[LAU] dynamic range analysis tool

[Raffaele Morelli]

2014-08-05 16:49 GMT+02:00 Fons Adriaensen <fons at linuxaudio.org>:

> On Tue, Aug 05, 2014 at 04:23:23PM +0200, Raffaele Morelli wrote:
>
> > Ok, works but I have a couple of question.
> >
> > I see only 751 records in the outfile. How ebur128 works? Is the file
> > scanned entirely and how?
>
> Yes, the entire audio file is processed. Internally ebumeter and ebur128
> compute two histograms, each consisting of 751 bins from -70 to +5 dB in
> steps of 0.1 dB.
>
> The first histogram is the 'momentary' loudness, the average over
> a sliding window of 400 ms. The second is the 'short-term' loudness,
> computed using a sliding window of 3 seconds.
>
> The histograms are then used to compute average loudness and
> loudness range according to the EBU-R128 standard. Ebumeter
> will show them in real-time.
>
> For the details, see my LAC 2011 paper which you can find here:
> <http://kokkinizita.linuxaudio.org/papers/index.html>.
>
> The output file of ebur128 consists of five columns:
>
> 1. X-axis, level in dB
> 2. Cumulative probability of the momentary loudness, this is
>    the histogram integrated and normalised to 1. In other words
>    the probability that the level is less than the X-axis value.
> 3. Same for the short-term loudness.
> 4. The momentary loudness histogram, counts for each bin.
> 5. Same for the short-term loudnes.
>
> The gnuplot commands I posted will plot 1 vs 4 or 1 vs 5.
>
> Ciao,
>
> --
> F
> ​A
>


​Great tool, I finally leaved it untouched as cumulative probability it's
enough for the scope*.

My 0.02€: I would suggest to add a cli option for output filename, leaving
'ebur128-prob' as default if none is specified

ciao
/r

* In the beginning of CD era it was common (I guess) to have album released
as they were on CD, lately we see more an more re-master editions of the
same material (plus something else that never made the original recording).
My curiosity is to "investigate" on the dynamic range of both releases.
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