Tabula Sonora — a spec for the Roland Sound Canvas VA voice

A readable, cross-platform-ready specification and reference implementation of the Roland Sound Canvas VA synth voice, reverse-engineered from SCCore.dll and validated against the DLL's own internal state (not fitted to audio).

The goal: given the (version-pinned) SCCore.dll, anyone — human or agent — can build an engine that reads the ROM + tables straight from the DLL and plays MIDI from an SMF file or a live keyboard. The Python here is a proof-of-concept reference, not the product; it exists so an implementation in any language has something exact to check against.

This is a preservation / interoperability effort on a discontinued product.

What's here

Path	What it is
scvx_engine.py	The synth voice: block-FP ADPCM codec → 4-tap resampler → TVF state-variable filter → TVA/pitch envelopes → LFO → pan/mix. Built from the reversed tables; no DLL at render time.
scvx_directory.py / scvx_partials.py	Patch resolution (program+note+vel → wave + ROM coords) and per-partial synthesis-parameter decode.
scvx_sequencer.py	Playback layer: SMF parsing + per-part controllers over time (CC7/11/1/10/64, bend, RPN tune, drum kits).
scvx_reverb.py / scvx_chorus.py / scvx_delay.py	The three GS send effects (reverb/chorus + system delay), transcribed DSP networks.
tables/manifest.json	The machine-readable map: every table's byte-exact DLL offset, size, dtype, symbol, purpose. The tables themselves (tables/*.bin, *.txt) are DLL-derived and not shipped — extract them locally (see below).
docs/	The reverse-engineering record — see below.
tools/extract_tables.py	Regenerates tables/*.bin from your own SCCore.dll using the manifest offsets (verifies the DLL hash first).
tools/decoder/	scdec, a C# harness that drives the real DLL for A/B ground truth (also produces the tables/*.txt effect-type dumps).
tools/gen_manifest.py	Regenerates tables/manifest.json (and DLL hashes) from any SCCore.dll.
tools/ghidra_scripts/	Headless Ghidra scripts that produce/annotate the decompile.

Start here

1. docs/DLL_LAYOUT.md — the pinned DLL identity (hashes, PE timestamp) and how every table/ROM/directory region maps to a raw file offset. Everything the engine needs lives inside SCCore.dll; the tables/*.bin cache is fully derivable from it.
2. docs/FINDINGS.md — the master log: every reversed algorithm, table, and offset, with confidence tags.
3. docs/PROVENANCE.md — what SCCore.dll is (a whole-stack port of the SC-88/88Pro/8820 hardware, original 24 MB wave ROM embedded intact) and the exact build this targets.
4. docs/SYMBOLS.md / docs/GLOSSARY.md — symbol map and terminology.
5. docs/COMPARING_RENDERS.md — how to judge a reimplementation's audio against the DLL's, and why comparing samples answers the wrong question. tools/compare_envelope.py implements it.

Getting it running

SCCore.dll and everything derived byte-for-byte from it (the wave ROM, the tables/*.bin, the Ghidra decompile) are copyrighted and not included. The repo ships only original work — the engine code, the docs, and tables/manifest.json (the offset map). To run the reference engine:

1. Obtain the exact SCCore.dll build identified in docs/DLL_LAYOUT.md (size 27,347,456; SHA-256 117E6AA1…C620BDB1; PE timestamp 2019-10-30).
2. Extract the tables from it:

   python tools/extract_tables.py "C:/Program Files/Roland VS/SOUND Canvas VA/SCCore.dll"
   

   This verifies the DLL hash and writes tables/*.bin. The effect-type dumps (tables/*.txt) come from building tools/decoder and running scdec revdump/chodump against the same DLL.
3. The engine reads the DLL directly at render time for the wave ROM, so keep it at the path above (or edit the path in scvx_engine.py).

A different DLL build may move tables — re-run tools/gen_manifest.py to re-derive the offsets.

Scope

The core voice + GS send effects are specified. The 66-algorithm insertion EFX subsystem is intentionally out of scope here — it belongs downstream in a concrete engine, layered on top of this.

Implementations

• DotNetAdministravit — a managed C# engine built to this spec. Renders MIDI to audio at ~15× realtime, reading SCCore.dll as a data file rather than loading it as code.

Licence

BSD 3-Clause — see LICENSE. That covers this repository's own work: the docs, the Python reference, the tooling, and tables/manifest.json. It grants nothing in Roland's DLL or the data inside it; see NOTICE.md.

The licence is permissive so that an implementation can be built from this spec under any licence, including the GPL.