VST3

Steinberg's VST3 is the most widely-supported plugin format in commercial DAWs. Truce implements it through a thin C++ shim (truce-vst3/shim/vst3_shim.cpp, MIT-licensed) that implements the COM vtables required by the VST3 ABI and forwards every callback into Rust.

#Status

Production. Shipped in the scaffold defaults. Passes pluginval at strictness level 5. Tested in Reaper, Ableton Live, FL Studio on macOS and Windows, and Reaper on Linux.

#Enable

Already on in scaffolded plugins. Otherwise:

[features]
default = ["clap", "vst3"]
vst3 = ["dep:truce-vst3"]

#Requirements

  • macOS: Xcode CLI tools for the C++ compiler. xcode-select --install.
  • Windows: MSVC toolchain (Visual Studio 2019+ with the "Desktop development with C++" workload).
  • Linux: GCC or Clang with C++17 support.

No Steinberg SDK required — the shim is a clean-room COM implementation with MIT licensing.

#Install paths

User-scope by default; pass --system for the system-wide path.

Platform User (default) System (--system)
macOS ~/Library/Audio/Plug-Ins/VST3/{Name}.vst3/ /Library/Audio/Plug-Ins/VST3/{Name}.vst3/ (sudo)
Windows %LOCALAPPDATA%\Programs\Common\VST3\{Name}.vst3\ %COMMONPROGRAMFILES%\VST3\{Name}.vst3\ (admin)
Linux ~/.vst3/{Name}.vst3/ same (Linux is user-only)

The .vst3 on disk is a real bundle directory with a proper Contents/ hierarchy:

{Name}.vst3/
└─ Contents/
   ├─ Info.plist                     (macOS)
   └─ {MacOS,x86_64-win,x86_64-linux}/
      └─ {Name}           (the dylib/dll/so)

cargo truce install builds the bundle and signs the binary for macOS. The user-scope default writes to your home directory with no elevation; pass --system to land in the system-wide directory (sudo on macOS, Administrator shell on Windows).

#Signing

  • macOS: bundles are codesigned with $TRUCE_SIGNING_IDENTITY during install. Host loaders on Apple Silicon refuse unsigned VST3 bundles; ad-hoc (-) is accepted for local use.
  • Windows: binaries aren't signed by install; cargo truce package Authenticode-signs them via signtool before bundling into the Inno Setup installer. Unsigned VST3 on Windows just produces a SmartScreen prompt for end users; DAWs still load it.
  • Linux: no signing.

#Build / install / package

cargo truce install --vst3           # build + install VST3 only
cargo truce install                  # all enabled (VST3 is on by
                                      # default)
cargo truce build --vst3             # bundle into target/bundles/
cargo truce package --formats vst3   # signed installer with just VST3

#Validate

cargo truce validate invokes Tracktion pluginval if installed (PLUGINVAL env var to override path). Strictness 5 exercises: channel layouts, parameter ranges, preset I/O, silent-input behavior, real-time safety heuristics.

#Hosts

Host Platform Status
Reaper macOS / Windows / Linux primary
Ableton Live macOS / Windows working
FL Studio macOS / Windows working
Cubase — not yet tested
Studio One — not yet tested

#Gotchas

  • Class ID (vst3_id) in truce.toml (auto-derived from vendor + plugin bundle_id if not set) must not change after release. VST3 hosts key automation and presets on it.
  • System-scope install needs elevation. macOS: /Library/Audio/Plug-Ins/VST3/ requires sudo. Windows: %COMMONPROGRAMFILES%\VST3\ requires an Administrator shell. The user-scope default (no flag, or --user) writes to ~/Library/... / %LOCALAPPDATA%\... and skips elevation — every modern VST3 host scans both roots.
  • IRunLoop on Linux: Reaper doesn't require the VST3 IRunLoop timer integration; Bitwig and Ardour on Linux may. Not yet verified — a known-possible risk for those hosts on Linux.