Record macOS CoreAudio Input Using FFmpeg

This article provides a straightforward, step-by-step guide on how to capture audio from any CoreAudio input device on macOS using the FFmpeg command-line tool. You will learn how to locate your system’s audio input devices using the AVFoundation framework and run the precise commands required to record high-quality audio directly to your local storage.

Step 1: Install FFmpeg

To get started, ensure you have FFmpeg installed on your Mac. The easiest way to install it is via Homebrew. Open your Terminal and run:

brew install ffmpeg

Step 2: List Available CoreAudio Devices

macOS handles audio and video devices through the AVFoundation framework. Before recording, you must identify the index number or the exact name of your audio input device (such as a built-in microphone or an external USB interface).

Run the following command to list all available input devices:

ffmpeg -f avfoundation -list_devices true -i ""

Look at the Terminal output under the “[AVFoundation input device list]” section. You will see a list of video devices followed by audio devices. Note the name or the index number of the audio device you want to capture. For example:

[AVFoundation input device list]
[AVFoundation @ 0x123456789] AVFoundation video devices:
[AVFoundation @ 0x123456789] [0] FaceTime HD Camera
[AVFoundation @ 0x123456789] AVFoundation audio devices:
[AVFoundation @ 0x123456789] [0] Built-in Microphone
[AVFoundation @ 0x123456789] [1] External Microphone

Step 3: Capture Audio from the Device

To record audio, use the AVFoundation format (-f avfoundation). In the input option (-i), specify the audio device using the syntax ":<device_index>" or ":<device_name>". The colon : tells FFmpeg to ignore video input and select only the audio stream.

Option A: Recording by Device Index

If your desired audio device is listed as index 0 (e.g., Built-in Microphone), run:

ffmpeg -f avfoundation -i ":0" output.wav

Option B: Recording by Device Name

Alternatively, you can specify the exact name of the device in quotes:

ffmpeg -f avfoundation -i ":Built-in Microphone" output.wav

Step 4: Stop the Recording

To stop the audio capture at any time, press q or Ctrl + C in your Terminal window. FFmpeg will safely close the file and save your recording.

Advanced Recording Options

You can customize the output quality, format, and channels by appending additional flags to your command:

• Record to MP3 with a specific sample rate and channels:

  ffmpeg -f avfoundation -i ":0" -ar 44100 -ac 2 output.mp3

  (This sets the audio sample rate to 44.1 kHz and the channels to 2 for stereo sound).

• Record to uncompressed WAV format:

  ffmpeg -f avfoundation -i ":0" -c:a pcm_s16le output.wav