The screen recorder built into macOS cannot capture the Mac’s system output directly, so additional software is required. This guide uses BlackHole to route and record that audio.

1. Install BlackHole

Run brew install blackhole-64ch to install BlackHole.

2. Configure BlackHole

  1. Open System Settings on the Mac and select Sound.
  2. Under Output, BlackHole appears as an available audio output device. Select it when you need to route audio into BlackHole.
  3. Under Input, you can likewise select BlackHole as an audio input device when you need to record the audio routed through it.

3. Use Cases and Examples

3.1 Audio recording and live streaming

  1. BlackHole helps content creators manage audio while recording a screen or streaming. For example, route a music player’s output to BlackHole, then select BlackHole as the input in the recording or streaming application. This adds background music to a recording or stream without disrupting other system audio outputs.
  2. BlackHole can also keep microphone input separate from system audio. During a game stream, for example, route and record game audio through BlackHole while recording the microphone on its own track. The tracks can then be adjusted independently during editing.

3.2 Audio mixing

  1. BlackHole is also useful for music production and audio mixing. Route the outputs of several audio applications into BlackHole, then mix them in an audio editor. One example is to send an instrument track from a DAW, along with sound effects from another player, into BlackHole. A mixing application can then combine them, adjust their levels, and add effects.
  2. When producing electronic music, you might create a drum pattern in one DAW and a melody in another, route both through BlackHole, and combine and refine them in a dedicated mixing application.

3.3 Audio testing and development

  1. BlackHole can simulate audio devices and routing scenarios during application development. Developers can test output at different sample rates and bit depths, or verify compatibility in a multichannel audio environment.
  2. When developing an audio player, route its output into BlackHole and inspect the signal with professional analysis tools. This helps verify playback quality and stream stability.

4. Considerations

  1. Manage audio routes carefully to avoid conflicts or interruptions. If several applications send audio to BlackHole at once, resource usage can rise and affect quality or stability. Close unused applications or disable routes that are no longer needed.
  2. Keep the BlackHole driver current so that it remains compatible with macOS and other audio applications. Updates commonly fix known defects and improve performance.
  3. Monitor audio levels while recording or mixing to prevent clipping and distortion. Adjust levels in the source application or audio editor so that the resulting recording meets your quality requirements.

5. Summary

BlackHole gives Mac users flexible audio-routing capabilities for recording, live streaming, mixing, testing, and development. With careful configuration, it can support high-quality audio workflows across all of these uses.