Comments for The DSP Dimension

Comment on Pitch Shifting Using The Fourier Transform by To tune automaticaly a standard guitar...

To tune automaticaly a standard guitar... — Mon, 29 Jun 2009 22:29:41 +0000

[…] FFT, although not in B4PPC CodeProject: How to implement the FFT algorithm. Free source code and programming help & slightly related, but possibly easier to comprehend some of the issues. Pitch Shifting Using The Fourier Transform - The DSP Dimension […]

Comment on The DFT “à Pied”: Mastering The Fourier Transform in One Day by Tato

Tato — Thu, 25 Jun 2009 10:32:03 +0000

Can I build a multi effects processor for my electric guitar using a DSP with the Fourier stuff and the C++ programming?

Comment on Pitch Shifting Using The Fourier Transform by Adam Sida

Adam Sida — Wed, 24 Jun 2009 10:54:50 +0000

Hello,
I’ve tried to compile in Visual C++ 2008 express and got error in smbFft function at row:
for (k = 0, le = 2; k < (long)(log(fftFrameSize)/log(2.)+.5); k++) {
compiler error, log(long _x) is not exist.

so I just replaced this by:
//updated by asida [AT] centrum [DOT] cz
long eol = (long)(log((double)fftFrameSize)/log(2.0)+.5);
//for (k = 0, le = 2; k < (long)(log(fftFrameSize)/log(2.)+.5); k++) {
for (k = 0, le = 2; k < eol; k++) {

Comment on The DFT “à Pied”: Mastering The Fourier Transform in One Day by Kyle Mew

Kyle Mew — Fri, 29 May 2009 21:08:10 +0000

very good - i’ve been looking for a jargon free explanation of dft and fft for ages - and this is just that - thank you

Comment on The DFT “à Pied”: Mastering The Fourier Transform in One Day by Kyle Mew

Kyle Mew — Fri, 29 May 2009 16:10:21 +0000

Thanks for this - it was very clear and well explained

Comment on On the Importance Of Formants In Pitch Shifting by Rainfly_X

Rainfly_X — Mon, 25 May 2009 17:10:33 +0000

Taimoor, I think I can answer your question. Formant frequencies aren’t dependent on the fundamental frequency (pitch) of the note, they depend on the vocal tract of the singer. So lets say you move the formants without changing the pitch. You can make the singer sound like a little girl or a Russian swimmer, but it’s still the same note on a scale. That’s why you don’t want to move the formants when you pitch shift, because it’s the note that’s changing, not the vocal tract of the singer.

Comment on Pitch Shifting Using The Fourier Transform by ApplistarVN

ApplistarVN — Mon, 25 May 2009 04:01:06 +0000

Thank you very much.

Comment on Pitch Shifting Using The Fourier Transform by Bernsee

Bernsee — Sat, 23 May 2009 14:02:13 +0000

The most likely cause why this doesn’t work is that your buffer contains 2 channels that are interlaced (left, right, left, right). smbPitchShift can only process single channel (mono) sound data. I would recommend you post any followup questions to our forum, thank you!

Comment on Pitch Shifting Using The Fourier Transform by ApplistarVN

ApplistarVN — Sat, 23 May 2009 13:53:07 +0000

Hi,
Thank you for your tutorial. I have met a problem with it, please help me!
I have tried it with my sound data having size as 65536 bytes. Its format is kAudioFormatLinearPCM, mSamplRate is 44100 Hz, 2channels/frame (it is stereo). I call the function as:
smbPitchShift (1.0, (long)65536/2, (long)2048, (long)32, 44100.0, inData,outData)
but the output voice is very very noisy.
inData and outData are float[65536/2] and inData contains all original sound data.
I also have scaled inData, outData (device and multi with 32768) but I don’t know why it is too noisy.

Comment on On the Importance Of Formants In Pitch Shifting by Taimoor Ahmed

Taimoor Ahmed — Fri, 08 May 2009 06:18:25 +0000

Hello!!
I would like to ask One baisc Question:
If Pitch is the fundamental frequency then are the formant integral multiples of Pitch i.e the harmonics?? I mean are they on 2f,3f,4f…so on???