[chbot] Software filter. Fast attack, slow decay

[Andrew Errington]

Something as simple as this?

if new > cur
  cur = new
else
  cur = (cur + new) / 2

It works in my head, but I may have overlooked something...

Andrew


On Sun, 19 Jun 2022, 16:35 Robin Gilks, <gb7ipd at gmail.com> wrote:

> Here's another question for you all!!
>
> I'm trying to implement "something like" a VU Meter in software (in an
> embedded system so it has to be small & fast).
> The hardware equivalent to a diode running into an RC filter
>
>           |\ |             R
>    in ----|  |----------vvvvvv--------- out
>           |/ |                    |
>                                  ___
>                                  ___  C
>                                   |
>                                   |
>  common ----------------------------------------
>
> My first port of call for filters is an IIR but that does not have the
> fast attack I'm after, especially if I want the long tail.
>
> Does anyone have any magic that doesn't disappear into a morass of DFTs
> and FFTs and 3 page equations summing integrals from 0 to infinity ;)
>
> Cheers - hopefully see you tomorrow.
>
> --
> Robin Gilks
>
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