ZzFX Parameters

0: Volume

1: Randomness

2: Frequency (Hz)

3: Attack (s)

4: Sustain (s)

5: Release (s)

6: Shape

0=sine, 1=tri, 2=saw, 3=tan, 4=noise, 5=square

7: Shape Curve

8: Slide (Hz/s)

9: Delta Slide

10: Pitch Jump (Hz)

11: Pitch Jump Time (s)

12: Repeat Time (s)

13: Noise (detune)

14: Modulation (Hz)

15: Bit Crush

16: Delay (s)

17: Sustain Volume

18: Decay

19: Tremolo

20: Filter (Hz)

ZzFX sound data

ZzFXTrack

With this app you can create musical content using ZzFXMicro.js synthesis with Strudel REPL interface or Arranger.

Export your creations as JSON files and use them in your games or other projects using the bundled ZzFXTrack Player.

The exported JSON is not compatible with the ZzFXM player and it's modified ZzFX engine. Strudel's internal ZzFX engine is not supported either.

About

ZzFXTrack is a music creation app that uses ZzFXMicro synthesis by Frank Force. It embeds Strudel for its REPL workflow and adds custom-made Arranger and Blocks tools with a tracker-style interface. The Arranger and Blocks are built on Strudel's patterns and scheduling, with one-way integration.

Instruments can be created using a streamlined editor with scrub inputs. Instrument playback is handled externally by ZzFXMicro instead of Strudel's internal sound engine. This keeps exported music optimal and predictable for games and demos.

Exported music can be played with the bundled ZzFXTrack Player, which takes inspiration from ZzFXM by Keith Clark and Frank Force. Developers can freely use it in their projects or build their own player. WAV export is also supported.

ZzFXTrack is not affiliated with or endorsed by the creators of Strudel, ZzFX (Frank Force), or ZzFXM (Keith Clark & Frank Force). It is not intended for small game compos. It was originally made for my personal projects, but I'm open to expanding the idea and collaborating.

Quick start

Open an Arrangement or Pattern from the left sidebar and hit play.
Select an Instrument from the left sidebar that is being used in the playback.
Make some changes to the parameters to see how the sound changes.
After that, try modifying Blocks, Arrangements, or the Strudel pattern.
You can then click Export in the footer and choose ZzFXTrack Player.
Next you can click the play button to preview ZzFXTrack Player playback.
The sound you hear now comes from the exported JSON file and ZzFXTrack Player.
Click Export WAV if you want a quick audio file to share or test.

How it fits together

Arranger: tracker-style workflow for composing loops with blocks.
Strudel: pattern notation and event scheduling.
ZzFXMicro: instrument parameter model and sound generation (registered as Strudel sounds for playback).
ZzFXTrack Player: the export target format for games/apps.

Alpha notes

Some Strudel features may preview fine but not export 1:1.
For best results, stick to simple, repeatable patterns and test with exported playback.
Phones are not supported, but tablets should work. Optimized for laptop-desktop widths.

Technical details

This app is a browser-based composition and export tool. It combines Strudel as the pattern language and live-coding interface, ZzFXMicro as the synth engine for sound generation, and an export pipeline whose main output is ZzFXTrack Player-compatible song JSON.

Composition UI and runtime

The editor is the embedded <strudel-editor> REPL component. When you press Play (or run code via Strudel shortcuts), Strudel evaluates your code and drives timing/scheduling in the browser.
Sound is produced by ZzFXMicro instruments: the app maps instrument definitions to ZzFXMicro parameters and uses them for preview playback and for export.
The app keeps a small amount of UI state (selected pattern, play state, export settings) and mirrors it into the sidebar, toolbar, and modals.
Auto-save is event-driven: changes are debounced to avoid excessive writes, but key actions (like leaving certain inputs) can trigger immediate saves.

