From b66fe786bccb0af34af1f31690e09400df4d8fb1 Mon Sep 17 00:00:00 2001
From: Michael Giacomelli <giac2000@hotmail.com>
Date: Fri, 20 Jun 2014 20:17:39 +0200
Subject: Explain the EQ settings in the manual more carefully.  Also, fix a
 leftover from when we still had 5 EQ bands.

Change-Id: I6a53abd1e08ca591dda52dce1ff81b7c29baacc8
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+% $Id$ %
+\screenshot{configure_rockbox/images/ss-sound-settings}{The sound settings screen}{}
+
+The sound settings menu offers a selection of sound settings you may 
+change to customise your listening experience.
+
+\section{\label{ref:volume}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.
+  \nopt{iriverh100,iriverh300,ondavx777}{%
+      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{iriverh100,iriverh300}{minimum of -84~dB to a maximum of 0~dB.}%
+  \opt{iaudiom3,iaudiom5,iaudiox5,ipod3g,ipod4g,gigabeatf,mrobe100,mpiohd200}{%
+      minimum of -73~dB to a maximum of +6~dB.}%
+  \opt{ipodnano}{minimum of -72~dB to a maximum of +6~dB.}%
+  \opt{ipodvideo,cowond2}{minimum of -89~dB to a maximum of +6~dB.}%
+  \opt{ipodnano2g,ipodcolor,ipod1g2g,iriverh10,iriverh10_5gb,sansa,sansaAMS}{minimum of 
+      -74~dB to a maximum of +6~dB.}%
+  \opt{gigabeats}{minimum of -90~dB to a maximum of +6~dB.}%
+  \opt{gigabeatf,vibe500}{minimum of -74~dB to a maximum of +6~dB.}%
+  \opt{fuzeplus}{minimum of -100~dB to a maximum of +6~dB.}
+  \opt{ipodvideo}{\\Remark: Lowering the volume below -57~dB will also affect the line-out 
+  and the recording gain.}
+  \opt{cowond2}{\\Remark: Lowering the volume below -57~dB will also affect the line-out.}
+
+\nopt{gigabeats}{  
+\section{Bass}
+  This setting emphasises
+  \nopt{iriverh100,iriverh300}{or suppresses}
+  the lower (bass) frequencies in the sound. A value of 0~dB means that bass
+  sounds are unaltered (flat response).
+  \opt{masd}{The minimum setting is -15~dB and the maximum is 15~dB.}%
+  \opt{masf}{The minimum setting is -12~dB and the maximum is 12~dB.}%
+  \opt{iriverh100,iriverh300}{The minimum setting is 0~dB and the maximum is 24~dB.}%
+  \opt{ipodnano,ipodnano2g,ipodcolor,mpiohd200}{%
+      The minimum setting is -6~dB and the maximum is 9~dB.}%
+  \opt{ipodvideo}{The minimum setting is -12~dB and the maximum is 12~dB.}%
+  \opt{iaudiom3,iaudiom5,iaudiox5,sansa,sansaAMS,iriverh10,iriverh10_5gb,vibe500,fuzeplus}{%
+      The minimum setting is -24~dB and the maximum is 24~dB.}
+
+\section{\label{ref:volume_limit}Volume Limit}
+  This setting adjusts the maximum volume of your music. The setting is by
+  default set to the maximum volume which equals to no limit. To set a volume
+  limit, select a volume from the list and the maximum volume will be limited to
+  the selected value all over the system.
+
+\opt{ipodvideo}{
+\section{Bass Cutoff}
+  This setting controls the frequency below which the bass adjustment applies.
+  The setting has a range from 1 to 4, where a bigger number affects a bigger
+  range of bass frequencies. The actual cutoff frequency used for each setting
+  value will vary with sample rate.
+}
+
+\section{Treble}
+  This setting emphasises
+  \nopt{iriverh100,iriverh300}{or suppresses}
+  the higher (treble) frequencies in the sound. A value of 0~dB means that
+  treble sounds are unaltered (flat response).
