[LAU] Record levels lower in Alsa than Jack

Fons Adriaensen fons at linuxaudio.org
Wed Nov 11 10:00:34 CET 2020

On Tue, Nov 10, 2020 at 05:16:29PM -1000, david wrote:

>  On 11/10/20 12:10 PM, Fons Adriaensen wrote:
> > If you want a constant loudness then normalisation as discussed in this
> > thread (i.e. on peak level) is _not_ the way to go. You should normalize
> > on RMS level or a dedicated loudness metric such as EBU-R128.
> Hmm. That's something I prefer, too. How do you do that?

To measure loudness of a sound file, use ebur128, e.g.

ebur128 sheryl_crow-all_i_wanna_do.wav

which will print:

Integrated loudness:      7.4 LU
Loudness range:           2.8 LU
Peak level                0.3 dB

A few lines of bash can parse this and call e.g. sox with the 
right arguments. 

In this case, to have standard loudness you'd reduce the level by
7.4 dB. Note that this file also has inter-sample peaks above
full scale.


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