BlackHole: macOS Audio Loopback Driver

Original Article ↗ Hacker News Discussion ↗

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.