Hello everyone.
This question is not important for the measurements, but it bothers me.
If you generate reference sinuses with software, we can see
that in 32 bits, we do not have the same noise floor depending on the generators.
Some reach ~ -155 dbFS and others can be below -192dBFS.
For 16 and 24 bits the problem does not arise, all reach respectively
~< -96dbFS and ~< -144dbFS.
As a reminder, the 32-bit noise floor must be ~< 192.6dbFS.
I use here 4 generators to show this difference, and I give
the versions of the 4, having had differences between an old "octave" version
and the one I use.
audacity : V 2.4.2
rew : 5.40 Beta 50
octave : 6.4.0
sox : v14.4.2
I work under Linux (Linux Mint 21.1 Vera, kernel 5.15.0-60-generic)
I scanned the possibilities of the generators if they existed I even
generated with audacity a sine in 64bits to validate the problem.
Octave has a BUG, if you ask it to generate 24 bits, it
generates 32 bits noise ~< -195dbFS, if you ask it to generate 32 bits
it generates 32 bits noise ~< -154 dbFS, don't ask me why.
Here are the measurements.
Files analyse using "ffmpeg"
We see that 2 generators can be close to -192 dbBFS, octave and sox,
octave can generate 32 bits with -154dBFS of noise as well as audacity and rew.
Counter example ::
I generated a noise of -170dBFS with rew and octave, I can't do it
with audacity and sox.
Rew should have a noise measurement at -154dBFS for octave
at -170 dBFS.
This is not the case, both generate noise at -170dBFS and measure -170dBFS in all 32-bit configurations.
So there is a problem with the "sine function", the -154dBFS stop is
present on 3 generators, so they must have the same type of sine function.
The question ::
Where is the problem really ????
-------------------------------------------------
If you tried the manipulation, do not use rew to measure, rew has a
low measurement stop, which does not prevent it from doing a great job.
The noise stop you will measure will be around -151dBFS for all
signals (wav files).
This question is not important for the measurements, but it bothers me.
If you generate reference sinuses with software, we can see
that in 32 bits, we do not have the same noise floor depending on the generators.
Some reach ~ -155 dbFS and others can be below -192dBFS.
For 16 and 24 bits the problem does not arise, all reach respectively
~< -96dbFS and ~< -144dbFS.
As a reminder, the 32-bit noise floor must be ~< 192.6dbFS.
I use here 4 generators to show this difference, and I give
the versions of the 4, having had differences between an old "octave" version
and the one I use.
audacity : V 2.4.2
rew : 5.40 Beta 50
octave : 6.4.0
sox : v14.4.2
I work under Linux (Linux Mint 21.1 Vera, kernel 5.15.0-60-generic)
I scanned the possibilities of the generators if they existed I even
generated with audacity a sine in 64bits to validate the problem.
Octave has a BUG, if you ask it to generate 24 bits, it
generates 32 bits noise ~< -195dbFS, if you ask it to generate 32 bits
it generates 32 bits noise ~< -154 dbFS, don't ask me why.
Here are the measurements.
Files analyse using "ffmpeg"
We see that 2 generators can be close to -192 dbBFS, octave and sox,
octave can generate 32 bits with -154dBFS of noise as well as audacity and rew.
Counter example ::
I generated a noise of -170dBFS with rew and octave, I can't do it
with audacity and sox.
Rew should have a noise measurement at -154dBFS for octave
at -170 dBFS.
This is not the case, both generate noise at -170dBFS and measure -170dBFS in all 32-bit configurations.
So there is a problem with the "sine function", the -154dBFS stop is
present on 3 generators, so they must have the same type of sine function.
The question ::
Where is the problem really ????
-------------------------------------------------
If you tried the manipulation, do not use rew to measure, rew has a
low measurement stop, which does not prevent it from doing a great job.
The noise stop you will measure will be around -151dBFS for all
signals (wav files).