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# Rockbox mail archive

Subject: RE: Optimum Audio Levels

# RE: Optimum Audio Levels

From: Stuart Tedford <stuart.tedford_at_piresearch.co.uk>
Date: Wed, 2 Jun 2004 11:24:14 +0100

Do volume levels depend on the gain (or normalisation) of your mp3s too? I
use mp3Gain http://mp3gain.sourceforge.net/ to normailise my entire
collection to 89dB. So my levels are:
90% : In the Car (plugged into cassete adaptor of car stereo)
75-95% : headphones - depending on background noise levels.
85-90% : connected to home stereo equipment.

Stu.

-----Original Message-----
From: BlueChip [mailto:cs_bluechip_at_webtribe.net]
Sent: 02 June 2004 09:15
To: rockbox development
Subject: Optimum Audio Levels

Hey all,

I need to do a little survey to optimise the new Audio Interface...

One question :)

============================================
What is the VOLUME range you use most often?
============================================

...If you use, say, one volume in the car, and another in bed at night.
Feel free to give two answers.

Personally I use:
85-95% in walkman mode
65-75% in bed
92% in the car

...unless you want all the techies-only stuff.

The volume scale inside the unit is measured in dB on the scale
{MUTE, -114, -113, ..., -2, 1, 0, +1, +2, ..., +11, +12}
Where 0dB is designed to produce "Line Level"

These values are numbered {0x00, ..., 0x7F} respectively
Such that {0=Mute, 1=-115dB, ..., 0x73=0dB, ..., 0x7F=+12dB}

The Rockbox volume scale is a linear transpose of the MAS scale.
That is: Actual_Volume = Rockbox_Volume*0x7F/100

...which interestingly enough means there is no Rockbox setting for
line level and you do not have fine control where required.

I have a non-linear scaling algorithm which allows greater control
in the most used volume ranges at the cost of less control in the
unused volume ranges.

At Rockbox=60%, you are down to 0x4C which is -39dB

I currently have FULL control over -18..+12dB but I think others,
particularly the audiophiles, may require accurate control at lower levels.

B
l
u
BlueChip
C
h
i
p

PS. Good news: I just found the MAS registers to turn your Jukebox into
a mixer and/or karaoke machine - so your jukebox can remove the old vocals
and add your in place, live and with a simple mixer :)

There's even an option for "3.0" sound if anyone is interested in even more
volume - lol

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