89e411b34c
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@10648 a1c6a512-1295-4272-9138-f99709370657
292 lines
15 KiB
TeX
Executable file
292 lines
15 KiB
TeX
Executable file
% $Id$ %
|
|
\screenshot{configure_rockbox/images/ss-sound-settings}{The sound settings screen}{}
|
|
|
|
The Sound Settings menu offers a selection of sound properties you may
|
|
change to customize your listening experience.
|
|
|
|
\section{Volume}
|
|
This setting adjusts the volume of your music. Like most professional
|
|
audio gear and many consumer audio products, Rockbox uses a decibel scale
|
|
where 0 dB is a reference that indicates the maximum volume that the \dap\
|
|
can produce without possible distortion (clipping). All values lower than this
|
|
reference will be negative and yield a progressively softer volume.
|
|
\opt{player, recorder, recorderv2fm, ondio, ipodnano, ipodvideo}{
|
|
Values higher than 0 dB are available and can be used to raise the
|
|
volume more than would otherwise be possible. These volume levels will
|
|
ordinarily lead to distorted sound, but might work nicely for music that has
|
|
an otherwise low volume level.}
|
|
The volume can be adjusted from a
|
|
\opt{player}{minimum of -78 dB to a maximum of +18 dB.}
|
|
\opt{recorder,recorderv2fm,ondio}{minimum of -100 dB to a maximum of +12 dB.}
|
|
\opt{h1xx,h300}{minimum of -84 dB to a maximum of 0 dB.}
|
|
\opt{ipodnano}{minimum of -72 dB to a maximum of +6 dB.}
|
|
\opt{ipodvideo}{minimum of -57 dB to a maximum of +6 dB.}
|
|
\opt{ipodcolor,x5}{minimum of -\fixme{??} dB to a maximum of +\fixme{??} dB.}
|
|
|
|
\section{Bass}
|
|
\opt{player,recorder,recorderv2fm,ondio}{This emphasises or suppresses the
|
|
lower (bass) sounds in the track. 0 means that bass sounds are unaltered
|
|
(flat response).}
|
|
\opt{h1xx,h300}{The bass setting can be used to increase (but not decrease)
|
|
frequencies below 300Hz. Bass boost can be set from 0 to 24 dB in
|
|
increments of 2 dB. A setting of 0 means that low frequencies are unaltered
|
|
(flat response).}
|
|
\opt{ipodnano,ipodcolor,ipodvideo}{This emphasizes or suppresses the
|
|
lower (bass) sounds in the track. 0dB means that bass in unaltered
|
|
(flat response). The minimum setting is -6dB and the maximum is 9dB.}
|
|
\opt{x5}{\fixme{add platform specific information here}}
|
|
|
|
\section{Treble}
|
|
\opt{player,recorder,recorderv2fm,ondio}{This emphasises or suppresses the
|
|
higher (treble) sounds in the track. 0 means that treble sounds are
|
|
unaltered (flat response).}
|
|
\opt{h1xx,h300}{The Treble setting can be used to increase (but not decrease)
|
|
frequencies above 1.5kHz. Treble boost can be set from 0 to 6 dB in
|
|
increments of 2 dB. A setting of 0 means that high frequencies are unaltered
|
|
(flat response).}
|
|
\opt{ipodnano,ipodcolor,ipodvideo}{This setting emphasizes or suppresses
|
|
the higher (treble) sounds in the track. 0dB means that treble is unaltered
|
|
(flat response). The minimum setting -6dB and the maximum is 9dB.}
|
|
\opt{x5}{\fixme{add platform specific information here}}
|
|
|
|
\section{Balance}
|
|
This setting controls the balance between the left and right channels. The
|
|
default, 0, means that the left and right outputs are equal in volume.
|
|
Negative numbers increase the volume of the left channel relative to the
|
|
right, positive numbers increase the volume of the right channel relative
|
|
to the left.
|
|
|
|
\section{Channels}
|
|
A stereo audio signal consists of two channels, left and right. The
|
|
\setting{Channels} setting controls if these channels are to be combined in
|
|
any way, and if so, in what manner they will be combined.
