Yes, correct. If the peaks reach the same level or are higher than theOn Sam, 2018-02-03 at 02:47 +0000, Dario Sanfilippo wrote:
> Thanks, Roman.
>
> On 2 February 2018 at 21:28, Roman Haefeli <reduzent@gmail.com>
> wrote:
> > On Fre, 2018-02-02 at 18:31 +0000, Dario Sanfilippo wrote:
> > > There's an implementation of a peak holder in this blog
> > post: http://
> > > dariosanfilippo.tumblr.com/post/162523174771/lookahead- limiting-
> > in-
> > > pure-data. I remember testing it but please let me know if you
> > find a
> > > bug.
> >
> > Very nice write up. Thanks for sharing.
> >
> > > The current peak is replaced to whatever the input is after a
> > desired
> > > time, and the counter is reset whenever a new peak is found. It
> > > should be easy to change it so that the peak is reset
> > periodically.
> >
> > It's not exactly equivalent with what I've asked, since your
> > implementation only takes new peaks into account after the hold
> > period
> > has ended.
> Perhaps my wording in the previous email was confusing: what happens
> is that every new peak will update the output immediately, and
> whenever that happens the countdown starts so that, should no other
> peak be detected after that time, the output will be set to whatever
> the input is in that moment.
>
> > Assume an input signal consisting of a series of 1-sample
> > impulses with a period that is slightly lower than the hold period.
> > The
> > output signal has a gap before each second impulse. For the use
> > case in
> > your article (which is also the use case I'm interested in), that
> > doesn't matter much, because the peak holder signal is fed to a
> > peak
> > enveloper which somewhat masks those gaps.
> In that case, we should expect a full-amp DC out of the peak holder
> for the impulses are faster than the hold time, and that's what we
> actually get:
ones before, then the hold period is prolonged. But when they have less
amplitude than the ones before, gaps appear. See:
https://netpd.org/~roman/tmp/peakholder_gaps.png
With a true max(x[0-(-N)], a downward stairway would appear and there
wouldn't be any gaps.
As I said, that is only small difference and for the purpose of a look-
ahead limiter it probably doesn't matter that much.
Roman
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