Project files

Patterns (Strudel files) are JavaScript modules stored under patterns/. A selected pattern is loaded into the editor and also used as the source of truth for export and playback.
Blocks are reusable patterns stored under blocks/. They can include an embedded trackerState object so the Tracker can re-open them for editing.
Arrangements live under arrangements/ and reference blocks, letting you build longer pieces out of smaller patterns.
Instruments are stored in instruments.js and mapped to ZzFXMicro parameters for both preview and export.

Local API (dev server)

During development, the app talks to a small local API exposed by Vite middleware (endpoints like /api/patterns, /api/pattern/<name>, /api/blocks, and rename endpoints). These endpoints read and write files in the project directories so your edits persist as real modules you can commit.

Tracker and blocks

The Tracker modal is a lightweight step sequencer. When you save a block, it generates a Strudel pattern string and stores the underlying grid state (trackerState) for later edits.
When inserting a block into a pattern, the app can optionally keep the block BPM, and it passes the block’s row count so insertion can align musically.

Export and preview

Export is the main feature: it turns your composition into a ZzFXTrack Player song array [instruments, patterns, sequence, BPM] (plus optional stats), designed to be deterministic and engine-friendly.
Preview uses the same exported ZzFXTrack Player structure and ZzFXMicro synthesis to let you verify the result before downloading.
Export WAV renders the exported song to PCM audio and encodes it as a WAV file (sample rate and bit depth are configurable in Export Settings).

Using the standalone ZzFXTrack Player

Exported JSON is for the ZzFXTrack Player, not the canonical ZzFXM player. To play songs in your game or project:

Copy the packages/zzfxtrack-player/ folder from this repo into your project.
Import: import { playZzFXTrackSong, stopZzFXTrackSong } from './zzfxtrack-player/index.js'; (adjust path as needed).
Call playZzFXTrackSong(songData, audioCtx, onEnded?) with your exported [instruments, patterns, sequence, BPM] array and an AudioContext.

The player has no dependencies. See packages/zzfxtrack-player/README.md in the repo for the full API.

Demo mode

In demo mode, pattern management is read-only and edits are kept in memory for the session. You can still download a ZIP to move the project files into a local workspace.

Mixing settings

Playback Loudness

Preset

Target Peak

Master dB

Clip Drive

Applied to ZzFXTrack Player preview and arrangement playback. Uses soft clipping to reduce harsh digital clipping.

Export Resolution

96 48 Custom

Rows per cycle. Lower = smaller JSON, less timing precision.

Advanced

Use simple export (Increases file size)

One pattern per arrangement row instead of per repeat. Turn on if you see playback issues or need the older format.

Limit channel usage

Normalize Layers

Reduce gain when the same note plays multiple times simultaneously (1/√n scaling)

WAV Export

Sample Rate

Bit Depth

System Settings

Color theme

Theme colors

Editing theme colors switches to the User theme and saves changes locally. The User theme starts from Phantom by default.

Background Foreground Card Card foreground Popover Popover foreground Primary Primary foreground Secondary Secondary foreground Muted Muted foreground Accent Accent foreground Tertiary Tertiary foreground Quaternary Quaternary foreground Border Input (border) Input background Destructive Destructive foreground Ring

REPL editor theme

Developer mode

Use with caution. Will enable functionality that can lead to unintended data loss.

Application data

Backup your Instruments, Arrangements, Blocks and Strudel patterns and import them to another device or browser.

Initializing...

ZzFXTrack

Data for ZzFXTrack Player

About

Quick start

How it fits together

Alpha notes

Open Source & Licenses

Technical details

Composition UI and runtime

Project files

Local API (dev server)

Tracker and blocks

Export and preview

Using the standalone ZzFXTrack Player

Demo mode

Change Log

Demo mode: On

Import data

Export Project

Import ZzFX sound

Instrument Conflict Detected

New Pattern

New Arrangement

Confirm

Delete pattern?

New Instrument

Delete instrument?

Mixing settings

External link

Settings

System Settings

Application data

Insert Blocks (Experimental)

Delete block?

Delete arrangement?

Arrangement

Delete row?

Save changes?

Clear notes, volume and effects?

Save changes?