[FFmpeg-user] Using 'ebur128' results to set 'loudnorm=measured_thresh'

Paul B Mahol onemda at gmail.com
Tue May 21 10:15:34 EEST 2024


On Tue, May 21, 2024 at 6:13 AM Mark Filipak <markfilipak.imdb at gmail.com>
wrote:

> I've attached ebur128.jpg. It's only 37 k-bytes.
>
> Do you see that first 'shelf' just below LU = -13? I want to boost that
> the most by percent, maybe
> double the power (3 dB). I want to boost LU = 9 not at all, and I want to
> boost everything below LU
> = -14 not at all.
>
> So the transform I want would be like this:
> LU = -18..-14 gets no boost.
> LU = -14..9 gets linear boost to -7..9.
> I assume 'LU' is Loudness Unit', eh? Heaven knows what the scale is and
> whether the scale is linear
> -- I'm used to dB, not LU. Of course, LU can't be dB because LU goes above
> zero.
>
> Now, the range of 'loudnorm=measured_thresh' is -99..0, so 100 steps.
> Heaven knows what the scale is
> and whether the scale is linear. No matter: Pressing on...
>
> If LU = -18..9 maps linearly to 'measured_thresh' = -99..0, then Lu = -14
> is 'measured_thresh' = -85.
>
> I'll try that and come back to this thread to report the results. Wish me
> luck.
>
> Disclosure: The audio and the video in ebur128.mp4 (upon which ebur128.jpg
> is based) are not
> perfectly synchronized and the more I listen to the audio while looking at
> the slope of the graph
> roll out, the less confident I become because the graph is not going up
> and down with the audio. The
> truth is, I don't know what the hell 'ebur128' is telling me!
>
>
>From long life experience I came to conclusion to just ignore kind of
people like you.



> --Mark._______________________________________________
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