[Dev] [OT] dB

Jussi Laako jussi.laako at linux.intel.com
Tue Oct 22 09:40:03 GMT 2013


On 22.10.2013 12:25, Łukasz Stelmach wrote:
> log(10) = 2.30258509299 (?)
> log(exp(1)) = 1

log10(10) == 1, decibels always use 10-base logarithm. Of course you can 
also use natural logarithm, but then:
log10(x) == ln(x)/ln(10)

By the way, I recommend using excellent open source software like Octave 
or Scilab. :)

> Indeed it is -29.473, that is even less than I though.  Why dBFS? There
> is no absolute Full-Scale in this case. Full-Scale might be the number
> of of packages available for the distribution rather than installed on
> your machine.

Full scale is just 100%, IOW factor of 1. Of course you can have also 
positive dBFS for values exceeding 100%. Decibels should never be used 
without reference point, because it is always a relative value.



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