+  \opt{masd}{The minimum setting is -15~dB and the maximum is 15~dB.}%
+  \opt{masf}{The minimum setting is -12~dB and the maximum is 12~dB.}%
+  \opt{iriverh100,iriverh300}{The minimum setting is 0~dB and the maximum is 6~dB.}%
+  \opt{ipodnano,ipodnano2g,ipodcolor,mpiohd200}{%
+      The minimum setting is -6~dB and the maximum is 9~dB.}%
+  \opt{ipodvideo}{The minimum setting is -12~dB and the maximum is 12~dB.}%
+  \opt{iaudiom3,iaudiom5,iaudiox5,sansa,sansaAMS,iriverh10,iriverh10_5gb,vibe500,fuzeplus}{%
+      The minimum setting is -24~dB and the maximum is 24~dB.}
+
+\opt{ipodvideo}{
+\section{Treble Cutoff}
+  This setting controls the frequency above which the treble adjustment applies.
+  The setting has a range from 1 to 4, where a bigger number affects a smaller
+  range of treble frequencies. The actual cutoff frequency used for each setting
+  value will vary with sample rate.
+}
+}
+
+\opt{gigabeats}{
+\section{Tone Controls}
+  There is a five-band equalizer built into your \dap{} that allows you to
+  control various different parameters for each band.  This equalizer is
+  implemented in hardware, and therefore does not tax the processor when in use.
+  Rockbox also features a more advanced five-band equalizer (see
+  \reference{ref:EQ}) that is implemented in software and allows more fine
+  grained control, but also requires more processor time. 
+
+  \begin{description}
+  \item[Band 1 Gain.]
+        This band acts as a low shelf filter that boosts or lowers all
+        frequencies below a certain frequency limit, much as a ``bass''
+        control found on ordinary stereo systems does. The ``gain'' parameter
+        controls how much the loudness of the band is adjusted. Positive
+        numbers make the EQ band louder, while negative numbers make that EQ
+        band quieter.
+  \item[Bands 2-4 Gain.]
+        These bands act as peaking filters that boost or lower a frequency
+        range centered at a certain frequency. Graphic equalizers in home
+        stereos are usually peaking filters. The ``gain'' parameter controls
+        how much each band is adjusted as with the the low shelf filter.
+  \item[Band 5 Gain.]
+        Band 5 acts as a high shelf filter, boosting or lowering all
+        frequencies above a certain frequency limit, much like a ``treble''
+        control found on ordinary stereo systems does. As with the other bands,
+        ``gain'' controls how much each band is adjusted.
+  \item[Advanced Tone Control Settings.]
+        This submenu allows you to change advanced parameters for each band.
+  \end{description}
+  
+  As a general guide, EQ band 1 should be used for low frequencies, EQ bands 2
+  to 4 should be used for mids, and EQ band 5 should be used for highs.\\*
+
+  \subsection{Advanced Tone Control Settings}
+    As in the previous menu, the ``gain'' setting controls how much the
+    loudness of the band is adjusted.  In addition the following parameters
+    can be adjusted:  
+
+  \begin{description}
+    \item[Band 1 Frequency.]
+        The ``frequency'' parameter sets where the shelving starts to take
+        effect. For example, a cutoff frequency of 80~Hz will adjust only very
+        low frequencies. A cutoff frequency of 175~Hz, on the other hand, will
+        adjust a much wider range of bass frequencies.
+  \item[Bands 2-4 Frequency.]
+        The ``frequency'' parameter for these bands sets the centre frequency of
+        the range that is affected by the gain set.
+  \item[Bands 2-4 Width.]
+        This parameter sets the width of the range around the centre frequency
+        that is affected by the tone control. The possible settings are
+        ``wide'' or ``narrow''.
+  \item[Band 5 Frequency.]
+        This works just as for band 1 frequency, except that it affects the
+        high frequency end of the spectrum instead of the low.
+  \end{description}
+
+}
+
+\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 determines if these channels are to be combined in
+  any way, and if so, in what manner they will be combined.
+  Available options are:
+  %
+  \begin{description}
+      \item[Stereo.]
+          Leave the audio signal unmodified.
+      \item[Mono.]
+          Combine both channels and send the resulting signal to both stereo
+          channels, resulting in a monophonic output.
+      \item[Custom.]
+          Allows you to manually specify a stereo width with the
+          \setting{Stereo Width} setting described later in this chapter.
+      \item[Mono Left.]
+          Plays the left channel in both stereo channels.
+      \item[Mono Right.]
+          Plays the right channel in both stereo channels.
+      \item[Karaoke.]
+          Removes all sound that is common to 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.
