I have never tried autotune. I gather from what you wrote that it can be used in realtime? It sounds a bit like the whammy pedal for a guitar to me, because the sound is altered. I always thought the signal was split in two parts, one used to analyse the spectrum, and one to analyse the pitch. In this model the pitch would be modified according to some rules and the timbre would be stamped back on it. That's what it sounds like to me, but i may be mistaken to a great extent.
Pierre
2010/8/17 martin brinkmann mnb@martin-brinkmann.de
On 08/16/2010 06:21 PM, Pierre Massat wrote:
Hi,
I've been thinking of writing a pd version of autotune, but before i get started i m wondering if anybody as ever tried doing this?
not in pd, but in reaktor and c. combining pitch-detection and a pitchshifter (and some quantization) works quite well, and should be not too hard to do in pd (fiddle and the pitchshifter from the docs). though this is quite good for subtle pitch correction, it does not create the typical, metallic, vocoder-like "cher-effect".
maybe something like taking single-cycle-samples of the input, when a constant pitch is detected, and playing these instead of the original audio would do better, but i have not tried yet. (and i think detecting zero-crossings in pd (vanilla) is rather difficult...)
I m assuming they're making a ton of money selling it, so there 's probably not much information available as to how it actually works, but i guess Miller Puckette's Phase vocoder example could be a good starting point.
i do not think that autotune uses fft-based methods, since it has very little latency (and does not need too much cpu).
bis denn! martin
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