I have recently taken interest to hacking Rakarrack ( http://rakarrack.sourceforge.net ) in the way of improving features or fixing/modifying the DSP algroithms within the source code.
My intent is to contribute any fruits of my labor back to the project, but also know that some things will not be included in any releases if the "hacks" do not fit into the project goals.
As a result, this blog will catalog my hacks, and provide instructions for modifying the source code for those who wish to have their own version of RakaHack.
For example, I got started with this when I determined the compressor doesn't behave as expected. I dug into the DSP algorithm within Compressor.C and found some faulty math. This fix has been submitted and included in CVS.
However, on the side I added a slider to the GUI to make the compressor knee user-adjustable. This feature was not added to the project CVS, so perhaps in my next blog I will provide instructions and/or rakarrack.cxx hacked file to add this feature to your own version of Rakarrack.
Now I have it in my mind to continue hacking the effects. Here are some ideas:
1) The distortion function needs up-sampling to reduce digital aliasing artifacts.
2) I want to add a compression-type distortion element (sort of a dynamic tube-like curve, but not really intended to be a tube emulator).
3) Model the phaser after an analog circuit.
4) Add a multiplyer cell for things like ring modulation -- many interesting things can be done here.
5) Split envelope detection to left channel only, so one can use external modulation sources to control the wah-wah. For example, a Crybaby can be used as a volume pedal by feeding high-pass filtered white noise into the Crybaby, then crybaby into the left channel. Guitar into the right channel. The compressor code is hacked to only detect input level on the left channel. Set compressor threshold quite low, and work the crybaby. As the filtered white noise changes in amplitude, the compressor modulates gain on the audio signal, and voila! a volume pedal. This same technique could be used to use your real Crybaby wah pedal to sweep the rakarrack wah.
See how much fun hacking can be?