|
|
Available options are:
|
|
%
|
|
\begin{table}
|
|
\begin{center}
|
|
\begin{tabularx}{\textwidth}{lX}\toprule
|
|
\textbf{Setting} & \textbf{Description} \\\midrule
|
|
Stereo
|
|
& Leave the audio signal unmodified. \\
|
|
%
|
|
Mono
|
|
& Combine both channels and send the resulting signal to both stereo
|
|
channels, resulting in a monophonic output. \\
|
|
%
|
|
Custom
|
|
& Allows you to manually specify a stereo width with the
|
|
\setting{Stereo Width} setting described later in this chapter. \\
|
|
%
|
|
Mono Left
|
|
& Plays the left channel in both stereo channels. \\
|
|
%
|
|
Mono Right
|
|
& Plays the right channel in both stereo channels. \\
|
|
%
|
|
Karaoke
|
|
& Removes all sound that is the same in both channels. Since most
|
|
music is recorded with vocals being equally present in both channels
|
|
to make the singer sound centrally placed, this often (but not always)
|
|
has the effect of removing the voice track from a song. This setting
|
|
also very often has other undesirable effects on the sound. \\
|
|
\bottomrule
|
|
\end{tabularx}
|
|
\end{center}
|
|
\end{table}
|
|
|
|
\section{Stereo Width}
|
|
Stereo width allows you to manually specify the effect that is applied
|
|
when the \setting{Channels} setting is set to \setting{Custom}.
|
|
All values below 100\% will progressively mix the contents of one channel into
|
|
the other. This has the effect of gradually centering the stereo image, until
|
|
you have monophonic sound at 0\%. Values above 100\% will progressively remove
|
|
components in one channel that is also present in the other. This has the
|
|
effect of widening the stereo field. A value of 100\% will leave the stereo
|
|
field unaltered.
|
|
|
|
\opt{recorder,recorderv2fm}{
|
|
\section{Loudness}
|
|
Loudness is an effect which emphasises bass and treble. This makes the
|
|
track seem louder by amplifying the frequencies that the human ear finds
|
|
hard to hear. Frequencies in the vocal range are unaffected, since the human
|
|
ear picks these up very easily.
|
|
}
|
|
|
|
\opt{recorder,recorderv2fm}{
|
|
\section{Auto Volume}
|
|
Auto volume is a feature that automatically lowers the volume on loud parts,
|
|
and then slowly restores the volume to the previous level over a time
|
|
interval. That time interval is configurable here. Short values like 20ms
|
|
are useful for ensuring a constant volume for in car use and other
|
|
applications where background noise makes a constant loudness desirable.
|
|
A longer timeout means that the change in volume back to the previous level
|
|
will be smoother, so there will be less sharp changes in volume level.
|
|
}
|
|
|
|
\opt{recorder,recorderv2fm}{
|
|
\section{Super Bass}
|
|
This setting changes the threshold at which bass frequencies are affected by
|
|
the \setting{Loudness} setting, making the sound of drums and bass guitar
|
|
louder in comparison to the rest of the track. This setting only has an
|
|
effect if \setting{Loudness} is set to a value larger than 0dB.
|
|
}
|
|
|
|
\opt{recorder,recorderv2fm}{
|
|
\section{MDB {}- Micronas Dynamic Bass}
|
|
The rest of the parameters on this menu relate to the Micronas Dynamic
|
|
Bass (MDB) function. This is designed to enable the user to hear bass
|
|
notes that the headphones and/or speakers are not capable of reproducing.
|
|
Every tone has a fundamental frequency (the ``main tone'') and also several
|
|
harmonics, which are related to that tone. The human brain has a mechanism
|
|
whereby it can actually infer the presence of bass notes from the higher
|
|
harmonics that they would generate.
|
|
|
|
The practical upshot of this is that MDB produces a more authentic sounding
|
|
bass by tricking the brain in believing it's hearing tones that the
|
|
headphones or speakers aren't capable of reproducing. Try it and see
|
|
what you think.
