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Introduction

What is bellplay~?​

bellplay~ is a framework and software for offline algorithmic audio in the bell programming language. It is designed to support symbolic and audio workflows within an out-of-the-box, integrated environment. This includes, but isn't limited to, sound design, music composition and analysis, data sonification, batch data processing, audio editing, and more.

In contrast to popular real-time systems like MaxMSP, SuperCollider, or TidalCycles, bellplay~ is asynchronous by design. This removes real-time concerns from the creative loop, which simplifies resource allocation (e.g., unlimited polyphony, automatic voice management), enables non-causal processing (e.g., reverse delay), and allows automating complex batch operations on audio data.

How does it work?​

At the core of bellplay~ is the concept of the buffer—a structured representation of an audio object, containing both technical metadata (e.g., sampling rate, duration) and optionally, analysis-derived features such as pitch, loudness, or spectral descriptors. These buffers can be generated, processed, and analyzed using bell.

The typical workflow in bellplay~ consists of three steps:

  1. Generation: Buffers are created using synthesis or sampling.
  2. Transcription: Selected buffers are placed on a timeline and visualized in staff notation as note events.
  3. Rendering: All transcribed buffers are compiled into a single output buffer, which can itself be re-used within the same script.

Here's a minimal example that synthesizes a 1-second 440 Hz sine tone and renders it:

$buff = cycle(@frequency 440 @duration 1000); ## generation
$buff.transcribe(); ## transcription
render() ## rendering

bellplay~ supports multi-pass rendering, batch processing, multi-channel audio, symbolic and audio feature extraction, concatenative synthesis, and more. It was originally developed for multimedia and pedagogical use but has since grown into a general-purpose environment for algorithmic composition and sound design.

If you're new to bell, check first the musician-friendly bell tutorials, then return here for an introduction to bellplay~.

For questions, feedback, or bug reports, join the community Discord.