oxideav-iff

Pure-Rust EA IFF 85 container support for oxideav — the chunk reader that underlies 8SVX (Amiga 8-bit sampled voice), ILBM (Amiga InterLeaved BitMap pictures), PBM (DPaint II / Brilliance chunky sibling), ANIM (animated ILBM), AIFF, SMUS, and friends. Today this crate ships a full read/write implementation of FORM/8SVX, a read-and-round-trip implementation of FORM/ILBM and FORM/PBM (1..=8 bitplanes, ByteRun1 / Auto compression, EHB, HAM6, HAM8, HasMask, transparent-colour keying, GRAB hotspot, SHAM per-line palette, PCHG small-format palette change list), and a read-only FORM/ANIM implementation (op-0 literal + op-5 byte-vertical delta). The shared chunk walker is reusable as AIFF / SMUS support is added. Zero C dependencies.

Part of the oxideav framework but usable standalone.

Installation

[dependencies]
oxideav-core = "0.1"
oxideav-codec = "0.1"
oxideav-container = "0.1"
oxideav-iff = "0.0"

Supported formats

8SVX — Amiga 8-bit Sampled Voice

Full read and write support for FORM / 8SVX:

• The exposed codec id is pcm_s8; Fibonacci-delta compression is transparent — decoded on demux, encoded on mux when the caller picks Compression::Fibonacci.
• Stereo BODY layout follows the common AmigaOS convention: the LEFT channel in full, then the RIGHT channel in full. For Fibonacci stereo each half carries its own [pad, initial_sample, nibbles...] header and is decoded independently.
• Fibonacci-delta table: [-34, -21, -13, -8, -5, -3, -2, -1, 0, 1, 2, 3, 5, 8, 13, 21] (16 entries, from the Amiga ROM Kernel Manual / AmigaOS wiki). A 4-bit code cannot address a 17th entry.
• Fibonacci-delta is lossy; round-trips reconstruct each sample within +-2 LSBs on smooth signals.

Quick use

Read an 8SVX voice

use oxideav_container::ContainerRegistry;
use oxideav_core::Error;

let mut containers = ContainerRegistry::new();
oxideav_iff::register(&mut containers);

let input: Box<dyn oxideav_container::ReadSeek> = Box::new(
    std::io::Cursor::new(std::fs::read("voice.8svx")?),
);
let mut dmx = containers.open_demuxer("iff_8svx", input)?;
let stream = &dmx.streams()[0];
assert_eq!(stream.params.codec_id.as_str(), "pcm_s8");

loop {
    match dmx.next_packet() {
        Ok(pkt) => {
            // pkt.data is interleaved pcm_s8 (mono or stereo L R L R ...).
        }
        Err(Error::Eof) => break,
        Err(e) => return Err(e.into()),
    }
}
# Ok::<(), Box<dyn std::error::Error>>(())

Write a stereo Fibonacci-delta voice

use oxideav_iff::svx::{Compression, SvxMuxer};

// `stream` describes 2-channel pcm_s8; `packet.data` is interleaved
// L R L R ... at 8 bits per sample.
let mut mux = SvxMuxer::new(out, &[stream])?
    .with_compression(Compression::Fibonacci);
mux.write_header()?;
mux.write_packet(&packet)?;
mux.write_trailer()?;

Container / codec IDs

• Container: "iff_8svx", probes FORM....8SVX and matches .8svx / .iff by extension.
• Codec (inside the stream): "pcm_s8".

ILBM — Amiga InterLeaved BitMap

Read + round-trip support for FORM / ILBM:

* PCHG big-format chunks are decoded but the writer round-trips the original raw bytes verbatim (no re-encode from the parsed entry list).

• Public API: ilbm::parse_ilbm, ilbm::encode_ilbm, ilbm::IlbmImage, ilbm::Bmhd, ilbm::Camg, ilbm::Grab, ilbm::Sham, ilbm::Pchg, ilbm::byterun1_decode_row / ilbm::byterun1_encode_row, ilbm::expand_ham_row, ilbm::expand_ehb_palette, ilbm::IlbmMuxer (with ilbm::MuxerMode selecting indexed / HAM6 / HAM8 / EHB / PBM and ilbm::IlbmMuxer::with_masking selecting HasMask / HasTransparentColor).
• Container id: "iff_ilbm", probes FORM....ILBM (and FORM....PBM ) and matches .ilbm / .lbm by extension. Single-stream rawvideo / Rgba.
• HAM encode picks the cheapest of (palette-lookup, modify-R, modify-G, modify-B) per pixel by squared channel distance against the running channel state. EHB encode quantises against a 64-entry expanded palette and emits 6 bitplanes regardless of input palette length.
• Compression::Auto (the muxer default) tries both None and ByteRun1 and emits whichever produces fewer bytes; the winning mode is recorded in BMHD so the file always self-describes correctly. Solid-colour and gradient images typically save >50 % over raw; pseudo-random images fall back to uncompressed.
• The IlbmMuxer streaming API exposes every encoder mode the one-shot encode_ilbm supports: pick MuxerMode::IndexedAuto (default — 1..=8 bitplanes, palette greedy-built from the first packet), MuxerMode::Ham6 / MuxerMode::Ham8 (CAMG-flagged Hold- And-Modify), MuxerMode::Ehb (32→64 EHB palette mirror), or MuxerMode::Pbm (chunky FORM/PBM ).
• Cross-validated end-to-end against ImageMagick's magick convert (delegate ilbmtoppm → PPM → pixel-compare). Set OXIDEAV_IFF_MAGICK_CROSS=1 to enable the cross-decode tests; they silently skip when the binary or its delegate isn't installed so CI stays green on hosts without ImageMagick.

PBM — DPaint II / Brilliance chunky sibling

FORM / PBM (note the trailing space) shares BMHD / CMAP / CAMG chunks with ILBM but stores the BODY as a chunky 8-bit-per-pixel byte stream (no bitplane interleave). Read + write supported with uncompressed and ByteRun1 BODY; HAM and HasMask-plane masking are not legal in PBM and are rejected on encode/decode.

ANIM — animated ILBM

Read-only support for FORM / ANIM (Aegis Animator / DPaint III):

• Public API: anim::parse_anim, anim::encode_anim_op0, anim::AnimImage, anim::Anhd.
• Container id: "iff_anim", probes FORM....ANIM and matches .anim by extension. Multi-frame rawvideo / Rgba stream; every frame is emitted as a keyframe packet.
• The op-0 muxer is used by the test suite to round-trip multi-frame ANIM through the public encoder; production-quality op-5 encode is not yet implemented.

Read an ILBM picture

let bytes = std::fs::read("picture.ilbm")?;
let img = oxideav_iff::ilbm::parse_ilbm(&bytes)?;
println!("{}x{} → {} bytes RGBA", img.width, img.height, img.rgba.len());
# Ok::<(), Box<dyn std::error::Error>>(())

Roadmap

The chunk walker (chunk.rs) is format-agnostic; AIFF (Apple audio), SMUS (music score) and MAUD are natural follow-ons that reuse the same FORM/LIST/CAT reader. ANIM op-5 encode and ANIM op-7/op-8 decode are open ILBM-side extensions, as are CRNG / CCRT colour- cycling chunks.

License

MIT - see LICENSE.