Crate atx_reader 

Parser and decoder for Apple .atx texture archives.

The .atx format is an AAPL-container (RIFF-style chunked file) that wraps ASTC-compressed image data. It is produced by Apple tooling and surfaces in third-party forensic exports such as Cellebrite UFED.

Quick start

use std::fs;

let bytes = fs::read("snapshot.atx").unwrap();

// High-level API — returns RGBA8 pixels at the original (width, height).
let img = atx_reader::decode(&bytes).unwrap();
assert_eq!(img.pixels.len(), (img.width * img.height * 4) as usize);

// With the `image` feature, you can save directly:
let rgba = atx_reader::decode_to_image(&bytes).unwrap();
rgba.save("snapshot.png").unwrap();

What this crate decodes

The format was reverse-engineered from real .atx samples. The current implementation handles the layout used by iOS lock-screen / thumbnail exports:

• AAPL\r\n\x1a\n container signature
• HEAD chunk carrying width / height / depth / mipmap count / a 16-byte texture UUID and two pixel-format discriminator words
• FILL padding chunks (skipped)
• An astc payload chunk holding raw ASTC blocks laid out in Apple’s macro-tiled Morton ordering

Single-mip, single-layer, 2D, ASTC 4×4 is the default decoding path. The lower-level AtxContainer / AtxDecoder API exposes everything else (chunk iteration, format codes, custom footprint, custom payload layout) for callers that need to support new samples.

Structs

AtxChunk

A non-owning view of one chunk inside an AAPL container.

AtxContainer

A zero-copy view over a .atx file’s bytes.

AtxDecoder

Lower-level decoder. Useful when you already hold a parsed header and payload, or want to tweak options between parsing and decoding.

AtxHeader

Parsed metadata from the HEAD chunk.

ChunkIter

Iterator over the chunks following the AAPL magic.

DecodeOptions

Options controlling the decode.

DecodedImage

An RGBA8 image produced by decode / decode_with.

Enums

AstcFootprint

All ASTC 2D block footprints, mirroring astc-decode::Footprint.

AtxError

Errors produced while parsing or decoding a .atx file.

PayloadLayout

How the raw ASTC blocks are laid out inside the astc payload.

TexturePayload

Texture payload variants exposed by AtxContainer::texture_payload.

Constants

AAPL_MAGIC

8-byte container signature: b"AAPL\r\n\x1a\n".

ASTC_TAG

astc chunk tag — raw ASTC payload, optionally swizzled.

FILL_TAG

FILL chunk tag — zero-padding for GPU alignment.

HEAD_TAG

HEAD chunk tag — texture metadata block.

LZFS_TAG

LZFS chunk tag — LZFSE-compressed ASTC payload (bvx2 stream).

Functions

decode

Convenience: parse + decode in one call, using default options (ASTC 4×4, Apple macro-tiled Morton with macro_blocks = 32).

decode_to_image

Decode an .atx to an image::RgbaImage.

decode_with

Convenience: parse + decode using custom options. Auto-detects the payload variant (astc chunk vs LZFSE-compressed LZFS chunk) and the appropriate default layout when the user did not specify one.

Type Aliases

Result