Difference between revisions of "ALSA"

Revision as of 16:15, 25 March 2021

ALSA or the Advanced Linux Sound Architecture provides audio support for Linux. It is a replacement for the old OSS linux sound system. The Alsa-utils package contains both the Alsamixer and Amixer utilities. Various linux distributions once used the Open Sound System, or OSS until ALSA superseded it. ALSA provides kernel driven sound card drivers and bundles a user space driven library for application developers.

You can control the audio properties of your sound cards through:

• Alsamixer-The graphical interface for ALSA
• Amixer-The command based utility for ALSA

CLI Utilities

alsamixer

ncurses based utility with visual representation of various levels.

alsamixer

Enable the microphone: switch to the Capture tab with F4 and enable a channel with Space.

mixer

Command line, operation performed per command.

amixer -c [card-number] set [control] [value]

To see what controls you can manage

amixer scontrols

If you are sudo there are more controls available

sudo amixer scontrols

apulse

The apulse utility lets you use ALSA for applications that support only PulseAudio for sound.

aplay

Alsa play - play an audio file

arecord

We can test the default audio input device, or the only audio input device on a simplistic configuration

arecord -vvv -f dat /dev/null

Watch while the audio input levels are displayed as a percentage.

We can specify an audio input device

arecord -vvv --device="hw:1,0" -f dat /dev/null

You can display a list of CAPTURE Hardware Devices. To figure out what audio input device is at hw: card,device use the following command

arecord -l

The output look for "Card X" and on the same line "device X" to know the card,device combination to specify.

speaker-test

as the name implies