BlackHole: macOS Audio Loopback Driver

Original Article ↗ Hacker News Discussion ↗

An open-source macOS tool called BlackHole is gaining attention as a free virtual audio loopback driver, letting users route sound from one app into another for tasks like streaming, recording calls, and complex studio setups. Commenters compare it extensively with Rogue Amoeba’s paid tools (Loopback, Audio Hijack), weighing BlackHole’s lack of GUI and setup complexity against its price and security advantages. The thread also highlights broader gaps and recent changes in macOS’s native audio capabilities, and mentions analogous solutions on Windows and Linux.

Overview & Purpose

  • BlackHole is a macOS virtual audio loopback device: it routes audio output from one app into another app’s input.
  • Many commenters use it as a modern replacement for Soundflower, which has compatibility and installation issues, especially on Apple Silicon.

Comparisons: BlackHole vs Commercial Tools

  • Frequently compared to Rogue Amoeba’s Loopback and Audio Hijack.
  • Functionality:
    • BlackHole can provide most of Loopback’s core routing features, but lacks a GUI and requires manual setup via Audio MIDI Setup or other tools.
    • Audio Hijack adds easy effects chains (e.g., EQ, compression, VSTs) and structured capture workflows that BlackHole alone doesn’t replace.
  • Cost/value debate:
    • Some call Loopback’s ~$100 price “price gouging” for “basic” routing.
    • Others argue it’s fairly priced, polished, saves time/confusion, and supports a small, specialty developer.

macOS Audio Limitations & New APIs

  • Complaints:
    • No per‑application volume control; seen as odd for an OS marketed to audio pros.
    • Historically no built‑in loopback device; users find third‑party drivers “unacceptable” for system‑audio recording.
  • Counterpoints:
    • Per‑app volume may be undesirable for some audio‑pro workflows.
    • Newer macOS versions add ScreenCaptureKit and a CoreAudio “Tap” API for capturing system/app audio, though these are developer‑oriented and poorly documented, not user‑facing tools.

Use Cases & Workflows

  • Routing DAWs (Ableton, Traktor, Serato, etc.) between each other or into streaming/meeting apps (Zoom, OBS).
  • Recording tutorials and screencasts with both app audio and microphone, often while wearing headphones.
  • Recording meetings for reference or “CYA.”
  • DJ/live performance setups, multi‑channel routing, and using virtual devices instead of physical loopback cables.
  • Occasional creative/novel uses (e.g., Halloween PA systems).

Latency, Stability, and Setup Complexity

  • BlackHole itself is advertised as 0 ms, but end‑to‑end latency accumulates from DAW buffers and interfaces; users report 20–30+ ms in complex chains.
  • Aggregate/multi‑output devices and clock‑source choices can affect crackles and stability; some found workarounds (e.g., using built‑in speakers as clock).
  • Several note that Audio MIDI Setup is confusing; Loopback’s GUI is preferred for non‑experts.

Cross‑Platform Comparisons

  • Linux: PulseAudio/Pipewire and JACK allow loopback with commands or graph UIs; highly flexible but sometimes CLI‑heavy.
  • Windows: tools like VB‑Cable, Voicemeeter, and Synchronous Audio Router fill a similar role, but ASIO and device sharing are often painful.
  • Overall sense: macOS is relatively stable for audio but lacks some built‑in routing conveniences that users now rely on tools like BlackHole to provide.