add note about sound control

Author: Czaki

docs/blog/posts/auto_switch_sound_devices.md

@@ -0,0 +1,103 @@
+---
+date: 2023-12-17
+categories:
+  - Ubuntu
+  - Sound
+  - PulseAudio
+  - Article
+tags:
+    - Ubuntu
+    - Sound
+    - Article
+---
+
+# Auto-selects sound devices on login
+
+## Motivation
+
+The Ubuntu prioritizes the USB sound card over the internal sound card. This is not always what one wants.
+Some examples:
+
+1. USB camera with not-so-good microphone, when a better microphone is connected to the internal sound card.
+2. USB microphone with option to monitor recorded sound, that is recognized as possible output, when speakers are connected to the internal sound card.
+
+In both scenarios, the system will select the USB device instead of the internal sound card. This is not always what one wants.
+
+## Solution
+
+!!! note 
+
+    This solution is tested on Ubuntu 22.04 with PulseAudio
+
+
+Set the preferred sound card in the system settings. Then run `pactl info` to get the name of preferred sound device. 
+
+```bash
+$ pactl info
+Server String: /run/user/1000/pulse/native
+Library Protocol Version: 35
+Server Protocol Version: 35
+Is Local: yes
+Client Index: 27
+Tile Size: 65472
+User Name: czaki
+Host Name: grzesiek-komputer
+Server Name: pulseaudio
+Server Version: 15.99.1
+Default Sample Specification: s16le 2ch 44100Hz
+Default Channel Map: front-left,front-right
+Default Sink: alsa_output.pci-0000_00_1f.3.analog-stereo
+Default Source: alsa_input.pci-0000_00_1f.3.analog-stereo
+Cookie: 057c:b811     
+```
+
+For single-line output one could use `pactl get-default-source` and `pactl get-default-sink` commands.
+
+Then create a file `~/.local/bin/sound.sh` with the following content, add execution permissions (`chmod +x ./sound.sh`) and add it to the startup applications:
+
+```bash
+#!/bin/bash
+pactl set-default-source 'alsa_input.pci-0000_00_1f.3.analog-stereo'
+pactl set-default-sink 'alsa_output.pci-0000_00_1f.3.analog-stereo'
+```
+
+Replace target devices with the ones from `pactl info` output. 
+
+
+## Additional scripts
+
+Here is my script that allows one to switch between sound devices build based on above information.
+
+If a Bluetooth device is connected then switch only the input device, otherwise switch both input and output devices between built-in and USB ones.
+You may need to adjust the names of the devices to your needs.
+
+```bash
+#!/bin/bash
+
+LANG=en_US  # to get consistent output from pactl
+
+BUILDIN_OUTPUT=$(pactl list sinks | grep  -oP "Name: \K.*pci.*")
+BUILDIN_INPUT=$(pactl list sources | grep  -oP "Name: \K.*input.*pci.*")
+NCX_USB_OUTPUT=$(pactl list sinks | grep  -oP "Name: \K.*NCX.*")
+NCX_USB_INPUT=$(pactl list sources | grep  -oP "Name: \K.*input.*NCX.*")
+BLUEZ=$(pactl list sinks | grep  -oP "Name: \K.*bluez.*")
+
+
+if [[ -n $BLUEZ ]]; then
+    if [[ -n $NCX_USB_INPUT ]] && [[ $BUILDIN_INPUT == *$(pactl get-default-source)* ]]; then
+        pactl set-default-source $NCX_USB_INPUT
+    else
+        pactl set-default-source $BUILDIN_INPUT
+    fi
+else
+    if [[ -n $NCX_USB_INPUT ]] && [[ $BUILDIN_INPUT == *$(pactl get-default-source)* ]]; then
+        pactl set-default-sink $NCX_USB_OUTPUT
+        pactl set-default-source $NCX_USB_INPUT
+    else
+        pactl set-default-sink $BUILDIN_OUTPUT
+        pactl set-default-source $BUILDIN_INPUT
+    fi
+fi
+```
+
+

mkdocs.yml

@@ -20,6 +20,10 @@ markdown_extensions:
       use_pygments: true
       anchor_linenums: true
   - pymdownx.superfences
+  - admonition
+  - pymdownx.details
+  - pymdownx.superfences
+