+  \end{description}
+
+\section{Stereo Width}
+  Stereo width allows you to manually specify the effect that is applied
+  when the \setting{Channels} setting is set to ``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{masf}{
+  \section{Loudness}
+  When listening at low volumes, the ear will tend to make bass and treble
+  frequencies sound quieter than they really are. To compensate for this, 
+  \setting{Loudness} is an effect which emphasises bass and treble in a fashion
+  suited to the human ear. Frequencies in the vocal range are unaffected, since
+  the human ear picks these up very easily at any sound level.
+  It is of course also possible to use this effect at higher volumes for 
+  enhanced bass and treble.
+}
+  
+\opt{masf}{
+\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. This setting allows this time interval to be configured. Short
+  values like 20~ms 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 fewer sharp changes in volume level.
+}
+
+\opt{masf}{
+\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 sound.  This setting only has an
+  effect if \setting{Loudness} is set to a value larger than 0~dB.
+}
+
+\opt{masf}{
+\section{MDB {}-- Micronas Dynamic Bass}
+  The rest of the parameters in this menu relate to the Micronas Dynamic
+  Bass (MDB) function. MDB 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 into believing it is hearing tones that the 
+  headphones or speakers are not capable of reproducing.
+
+  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 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, 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{rbtabular}{0.5\textwidth}{Xc}{Setting & Value}{}{}
+          MDB Strength & 50~dB \\
+          MDB Harmonics & 48\% \\
+          MDB Centre Frequency & 60~Hz \\
+          MDB Shape & 90~Hz \\
+       \end{rbtabular}
+    \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 time
+  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{\label{ref:EQ}Equalizer}
+  \screenshot{configure_rockbox/images/ss-equalizer}{The graphical equalizer}{}
+  Rockbox features a parametric equalizer (EQ). As the name suggests, a
+  parametric EQ lets you control several different parameters for each
+  band of the EQ. \nopt{gigabeats}{In some ways the EQ is similar to the
+  \setting{Bass} and \setting{Treble} settings described earlier, but the EQ
+  allows you to control the sound much more carefully.  Note that the parameteric
+  EQ bands will be applied in addition to any bass or treble tone controls. 
+  } \opt{gigabeats}{The EQ  is similar to the \setting{Tone Controls} described 
+  above, but allows more   delicate control.}\\
+  
+  \note{A maximum of 10 EQ bands are possible on most devices, but using more
+        than are required will waste battery and introduce additional rounding
+        noise.  For best results, use the fewest number of bands required.}
+
+  Rockbox's parametric EQ is composed of five different bands:
+  \begin{description}
+  \item[Band 0: Low shelf filter.]
+        The low shelf filter boosts or lowers all frequencies below a certain
+        frequency limit, much as the ``bass'' control found on ordinary
+        stereo systems does.
+        Adjust the ``cutoff'' frequency parameter to decide 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.
+        The ``gain'' parameter controls how much the loudness of the band is
+        adjusted. Positive numbers make the EQ band louder, while negative
+        numbers make that EQ band quieter.
+        The ``Q'' parameter should always be set to 0.7 for the shelving
+        filters. Higher values will add a small boost around the cutoff
+        frequency that is almost always undesirable.
+  \item[Bands 1-8: Peaking filters.]
+        Peaking EQ filters boost or lower a frequency range centered at the
+        centre frequency chosen.
+        Graphic equalizers in home stereos are usually peaking
+        filters. The peaking filters in Rockbox's EQ lets you adjust three
+        different parameters for EQ bands 1 through 8. The ``centre'' parameter
+        controls the centre frequency of the frequency range that is affected
+        as described above.
+        The ``gain'' parameter controls how much each band is adjusted, and
+        works as for the low shelf filter.
+        Finally, the ``Q'' parameter controls how wide or narrow the affected
+        frequency range is. Higher Q values will affect a narrower band of
+        frequencies, while lower Q values will affect a wider band of
+        frequencies.
+  \item[Band 9: High shelf filter.]
+        A high shelf filter boosts or lowers all frequencies above a certain
+        frequency limit, much as the ``treble'' control found on ordinary
+        stereo systems does.
+        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}
+  As a general guide, EQ band 0 should be used for low frequencies, EQ bands 1
+  through 8 should be used for mids, and EQ band 9 should be used for highs.
+
+\begin {description}
+  \item[Enable EQ.]
+  This option controls whether the EQ is on or off.
+
+  \item[Graphical EQ.]
+  This option brings up a graphic EQ screen, which allows adjustment of each of
+  the three parameters described above (gain, centre frequency, and Q) for each
+  of the five EQ bands.
