[flac-dev] Supporting 32 bit data

Richard Ash richard at audacityteam.org
Sat Sep 26 12:56:50 PDT 2015

On Sat, 26 Sep 2015 17:22:40 +1000
Erik de Castro Lopo <mle+la at mega-nerd.com> wrote:
> * Would adding this break brackwards compatibility too badly?
> Obviously decoding of 32 bit encoded data would not work with older
> versions of flac.
> * This is nuts. 24 bits has a dynamic range of ~140dB which is roughly
>   the difference between a quiet whisper in a quiet room, to the sound
>   of a jet engine at 10 meters. Surely that is enough?

On the narrow question of legitimate requirements for very high
resolution data, Audacity uses 32-bit float so that it's essentially
impossible to either clip or loose into noise any intermediate signal,
no matter how strong or weak.

As every intermediate goes to disk (for undo, save and so on), we use
uncompressed .AU 32-bit float format files at the moment. It would be
nice to be able to reduce the size of projects (for archive and
sharing) by lossless compressing them, but at the moment we don't have
many sensible options.

Now this probably doesn't need full floating point support, something
that normalised short blocks and stored the normalisation
coefficients to restore them at decode would be adequate.


More information about the flac-dev mailing list