Re: VU meters on LCD
- From: "Bill Davy" <Bill@xxxxxxxxxxxxxxx>
- Date: Thu, 26 Jan 2006 09:47:20 +0000 (UTC)
"Richard Sloan" <rsloan2003@xxxxxxxxxxx> wrote in message
news:sJPBf.20343$ve.346276@xxxxxxxxxxxxxxxxxxxxxxxx
>I am having difficulty displaying nice VU meter on a character display,
>right now I have allowed for 8 segments per channel, which I may make into
>40 as you get 5 dots across per character.
>
> Now the issue is the bars and very jumpy, either showing a couple or all
> of them....
>
> I sample the audio every 1/10s and display the bars, I can sample more,
> but refreshing the display at a high rate is hard due to the fact I need
> to keep streaming MP3 data and can not miss any.
>
> I also know audio is more logrithmic than what I am doing...
>
> The difference from the softest to loudest on the ADC right now is 80
> counts.
>
> I would think I could make a nicer looking VU meter that "follows" the
> music better.
>
> Any thoughts?
I thought VU meters used some sort of fast attack system (ie rise time <
fall time). So
Take sample (could be average of a few readings)
if sample > displayed value
Displayed Value = Sample
else
Displayed Value = ( (Denominator-n)* Dsiplayed Value + n * Sample )
/Denominator
NB Denominator and n are to make for easier arithmetic. Perhaps Denominator
= 256 and n= 4, but values will need to be tuned for your sampling rate to
achieve a visually attractive decay time.
And then you need some way of making Displayed Value logarithmic. With so
few bars, perhaps a table holding the display threshold for each bar.
But that is just guess work. Still, it may pass as a thought.
Bill
>
> Thanks,
> Richard.
>
.
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