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Running a patch in a DAW

The CLAP plugin loads a .patches file inside any CLAP host and runs it under that host’s transport, audio routing, and MIDI. The same DSL, modules, and engine — just hosted, with the DAW responsible for audio I/O and clock instead of the player binary.

The bundle ships two descriptors from a single dylib:

  • Patches — an instrument. Appears under the host’s instrument browser. Takes MIDI in, produces stereo audio out.
  • Patches FX — an audio effect. Appears under the host’s effect browser. Takes stereo audio in, produces stereo audio out, still accepts MIDI for control.

Pick the descriptor that matches what you want to do; the underlying engine is the same.

Loading a patch

  1. Add Patches to a MIDI track (or Patches FX to an audio track).
  2. The plugin window shows a small webview-based GUI with a header strip carrying the current patch path and two buttons — Browse… and Reload — and a tabbed body (Modules, Diagnostics, scope/meter taps if the patch declares any).
  3. Hit Browse… and pick a .patches file. The plugin compiles it, swaps the graph in, and starts producing audio on the next block.

Diagnostics appear in the Diagnostics tab’s Event log. If a file fails to compile, the plugin reports the error there and keeps the previous patch running.

Host examples

REAPER

  • Insert → Virtual Instrument on New Track → pick Patches from Instruments (CLAP).
  • Or, on an audio track, FX → Add → Patches FX.
  • MIDI routing is automatic from the track’s MIDI items.
  • Options → Preferences → Plug-ins → CLAP lists the directories scanned; the user-local default (~/Library/Audio/Plug-Ins/CLAP/ on macOS) is included by default.

Bitwig Studio

  • Drop Patches onto an instrument track from the device browser under Instruments → CLAP.
  • For audio processing, drop Patches FX onto an audio track.
  • Bitwig rescans on launch; trigger a manual rescan via Settings → Locations → CLAP plug-ins → Refresh if a freshly installed bundle doesn’t appear.

Other CLAP hosts (Ableton Live 11.3+, FL Studio 21.2+, Studio One 6.5+) follow the same pattern: instrument bucket for Patches, effect bucket for Patches FX.

MIDI

The host routes MIDI to the plugin. For Patches that means notes flow into MidiToCv / PolyMidiToCv modules and CC traffic flows into MidiCC modules. The plugin doesn’t open MIDI ports of its own — the host handles all device selection.

Self-contained patches (those driven by a MasterSequencer / PatternPlayer rather than MidiToCv) ignore inbound MIDI and play themselves. Sequenced and externally-driven approaches can be mixed within a single patch.

Automation

Host controls declared in a patch via the knob / slider / toggle / trigger declarations show up in the host’s parameter list for automation, modulation, and per-track recall. Manipulate them from a DAW lane the same way you would any other plugin parameter.

Parameter values move through the persisted-settings layer, so an automated value at the start of playback is restored from the saved project state.

Project save and recall

When the host saves its project, the plugin’s persisted state goes into the project file. That state captures:

  • the absolute path to the loaded .patches file
  • the DSL source itself (stored verbatim, so the project survives a missing or moved file)
  • host-control values
  • per-tap display options (scope decimation, spectrum FFT size, etc.)
  • the GUI window size
  • the user’s persisted bundle-dir list

Reopening the project restores all of it. If the original file path no longer resolves, the plugin falls back to the embedded DSL source — the patch still plays; Browse re-points it at a live file.

The persisted-settings format is local to the plugin, so a project moved to another machine keeps its audio behaviour even if the file path doesn’t transfer.

GUI tour

  • Header strip — current patch path, plus Browse… and Reload buttons.
  • Modules tab — list of registered modules with an intent bar carrying Rescan (re-probe the bundle directories for FFI module bundles, used after dropping in a new .dylib) and Add bundle dir… (add to the per-project module search path).
  • Diagnostics tab — Event log with compile diagnostics, hot-reload events, rescan reports, halt notifications, plus the current diagnostics summary.
  • Tap views (separate tabs when the patch declares scope / meter / spectrum taps) — per-tap panels render the live signal. Display options (decimation, FFT size, heatmap on/off) persist with the project.

The internals of the plugin — webview IPC, snapshot pushes, halt handling — live in CLAP plugin internals.