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Subject: Re: [patch] volume peak meter in wps
From: Jack Peel (jhp_at_cypress.com)
Date: 2002-09-18


Hmm.. I'm not sure who would actually use linear meters,
as they don't tell you nearly as much as the dB meters.
Although some people might like the way it "looks"
(you know the guys with neon lights under their cars ;)
But I don't think it would hurt anything to have them
as an option :)

As far as the scale. I was also thinking about the fonts
being a problem. A solution I was thinking about would be
to put hash marks on the meters themselves (like between the
l/r meters, or on the edges. Then let the user put numbers
by them with the custom wps screen if they want them.
The hash marks just need to be documented so that we
know which meter is which.

Another thing to think about as far as the scaling of the
meters is that usually meters have more resolution as
you get closer to 0 dB. I'm not sure how to put this into
words, but I can certainly put it into pictures. The point
that I'm trying to make is that the scale is usually not
linear. It might just come out that way when you do
take the logarithm of the data, but I'm not sure.

So my thought is to make them look like

-40 -20 -10 -6 -3 -2 -1 0

This might require you to "shape" the data
coming into the display portion of the code.
If you have to do this it probably isn't worth it.
But it would make it look more "pro" :)

Also I notice that when I play my "clipping"
mp3 the peak hold bars disappear (I assume
they are just going off the end) It would be good
if you could turn them into clip icons and have them
hold longer.

For the recording end it might be nice to have
an option for the peak hold bars to hold until cleared
kind of thing so that we can see what the peek
value is of the recording. You could probably
implement this now or later. It doesn't really matter
for playback.

Jack

Philipp Pertermann wrote:

> Jack wrote:
>
> > Now here is a question. What is the scale ? It almost
> looks like
> > a linear scale vs. a log (dB) scale. Do the meters go all
> the way to
> > the right edge of the screen ?
>
> Yes, it's linear. I've already gotten some links to learn
> how to do the dbfs math. I'm working on that. I have to make
> some conversion tables. It will be a user selectable option
> to switch from linear to dbfs.
>
> > Could you add a scale as an option in the WPS screen, like
> > if you put %pms on the line above it put marks with their
> dB values,
> > like -10 -6 -3 -1 and so on ?
>
> I consider that as problematic with loadable fonts. But what
> I could do is put in some inverted vertical lines at magic
> values. And a few new tags to read out the peak values as
> numerical values
>
> > Also could you put "clip" "lights" on it so that if the
> MP3 goes
> > to full scale it shows a different symbol and it hangs out
> longer
> > so that we know if the MP3 itself is clipping ?
>
> Yes, I could.
>
> > In conclusion Good Job!
>
> Thanx! Your input is highly appreciated.
>
> Phil



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