On Sat, September 25, 2010 7:17 am, fons@xxxxxxxxxxxxxxx wrote: > On Fri, Sep 24, 2010 at 09:51:07PM -0700, Patrick Shirkey wrote: > >> IIRC Fons suggested the sc4 compressor algorithm was similar to a >> vocoder. > > I did never suggest anything of the sort concerning the sc4 compressor. > > More precisely, the * FFT-based equaliser * is not a linear filter but > a vocoder. You just have to inspect the code to see this. The problems > resulting from this are mitigated to a large extent by using a large > overlap factor, at the price of much increased CPU usage. To the point > that a real filter implementation using linear convolution would in fact > be simpler and more efficient. > Thanks for clarifying. I recall the parametric eq was chosen because that was recommended as the tool to use by the professionals mastering engineers who were contributing to the development discussions. > If this were all I'd have provided a patch years ago. But there are other > problems with this type of filter: it provides way too much detail in the > mid and high frequency regions. There is really no point in having any > significant gain difference between say 4000 Hz and 4020 Hz, the only > result would be a very bad impulse respons that destroys all transients. > Yet the user interface makes it easy to get this sort of thing, even just > accidentally. It's a good example of textbook DSP being applied blindly > and without understanding the consequences. > To clarify further, are you referring to the entire ui or specifically to the parametric eq ui which Jan designed? I think Jan would be the first to admit that he is not a dsp expert but was instead attempting to provide a user friendly interface for the specific plugin. If the latter, it's trivial from a backend perspective to add a linear filter in place of the parametric eq. After all it is just a ladspa plugin with a custom gui. No doubt you have already released one. The much more complex problem will be adding a frontend that allows for proper control. However if the interface is similar to the parametric eq ui it is probably only a weeks work or less. Do you have an example of what the ui for a linear filter should look like from an ui perspective? I could look around online for example but no doubt there is a correct way to represent it so I would rather see that first. IIUC there is nothing to stop us from adding a linear filter as an option for the eq section. -- Patrick Shirkey Boost Hardware Ltd. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
