How to List ALSA Audio Devices Using FFmpeg

To record audio on Linux, you first need to identify the correct input source. This article provides a quick and direct guide on how to list all available ALSA (Advanced Linux Sound Architecture) audio capture devices using FFmpeg, allowing you to easily find the correct device identifier for your audio recording and streaming commands.

To list all available ALSA audio capture devices, open your terminal and run the following FFmpeg command:

ffmpeg -sources alsa

This command queries the ALSA demuxer through FFmpeg’s device framework and outputs a list of recognized input sources.

Understanding the Output

The output will display the recognized devices in a structured format. Look for the lines under the source list, which will typically look like this:

Auto-detected sources for alsa:
  default [Default ALSA Output (currently PulseAudio Media Role...)]
* hw:0,0  [HDA Intel PCH, ALC3232 Analog]
  hw:0,2  [HDA Intel PCH, ALC3232 Alt Analog]

Device Identifier: The string on the left (e.g., hw:0,0 or default) is the short name of the device. This is the identifier you must pass to FFmpeg when recording.
Device Description: The text inside the brackets on the right provides a user-friendly description of the hardware, helping you determine which physical microphone or line-in port it refers to.
**The Asterisk (*):** The asterisk indicates the system’s current default audio capture device.

How to Record Using the Identified Device

Once you have identified your desired ALSA device from the list, you can use it in an FFmpeg command to capture audio. For example, to record audio from the device hw:0,0 and save it as an MP3 file, use the following command:

ffmpeg -f alsa -i hw:0,0 output.mp3

Alternative: Using System ALSA Tools

If your version of FFmpeg was compiled without the device listing capability, you can retrieve the exact same hardware identifiers using the native ALSA tool arecord:

arecord -l

This will print a list of digital audio capture hardware devices, showing the card number and device number (e.g., card 0: PCH ..., device 0: ALC3232 Analog), which maps directly to the hw:0,0 format used in FFmpeg.