Re: [Audacity-nyquist] hp filter was Problem with this plug-in...

[Sami J. <sam...@gm...>]

On 28/11/05, David R. Sky <dav...@sh...> wrote:
> Hi Edgar,
>
> I just had an idea - what about an 'inverse' normalization process to
> remove the dc bias?, using s-min to find the lowest point of the audio,
> comparing this with the result of the s-max (or peak) function, and
> adjusting accordingly? That way we wouldn't need the hp filter?

Hi,

if you guys just understood something about the audio itself instead
of just witing DSP code... ;)

Firstly, we cannot "center" the audio by the use of min / max peaks.
What counts, is the "weight balance" of the signal. To find out that,
we need to calculate the average with n samples. However, we cannot do
that with a fixed number of samples, nor with the whole audio file -
because the average varies constantly.

We need to remove the DC component, and DC (or high-pass) filter is
just the tool for doing that. In real life, we let the audio go
through a capacitor with suitable resistance to ground to discharge
the capacitor.

--
Sami "Some-E" Jumppanen
sam...@gm...
http://netti.nic.fi/~some-e/