Keyboard Live Sampler

Introduction

Keyboard Live Sampler is a browser-based platform for real-time music performance and manipulation, built using WebChucK. Our inspiration is physical hardware samplers that give users the ability to record, edit, and perform audio directly on the keyboard.

The system includes a smart recording engine that automatically detects audio onsets, quantizes loops to a global tempo, and supports real-time transformations such as mixing, concatenation, reversing, pitch shifting, and applying reverb.

Core Functionality

Performance

• 10-Slot Sample Bank: Access 10 independent audio buffers (keys 1–0), each capable of holding up to 10 seconds of audio.
• Smart Recording: When armed (key R), the system waits for an audio threshold before capturing, ensuring clean start points without silence at the beginning.
• Auto-Quantization: Recordings are automatically trimmed and snapped to the nearest musical beat based on the BPM. If a user records 3.8 beats, the system rounds it to 4.0 beats and inserts the necessary silence to maintain perfect rhythm.
• Looping & Retriggering: Users can toggle looping per slot or rapidly retrigger samples for stutter effects.

Sound Manipulating & Editing

• Effects: Render effects permanently into new slots (Reverb, Reverse, Pitch Shift).
• Macro Modes: Use Concatenate (Key F) to sequence samples or Mix (Key G) to layer them.

File Integration

• Uploading & Playback: Users can upload local audio files (MP3/WAV) and assign them into the live slots using the keys Q-W-E-A-S-D.

Technical Overview

The project follows a hybrid architecture, using HTML/JavaScript for the interface and ChucK for audio processing.

Frontend (HTML/JS)

The visual interface manages user interactions, file decoding, and status indicators.

• Bridge Architecture: The script.js file initializes the WebChucK instance. It handles the AudioContext to decode uploaded files into raw PCM data (Float32Array) before sending them to the ChucK engine via the loadBuffer global array.

Audio Engine (ChucK)

The core logic resides in main.ck

• Concurrency (Shreds): The audio engine uses multiple concurrent shreds, such as:
• runClock(): Maintains the global tempo.
• monitorMic(): Analyzes input volume for visualization.
• bufferLoaderLoop(): Receives sample data from JavaScript.
• Memory Management (LiSa): The project uses LiSa (Live Sampling) objects for audio manipulation. It is configured with feedback set to 0, ensuring that new recordings completely replace old data (Tape Recorder behavior) rather than overdubbing.
• Signal Flow: Mic Input -> Gain -> LiSa (Sampler) -> Reverb -> Limiter -> Speakers.

Demo Video