19 Mar
2013
19 Mar
'13
1:31 a.m.
On March 18, 2013 11:58:48 PM Fons Adriaensen wrote:
On Mon, Mar 18, 2013 at 07:43:32PM -0400, Tim E. Real
wrote:
Cool. Got it. And the response to James. Thanks very much.
It is here at the mixing stage that I want to limit control motions.
All our controller graphs are sample-accurate and it's possible to
deliberately draw sudden changes, also it's possible to suddenly
change a GUI slider or knob's position.
Tim.
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,