Module chunks 

One codec per chunk type ([spec/03-chunks.md], [spec/09-layer-data.md], [spec/10-scene-chunks.md]).

Each codec deals in plaintext payload bytes: decryption and the zstd layer are the caller’s business, because whether a chunk carries a zstd frame is a property of its type (section 6.3) while whether it is sealed is a property of its descriptor.

Re-exports

pub use extd::Extension;

pub use head::Head;

pub use lhas::LayerHashes;

pub use ltbl::LayerEntry;

pub use ltbl::LayerTable;

pub use preview::Preview;

pub use preview::PreviewRole;

pub use zdic::ZstdDictionary;

Modules

extd

The EXTD chunk: vendor and future-standard extensions ([spec/10-scene-chunks.md] section 4.12).

head

The HEAD chunk: display dimensions, layer count and encoder identity ([spec/04-head.md] section 4.1).

json_chunks

The JSON chunks: META, PROF and LROV ([spec/05-meta.md], [spec/06-prof.md], [spec/08-print-control.md]).

layr

The LAYR chunk: one sector’s mask data for one group of layers, as a single zstd frame ([spec/09-layer-data.md] section 4.9).

lhas

The LHAS chunk: per-layer leaf hashes and a Merkle root ([spec/09-layer-data.md] section 4.10).

ltbl

The LTBL chunk: the layer table ([spec/09-layer-data.md] section 4.7).

preview

The PREV chunk: a PNG preview, with its role in the descriptor flags ([spec/08-print-control.md] section 4.6).

voxl

The VOXL chunk: an embedded scene, opaque to LUMEN ([spec/10-scene-chunks.md] section 4.11).

zdic

The ZDIC chunk: the zstd dictionary shared by every LAYR frame ([spec/09-layer-data.md] section 4.8).

Constants

MAX_ZSTD_RATIO

The largest expansion zstd can produce for a chunk payload, used as a coarse guard before a bound specific to the chunk is available.

Functions

allocation_bound

The decompressed-size bound a LAYR chunk’s frame may not exceed.

check_allocation

Reject a declared size above the bound the file’s own structure allows.

compress

Compress a chunk payload into a zstd frame, optionally against a dictionary.

decompress

Decompress a zstd frame, checking the result is exactly uncompressed_size.

decompress_frame

Decompress a LAYR frame, sizing its output from the frame’s own header and bounding it by bound.

decompress_within

Decompress a zstd frame, refusing a declared size above bound.

dictionary_id

The dictionary ID a raw dictionary reports.

frame_content_size

The decompressed length a frame’s own header declares.

frame_dict_id

The dictionary ID a frame reports, or 0 when the frame used no dictionary.

train_dictionary

Train a zstd dictionary from layer samples (section 6.2).