Script for dynamically changing your default PulseAudio sink on hotplug events for USB peripherals, etc.

autopulse uses only one configuration file called autopulse.yml, located either in $HOME/.config/autopulse.yml or /etc/autopulse.yml. This file's format is as follows:

---
default: "abcd:ef01"
hotplug:
  - "dead:beef"
  - "cafe:babe"

One default sink must be named, and as many hotplug sinks as desired can be listed. The script chooses the first present hotplug sink found, otherwise falls back to the default sink.

Device identifiers can be listed as follows:

$ autopulse ls
  1002:aab0 Cape Verde/Pitcairn HDMI Audio [Radeon HD 7700/7800 Series] Digital Stereo (HDMI)
  8086:0d0c Built-in Audio Digital Stereo (HDMI)
  8086:8c20 Built-in Audio Analog Stereo
* 0d8c:1066 I'm Fulla Schiit Analog Stereo

The current sink is prefixed with a * character.

The easiest way to get auto hotplugging working is via systemd and udev. Create a systemd unit at /etc/systemd/system/autopulse@.service:

[Unit]
Description=PulseAudio Hotplug Service

[Service]
Type=oneshot
Environment=DISPLAY=:0
User=%i
ExecStart=/usr/local/bin/autopulse switch

Next, we'll create a udev rule which calls this unit:

SUBSYSTEMS=="usb", ATTRS{idVendor}=="0d8c", ATTRS{idProduct}=="1066", ENV{SYSTEMD_WANTS}="autopulse@naftuli.service"

Whenever a USB device with the given product and vendor ids is attached, detached, or changed, the systemd unit will be called, running as user naftuli.

NOTE: It's still unfortunately necessary to set DISPLAY so that the script can find the PulseAudio daemon. If anyone knows a better solution for this, please send it my way.