[vorbis-dev] vorbis.com

Monty xiphmont at xiph.org
Sun Dec 31 12:37:12 PST 2000

On Sat, Dec 30, 2000 at 02:47:52PM -0800, OmegaDan wrote:
> Question about dynamic range ...
> Is the 1bit = 6db rule hard and fast ?  

In linear PCM, yes.  A factor of two is roughly 6dB, and one bit
doubles the [linear] dynamic range.

> I've been shopping around for 24/96
> cards to use in my project studio, and the best cards seem to be only able
> to achieve a dynamic range of 116db (and most are more like 100 - 110) ...
> shouldn't it be 24bits * 6 db = 144db ?

Yes.  Your ears are going to be damaged by trying to take in greater
than roughly 120 dB range at once anyway.

24 bits is useful mostly for mixing headroom (eg, adding two 16 bit
96dB[theoretical] signals gets you a 17 bit 102dB[theoretical]
output).  Generally, any losses in mixing are done in the last stage
of mix-down so it's good to have 'working space'.  24 bits also
simplifies noise management in synthesis and D->A by giving more
effective room for error.

Vorbis, BTW, can handle, for sake of programming simplicity, >200dB
range.  Just for kicks.


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