From b66fe786bccb0af34af1f31690e09400df4d8fb1 Mon Sep 17 00:00:00 2001 From: Michael Giacomelli 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 --- .../manual/configure_rockbox/sound_settings.tex | 626 +++++++++++++++++++++ 1 file changed, 626 insertions(+) create mode 100644 e200man/manual/configure_rockbox/sound_settings.tex (limited to 'e200man/manual/configure_rockbox/sound_settings.tex') diff --git a/e200man/manual/configure_rockbox/sound_settings.tex b/e200man/manual/configure_rockbox/sound_settings.tex new file mode 100644 index 0000000000..6ec49a057d --- /dev/null +++ b/e200man/manual/configure_rockbox/sound_settings.tex @@ -0,0 +1,626 @@ +% $Id$ % +\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. +} -- cgit v1.2.3