ALSA Hook

A simple ALSA hook is used to publish MQTT messages when a hooked ALSA PCM is opened or closed. It works with the ALSA hooks plugin.

Install

sudo apt install libasound2-dev
make
sudo make install

Configure

add the hooked pcm to /etc/asound.conf or ~/.asoundrc

# hook entry
pcm_hook_type.voicen {
    install "_snd_pcm_hook_voicen_install"
    lib "alsa_hook_voicen.so"
}

pcm.hooked {
    type hooks
    slave.pcm "hw:0"

    hooks.0 {
        type "voicen"
    }
}

MQTT messages

1. when a hooked pcm is opened

   • topic: /voicen/pcm/open
   • message: {pid}

2. when a hooked pcm is closed

   • topic: /voicen/pcm/close
   • message: {pid}