github user GithubUser5462

Firefox video playback broken after FFmpeg 9 on Arch Linux

Date: 2026-08-09
Affected setup: Arch/EndeavourOS, Firefox/Firefox Developer Edition, FFmpeg 9

Symptoms

After Arch upgraded FFmpeg from 8.x to 9.0, Firefox could no longer play some H.264/AAC video streams. Twitch, for example, could fail with:

This video is either unavailable or not supported in this browser. (Error #4000)

Restore the old working directory for JetBrains Markdown code blocks

Starting with JetBrains IDEs based on the 2026.2 platform, runnable Markdown code blocks execute from the project root by default.

Previously, commands ran from the directory containing the Markdown file.

This can affect Markdown runbooks that use paths relative to the document:

project/

Disable the “Hold Key for Alternate Characters” Popup in KDE Plasma Login Manager

KDE Plasma can show a popup with accented or alternate characters when a key is held down.

Disabling it in your normal Plasma session does not necessarily disable it on the login screen, because Plasma Login Manager runs under its own system user and has its own configuration directory.

This guide applies to Plasma Login Manager (plasmalogin), not SDDM.

1. Disable the popup in your Plasma session

Fixing "no sound" over a USB / USB-C dock or DAC on Linux (PipeWire)

You plugged headphones/speakers into a USB-C dock (or a USB DAC), the device shows up in your sound settings, volume is up... and there's still silence.

This guide walks the full decision tree. The gotcha most guides miss is the last step: a USB DAC can have its own hardware mute switch at the raw ALSA level that your desktop's volume slider never touches.

Tested on Arch/CachyOS with PipeWire + WirePlumber, but the ALSA/PipeWire

Floating Page Element Bookmarklet

javascript:(()=&gt;{const PICK="__float_pick_active__",CSS="__float_pin_css__";if(window[PICK]?.cancel){window[PICK].cancel();return}document.getElementById(CSS)?.remove();const style=document.createElement("style");style.id=CSS;style.textContent=`.__float_pin_panel{position:fixed;top:20px;right:20px;width:520px;height:360px;min-width:220px;min-height:120px;z-index:2147483647;background:#111;color:#fff;border:1px solid #555;box-shadow:0 10px 40px #000b;border-radius:8px;overflow:hidden;display:flex;flex-direction:column}.__float_pin_bar{height:32px;flex:0 0 32px;display:flex;align-items:center;justify-content:space-between;gap:8px;padding:0 8px;cursor:move;background:#222;color:#fff;border-bottom:1px solid #444;font:13px system-ui,sans-serif;user-select:none}.__float_pin_title{overflow:hidden;text-overflow:ellipsis;white-space:nowrap;min-width:0;flex:1}.__float_pin_buttons{display:flex;gap:4px;align-items:center;flex:0 0 auto}.__float_pin_btn{border:0;background:transpa

Resolving “Required key not available” When Mounting an Encrypted Bcachefs Volume

Problem Overview

When mounting an encrypted Bcachefs filesystem (after unlocking it with a passphrase), you may encounter the error:

mount: ... Required key not available  
ERROR - bcachefs::commands::cmd_mount: Fatal error: Required key not available

🖥️ Weston VNC Remote Desktop Setup (Wayland)

✅ Server Setup (Arch-based systems)

Install required packages:

sudo pacman -S --needed weston xorg-server-xwayland libvncserver

🖥️ Headless Remote Access Under Wayland with KDE Plasma

📚 Source

Headless remote access under Wayland - KDE Discuss

This is a workaround to enable headless remote access to a KDE Plasma system running on Wayland.

ERROR: unable to configure virtual network port: could not open TUN/TAP device: No such file or directory

The error message you are seeing is related to the TUN/TAP device. This device is used to create virtual network interfaces. The error message suggests that the device is not available or not configured correctly.

You can try the following steps to resolve the issue:

1. Kernel module

Check if the TUN/TAP device is loaded by running the command lsmod | grep tun
If it is not loaded, you can load it by running sudo modprobe tun

	package main

	import (
	"bytes"
	"encoding/json"
	"fmt"
	)

	type User struct {
	Name string `json:"name"`