How can I switch between different audio output hardware using the shell?

Question

I use my laptop with an external monitor which has speakers. When the monitor is attached through HDMI I can switch (using the GUI: Sound Setting --> Hardware) between the normal laptop audio output and the monitor output.

I repeat this procedure a lot of time and I started to wonder if I can automate it or, anyway, execute it in a faster way using the shell.

My distro is Ubuntu 12.04 with gnome 3.

EDIT:

I tried using pacmd, but list-sinks gives me only the device I'm currently using:

pacmd list-sinks | grep name:
name: <alsa_output.pci-0000_00_1b.0.hdmi-stereo>

After a switch from GUI:

pacmd list-sinks | grep name:
name: <alsa_output.pci-0000_00_1b.0.analog-stereo>

And if I try to change it I get:

pacmd set-default-sink alsa_output.pci-0000_00_1b.0.hdmi-stereo
Welcome to PulseAudio! Use "help" for usage information.
Sink alsa_output.pci-0000_00_1b.0.hdmi-stereo does not exist.

Answer 1

You can use pactl, read its man page for more information.

Answer 2

In this case the card is always the same. What is changing between a switch and another is the "card-profile".

So the solution which actually worked is:

pacmd set-card-profile <cardindex> <profilename>

In my case I found all the card profiles with:

pacmd list-cards

And after I can switch between monitor and laptop speakers with:

pacmd set-card-profile 0 output:hdmi-stereo

And:

pacmd set-card-profile 0 output:analog-stereo+input:analog-stereo

Where 0 is the index of the card:

pacmd list-cards
Welcome to PulseAudio! Use "help" for usage information.
>>> 1 card(s) available.
    index: 0
    name: <alsa_card.pci-0000_00_1b.0>

And finally, in order to make the switch faster, I set up two alias in my .bashrc file:

alias audio-hdmi='pacmd set-card-profile 0 output:hdmi-stereo+input:analog-stereo'
alias audio-laptop='pacmd set-card-profile 0 output:analog-stereo+input:analog-stereo'

This way I can switch between audio from the monitor or from the laptop (headphones) typing in the shell: audio-hdmi or audio-laptop