+  
+    \begin{btnmap}
+      \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,IAUDIO_X5_PAD,GIGABEAT_PAD%
+          ,GIGABEAT_S_PAD,SANSA_C200_PAD,IAUDIO_M3_PAD,MROBE100_PAD%
+          ,SANSA_CLIP_PAD,SANSA_FUZEPLUS_PAD}{\ButtonRight}
+      \opt{SANSA_E200_PAD,SANSA_FUZE_PAD,IPOD_4G_PAD,IPOD_3G_PAD}{\ButtonScrollFwd}
+      \opt{IRIVER_H10_PAD}{\ButtonScrollUp}
+      \opt{PBELL_VIBE500_PAD}{\ButtonUp}
+      \opt{MPIO_HD200_PAD}{\ButtonVolUp}
+      \opt{MPIO_HD300_PAD}{\ButtonScrollUp}
+      \opt{touchscreen}{\TouchMidRight}
+          &
+      \opt{HAVEREMOTEKEYMAP}{
+          \opt{GIGABEAT_RC_PAD}{\ButtonRCFF}
+          \opt{IAUDIO_RC_PAD}{\ButtonRCRight}
+          &}
+      Raises the highlighted parameter.
+          \\
+      %
+      \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,IAUDIO_X5_PAD,GIGABEAT_PAD%
+          ,GIGABEAT_S_PAD,SANSA_C200_PAD,IAUDIO_M3_PAD,MROBE100_PAD%
+          ,SANSA_CLIP_PAD,SANSA_FUZEPLUS_PAD}{\ButtonLeft}
+      \opt{SANSA_E200_PAD,SANSA_FUZE_PAD,IPOD_4G_PAD,IPOD_3G_PAD}{\ButtonScrollBack}
+      \opt{IRIVER_H10_PAD}{\ButtonScrollDown}
+      \opt{PBELL_VIBE500_PAD}{\ButtonDown}
+      \opt{MPIO_HD200_PAD}{\ButtonVolDown}
+      \opt{MPIO_HD300_PAD}{\ButtonScrollDown}
+      \opt{touchscreen}{\TouchMidLeft}
+          &
+      \opt{HAVEREMOTEKEYMAP}{
+          \opt{GIGABEAT_RC_PAD}{\ButtonRCRew}
+          \opt{IAUDIO_RC_PAD}{\ButtonRCLeft}
+          &}
+      Lowers the highlighted parameter.
+          \\
+      %
+      \opt{IPOD_4G_PAD,IPOD_3G_PAD,PBELL_VIBE500_PAD}{\ButtonLeft}
+      \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,IAUDIO_X5_PAD,SANSA_E200_PAD,SANSA_C200_PAD%
+          ,SANSA_FUZE_PAD,GIGABEAT_PAD,GIGABEAT_S_PAD,IAUDIO_M3_PAD,MROBE100_PAD%
+          ,SANSA_CLIP_PAD,SANSA_FUZEPLUS_PAD}{\ButtonUp}
+      \opt{IRIVER_H10_PAD,MPIO_HD200_PAD,MPIO_HD300_PAD}{\ButtonRew}
+      \opt{touchscreen}{\ActionStdPrev}
+          &
+      \opt{HAVEREMOTEKEYMAP}{
+          \opt{IRIVER_RC_H100_PAD}{\ButtonRCRew}
+          \opt{GIGABEAT_RC_PAD}{\ButtonRCVolUp}
+          \opt{IAUDIO_RC_PAD}{\ButtonRCUp}
+          &}
+      Moves to the previous EQ band.
+          \\
+      %
+      \opt{IPOD_4G_PAD,IPOD_3G_PAD,PBELL_VIBE500_PAD}{\ButtonRight}
+      \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,IAUDIO_X5_PAD,SANSA_E200_PAD,SANSA_C200_PAD%
+          ,SANSA_FUZE_PAD,GIGABEAT_PAD,GIGABEAT_S_PAD,IAUDIO_M3_PAD,MROBE100_PAD%
+          ,SANSA_CLIP_PAD,SANSA_FUZEPLUS_PAD}{\ButtonDown}
+      \opt{IRIVER_H10_PAD,MPIO_HD200_PAD,MPIO_HD300_PAD}{\ButtonFF}
+      \opt{touchscreen}{\ActionStdNext}
+          &
+      \opt{HAVEREMOTEKEYMAP}{
+          \opt{IRIVER_RC_H100_PAD}{\ButtonRCFF}
+          \opt{GIGABEAT_RC_PAD}{\ButtonRCVolDown}
+          \opt{IAUDIO_RC_PAD}{\ButtonRCDown}
+          &}
+      Moves to the next EQ band.
