[PD] headroom in Pd

Chris Clepper cgclepper at gmail.com
Wed Jan 1 19:50:07 CET 2014

Nope, the DAC can freely construct intersample peaks as it sees fit and
those can easily exceed 0 dBFS.  It has been common practice in the
industry for more than a decade to reconstruct clipped samples well above 0
dBFS - partially to make up for shitty mixing and mastering prevalent in
music, and also because it's the right way to do it.

16 bits full scale and 24 bits full scale are the same 0dBFS signal.  The
bits are added at the bottom not the top.

On Wed, Jan 1, 2014 at 1:34 PM, Martin Peach <martin.peach at sympatico.ca>wrote:

> On 2013-12-31 19:32, Chris Clepper wrote:
>> It's very, very easy to avoid any sort of clipping processing by using
>> hardware with drivers that don't have any!  Avid, Apogee, MOTU, RME, and
>> many others have bit transparent OSX CoreAudio drivers.
>> Also, any DAC worth it's using can reconstruct far beyond 0dBFS without
>> distortion, so hearing volume increase past -1..1 in software is not
>> surprising.  I recall the ADI 1955 and equivalent TI part putting out
>> +12dBFS or something ridiculous, but those ain't Wolfson low power
>> headphone codecs neither!
> A DAC can only go to 0dBFS by definition. If it appears to go beyond that
> then something is scaling the input to be less than full scale at "full
> scale".
> For instance a 24-bit DAC could be sent 16 16-bit full-scale streams and
> not clip. Only if 16-bits is considered "full scale" does that make it
> +12dBFS.
> Martin
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