How to programmatically change volume in Ubuntu

python audio ubuntu gnome alsa
Cerin picture Cerin · May 24, 2012 · Viewed 29.2k times · Source

How do you programmatically change volume in Gnome on Ubuntu, either from the command line or an API (Python preferrably)?

The only answers I found to similar questions use amixer, which seems to have no effect on Ubuntu 12.04. Running:

amixer set Headphone 10-

shows:

Simple mixer control 'Headphone',0
  Capabilities: pvolume pswitch penum
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 115
  Mono:
  Front Left: Playback 0 [57%] [-57.50dB] [on]
  Front Right: Playback 0 [57%] [-57.50dB] [on]

The x% changes each time I run it. Unfortunately, it has no effect on the actual volume. Eventually it says 0%, but volume is still at full blast.

The other downside is I have to specify the exact active output device, which I might not know if there are multiple devices. For example, if I have a "Master" and "Headphone", how do I determine which one is the active device?

Answer

mata picture mata · May 24, 2012

Ubuntu uses pulseaudio as sounderver. It can be controlled from the command line using the pactl and pacmd utilities, for example:

pactl set-sink-volume 0 20%

would set the volume of the sink #0 to 20%.

see: man pactl and pacmd help

edit:

to avoid -xx being interpreted as command line option you must prefix it with --. That stops option parsing from that point:

pactl set-sink-volume 0 -- -20%    # or:
pactl -- set-sink-volume 0 -20%    # doesn't matter where the `--` goes

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