|
|
|
|
The MDB parameters are as follows.
|
|
%
|
|
\begin{description}
|
|
\item[MDB enable:]
|
|
This turns the MDB feature on or off. For many users this will be the
|
|
only setting they need, since Rockbox picks sensible defaults for the
|
|
other parameters. MDB is turned off by default.
|
|
\item[MDB strength:]
|
|
How loud the harmonics generated by the MDB will be.
|
|
\item[MDB Harmonics:]
|
|
The percentage of the low notes that is converted into harmonics.
|
|
If low notes are causing speaker distortion, this can be set to 100\%
|
|
to eliminate the fundamental completely and only produce harmonics in the
|
|
signal. If set to 0\% this is the same as turning the MDB feature off.
|
|
\item[MDB Centre Frequency:]
|
|
The cutoff frequency of your headphones or speakers. This is usually
|
|
given in the specification for the headphones/speakers.
|
|
\item[MDB shape:]
|
|
It is recommended that this parameter be set to 1.5 times the centre frequency.
|
|
|
|
This is the frequency up to which harmonics are generated. Some of the
|
|
lower fundamentals near the cut{}-off range will have their lower
|
|
harmonics cut off, since they will be below the range of the speakers.
|
|
Fundamentals between the cut{}-off frequency and the lower frequency
|
|
will have their harmonics proportionally boosted to compensate and restore
|
|
the `loudness' of these notes.
|
|
|
|
For most users, the defaults should provide an improvement in sound
|
|
quality and can be safely left as they are. For reference, the defaults
|
|
Rockbox uses are:
|
|
%
|
|
\begin{table}[h!]
|
|
\begin{center}
|
|
\begin{tabular}{@{}lc@{}}\toprule
|
|
Setting & Value \\\midrule
|
|
MDB Strength & 50dB \\
|
|
MDB Harmonics & 48\% \\
|
|
MDB Centre Frequency & 60Hz \\
|
|
MDB Shape & 90Hz \\\bottomrule
|
|
\end{tabular}
|
|
\end{center}
|
|
\end{table}
|
|
|
|
\end{description}
|
|
}
|
|
|
|
\opt{SWCODEC}{
|
|
\section{Crossfeed}
|
|
Crossfeed attempts to make the experience of listening to music on
|
|
headphones more similar to listening to music with stereo speakers. When you
|
|
listen to music through speakers, each ear will hear sound originating from
|
|
both speakers. However, the sound from the left speaker reaches your right
|
|
ear slightly later than it does your left ear, and vice versa.
|
|
|
|
The human ear and brain together are very good at interpreting the timing
|
|
differences between direct sounds and reflected sounds and using that
|
|
information to identify the direction that the sound is coming from. On the
|
|
other hand, when listening to headphones, each ear hears only the stereo
|
|
channel corresponding to it. The left ear hears only the left channel and
|
|
the right ear hears only the right channel. The result is that sound from
|
|
headphones does not provide the same spatial cues to your ear and brain as
|
|
speakers, and might for that reason sound unnatural to some listeners.
|
|
|
|
The crossfeed function uses an algorithm to feed a delayed and filtered
|
|
portion of the signal from the right channel into the left channel and vice
|
|
versa in order to simulate the spatial cues that the ear and brain receive
|
|
when listening to a set of loudspeakers placed in front of the listener. The
|
|
result is a more natural stereo image that can be especially appreciated in
|
|
older rock and jazz records, where one instrument is often hard-panned to just
|
|
one of the speakers. Many people will find such records tiring to listen to
|
|
using earphones and no crossfeed effect.
|
|
|
|
Crossfeed has the following settings.
|
|
\begin{description}
|
|
\item[Crossfeed:]
|
|
Selects whether the crossfeed effect is to be enabled or not.
|
|
\item[Direct Gain:]
|
|
How much the level of the audio that travels the direct path from a speaker
|
|
to the corresponding ear is supposed to be decreased.
