Looking forward to testing this! Let's see how it stacks up to hardware crossfeed and bs2b (which cites the same link by Meier and also says it's is as close as possible to linear phase)
Didn't know about Faust. Looks like a cool route to make VST stuff. Code definitively looks weird.
This crossfeed is special, as it is probably the only one that's linear for mono signals. (As linear as linear-phase FIR gets.)Zero combing is possible for mono signals and it should be vastly lower for side signals as well thanks to phase linearity.
This is true, it's as close as possible given its design - in that it uses minimum phase first order IIR filters, that gives 60 degree phase shift at bass.
BS2b implements a Chu Moy's crossfeed - like Meier's first one published on Headroom, except with compensatory highs boost.The first order IIR filters cause a bass boost and mild subbass distortion, as well as a relatively shallow wide dip in the knee range (depending on crossfeed frequency) in the central signal plus very minor high frequency combing.The inverted bass cut is both due to the phase shift and requirement for more aggressive feeding due to lack of real ITD simulation - the filter delay acts as one and it's very short. BS2b doesn't specifically feed higher frequencies at all either, only the bass, but the IIR filter used has very low stopband rejection due to being first order, so a tiny amount of feeding is present.
Not just VST, it has many "architecture" files. Including a command line application.The language isn't precisely well known due to being quite new and very domain-specific. It feels in writing like Verilog for audio - you're designing a simplified electrical circuit in textual flow form with some math sprinkled on top.< br />The main issue with it is that it's almost purely functional - there are very few stateful facilities (like a mutable buffer) and this makes some things look quite awkward.Also makes some major algorithms unavailable except by C binding, which works excellent. There's also no support for oversampling yet, but there's work being done in this regard.Of major unavailable algorithms, resampling or FFT is not possible, neither is thus fast convolution. There's no stdio or direct file access either. For those, C has to be used.String handling is nonexistent - only very limited numeric substitution.UIs are relatively spartan too, no nice controls like a spectrum analyzer or oscilloscope are included, but the basic buttons, checkboxes, entry fields, sliders and knobs are there. Of display controls, VU meters and LED are available.
A first order low-pass IIR should act as a clumsy bass boost deal but shouldn't cause subbass issues or combing on its own... Do you mean after left and right channel combination?
Quote from: AstralStorm on July 15, 2013, 06:57:12 AMThis crossfeed is special, as it is probably the only one that's linear for mono signals. (As linear as linear-phase FIR gets.)Zero combing is possible for mono signals and it should be vastly lower for side signals as well thanks to phase linearity.The link looks interesting. Not sure if this is what they (CORDA guys) do, but I guess one could generate a left, center, right, or more channels from stereo, and use a different crossfeed approach for each (like almost-no or no crossfeed to the center channel).
Sorry, not sure what you mean by "...inverse phase signals are properly localized..." What inverse phase signals you mean?
