Differences

This shows you the differences between two versions of the page.

--- alsa_only_audio [2025/07/08 00:28] – created ethan
+++ alsa_only_audio [2025/07/09 07:48] (current) – ethan
@@ Line 3: / Line 3: @@
 I will be showing changes to ///etc/asound.conf// as to effect all users (including daemons such as MPD). you can also use //~/.asoundrc// for setup specific to your user.
-=====dmix=====
+=====devices=====
+multiple commands can list available audio cards and devices.
+**alsactl** can be used:
+<code bash>
+$ alsactl info 1
+#
+# Sound card
+#
+- card: 1                    # card number.
+  id: sofhdadsp
+  name: sof-hda-dsp
+  longname:
+  driver_name: sof-hda-dsp
+  mixer_name: Realtek ALC233
+  components:
+  controls_count: 54
+  pcm:
+    - stream: PLAYBACK
+      devices:
+        - device: 1          # device number.
+          id: HDA Analog (*) # name.
+          name:
+          subdevices:
+            - subdevice: 0
+              name: subdevice #0
+...
+</code>
+by default //alsactl info// will show card 0. you most likely have multiple cards.
+**aplay** will also list sound cards and devices.
+<code bash>
+$ aplay -l
+**** List of PLAYBACK Hardware Devices ****
+card 0: HDMI [HDA ATI HDMI], device 0: HDMI 0 [HDMI 0]
+  Subdevices: 1/1
+  Subdevice #0: subdevice #0
+...
+card 1: sofhdadsp [sof-hda-dsp], device 1: HDA Analog (*) []
+  Subdevices: 1/1
+  Subdevice #0: subdevice #0
+...
+</code>
+card 1 and device 1 will be used for this guide. in most places, this is specified with **"hw:1,1"**. the first number is the card and the second is the device.
+=====mixing=====
 [[https://www.alsa-project.org/wiki/Asoundrc#dmix|dmix]] is a software mixer for audio output. it will allow multiple programs to simultaneously play sound at the same time.
@@ Line 22: / Line 69: @@
 </file>
-=====S/PDIF surround sound=====
+=====S/PDIF multichannel=====
 the **a52** alsa plugin can be used to output Dolby Digital 5.1 (or lower) multichannel audio through S/PDIF.
@@ Line 39: / Line 86: @@
 }
 </file>
+=====equalization=====
+[[https://github.com/bassdr/alsaequal|alsaequal]] is a 10-band software equalizer in the form of an ALSA plugin.
+each user has their own persistent settings, stored in //~/.alsaequal.bin//. if, for example, you are running MPD as its own mpd user, you must either copy or link the //alsaequal.bin// file to its home directory, or manually configure it seperately.
+the following configuration builds on the previous section on dmix. an asoundrc using solely alsaequal can be very simple.
+<file bash /etc/asound.conf>
+pcm.dmix_stereo {
+        type dmix
+        ipc_key 1024
+        ipc_key_add_uid false
+        ipc_perm 0666
+        slave {
+                pcm "hw:1,1"
+                period_time 0
+                period_size 1024
+                buffer_size 4096
+                rate 48000
+        }
+        bindings {                     # channel configuration (stereo, quad, 5.1, ...).
+0
+1
+        }
+}
+pcm.plug_eq_stereo {
+        type equal
+        slave.pcm "plug:dmix_stereo"
+}
+pcm.eq_stereo {                       # this plug is needed to make the alsaequal output suitable for use by most applications.
+        type plug
+        slave.pcm "plug_eq_stereo"
+}
+ctl.eq_stereo {                       # this ctl is what allows adjustment in alsamixer (or similar utilities).
+        type equal
+}
+pcm.!default eq_stereo
+</file>
+with this configuration, the equalizer can be changed with ctl **eq_stereo**:
+<code bash>
+alsamixer -D eq_stereo
+</code>
+====multichannel====
+here is an example of using alsaequal with **a52**.
+<file bash /etc/asound.conf>
+...
+pcm.surround {
+        type a52
+        slavepcm "hw:1,1"
+        channels 6
+        bitrate 1000
+        rate 48000
+        format S16_LE
+}
+pcm.plug_eq_surround {
+        type equal
+        channels 6                         # changes channel configuration to 5.1.
+        controls ".alsaequal.surround.bin" # sets the control information file to at ~/.alsaequal.surround.bin. this must be changed if there are to be multiple alsaequals of differing channel configurations.
+        slave.pcm "plug:surround"
+}
+pcm.eq_surround {
+        type plug
+        slave.pcm "plug_eq_surround"
+}
+ctl.eq_surround {
+        type equal
+        channels 6
+        controls ".alsaequal.surround.bin"
+}
+...
+</file>
+the surround equalizer can be changed with ctl **eq_surround** using this configuration.
 {{tag>audio alsa linux}}