+          \\
+      %
+      \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,GIGABEAT_PAD,GIGABEAT_S_PAD,IAUDIO_X5_PAD%
+          ,SANSA_C200_PAD,IPOD_4G_PAD,IPOD_3G_PAD,IPOD_VIDEO_PAD,SANSA_E200_PAD%
+          ,SANSA_FUZE_PAD,MROBE100_PAD,SANSA_CLIP_PAD,SANSA_FUZEPLUS_PAD}{\ButtonSelect}
+      \opt{MPIO_HD200_PAD}{\ButtonFunc}
+      \opt{MPIO_HD300_PAD}{\ButtonEnter}
+      \opt{PBELL_VIBE500_PAD}{\ButtonOK}
+      \opt{IRIVER_H10_PAD}{\ButtonRight}
+      \opt{IAUDIO_M3_PAD}{\ButtonPlay}
+      \opt{touchscreen}{\TouchCenter
+          \opt{COWON_D2_PAD}{/ \ButtonMenu}}
+          &
+      \opt{HAVEREMOTEKEYMAP}{     
+          \opt{IRIVER_RC_H100_PAD}{\ButtonRCSelect}
+          \opt{GIGABEAT_RC_PAD,IAUDIO_RC_PAD}{\ButtonRCPlay}
+          &}
+      Toggles the cursor among the three parameters (gain, centre frequency,
+      Q) for the selected EQ band
+          \\
+      %
+      \opt{IRIVER_H100_PAD,IRIVER_H300_PAD}{\ButtonMode}
+      \opt{IPOD_4G_PAD,IPOD_3G_PAD,MPIO_HD300_PAD}{\ButtonMenu}
+      \opt{IAUDIO_X5_PAD}{\ButtonPower/\ButtonRec}
+      \opt{IAUDIO_M3_PAD,MPIO_HD200_PAD}{\ButtonRec}
+      \opt{SANSA_E200_PAD,SANSA_FUZE_PAD,IRIVER_H10_PAD}{\ButtonLeft}
+      \opt{GIGABEAT_PAD,GIGABEAT_S_PAD,SANSA_C200_PAD,MROBE100_PAD,SANSA_CLIP_PAD}{\ButtonPower}
+      \opt{PBELL_VIBE500_PAD}{\ButtonCancel}
+      \opt{SANSA_FUZEPLUS_PAD}{\ButtonBack}
+      \opt{touchscreen}{\TouchTopLeft
+          \opt{COWON_D2_PAD}{/ \ButtonPower}}
+          &
+      \opt{HAVEREMOTEKEYMAP}{ 
+          \opt{IRIVER_RC_H100_PAD}{\ButtonRCStop}
+          \opt{GIGABEAT_RC_PAD}{\ButtonRCDsp}
+          \opt{IAUDIO_RC_PAD}{\ButtonRCRec}
+          &}
+      Exits the graphic EQ screen.
+          \\
+    \end{btnmap}
+
+  \item[Pre-cut.]
+  If too much positive gain is added through the graphical EQ, your music may 
+  distort.  The \setting{Precut} setting allows you to apply a global negative
+  gain to decoded audio, cancelling out positive gain from the EQ.  This will
+  prevent distortion when boosting certain frequency ranges, at the expense of 
+  making audio quieter.
+  
+  Alternatively, precut can be used with a flat EQ curve to implement a volume
+  cap.  For example, on a player that allows overdriving the headphone output
+  to +6dB, maximum volume can be capped to +0dB by applying 6dB of precut. Note
+  that precut is not applied if EQ is disabled.  
+
+\item[Simple EQ.]
+This option provides an easier alternative for those who are daunted by all of
+the parameters that can be adjusted using the graphical EQ. With the
+\setting{Simple EQ}, the only parameter that can be adjusted is the gain.
+
+\item[Advanced EQ.]
+This sub menu provides options for adjusting the same parameters as the
+\setting{Graphical EQ}. The only difference is that the parameters are
+adjusted through textual menus rather than through a graphic interface.
+
+\item[Save EQ Preset.]
+This option saves the current EQ configuration in a \fname{.cfg} file.
+
+\item[Browse EQ Presets.]
