VST workflow

VST plugins are the most involved source to work with, because VST plugins don’t offer any standard way to enumerate their presets from outside the GUI. patch-press solves this in two steps: a companion tool called patch-probe captures preset state through the plugin’s own GUI, then patch-press replays that state note-by-note to build a multisample.

flowchart LR
    G[Plugin GUI] -->|user clicks<br/>through presets| PP[patch-probe]
    PP -->|writes YAML with<br/>base64 raw_state| Y[probe/*.yaml]
    Y --> S[scan-from-probe]
    S -->|re-renders one probe<br/>note per preset to<br/>classify sustain type| C[configs/*.yaml]
    C --> B[batch]
    B -->|renders every note<br/>across the range| A[analyze pipeline]
    A --> D[SD card / preset files]

1. Capture state with patch-probe

patch-probe is a small JUCE host that loads a plugin, lets you click through its preset browser, and captures the plugin’s raw state blob every time you change presets. You run it once per plugin.

The output is a directory of YAML files — one per preset — each containing:

preset_name: "BRASS   1"
plugin_path: "/path/to/Dexed.vst3"
raw_state: "<base64-encoded plugin state>"
timestamp: "..."

The raw_state is the important part. It’s the plugin-defined blob that a plugin’s own “restore state” call takes to reconstruct exactly what the user had loaded. patch-press hands this blob back to the plugin when it renders the preset — no preset-lookup, no name-matching, just a bit-exact restoration.

2. Turn probe YAMLs into configs 

patch-press scan-from-probe ~/patch-probe/Dexed configs/Dexed

For each YAML in the probe directory, scan-from-probe:

  1. Loads the plugin with that preset’s raw_state.
  2. Renders one note (default: MIDI 60 / C4, velocity 100) and holds it for --duration seconds (default: 15).
  3. Analyzes the rendered audio to classify sustain type:
    • pluck — no meaningful sustain after the attack
    • synth — flat, steady sustain
    • pad — sustained but evolving (LFO, filter sweep, chorus movement)
  4. Picks the matching profile.
  5. Writes configs/Dexed/BRASS_1.yaml with source.raw_state baked in.

You get one config per preset. No further probing happens later — the full render only runs during batch.

3. Render and export 

patch-press batch "configs/Dexed/*.yaml" --path /media/DELUGE --format deluge

For each config, batch:

  1. Renders the plugin across [start-note, end-note] at note-step intervals (default: C1 to C6 every 3 semitones).
  2. Runs the analysis pipeline — trim, envelope, loop detect, normalize.
  3. Writes the preset in whatever --format you asked for — Deluge XML in SYNTHS/, WAVs in SAMPLES/, or a self-contained Polyend Tracker .pti with --format pti.

If the output already exists, batch skips it. Use --no-skip to re-render.

Full walkthrough: Dexed 

# One-time: install patch-press and patch-probe.
pip install -e .

# Step 1 — capture presets. patch-probe opens a small GUI showing Dexed.
# Click through every preset you want to keep. Close the window when done.
patch-probe ~/.vst3/Dexed.vst3 ~/patch-probe/Dexed

# Step 2 — one config per preset.
patch-press scan-from-probe ~/patch-probe/Dexed configs/Dexed

# Step 3 — render everything to the SD card.
patch-press batch "configs/Dexed/*.yaml" --path /media/DELUGE --format deluge

That’s it. Every Dexed preset you captured is now a Deluge synth preset with a full multisample (swap --format pti for a Polyend Tracker .pti instrument instead — see Outputs).

scan-from-probe options

Option Default What it does
--profile pluck\|synth\|pad\|drums auto Override the auto-detected profile.
--sample-rate 44100\|48000\|96000 48000 Rendering sample rate. Match your Deluge project’s rate if you care about downsampling.
--tempo-bpm BPM 120 Tempo passed to the analysis stage for rhythm/LFO detection.
--probe-note MIDI 60 Which note gets rendered during the classification probe.
--probe-velocity VEL 100 Velocity used during the probe.
--note-step INT 3 Semitones between sampled notes at batch time (1 = every note; 12 = every octave).
--duration FLOAT 15.0 Probe hold length in seconds. Long enough to detect slow LFOs.
--start-note NOTE C1 Lowest note to capture at batch time. Accepts C1, A#0, MIDI numbers, etc.
--end-note NOTE C6 Highest note to capture at batch time.

Global flags:

  • -v / --verbose — show each preset as it’s classified.
  • --debug — process only 5 presets, useful when you’re trying settings on a big directory.

raw_state vs preset name

patch-press’s config carries both:

source:
  type: vst
  plugin: /path/to/Plugin.vst3
  preset: "BRASS   1"           # documentation only
  raw_state: "<base64 blob>"    # the real state

raw_state, when present, is what actually gets loaded — the preset name is just there for readability and filenames. If you’re crafting a config by hand and you know a preset name will load correctly through the plugin’s own preset API, you can omit raw_state and rely on preset, but plugins vary in how reliably that works. The raw_state path is the reliable one.

Common issues

Probe classifier picks the wrong profile. Override with --profile on the scan, or edit profile: in the generated YAML and re-run sample.

Plugin crashes patch-render partway through a batch. --workers 1 (default) processes one preset at a time; if a specific preset is toxic, batch prints an error and continues to the next. The bad preset’s config file tells you which one to investigate.

Notes bleed past the release tail. Increase capture.release_tail_s in the config (the profile default is 2 seconds; pads go to 5). The Deluge doesn’t need the plugin’s full release to be baked in — you’ll re-add release in the preset’s amp envelope on the Deluge itself.

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