Re: [LAD] Mixing audio: Noiseless volume changes

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To: <linux-audio-dev@...>
Date: Monday, March 18, 2013 - 11:58 pm

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:

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

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)

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Messages in current thread:
[LAD] Mixing audio: Noiseless volume changes, Tim E. Real, (Mon Mar 18, 9:50 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Fons Adriaensen, (Mon Mar 18, 11:05 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Paul Davis, (Mon Mar 18, 10:47 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Tim E. Real, (Mon Mar 18, 11:05 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Tim E. Real, (Mon Mar 18, 11:43 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Fons Adriaensen, (Mon Mar 18, 11:58 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Tim E. Real, (Tue Mar 19, 12:31 am)
Re: [LAD] Mixing audio: Noiseless volume changes, James Morris, (Mon Mar 18, 11:28 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Fons Adriaensen, (Mon Mar 18, 11:45 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Harry van Haaren, (Tue Mar 19, 2:09 am)
Re: [LAD] Mixing audio: Noiseless volume changes, Tim Goetze, (Tue Mar 19, 3:17 am)
Re: [LAD] Mixing audio: Noiseless volume changes, Fons Adriaensen, (Tue Mar 19, 1:02 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Tim Goetze, (Tue Mar 19, 1:53 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Fons Adriaensen, (Tue Mar 19, 3:08 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Tim Goetze, (Tue Mar 19, 3:37 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Fons Adriaensen, (Tue Mar 19, 4:31 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Tim Goetze, (Tue Mar 19, 7:06 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Charles Z Henry, (Tue Mar 19, 10:26 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Fons Adriaensen, (Tue Mar 19, 10:57 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Charles Z Henry, (Tue Mar 19, 11:12 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Fons Adriaensen, (Tue Mar 19, 11:30 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Fons Adriaensen, (Tue Mar 19, 10:26 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Harry van Haaren, (Tue Mar 19, 1:31 pm)
Re: [LAD] Mixing audio: Noiseless volume changes, Harry van Haaren, (Tue Mar 19, 4:30 am)
Re: [LAD] Mixing audio: Noiseless volume changes, Tim Goetze, (Tue Mar 19, 3:22 am)