From: <edgarrft@we...>  20090628 08:07:18

> Edgar wrote in a former mail: > You can "invert" a sound (make the negative samples become positive > and vice versa) by using Nyquist "scale" or "mult" with a factor > of "1". > Thank you but this doesn't work. See my response to Roger. Sorry, I was cleaning up my mailbox and hadn't realized that Roger already had answered before. > All my original audio signals s have absolute amplitudes > less than 1 so the energy waveform of s is always negative. I assume you're talking about "normalized float" samples (like used in Nyquist and Audacity) with maxPeak=1.0, minPeak=1.0, what leads to absolute peak values between min=0.0 and max=1.0, so lg(absPeak) is always negative. One of the first things I would try whould look like this: (scale 1 (slog (sabs sound))) > That's a part of the energy normalization they were referring to > and had me scratching my head way the formula gave only zero and > negative values. Who is "they"? Can you tell what document? Is it one of the CCRMA/JOSIII papers? I wasn't able to find out by reading the mails from last week. In Nyquist you often have to "compute around the corner", so maybe we need to rearrange the formula, but therefore I would need the complete context of the original paper. Other ideas: In Nyquist there is e.g. "sndavg", which can compute the RMSpower of blocks of samples.  edgar 