[PD] Re: removing clicks

[hard off]

hi...

the common way people do it is to send a line message to send the
audio level to zero at the start and end of each sound / loop /
whatever.  a line ramp taking only 5 or 10 milliseconds usually works.

i was doing this for a long time, but now i crossfade the end of the
first loop / beat, with the start of the next loop / beat.  this means
you don't get an audio drop (even a tiny one) at the end of each loop.



On 5/23/05, matthew jones <mj at isvr.soton.ac.uk> wrote:
> > filter which looks for discontinuities greater than a certain amplitude
> 
> Well at first that sounds just like a low-pass filter...
> Which would probably ruin the sound of the signal passing through it.
> 
> Two things: you could write an abstraction/external to do a fancy non-linear
> 
> filtering, based on a threshold.  I think I remember seeing stuff in Max 
> related to this, like the 'temperature' of the signal which was simply the 
> difference between this sample and the last (..?).  So you could possibly 
> control the cutoff of the low-pass filter based on the output of a 1-tap 
> high-pass IIR filter that simply gave you the difference between consecutive
> 
> samples..  But this would bring plenty of difficulties related to reaction 
> speed and distortion.  Oh, but you know when it is going to click..anyway..
> 
> Secondly, the nicest approach would be to use windows (or envelopes) where 
> before you jump to a new place in the array, you begin fading in the new 
> position output (and fading out the old position output).  If you use 
> half-sine waves around 50ms in length as your windows then I would be 
> surprised if you ever heard any more clicks.
> 
> 
> Matt
> 
> -=-=-=-=-=-=-=-=-=-=-=-
> http://www.loopit.org
> -=-=-=-=-=-=-=-=-=-=-=-
> ----- Original Message ----- 
> From: "Chris McCormick" <chris at mccormick.cx>
> To: <pd-list at iem.at>
> Sent: Monday, May 23, 2005 8:01 AM
> Subject: [PD] removing clicks
> 
> 
> > Hi!
> >
> > Though this seems to be discussed every second day on the music-dsp
> > list, I couldn't find anything pd-specific in the archives. If anyone
> > has a pd specific idea of implementation of this I'd be grateful,
> > preferably using native pd elements (I'd rather build it as an
> > abstraction than as an external).
> >
> > There's a GOP abstraction which I constructed some time ago and have
> > been using for months. It's pretty elementary - loops drum beats and
> > jumps between different positions in the beat. My problem is a decades
> > old one - discontinuities in the wave-form at the jump time result in an
> > audible 'click' when the amplitude of the wave is loud enough to hear it.
> >
> > Someone is painting the office downstairs so this might be a paint-fume
> > infused dsp-n00b simplification, but I guess what I'm looking for is a
> > filter which looks for discontinuities greater than a certain amplitude
> > and only lets the wave jump by a smaller amount than that. Is there any
> > way I can use expr~ to evaluate an expression which takes into account
> > previous values which passed through it?
> >
> > Best regards,
> >
> > Chris. 
> 
> 
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