+This menu displays a list of EQ presets, as well as any EQ configurations saved
+using the \setting{Save EQ Preset} option. Users unfamiliar with the
+operation of a parametric EQ may wish to use the presets instead of trying to
+configure the EQ, or use the presets for designing their own custom EQ
+settings.
+
+\end{description}
+}
+
+\opt{swcodec}{
+\section{Dithering}
+This setting controls the dithering and noise shaping functionality of Rockbox.
+
+Most of Rockbox' audio file decoders work at a higher bit depth than the 16 bits
+used for output on the \daps{} audio connectors. The simplest way to
+convert from one bit depth to another is simply discarding all the surplus bits.
+This is the default behaviour, and adds distortion to the signal that will
+vary in character along with the desired sound.
+
+Dithering adds low-level noise to the signal prior to throwing away the surplus
+bits, which gives the resulting signal a uniform noise floor which is
+independent of the signal. Most people find this noise preferable to the
+time-varying noise heard when not performing dithering.
+
+After dithering, noise shaping is performed. This basically just pushes the
+dithering noise to the parts of the frequency spectrum humans cannot hear so
+easily. In Rockbox' case, some of the noise is pushed up to above 10~kHz.
+
+This setting will be put to its best use when listening to dynamic music with
+frequently occuring quiet parts, classical music being a typical example. It is
+worth noting that the effects of dithering and noise shaping are very subtle,
+and not easily noticable.
+
+Rockbox uses highpass triangular distribution noise as the dithering noise
+source, and a third order noise shaper.
+}
+
+\opt{swcodec}{%
+\opt{pitchscreen}{%
+\section{Timestretch}
+Enabling \setting{Timestretch} allows you to change the playback speed without
+it affecting the pitch of the recording. After enabling this feature and
+rebooting, you can access this via the \setting{Pitch Screen}. This function is
+intended for speech playback and may significantly dilute your listening
+experience with more complex audio. See \reference{sec:pitchscreen} for more
+details about how to use the feature.
+}
+}
+
+\opt{swcodec}{
+\section{Compressor}
+The \setting{Compressor} reduces, or compresses, the dynamic range of the audio
+signal.  This makes the quieter and louder sections closer to the same volume
+level by progressively reducing the gain of louder signals.  When subsequently
+amplified, this has the effect of making the quieter sections louder while
+keeping the louder sections from clipping.  This allows listening to the quiet
+sections of dynamic material in noisy environments while preventing sudden loud
+sections from being overbearing.
+
+There are several settings associated with the compressor.  The first, and most
+important, is the \setting{Threshold}.  The threshold is the audio input level
+at which the compressor begins to act.  Any level louder than the threshold
+will be compressed to some extent.  The maximum amount of compression, or the
+quietest level at which the compressor will operate, is -24~dB.  The default of
+Off disables the compressor.
+
+The \setting{Makeup Gain} setting has two options: Off and Auto.  Off means
+that the compressed audio will not be amplified after compression.  The default
+of Auto will amplify the signal so that the loudest possible signal after
+compression will be just under the clipping limit.  This is desirable because
+the compressed signal without makeup gain is quieter than the input signal.
+Makeup Gain in Auto restores the signal to the maximum possible level and
+brings the quieter audio up with it.  This is what makes it possible to hear
+the quieter audio in noisy environments.
+
+The \setting{Ratio} setting determines how aggressively the compressor reduces
+gain above the threshold.  For example, the 2:1 setting means that for each
+two decibels of input signal above the threshold, the compressor will only
+allow the output to appear as one decibel.  The higher the ratio, the harder
+the signal is compressed.  The ratio setting of Limit means essentially a ratio
+of infinity to one.  In this case, the output signal is not allowed to exceed
+the threshold at all.
+
+The \setting{Knee} setting determines how abrupt the transition is from a
+non-compressed signal to a compressed signal.  Hard Knee means that the
+transition occurs precisely at the threshold.  The Soft Knee setting smoothes
+the transition from plus or minus three decibels around the threshold.
+
+The \setting{Attack Time} setting sets the delay in milliseconds between the
+input signal exceeding the activation threshold and acting upon it.
+
+The \setting{Release Time} setting sets the recovery time after the signal is
+compressed.  Once the compressor determines that compression is necessary,
+the input signal is reduced appropriately, but the gain isn't allowed to
+immediately return to normal levels.  This is necessary to reduce artifacts
+such as ``pumping.''  Instead, the gain is allowed to return to normal at the
+chosen rate.  Release Time is the time for the gain to recover by 10~dB.
+}
-- 
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