Thursday, 24 January 2013

Recursive construction of a Sierpinski carpet by using the HTML5 canvas element and JavaScript

Yesterday I posted an page which shows how to draw a Sierpinski triangle with the HTML5 canvas element. Besides this Mr. Sierpiński also was a fractal carpet knotter. Here is my version of the Sierpinski carpet:

Wednesday, 23 January 2013

Recursive construction of a Sierpinski triangle by using plain HTML5 + JavaScript

Here's a little page I wrote which demonstrates how to construct a Sierpinski triangle with JavaScript and the HTML5 canvas element. You can interactively modify the recursion depth between 0 and 10.

Monday, 14 November 2011

Tak3Tik® Version 1.3

A new version of my iPad/iPhone app Tak3Tik® is available in the app store. I added a new "sky" design which looks quite pretty.

Get it here:

See the app in action:

Monday, 2 May 2011

How to export Rhythmbox radio stations?

Rhythmbox is currently my favorite audio player. I often listen to internet radio stations.

Now I wanted to export the stations which I added to Rhythmbox. Unfortunately you can't do this with Rhythmbox itself. It's possible to export normal playlists, but it's not possible to export your radio stations.

Rhythmbox stores meta information of your media library in an XML file which is located at

You will probably see that most of the elements starts with <entry type="ignore"> or <entry type="song">

The type of internet radio stations is "iradio". E.g.:
<entry type="iradio">
    <title>Radio Swiss Jazz</title>
    <genre>Jazz Music</genre>

What we need is a way to extract all titles and locations of xml entries of type iradio. This can easily done with a XPath query. I use XMLStarlet for this purpose (I like to work in the command line). You can install it with

sudo apt-get install xmlstarlet

Now we have the tool to work with and we know what we are looking for. Here comes the magic:

xmlstarlet sel -t -m "/rhythmdb/entry[@type='iradio']" -v title -n -v location -n ~/.local/share/rhythmbox/rhythmdb.xml

This will give you a list of you stations with their names and addresses. In my case it looks like this:

Rock Antenne
Bremen 1
Radio Swiss Jazz
Radio Stephansdom


Thursday, 14 April 2011

Ogg Dateien mit VLC nach mp3 konvertieren

Der VLC Media Player ist hauptsächlich als hervorragendes Freeware Tool zum Abspielen der verschiedensten Medien bekannt. Man kann ihn aber auch zum Konvertieren von Audio Dateien verwenden.

Nachfolgend wird erklärt wie man mit dem VLC eine Ogg Audiodatei in eine mp3 Datei umwandeln kann.

1. VLC starten

2. In dem Menü "Medien" den Punkt "Konvertieren/Speichern" auswählen.

3. Den Reiter "Datei" auswählen und auf "Hinzufügen" clicken. Dann die Ogg Datei, die konvertiert werden soll, auswählen.

4. Auf "Konvertieren/Speichern" clicken.

5. Nun muss der Name der Zieldatei angegeben werden. Da wir nach mp3 konvertieren wollen, muss diese mit ".mp3" enden. Danach aus der Liste der Profile "Audio - MP3" auswählen.

6. Weitere Einstellungen für die Konvertierung können vorgenommen werden, in dem man auf das Werkzeug Icon neben der Profil Liste clickt und danach den Reiter "Audiocodec" auswählt.

7. Die Konvertierung wird nun mit "Start" gestartet.

8. Im Hauptfenster des VLCs sieht man nun den Fortschritt der Konvertierung.


Friday, 15 October 2010


My iPhone app Tak3Tik® is now available in the iTunes App store. There is a Lite version which supports the "Human vs. Human" mode and a full version which provides a computer opponent. Check it out!


Future plans for the full version are iPad HD support and game center support.

Thursday, 18 March 2010

Breakpoints are not working in Xcode

You defined breakpoints in your code, your active configuration is "Debug" but still Xcode refuses to stop when it reaches a breakpoint.

Most likely this will help:

Go to "Xcode -> Preferences" and click on "Debugging". Now make sure that "Load symbols lazily" is not checked. Voilà!