|
|
\item[Cross Gain:]
|
|
How much the level of the audio that travels the cross path from a speaker
|
|
to the opposite ear is to be decreased.
|
|
\item[High-Frequency Attenuation:]
|
|
How much the upper frequencies of the cross path audio will be dampened.
|
|
Note that the total level of the higher frequencies will be a combination
|
|
of both this setting and the \setting{Cross Gain} setting.
|
|
\item[High-Frequency Cutoff]
|
|
Decides at which frequency the cross path audio will start to be cut
|
|
by the amount described by the \setting{High-Frequency Attenuation} setting.
|
|
\end{description}
|
|
|
|
Most users will find the default settings to yield satisfactory results, but
|
|
for the more adventurous user the settings can be fine-tuned to provide a
|
|
virtual speaker placement suited to ones preference.
|
|
% TODO: adapt the guidelines for crossfeed settings found here?
|
|
% http://www.ohl.to/interests-in-audio/crossfeed-and-eq-for-headphones/
|
|
|
|
Beware that the crossfeed function is capable of making the audio distort
|
|
if you choose settings which result in a too high output level.
|
|
}
|
|
|
|
\opt{SWCODEC}{
|
|
\section{Equalizer}
|
|
\screenshot{configure_rockbox/images/ss-equalizer}{The graphical equalizer}{}
|
|
Rockbox features a parametric equalizer. As the name suggests, a parametric
|
|
equalizer lets you control several different parameters for each band of the
|
|
equalizer. Rockbox's parametric EQ is composed of five different EQ bands:
|
|
\begin{description}
|
|
\item[Band 0: Low shelf filter.] A low shelf filter boosts or lowers all
|
|
frequencies below the designated cutoff point. The ``bass''control on
|
|
most home or car stereos is an example of a low shelf filter. The low shelf
|
|
filter in Rockbox is more flexible than a simple ``bass'' control, because
|
|
a simple bass control only lets you adjust the amount of gain that is
|
|
applied. Rockbox lets you control the amount of gain that is applied
|
|
(i.e., the amount that the bass is boosted or cut) too, but Rockbox also
|
|
allows you to adjust the ``cutoff'' frequency where the shelving starts
|
|
to take effect. For example, a cutoff frequency of 50 Hz will adjust only
|
|
very low frequencies. A cutoff frequency of 200 Hz, on the other hand,
|
|
will adjust a much wider range of bass frequencies.
|
|
\item[Bands 1-3: Peaking filters.]
|
|
Peaking EQ filters boost or low a center frequency that you select, as
|
|
well as the frequencies within a certain distance of that center. Graphic
|
|
equalizers in home stereos are usually peaking filters. The peaking EQs
|
|
on Rockbox's parametric equalizer let you adjust three different
|
|
parameters for each EQ band 1 through 3. The ``center'' parameter
|
|
controls the center frequency that is adjusted by that EQ band. The
|
|
``gain'' parameter controls how much each band is adjusted. Positive
|
|
numbers make the EQ band louder, while negative numbers make that EQ band
|
|
quieter. Finally, the ``Q'' parameter controls how wide or narrow each EQ
|
|
band is. Higher Q values will affect a narrow band of frequencies, while
|
|
lower EQ values will affect a wider band of frequencies.
|
|
\item[Band 4: High shelf filter.]
|
|
A high shelf filter boosts or lowers all frequencies above a designated
|
|
cutoff point. The ``treble'' control on most home or car stereos is an
|
|
example of a high shelf filter. The high shelf filter is adjusted the
|
|
same way as the low shelf filter, except that it works on the high end
|
|
of the frequency spectrum rather than the low end.
|
|
\end{description}
|
|
|
|
So, as a general guide, EQ band 0 should be used for lows, EQ bands 1
|
|
through 3 should be used for mids, and EQ band 4 should be used for highs.
|
|
You can find more information about setting the parametric equalizer and
|
|
using equalizer presets in the Advanced Topics chapter of this manual.
|
|
}
|