[LAD] relative_dynamics.lv2

Fons Adriaensen fons at linuxaudio.org
Sat Nov 19 11:28:56 CET 2022

On Thu, Nov 17, 2022 at 12:49:25PM +0100, Florian Paul Schmidt wrote:

> this is another "weird" plugin which I finally found the time to
> implement. It's a dynamics processor that doesn't care about absolute
> thresholds. It just computes two envelopes, env1 and env2, filtered with
> exponential smoothing filters with different time constants t1 and t2
> (usually t1 < t2). Their ratio r is computed and the audio signal is
> then multiplied by 1/r.

I wrote something similar a few months ago. It doesn't change the gain,
but replaces short (a few ms) high level fragments by a recent lower
level one, crossfading between them with some look-ahead.

The purpose was to remove the high level impulsive noise (caused by
little pebbles being moved in the nearby surf) from the audio of an
underwater webcam:


BTW, this is one of the places I go to for scuba diving in the summer. 
The 'landscape' is entirely artifical, created by the local diving
center by moving big and small rocks from another site about 1 km
away. This is the place they use for the 'discover scuba diving' program,
a 60-90 minutes excursion for people who don't yet have a scuba
certification (depth is less than 10 m). It has become very popular
with the local fish population (including lots of moray eels) who will
show up in big numbers as soon as they notice the divers.




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