Recorder.js

Recorder.js is a specification-focused tool that describes a web audio recorder library. It outlines the domain objects, inputs, outputs, and the lifecycle of a recording session. Conceptually, it treats recording as a sequence: request media access, initialize an encoder, capture PCM samples, and produce a deliverable binary blob. Beneficiaries include frontend engineers, API designers, QA engineers, and product managers who plan to integrate audio capture in web apps. The tool emphasizes concrete, testable behaviors such as supported mime types, sample rates, channel counts, and duration handling. It highlights unique value by aligning encoding strategies with browser capabilities and by documenting fallback paths when a preferred format is unavailable. Core features described include permission handling, MediaStream capture, optional processing via Web Audio nodes, and output generation in common formats like WAV, WebM/Opus, or OGG. Use cases range from voice notes in productivity apps to in-browser podcasting tools and customer feedback widgets. The tool also details edge considerations like cross-browser timing, silent or partial encodings, and resource cleanup after stop. It differentiates between required specifications (permissions, sample rate bounds, media track configuration) and optional enhancements (live visualization hooks, on-the-fly resampling, and post-encode streaming). The result is a precise reference for developers to implement, test, and evolve recording features while maintaining consistent expectations across environments.