On Mon, Mar 18, 2013 at 07:43:32PM -0400, Tim E. Real wrote: > Ah, I may have answered my own question when I said: > "(One cannot simply wait for the current data value to be 'zero' because > for example with a perfect square wave signal the 'current' value will never > approach zero, hence the zero-crossing detection requirement.)"
The analog waveform always 'approaches' zero - it's bandlimited and hence continuous - it just may not happen at a sample point. In fact the chance that it happens exactly at a sample point is zero. > So having no choice but to apply the volume at this cross point the popping > noise might still be heard. I guess that's what Fons meant by 'reduced'... > and what Paul meant by... bogus. Right? Imagine a signal slowly passing through zero, e.g. a low frequency sine wave. If you switch gain at an arbitatry point there will be a 'step', having a 1/F spectrum (just like a square wave). If you switch at a zero crossing there will be 'sharp corner', and this has a 1/(F^2) spectrum (like a triangular wave). So instead of a sharp click there will be something more like a 'thump'. The only real solution is to never switch the gain, but change it smoothly. Caio, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
