truce-lv2

LV2 format wrapper for the truce audio plugin framework.

Overview

Bridges a truce PluginExport implementation to the LV2 plugin API. LV2's C ABI is small and stable, so the bindings are hand-rolled rather than pulled from a large lv2-sys crate. Supports audio, MIDI, state, and UI on every truce platform - X11UI on Linux, CocoaUI on macOS, WindowsUI on Windows.

User plugins typically take a direct optional dep on this crate (truce-lv2 = { workspace = true, optional = true }) gated behind an lv2 Cargo feature; the truce::plugin! macro emits a ::truce_lv2::export_lv2!(...) call when that feature is on. cargo truce build --lv2 / install --lv2 selects it at the CLI.

What it handles

• LV2 lv2_descriptor entry point and bundle layout
• Audio + control + atom port layout
  • 0..num_in - audio input (one port per channel)
  • num_in..num_in+num_out - audio output (one port per channel)
  • next N - control input (one port per parameter)
  • one AtomPort for MIDI input (if the plugin accepts MIDI)
• State save/restore via the LV2 State extension
• UI hosting per platform (X11UI / CocoaUI / WindowsUI)
• Turtle (manifest.ttl, plugin.ttl) sidecars emitted by the export_lv2! proc-macro at compile time

Key macro

• export_lv2! -- generates the LV2 entry point for a PluginExport type

Part of truce. Docs.