[LAD] Floating point processing and high dynamic range audio

[fons at kokkinizita.net]

On Wed, Jul 21, 2010 at 01:26:40PM -0400, Paul Davis wrote:

> floating point -1.0 == minimum value of an integer sample == -inf dBFS
> floating point 1.0  == maximum value of an integer sample == 0dBFS

??? At least the first of these makes no sense at all,
and the second applies if the dB value indicates a digital
peak level. More accurately: 0dB digital peak corresponds
to a sample value of + or - 1.

For RMS or average, 0dB usually means the level of a sine
wave with amplitude 1, i.e. having a peak value of +/- 1.
It can be confusing as the RMS or average levels of such
are signal are not unity.
 
> > If I muliply float by 2.0, do I get twice the sound pressure or twice the
> > sound intensity, or something else?

> you get samples that are twice as loud. this doesn't have a linear
> relationship with sound pressure or intensity or perceived volume
> other than "its louder"

An audio signal represents pressure variation as a function of
time. Multiplying it by two will give 2 times the pressure,
and 4 times the power. The subjective result is another matter.

Ciao,

-- 
FA

There are three of them, and Alleline.