Re: [LAD] Floating point Denormals: C++ and Waf

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To: Harry van Haaren <harryhaaren@...>
Cc: Linux Audio Developers <linux-audio-dev@...>
Date: Friday, August 3, 2012 - 12:08 am

[Harry van Haaren]

>Thanks all for the replies, I've certainly learnt a lot.

Some useful numeric suggestions have already been made, and the why
amounts to this:=20

http://en.wikipedia.org/wiki/Single-precision_floating-point_format :

"""The minimum positive normal value [of a 32-bit float] is 2=E2=88=92126 =
=E2=89=88
1.18 =C3=97 10=E2=88=9238"""

1.0f corresponding to 0dB makes 1.18e-38 equivalent to around -758dB.

Roughly speaking, 16 bit samples cover around 90 dB (1./(1<<15)), 24
bits give you 138 dB (1./(1<<23)). =20

For all intents and purposes involving current digital audio hardware
and human beings at their current point of hearing evolution, anything
past that is surely perfectly inaudible, so a sensible approach is to
choose any amplitude between this and the above mentioned smallest
normal float for your injected "normalising" signal, keeping in mind
subsequent amplification factors in your signal path, and that
amplitudes can decrease quickly in IIR filters, especially when you
stack them (one feeding the next).=20

Tim

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Messages in current thread:
[LAD] Floating point Denormals: C++ and Waf, Harry van Haaren, (Thu Aug 2, 12:07 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, David Robillard, (Thu Aug 2, 2:46 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, Paul Davis, (Thu Aug 2, 3:28 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, David Robillard, (Thu Aug 2, 4:02 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, Paul Davis, (Thu Aug 2, 4:41 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, J. Liles, (Thu Aug 2, 6:24 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, Martin Homuth-Rosemann, (Thu Aug 2, 12:39 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, Charles Henry, (Thu Aug 2, 3:14 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, Martin Homuth-Rosemann, (Thu Aug 2, 6:31 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, David Robillard, (Thu Aug 2, 6:52 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, Martin Homuth-Rosemann, (Fri Aug 3, 7:40 am)
Re: [LAD] Floating point Denormals: C++ and Waf, Tim Goetze, (Thu Aug 2, 8:15 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, Harry van Haaren, (Thu Aug 2, 8:56 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, Tim Goetze, (Fri Aug 3, 12:08 am)
Re: [LAD] Floating point Denormals: C++ and Waf, Fons Adriaensen, (Thu Aug 2, 9:18 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, Robin Gareus, (Thu Aug 2, 9:17 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, Harry van Haaren, (Fri Aug 3, 2:50 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, Jens M Andreasen, (Sat Aug 4, 8:51 am)
Re: [LAD] Floating point Denormals: C++ and Waf, Charles Henry, (Thu Aug 2, 3:17 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, Robin Gareus, (Thu Aug 2, 12:20 pm)
Re: [LAD] Floating point Denormals: C++ and Waf, James Warden, (Thu Aug 2, 12:33 pm)