Skip to content

Latest commit

 

History

History
105 lines (80 loc) · 2.73 KB

alsa-eq.md

File metadata and controls

105 lines (80 loc) · 2.73 KB
Raw

ALSA Equaliser

This image incudes the libasound2-plugin-equal package which allows the user to enable and apply equalisation to your ALSA ouputs.

HOW-to

Method 1

This method will apply the equalisation to the default output created when running the container.

First create asoundrc.txt file and mount it to /user/config/asoundrc.txt. This file should contain the following:

pcm.!default {
  type plug
  slave.pcm plugequal;
}
ctl.!default {
  type hw card 0
}
ctl.equal {
  type equal;
}
pcm.plugequal {
  type equal;
  slave.pcm "plughw:0,0"; # NOTE this line MUST be your hardware device.
}
pcm.equal {
  type plug;
  slave.pcm plugequal;
}

Method 2

This method will apply the equalisation to a separate output created when running the container. It will not affect your default output.

First create asoundrc.txt file and mount it to /user/config/asoundrc.txt. This file should contain the following:

ctl.equal {
  type equal;
}
pcm.plugequal {
  type equal;
  slave.pcm "plughw:0,0"; # NOTE this line MUST be your hardware device.
}
pcm.equal {
  type plug;
  slave.pcm plugequal;
}

Now create a separate output by adding this your additional-outputs.txt:

audio_output {
  type "alsa"
  name "ALSA EQ" # You can name it as you like
  device "plug:plugequal"
}

Playing audio through this output will have the equalisation applied.

ALSA EQ CLI

The ALSA EQ cli can be accessed by running the following command:

docker exec -it mpd alsamixer -D equal

ALSA EQ cli

EQ Presets

ALSA EQ Presets can be created in the form of bash scripts which then later can be ran to apply different EQ Preset of choice.

EQ Preset (example script)

Here 66 = base value of each frequency. Value ranges from 0 to 100. Below 66 is negative value and above 66 is positive value.

default.sh
...
#!/bin/bash
/usr/bin/amixer -D equal -q set '00. 31 Hz' 66
/usr/bin/amixer -D equal -q set '01. 63 Hz' 66
/usr/bin/amixer -D equal -q set '02. 125 Hz' 66
/usr/bin/amixer -D equal -q set '03. 250 Hz' 66
/usr/bin/amixer -D equal -q set '04. 500 Hz' 66
/usr/bin/amixer -D equal -q set '05. 1 kHz' 66
/usr/bin/amixer -D equal -q set '06. 2 kHz' 66
/usr/bin/amixer -D equal -q set '07. 4 kHz' 66
/usr/bin/amixer -D equal -q set '08. 8 kHz' 66
/usr/bin/amixer -D equal -q set '09. 16 kHz' 66
echo "EQ: ${0##*/} applied"

Also make it executable by doing chmod +x default.sh. You can create your own presets by getting the values using ALSA EQ cli.

Presets Volume & Applying

Mount a directory containing all your preset scripts to /user/config/eq-presets and then run docker exec -it mpd sh /user/config/eq-presets/<preset-name>.sh