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Yesterday I did some DSP-related code again after several years (those AtomixMP3 days...). Read Stephan M. Bernsee's "The DFT a Pied" to "get" the DFT/FFT again, and then started to concentrate on beat detection of acoustic signals. Read Eric D. Scheirer's paper on acoustical beat detection, which is kinda heavy and theoretical (although very interesting at the same time :-)), and then found this article originating from this fantastic website. The article builds up things very well, it's very easy to understand everything as long as you got some very basic math knowledge. The author starts with some very simple energy based algorithm, then builds it up to more complex analyse methods.
I implemented algorithm #2 from that article together with some simple wave file reader/player in C yesterday, it needs some more tweaking, but the basics do work. Once I get it working fine I'll implement it as a GStreamer plugin. Lots of thanks to the people at #gstreamer@freenode.net for helping me out at coding the thing, I really need to learn some more about primitive data types and their size ;-)

Next task: use my current code to implement #3, enhance the visual beat tap, and make the code better (it's not optimized at all right now). Then I can put it into a GST plugin (after I read the GStreamer Plugins Writers Guide).

I've been testing several free groupware applications at VTK lately, none of them do everything I want untill now :-( egroupware comes close thanks to it's integration with LDAP, but it's buggy as hell (on our system at least): I can't even add a simple event to my calendar, and some of the "applications" just generate PHP errors and die. If anyone got experience with FOSS groupware applications (especially if they got support for LDAP as account and/or addressbook backend, or even Evolution and/or MS Outlook support) please let me know which apps I should try.