Re: [SoX-users] bit depth

[Eric W. <nor...@yh...>]

R Kimber <ric...@bt...> wrote:
> If I use sox to convert a 16 bit 44100 file to a 24 bit file, test.flac

<snip>

> But if I do sox test.flac -n stats I get (inter alia):-
> Bit-depth      16/16
> Num samples    21.6M
> 
> Why is this?

I'm no expert in this, either; but I'll try to explain as well as I can.

24-bit audio has more dynamic range than 16-bit audio (144dB vs 96dB,
you get 6dB per-bit) and thus a lower noise floor.

However, when you convert a 16-bit file to 24-bit, you do not lower the
noise floor automatically.  All the background noise in the 16-bit file
stays there since it was in the original file.  You don't lose anything,
going from 16 to 24, but you don't gain anything, either.  The extra 8
bits is just background noise (inaudible at normal listening levels).

Keep in mind even the best audio equipment cannot record or playback the
entire 24-bit range of 144dB.  The best studio ADC and DAC equipment is
probably around 120dB nowadays (plenty enough).

SoX and nearly all audio software converts to 32-bit (or even 64-bit)
internally.  This gives plenty of headroom for effects and eases
calculation for CPUs.  So if you run some effects which alter the audio,
you'll end up with a file that takes advantage of what 24-bit offers.