Hi guys, I just added convolution via FFT to my audio program so I can convolve two arbitrary signals (sounds), I have a few questions. In Numerical Recipes in C it says to setup the response in wrap-around order, in other tutorials I don't see that being done. Should I be doing that ? Also, if I convolve two signals both in the range [-1.0,1.0] is it normal for the result to be outside that range ? Mine always are and I have to normalize them, which is fine. But maybe I'm doing something wrong and they shouldn't be out of range to begin with ? Thank you, Robert A.
Convolution via FFT
Started by ●January 25, 2007
Reply by ●January 25, 20072007-01-25
"Robert A." <invalid@invalid.org> writes:> Also, if I convolve two signals both in the range [-1.0,1.0] is it > normal for the result to be outside that range ?It is possible depending on what the signals are. Let f1(t) and f2(t) be your two signals. Then f1(t) may in general undergo a maximum magnitude change of \int_{-\infty}^{\infty} |f2(t)| dt. The worst-case "gain" occurs when f1(t) = sgn(f2(t)), where sgn(x) is the sign of x - in other words, when f1(t) has maximum magnitude and sign of f2(t). -- % Randy Yates % "Though you ride on the wheels of tomorrow, %% Fuquay-Varina, NC % you still wander the fields of your %%% 919-577-9882 % sorrow." %%%% <yates@ieee.org> % '21st Century Man', *Time*, ELO http://home.earthlink.net/~yatescr