[linux-audio-dev] Announcing initial release of FreqTweak

Announcing the initial release of FreqTweak (v0.4) http://freqtweak.sourceforge.net FreqTweak is a tool for FFT-based realtime audio spectral manipulation and display. It provides several algorithms for processing audio data in the frequency domain and a highly interactive GUI to manipulate the associated filters for each. It also provides high-resolution spectral displays in the form of scrolling- raster spectragrams and energy vs frequency plots displaying both pre- and post-processed spectra. It currently relies on JACK for low latency audio interconnection and delivery. Thus, it is only supported on Linux. FreqTweak is an extremely addictive audio toy, I have to pry myself away from playing with it so I can work on it! I hope it has value for serious audio work too (sound design, etc). The spectrum analysis is pretty useful in its own right. FreqTweak supports manipulating the spectral filters at several frequency resolutions (64,128,256,512,1024, or 2048 bands) depending on your needs and resources. Overlap and windowing are also selectable. The GUI filter graph manipulators (and analysis plots) have selectable frequency scale types: 1x and 2x linear, and two log scales to help with modulating the musical frequencies. Filters can be linked across multiple channels. The plots are resizable and zoomable (y-axis) to allow precise editing of filter values. The current processing filters are described below in the order audio is processed in the chain. Any or all of the filters can be bypassed. The state of all filters can be stored or loaded as presets. Spectral Analysis -- Multicolor scrolling-raster spectragram, or energy vs. freq line or bar plots... one shows pre-processed, another shows post-processed. EQ -- Your basic multi-band frequency attenuation. But you get an unhealthy number of bands... Pitch Scaling -- This is an interesting application of Sprengler's pitch scaling algorithm (used in Steve Harris' LADSPA plugin). If you keep all the bins at the same scale, it is equivalent to Steve's plugin, but when you start applying different scales per frequency bin, things quickly get weird. Gate -- This is a double filter where a given frequency band is allowed to pass through (unaltered) if the power on that band is between two dB thresholds... otherwise its gain is clamped to 0. Delay -- This lets you delay the audio on a per frequency-bin basis yielding some pretty wild effects (or subtle, if you are careful). A feedback filter controls the feedback of the delay per bin (be careful with this one). This is basically what Native Instrument's Spektral-Delay accomplishes. Granted, I don't have all the automated filter modulations (yet ;). See their website for audio examples of what is possible with this cool effect. Have fun... report bugs... Jesse Chappell <jesse(a)essej.net>