Using KDE systray notifications from bash scripts

I just improved my Extract audio script to show a system notification when it’s finished. In the meantime I also have a “convert to mp3” script which proves useful if you don’t care about the original audio stream and/or you target a platform with limited decoding abilities:

ffmpeg -i %u -acodec libmp3lame -ar 44100 -ab 160k %u.mp3

To popup a KDE4 system tray notification at the end of the encoding process, simply add the following:

kdialog --passivepopup 'Finished converting %u' 3

The last value simply specifies the timeout in seconds. To chain the commands together, use a semicolon, so it also executes when the encode fails.

Mouse locating kwin effects

Ever felt lost on your desktop? Or more precisely: unable to find your mouse pointer within a (few) second(s)? I know I have, and nowadays on 2 monitors or more (or a huge 48″ tv), this isn’t an exception.

In KDE, we always had the track mouse effect which draws circling yellow stars around your pointer. Unfortunately, this is not adequate anymore. That’s why I thought it would be fun to write my own effect which would do a better job. The key to success seems to me that it should be a full screen effect drawing the attention to the right spot no matter where at the screen you’re looking.

For now, I’ve devised 3 effects:

  1. Looney tunes zoom: fancy term for describing an effect which darkens the background and zooms in on the cursor with a spotlight. I somehow associated that with intro or outro from looney tunes, not sure if that makes sense. :p
  2. Sunray: animates some kind of rays around the mouse position.
    kwin sunray mouse locate effect
  3. Radial texture animation: least fancy name, as it is so generic. 🙂 It just animates a texture from outer to inner. The concrete application is to show arrows pointing to the mouse.
    kwin arrow mouse locate effect

For the last 2 effects, I don’t have screencasts yet, don’t ask, I’ve been through hell to create the first one. Also, for the last one, I have to fix the texture uv map generation, or use a better mesh (or maybe a different technique 🙂 ).

Configuring numlock indicator in KDE4

My brother has this really neat wireless keyboard with built-in trackball for his mediacenter. There is only one downside: it doesn’t have a numerical keypad and you never really know if the numlock is on or off. I think it is off at boot, but after turning it on and logging on, it is off again, unless you did a reboot.. or something like that.. Anyway, since it can be quite a challenge to enter passwords correctly, I started looking for a numlock plasmoidish solution.

First thing that turned up in the searches was the Keyboard Status applet. However, in the comments someone rightfully asks why it doesn’t use the keystate DataEngine. Great idea, because this is already packaged with vanilla kde. So I started searching for a general LED plasmoid which I could connect any datasource to using some mapping. No such luck. But then I wondered: why would someone write a plasma DataEngine and then not use it? 🙂 There must be some existing plasmoid! It turned out to be the Key State plasmoid which is currently hosted at gitorious.

Since it is a javascript plasmoid, you can install it as follows:

git clone git://
plasmapkg -i keystate

Done! It should now be in the list when adding plasmoids under the name “Key State”. You can configure a custom color for each special key. There are some advanced options as well which I didn’t try out. Here is what it looks like:

Key State plasmoid

A simple rectangle shows my numlock is active. I know, nothing fancy but it’s all we need and it does the job! Thank you Martin Blumenstingl. 🙂

Extract audio from AV container service menu for KDE4

Nowadays, we live in a KDE4 world for real, so it’s time to update my “dump audio from video file” service menu 😉 It should work both in Konqueror and Dolphin.

Create a file with the following contents and put it in one of your service directories (which you can find out by running “kde4-config –path services” , typically you will have something like $HOME/.kde4/share/kde4/services )

[Desktop Entry]

[Desktop Action extractaudio]
Name=Extract audio
Name[en-GB]=Extract audio
Exec=mplayer -dumpaudio %u -dumpfile %u.dump