[opus] Antw: [EXT] Audacity adds noise to silence! (Was: Why silence is encoded with so many bits?)

Ulrich Windl Ulrich.Windl at rz.uni-regensburg.de
Tue Apr 20 06:54:15 UTC 2021

>>> Jesus Cea <jcea at jcea.es> schrieb am 19.04.2021 um 20:54 in Nachricht
<8d87d942-bd32-3c7d-9d71-ed36e1310589 at jcea.es>:
> Studying the audacity generated WAV file, I noticed it is not actually 
> absolute silence!. It is a very faint noise. For instance, exporting a 
> 16 bits PCM audio WAV file and checking the file by hand I see values 
> +‑3 at random. The last three bits seems random. Maybe Audacity is 
> adding dithering when exporting to WAV. That "dithering" is done even 
> when exporting to 32 bit float wav.
> With this new realization, I looked up "audacity wav export dithering" 
> and I got this webpage: https://manual.audacityteam.org/man/dither.html 
> In that page they say that dithering is applied in all exports except 32 
> bits PCM audio... but "opusenc" notably doesn't supports that format:

IMHO adding dithering to absolute silence does not make any sense at all
(unless absoluite silence cannot be presented in the data format).



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