On Sat, September 25, 2010 10:48 am, fons@xxxxxxxxxxxxxxx wrote: > On Sat, Sep 25, 2010 at 10:07:46AM -0700, Patrick Shirkey wrote: > >> 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. > > The confusion continues :-) > > AFAIK Jamin does not have a parametric EQ. It uses an FFT-based > method with a graphical interface that makes it look either like > a combination of 'freehand' frequency response and parametric, > or as a 30-band 'graphic EQ'. But it's the same algorithm in all > cases, and it's not a plugin. > > If works by taking the FFT of the input, multiplying in the > frequency domain by some precomputed values, and transforming > back using an IFFT. This modifies the frequency response of > course, but it is *not* a linear filter and produces side > effects (modulation). Jamin minimises this by 1) windowing, > which amounts to crossfading between processed blocks of > samples, and 2) processing much more overlapping blocks than > the minimum required to do crossfading (which would be 2). > > The proper way to implement a filter of this type (with a FR > defined at all multiples of Fsamp / 1024) would be by using > linear convolution rather than cyclic. But as said, this is > not the right kind of filter anyway. > Just to clarify again, are you saying here that convolution will produce a cleaner result than fft? Or that the implementation of the fft algorithm in jamin is not the most efficient method of doing the transform? -- Patrick Shirkey Boost Hardware Ltd. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
