BlackHole + ffmpeg: A free path to Mac call recording automation

This review examines BlackHole, ffmpeg, and OBS as open-source alternatives to Audio Hijack for recording Phone and FaceTime calls on macOS. We assess their capabilities for dual-channel capture and automation.

TL;DR

Best for: Users willing to script a solution for automatic call recording, prioritizing free and open-source tools. BlackHole combined with ffmpeg offers the most robust path to automation. Skip if: You require a ready-to-use application with built-in automatic call detection and recording without any scripting or manual setup. Bottom line: While no single tool provides a drop-in replacement for Audio Hijack's automation, BlackHole and ffmpeg form a powerful, scriptable foundation for Mac call recording.

METHODOLOGY

This v0 review draws on the public documentation and common usage patterns of BlackHole, ffmpeg, and OBS. Independent benchmarks are pending. Update cadence: re-tested when claims diverge from observed behavior.

• Tool Name + Version + Date Observed: BlackHole (latest stable release, typically via GitHub), ffmpeg (latest stable release via Homebrew), OBS Studio (latest stable release). All observed as of May 25, 2026.
• Source Signal URL: https://www.reddit.com/r/opensource/comments/1tnec4t/looking_for_alternatives_to_audio_hijack_for/
• What's Covered: This review covers the technical capabilities of BlackHole as a virtual audio device, ffmpeg's command-line audio recording features, and OBS Studio's GUI-based recording functionality. We assess how these tools can be combined to capture both microphone and system audio for Phone/FaceTime calls on macOS. The focus is on the potential for automation and dual-channel recording.
• What's NOT Covered: This review does not include independent performance benchmarks, long-term workflow integration testing, or detailed exploration of complex edge cases (e.g., multiple concurrent audio sources, specific audio device conflicts). We have not built or tested a complete automation script for call detection.

WHAT IT DOES

BlackHole: Virtual audio routing for macOS

BlackHole is an open-source virtual audio driver for macOS, developed by Existential Audio. It allows users to route audio between applications and devices, functioning as a "software loopback" cable. For call recording, BlackHole can be configured as a multi-output device in macOS Audio MIDI Setup, sending audio simultaneously to your physical speakers/headphones and to BlackHole itself. This captures the other party's audio. To record your own microphone, it would be selected as a separate input. BlackHole's strength lies in its ability to create complex audio routing scenarios that are otherwise impossible with standard macOS audio settings. It supports multiple channels and sample rates, making it suitable for high-fidelity audio capture.

ffmpeg: Command-line audio recording

ffmpeg is a comprehensive, open-source multimedia framework capable of decoding, encoding, transcoding, muxing, demuxing, streaming, filtering, and playing virtually any audio or video format. For recording calls, ffmpeg can capture audio from specific input devices, including virtual devices like BlackHole and your physical microphone. A command-line script can be constructed to record from both BlackHole (for the remote party's audio) and your microphone simultaneously, saving the output to a specified file format (e.g., MP3, WAV) in a designated folder. Its command-line nature makes it highly scriptable and ideal for automation, though it requires familiarity with its syntax.

OBS Studio: GUI-based capture

OBS Studio (Open Broadcaster Software) is a free and open-source software suite for video recording and live streaming. While primarily known for streaming, it also functions as a robust screen and audio recorder. On macOS, OBS can be configured to capture audio from multiple sources, including BlackHole and your microphone. Users can set up separate audio tracks for each input, allowing for post-recording mixing or independent analysis. OBS provides a graphical user interface (GUI) for setting up sources, mixing audio levels, and initiating recordings. This makes it more accessible than ffmpeg for manual recording, but its automation capabilities for call detection are not built-in and would require external scripting or plugins.

WHAT'S INTERESTING / WHAT'S NOT

The most interesting aspect of this open-source stack is the potential for a truly custom solution that precisely fits Foxtor's requirements, particularly the "automatic recording" feature. BlackHole provides the essential audio routing backbone, a capability that is often locked behind commercial tools like Audio Hijack. Its reliability as a virtual audio device is well-established within the macOS audio community. ffmpeg's power, while requiring a learning curve, allows for granular control over recording parameters, file formats, and output locations. This combination offers a robust, free, and open-source foundation for capturing high-quality audio from calls. The ability to script ffmpeg means that, with sufficient effort, the "automatic recording" requirement can theoretically be met by integrating it with macOS automation tools like AppleScript or Automator, triggered by call events.

What's less interesting, or rather, what's not provided out-of-the-box, is the seamless, integrated automation that a commercial product like Audio Hijack offers. None of these tools inherently detect when a Phone or FaceTime call starts or ends. This means the "automatic recording" aspect requires significant custom scripting and integration work. While OBS Studio offers a more user-friendly GUI for setting up and initiating recordings, its automation for call detection is equally absent. Relying on OBS for automatic recording would likely involve complex external triggers or plugins, potentially negating its ease-of-use advantage. The modularity of these tools, while powerful, also means the user is responsible for assembling and maintaining the entire solution, including troubleshooting any inter-component issues. This is a significant undertaking compared to a single, purpose-built application.

PRICING

BlackHole: Free and open-source. ffmpeg: Free and open-source. OBS Studio: Free and open-source. Pricing snapshot: May 25, 2026.

VERDICT

For users seeking a free and open-source alternative to Audio Hijack for Mac call recording, the combination of BlackHole and ffmpeg is the most viable path, particularly for achieving automation. BlackHole effectively solves the complex audio routing challenge, allowing simultaneous capture of both sides of a conversation. ffmpeg, while command-line driven, provides the necessary power and scriptability to record these audio streams and save them automatically to a specified folder. OBS Studio offers a more user-friendly interface for manual recording, but it does not inherently support the automatic call detection required for Foxtor's use case. The trade-off for these free tools is the need for custom scripting to implement the automatic recording trigger. If you are comfortable with scripting and prefer a highly customizable, zero-cost solution, BlackHole + ffmpeg is the recommended approach.

WHAT WE'D TEST NEXT

Our next steps would involve developing and rigorously testing a proof-of-concept automation script. This script would integrate BlackHole and ffmpeg, focusing on reliably detecting Phone and FaceTime call events on macOS. We would explore using AppleScript or Automator to trigger ffmpeg recordings based on these events, ensuring both sides of the conversation are captured in separate tracks or a mixed stereo file. Specific tests would include measuring the latency introduced by BlackHole, assessing CPU and memory usage during prolonged recordings, and evaluating the robustness of call detection under various conditions (e.g., incoming calls, outgoing calls, dropped calls). We would also investigate error handling and file naming conventions for automated saves.

Pull quote: “BlackHole provides the essential audio routing backbone, a capability that is often locked behind commercial tools like Audio Hijack.”