[PD] The (not) doppler distortion (was: overdriven speaker)

[Martin Schied]

Hi!

On 20.11.2010 05:25, Mathieu Bouchard wrote:
> On Sat, 20 Nov 2010, Martin Schied wrote:
>
>> no, sorry, I can't on the quick. but I know for sure that frequency 
>> modulation only produces harmonics if the carrier and modulator are 
>> in "simple" relations like 1:5 or your example 200 to 1000.
>
> I think that my reasoning is mostly correct and that our difference is 
> that while I'm insisting that periodic signals remain periodic, you 
> are insisting that nonperiodic signals remain nonperiodic, or 
> something like that.
yes. My thinking of 'non harmonic" distortion is if you have a signal 
whose preceived pitch frequency is harmonically unrelated to the new 
perceived pitch after distortion. So if you had a signal of 100Hz (200, 
300, 400 ... Harmonics) base pitch and add a 70Hz and 130Hz they would 
not fit the old spectrum very well. You will again find a common 'base' 
frequency, for example 10Hz in this case, but 10Hz bands are too small 
in frequencies of 200, 300, 400Hz to be perceived as harmonics. But it's 
difficult to argue about such effects as we had to do many listening 
experiments before...


>
> The correction I made just uses a [delread~].
>
> For example if you have [+~ 1]-[*~ 5]-[+~ 2], you need a [delread~ a 
> 7], because 1*5+2 = 7.
oh, great indeed :)
>
>> it's only because of the slight delay I'd be interested to eliminate. 
>> But as you also said I don't expect any big difference between the 
>> delay free case and the vd~ case as the modulations occuring with a 
>> slight off phase will not sound any different. (however 2ms can be 
>> quite different for short percussive signals)
>
> Well, it does sound different in some way, but the changes I get by 
> changing that delay, are less special than what I get by making that 
> effect happen in the first place, instead of not. It makes me think of 
> other delay tricks such as comb filters.
I'm curious what you planned...
>
>> yep, that's also one of the effects I wanted to eliminate by the 
>> moving write head.
>
> If you make a "moving write head" thing, though, it needs to be additive,
that's easy doable
> and the energy has to get stretched like the derivative of the motion 
> (the speed of the head).
or accumulated. there also might happen a supersonic bang (but before, 
there are problem with the sampling theoreme not been met anymore).
> The data may have to be spread into a not-very-bounded amount of array 
> elements.
its bounds could be set to a fixed maximum, like for [delwrite 1000].

too much to start off for me, I should learn proper c before and know 
more about interpolation (and the internals of pd too).

Martin
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