[LAU] [Sort of OT] Ringing in filters

Fons Adriaensen fons at kokkinizita.net
Tue May 18 20:56:44 UTC 2010


On Mon, May 17, 2010 at 02:29:01AM -0700, Ken Restivo wrote:

> Well, Fons kind of sniffed at Jamin-- "you are mastering through a vocoder"

Well, that is not really what I wrote:

Responding to:

>> I was thinking about tearing into the code for
>> something like Jamin to look at what's done there. Maybe there are
>> better examples for me to use though?

I wrote:

> Jamin's FFT based filter is not really a filter, it's a vocoder
> being used as a filter and it has side effects. 

Which is just true. It's also true that changing the window
function and increasing the FFT overlap has reduced the
artefacts to below -80..-90 dB w.r.t. the signal. But that's
not a solution but a cover-up, coming at the expense of a lot
of wasted CPU load - Jamin takes 35% on my 2GHz P4. For what
it is doing 5% would be reasonable. And it doesn't help to
bypass the EQ: it is *always* in circuit, even if the response
is forced to flat when you enable the 'bypass' checkbox. Nor
does it help to improve the atrocious type of responses that
the 'HD' filter will generate if you are just a bit unlucky. 

Ciao,

-- 
FA

O tu, che porte, correndo si ?
E guerra e morte !


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