[PD] Max Smoother Audio than Pd?

[cyrille henry]

Claude Heiland-Allen a écrit :
> cyrille henry wrote:
>>
>>
>> Claude Heiland-Allen a écrit :
>>> Alexandre Porres wrote:
>>>> "I feel Max produce a smoother audio than Pd. Didit"
>>>
>>> Well, if you use [tabread4~] or any of the many other Pd objects that 
>>> use the same broken interpolation algorithm (copy/paste programming), 
>>> you get horrible noise.  If you use [tabread4] to interpolate 
>>> graphical parameters for animations, the discontinuities in the 
>>> derivatives are really obvious.
>>>
>>> See attached patch - it would be interesting to see if a Max/MSP port 
>>> of this patch exhibits the same problem.
>>
>> well, the cos~ object does not internally use a 4 points interpolation.
>> see code : *out++ = f1 + frac * (f2 - f1);
>> it's a 2 points linear interpolation.
> 
> Oops!  Sorry for making assumptions and not checking the source :-/
> 
>>> nusmuk audio tabread4c~ uses the correct interpolation algorithm, 
>>> correct me if I'm wrong.
>> i don't think there is a correct interpolation algorythm.
> 
> True - it depends on the purpose.
> 
> But IMHO if you're doing piecewise cubic interpolation, it's a bit of a 
> nonsense to have a cubic that goes through all 4 points when it's only 
> being used between the inner-most 2 points (a new cubic equation is 
> calculated each time you go past another sample in the table).
i think the interpolation used by miller is the one that minimise the error.
other interpolating methods could have more error, but sound better.


> 
>> I heard that software like reaktor use very diferent algorythm, with 
>> lot's more points, in order to have a band limited interpolation.
> 
> Interesting. Maybe some kind of FFT-based interpolation could be used?
it's more something using sinc to instead of dirac to reconstruct the signal.

http://en.wikipedia.org/wiki/Sinc
Cyrille

> 
> 
> Claude