Language Learning Audio Looper

Local-only dark-themed A/B audio looper for language learning and close listening.

The app runs entirely in the browser. There is no backend, no uploads, and no cloud dependency. Open a local audio file, inspect its waveform, set or drag loop boundaries, and jump through detected speech sections.

Features

• Open local audio files such as mp3, wav, ogg, m4a, and aac when the browser can decode them
• Dark waveform view with draggable loop region and visible section dividers
• Playback rate controls with pitch preservation
• Silence-based sentence/section detection with tunable sensitivity sliders
• Manual section editing by splitting at the playhead, dragging dividers, or deleting dividers to merge sections
• Per-file persistence for loop region, zoom, playback rate, detection settings, and custom sections

Quick Start

1. Install dependencies:

npm install

2. Start the dev server:

npm run dev

3. Open:

http://127.0.0.1:5173/index.html

Production Build

Build the app:

npm run build

Serve the built files locally:

python3 -m http.server 4173 --directory dist

Then open:

http://127.0.0.1:4173/index.html

The production build emits dist/index.html as the primary entry point.

Controls

• Space: Play / pause
• Left Arrow: Skip back 2 seconds
• Right Arrow: Skip forward 2 seconds
• Delete or Backspace: Delete the selected divider and merge neighboring sections
• Double-click the waveform: Split the current section at that point
• Drag the loop overlay: Adjust loop start/end directly on the waveform
• Drag a divider: Retime a section boundary

Notes

• Use a local HTTP server or Vite during development. Opening module files directly via file:// is not recommended.
• MP3 timing can vary slightly depending on browser decoding behavior, so testing in your target browser is still a good idea.

Scripts

• npm run dev: Start the Vite dev server
• npm run build: Type-check and build the production bundle
• npm run preview: Preview the production build through Vite
• npm test -- --run: Run the test suite once