Rockbox.org home
release
dev builds
extras
themes manual
wiki
device status forums
mailing lists
IRC bugs
patches
dev guide



Rockbox mail archive

Subject: Re: berzerk peak meter? Alpha testers wanted.
From: Jack Peel (jhp_at_cypress.com)
Date: 2002-09-23


Well in the normal mode the peak meters don't seem to
catch nearly as many peaks. Especially on songs that
have big transients (like a snare drum).

The meters look to be running a little slow, I think I would
crank up the meters a little bit as they seem to be lagging
the program noticeably, and also seem to be a little jerky.

It's also kinda hard to tell since it is still linear and I'm so
used to looking at log meters, it's hard to tell.

It seemed that the patch you sent out earlier was a little
smoother (although I think it lagged a little bit).

An interesting thing happened when I we back to the
version that I was using before. The new hash marks
stayed, and half of the peak meter menu stayed, and
now it runs really blocky. This is really weird, the only
thing I can think of is the information that rockbox
writes to the disk to act as non volatile memory. I even
went back to the archos firmware and back to my
rockbox (built from my cvs with your old patch) and
it is still has your new hash marks AND two of the
settings in the peak meter menu ( that used to be only
the hold time for the peaks) The one that is still sticking
around is the overflow release. Strange !

Can you tell me how to get this back ? is there a magic file
somewhere or will removing the batteries solve it ?

Also I think the hash marks would look better reversed. I
think the meters look better when they are separated a little bit.
With this new hash marks it starts to look like 1 big bar. Maybe
if you added a space between the hash marks and the actual
meter it would look better (by making the bar itself 1 pixel thinner)

Jack

Philipp Pertermann wrote:

> 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?
>
> Phil



Page was last modified "Jan 10 2012" The Rockbox Crew
aaa