This minimal script creates a PulseAudio source and pipes a media file or stream into it.

• any POSIX compliant shell
• PulseAudio
• FFmpeg
• mktemp (optional, not needed when virtualmic is run with -p filename)

Copy the script to any of your $PATH directories. On most systems, /usr/bin would be the most sensical directory.

Usage: virtualmic [-p pipe_filename] [-n source_name] [-f format]
       [-r rate] [-c channels] [-v] [-d] [-h] [input_filename]

  input_filename  This file is piped to the virtual mic (can be an url) (default: stdin)
  -p, --pipe      Set audio pipe filename (use mktemp otherwise)
  -n, --name      Set PulseAudio source_name (default: virtualmic)
  -f, --format    Set audio format (default: s16le)
  -r, --rate      Set audio sampling frequency (default: 44100)
  -c, --channels  Set number of audio channels (default: 1)
  -v, --verbose   Make output verbose
  -d, --default   Set virtual microphone as PulseAudio default source
  -h, --help      Show this help

The most basic example is to use an audio file as virtual microphone:

virtualmic file.mp3

virtualmic reads from stdin by default:

<command that generates audio> | virtualmic

I wrote this script initially to use my smartphone as mic after the sound card on my laptop got broken.

For this to work you first need to install an app on your phone to broadcast audio, I'm using IP Webcam on Android. When you run the app on your phone, you can connect to it with virtualmic.

With an IP Webcam URL, this is what the command looks like:

virtualmic http://192.168.0.5:8080/audio.opus

There will of course be some latency, but the latency due to virtualmic should be very little.

On Android devices you can use ADB to connect over USB for a better connection. In my previous example with IP Webcam, the phone broadcasts audio over port 8080. This port can be forwarded to a connected computer using ADB:

adb forward tcp:8080 tcp:8080

Then you can connect virtualmic to your local port:

virtualmic http://localhost:8080/audio.opus