Metronome

A small command-line metronome for Linux that I wrote for my drumming practice.

It utilizes the ALSA (Advanced Linux Sound Architecture) API for audio playback and Unix timers for interval management.

Features

• Direct ALSA PCM interface for low-latency audio.
• Precise timing using SIGALRM and setitimer.
• Support for custom BPM and time signatures.
• Minimalist implementation with a custom WAV parser and allocator wrapper.

Prerequisites

• Zig 0.15.2 or later.
• ALSA development headers (e.g., libasound2-dev on Ubuntu/Debian or alsa-lib on Arch Linux).

Building

To build the project using the Zig build system, run:

zig build -Doptimize=ReleaseSmall

The executable will be located at zig-out/bin/metronome.

Alternatively, a Makefile is provided for convenience. The default target builds and runs the application in Debug mode. Available commands:

make          # Build and run (default: OPTIMIZE=Debug)
make debug    # Build for debugging
make release  # Build for ReleaseSmall
make clean    # Remove build artifacts

Usage

The application provides an interactive command-line interface. The following commands are available:

• <num>: Set the tempo in Beats Per Minute (BPM). Example: 120.
• /sig <num>: Set the time signature (beats per measure). Example: /sig 4.
• q: Terminate the application.

Implementation Details

• Audio: The engine opens the default ALSA PCM device and writes 16-bit signed little-endian (S16_LE) samples.
• Timing: Intervals are managed by the Linux kernel via setitimer(ITIMER_REAL), which triggers SIGALRM at calculated intervals based on the BPM.
• Memory: A custom allocator wrapper switches between std.heap.DebugAllocator in debug builds and std.heap.c_allocator in release builds for optimal performance.