Le 28/10/2017 à 02:08, Alexandre Torres Porres a écrit :
2017-10-27 19:12 GMT-02:00 cyrille henry <ch@chnry.net mailto:ch@chnry.net>:
depending on the input you can also LP filter the signal before the distortion. oversampling and filtering is the worst way to deal with aliasing, but sometimes there is no other solution.recently I found out the results were kinda terrible and there wasn't much I could do about it, oversampling it to an insane amount like 512x didn't improve significantly at all...
so I was wondering: - 1) why?
if you start with a 1KHz sinuzoid, and add 10 harmonics, the last harmonics frequency is 1K * 2^10, so about 1MHz and this is just a "small" distortion.... according to what I read on the web, a good oversampling factor is between 2^8 and 2^14.
So, a 512x oversampling is not perfect but should improve a lot. (I suspect a patch problem if you did not have any improvement)
Is there any other way?
if you don't want to oversample, you must manipulate the sound in a way that did not generate harmonics higher that SR/2 this is what antialiased oscillators are doing.
You say sometimes "no", but when can you? I assume you could do it better if you're designing oscillators and things like that, but for this kind of alias generated by digital audio manipulations, maybe there's nothing else at all? is that it?
I did not find any interesting algorithm searching on the web, but I may have missed something.
cheers c
thanks cheers
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