:

Own the container, not the codec. It serializes the ISOBMFF box tree (ftyp, meta, mdat, …) and leaves the coded bitstream to the codec crates, so AVIF and HEIC share one container implementation.
Emit the minimal valid box set. M0 writes exactly the boxes a single still-image item needs (AVIF v1.2.0 §9.1.1): ftyp, then a meta box holding hdlr/pitm/iloc/iinf(infe)/ iprp(ipco+ipma), followed by an mdat carrying the AV1 temporal unit — see [write_avif_still].
Stay spec-faithful and cross-checked. Box byte layouts follow ISO/IEC 14496-12 (ISOBMFF) and ISO/IEC 23008-12 (HEIF) — paywalled and not in ../../references/ — verified against the public AVIF v1.2.0 box table and libavif/ffmpeg output, and validated with avifdec.
Stay memory-safe. #![forbid(unsafe_code)].

Usage

use gamut_isobmff::{Av1cConfig, AvifStillImage, NclxColr, write_avif_still};

// `item_data` is the AV1 temporal unit produced by `gamut-av1`; `av1c`/`nclx` mirror the
// AV1 sequence header. `gamut-avif` wires these together for you end to end.
let img = AvifStillImage {
    width: 64,
    height: 64,
    bit_depth: 8,
    num_channels: 3,
    av1c: av1c_config,   // Av1cConfig: seq_profile, level, subsampling, ...
    nclx: nclx_colr,     // NclxColr: CICP code points + full_range
    item_data: &obus,    // AV1 temporal unit
};
let avif_bytes: Vec<u8> = write_avif_still(&img);

See gamut-avif for the full encode path that drives this crate.

Status

M0 writes the minimal box set for a single lossless AVIF still image. The richer item set — alpha (auxl), grid, transform properties, and sequence tracks (moov/trak), plus HEIC hvc1 support — is deferred per gamut-avif/STATUS.md.

Roadmap

Alpha auxiliary items, image transforms (irot/imir/clap), and grids.
Sequence tracks for animated AVIF.
HEIC/HEVC item support, shared with this crate.

License