oxideav-mod

Amiga ProTracker / SoundTracker module (MOD) codec for oxideav.

Part of the oxideav framework — a 100% pure Rust media transcoding and streaming stack. No C libraries, no FFI wrappers, no *-sys crates.

What it does

• Container: reads the whole .mod file (ProTracker / SoundTracker) into a single packet. Probes the 4-byte signature at offset 1080 (M.K., M!K!, 4CHN/6CHN/8CHN, FLT4/FLT8, OCTA, CD81, xxCH for 10..=32 channels). Populates stream metadata (title, sample names, pattern / channel counts) and an upper-bound duration.
• Decoder: parses the header, patterns, and raw signed-8-bit sample bodies; drives a PlayerState (rows → ticks, Paula periods, Protracker sine-table vibrato / tremolo, sample-offset, tone portamento, pattern loop, note-delay / note-cut, pattern-delay, full 16-finetune × 36-note period table); mixes samples with linear interpolation.
• Decode only — there is no MOD encoder, by design.

Output modes

Two decoder implementations are registered with distinct codec IDs:

The mixed mode applies the Amiga hard-pan convention (channels 0 & 3 left, 1 & 2 right; the pattern repeats every 4 for >4-channel files) and a 1/(N/2) headroom scale so a fully-saturated 4-channel MOD stays within -1..1.

The planar mode emits each tracker channel post-volume but pre-pan and pre-mix — consumers get the raw per-channel signal and can apply their own panning / mixing / effects downstream.

Both modes are driven by the same PlayerState tick machinery, so they sample each channel from the same engine; only the output projection differs.

Usage

[dependencies]
oxideav-mod = "0.0"

use oxideav_codec::CodecRegistry;
use oxideav_container::ContainerRegistry;

let mut containers = ContainerRegistry::new();
let mut codecs = CodecRegistry::new();
oxideav_mod::register_containers(&mut containers);
oxideav_mod::register_codecs(&mut codecs);

// Select mixed stereo output:
//   CodecId::new(oxideav_mod::CODEC_ID_STR)          // "mod"
// Or planar per-channel output:
//   CodecId::new(oxideav_mod::CODEC_ID_PLANAR_STR)   // "mod_planar"

Status

Spec-level effect coverage per Protracker-v1.1B-mod.txt:

Loop handling is forward-only per MOD spec — ping-pong / bidi loops are an XM/IT/S3M-era extension and are deliberately not used here.

License

MIT — see LICENSE.