smplr

A MIDI-controlled audio sampler with a terminal user interface.

Features

• 🎹 MIDI Control: Trigger WAV samples via MIDI notes
• 🎚️ Pitch Shifting: Adjust pitch per sample (-12 to +12 semitones) with offline rendering using RubberBand
• 📊 Waveform Display: Visual feedback with adjustable start/end markers
• ✂️ Sample Trimming: Edit samples directly in the interface
• 🎙️ Audio Recording: Record system audio using ScreenCaptureKit
• ⚡ Low Latency: Native CoreAudio playback via Swift bridge
• 🖥️ Terminal UI: Keyboard-driven interface powered by Bubble Tea

Prerequisites

• macOS 12.3 or later (requires ScreenCaptureKit API)
• Go 1.21 or later
• Swift compiler
• RubberBand audio library
• MIDI controller (optional)

Installation

Via Homebrew

Install RubberBand:

brew install rubberband

Building from source

./build.sh

This compiles the Swift audio bridge and builds the Go application.

Running

./smplr

The application will load WAV files from the current directory and map them to incremental MIDI notes starting from note 1 on channel 1.

Keyboard Controls

• j/k or ↑/↓: Navigate through samples
• c: Edit MIDI channel
• n: Edit MIDI note
• p: Edit pitch shift
• Space: Play selected sample
• Enter: Play region (between start/end markers)
• t: Trim sample to region
• r: Start/stop recording
• h/l: Adjust start marker (when selected)
• H/L: Adjust end marker (when selected)
• q: Quit

Architecture

• Go: Main application, TUI, MIDI handling, and file management
• Swift: Low-level audio playback, recording, and pitch shifting via CoreAudio/AVFoundation
• RubberBand: High-quality pitch shifting engine
• Bubble Tea: Terminal UI framework
• CGO: Bridge between Go and Swift

Releases

See the releases page for pre-built binaries.