Microtonal pitch shifting software

Hello,

Does anyone know of software that can shift pitch in increments of less
than 1 cent?
For instance if I have a sample (a wav file) and I want to raise its pitch
by 0.1 cents, how do I do it?

Thank you,
Srijan

Hi Srijan,

When you have a wave file you could play it faster or scale its overall
length by the factor 1/2^(1/12000) = 0.999942239403161 which means
downscaling by 0.00577605968390404% or increasing the speed by the
factor 2^(1/12000) = 1.00005776393332 or adding 0.005776393332%.

For the rescaling I would recommend a filter that does proper
subsampling with high resolution (e.g. double floating point). Some of
the fliters just omit samples and leave the rest to the low pass filter
of the sound card. Besides that you can use any DAW software. Probably
Audacity would be enough if it has such a filter.

I just sampled two sine waves with 440 Hz and 440 Hz + 0.1ct with a
192kHz sampling rate and 24 bit resolution and got a maximal difference
between the two signals of approximately -87 dB full scale.

When you are working with MIDI you can use Mutabor
(http://www.math.tu-dresden.de/~mutabor/) to do any tuning that can be
encoded using pitch and pitch bend information. Which means the smalest
step is a 8192th of a semitone.

There are several issues with this approach:
• Many instruments support only 7bit pitch bend, which lead to a
resolution of ±1/64 semitone.
• The oscillators in the instrument may differ by more than 0.1ct. So
that such a pitch shifting might get lost in the tolerance of the
instrument.
• As far as I know the cochlear resolution is about 1 to 3 ct. This does
not necessarily mean that the ear has this resolution as the signal is
transferred in the nerve fibers phase aligned to the vibrating of the
basilar membrane (but only up to 4kHz). Theoretically there could be
some neural correlators that can sense the difference between the
signals. On the other hand the difference could be lost in the
stochastic noise of the neural pulses.

Tobias

On 11.09.2015 17:26, Srijan Deshpande srijand@gmail.com [TUNING] wrote:
>
> Hello,
>
> Does anyone know of software that can shift pitch in increments of
> less than 1 cent?
> For instance if I have a sample (a wav file) and I want to raise its
> pitch by 0.1 cents, how do I do it?
>
> Thank you,
> Srijan
>

Erik de Castro Lopo's Secret Rabbit Code library does that.

http://www.mega-nerd.com/SRC/

On Fri, 11 Sep 2015, Srijan Deshpande srijand@... [TUNING] wrote:

>  
> > Hello,
> Does anyone know of software that can shift pitch in increments of less than 1
> cent? 
> For instance if I have a sample (a wav file) and I want to raise its pitch by
> 0.1 cents, how do I do it?
> > Thank you,
> Srijan
> > >

It seems that less than a cent is nearly indescernable to the ear, and I
don't know of any actual cutoff as to what software could handle. But I
would recommend trying Audacity which has some kind of pitch shifting
command. I don't remember how precise it is however.

I know MIDI can adjust pitches (as least in theory) down to 1/4096 of a
semitone using a pitchbend.