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Subject: RE: berzerk peak meter? Alpha testers wanted.
From: Benoit Lubek (BLubek_at_icominfo.fr)
Date: 2002-09-23


I think it's a good idea to include both code, with the setting in the menu
to choose the implementation the user wants (with default to "normal" mode).
But of course don't forget to include the tradeoffs for both solutions in
the documentation :)

BoD

> -----Message d'origine-----
> De : Philipp Pertermann [mailto:philipp.pertermann_at_web.de]
> Envoyé : dimanche 22 septembre 2002 17:29
> À : rockbox_at_cool.haxx.se
> Objet : berzerk peak meter? Alpha testers wanted.
>
>
> I still am fiddling with the volume meter. Now I've come to
> a point where I have to make a decision concerning the
> tradeoff
> system load <-> precision.
>
> The problem:
> The MAS chip provides a 'quasi peak detector' that we can
> read values from. It doesn't work very well. If a peak
> happens in the music somewhen between two read outs we miss
> it. Thus the more often we read values the higher ist the
> probability that we actually hit a peak.
> But:
> Reading out the MAS often is not a good idea in two
> respects:
> 1.) it increases the power consumption
> 2.) it increases the system load. If the system load becomes
> too
> high stops / skips might occur.
>
> The solutions:
> I've implemented two strategies for reading out the MAS
> peak.
>
> normal mode | berzerk mode
> reads once per redraw | 1 - 20 reads per redraw
> --------------------------+-----------------------------
> - lower precision | + higher precision
> - clips undetectable | + clips detectable
> + lower power consumption | - higher power consumption
> + lower system load | - higher system load
>
>
> In both modes the 'frame rate' is the same so you don't see
> much difference unless you watch out for peaks.
>
> I put an unofficial version on
> www.x-phobie.de/ajbrec.ajz
> In the menu General settings ->Display->Peak meter you can
> switch berzerk mode on / off.
>
> Now I want to know what you think: Do we need that berzerk
> mode or is the normal mode enough? Do you encounter any
> problems playing back mp3 in berzerk mode?
>



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