| % $Id$ % |
| \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 customise 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, x5, h10, |
| h10_5gb, sansa}{ |
| 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{x5}{minimum of -73 dB to a maximum of +6 dB.}% |
| \opt{ipodcolor,h10,h10_5gb,sansa}{minimum of -74 dB to a maximum of +6 db.} |
| |
| \section{Bass} |
| \opt{player,recorder,recorderv2fm,ondio}{This emphasises or suppresses the |
| lower (bass) frequencies 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}{This emphasises or suppresses the |
| lower frequency (bass) sounds in the track. 0dB means that bass in unaltered |
| (flat response). The minimum setting is -6dB and the maximum is 9dB.} |
| \opt{ipodvideo}{This emphasises or suppresses the |
| lower frequency (bass) sounds in the track. 0dB means that bass in unaltered |
| (flat response). The minimum setting is -12dB and the maximum is 12dB.} |
| \opt{x5,sansa,h10,h10_5gb}{This emphasises or suppresses the |
| lower frequency (bass) sounds in the track. 0dB means that bass in unaltered |
| (flat response). The minimum setting is -24dB and the maximum is 24dB.} |
| |
| \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} |
| \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}{This setting emphasises or suppresses |
| the higher frequency (treble) sounds in the track. 0dB means that treble is |
| unaltered (flat response). The minimum setting -6dB and the maximum is 9dB.} |
| \opt{ipodvideo}{This setting emphasises or suppresses |
| the higher frequency (treble) sounds in the track. 0dB means that treble is |
| unaltered (flat response). The minimum setting -12dB and the maximum is 12dB.} |
| \opt{x5,sansa,h10,h10_5gb}{This setting emphasises or suppresses |
| the higher frequency (treble) sounds in the track. 0dB means that treble is |
| unaltered (flat response). The minimum setting -24dB and the maximum is 24dB.} |
| |
| \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. |
| } |
| |
| \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 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. \\ |
| \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 ``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} |
| 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{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. This setting allows this time interval to be configured. 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 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. 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 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{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 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. 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. |
| |
| 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 like what a ``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 1-3: Peaking filters] |
| Peaking EQ filters boost or lower a frequency range centered at the |
| center 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 3. The ``center'' parameter |
| controls the center 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 4: High shelf filter] |
| A high shelf filter boosts or lowers all frequencies above a certain |
| frequency limit, much like what a ``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 lows, EQ bands 1 |
| through 3 should be used for mids, and EQ band 4 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, center frequency, and Q) for each |
| of the five EQ bands. |
| |
| \begin{table} |
| \begin{btnmap}{}{} |
| \opt{IPOD_4G_PAD,IPOD_3G_PAD,IPOD_VIDEO_PAD}{\ButtonScrollFwd} |
| \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,IAUDIO_X5_PAD}{\ButtonUp} |
| \opt{SANSA_E200_PAD}{\ButtonScrollBack} |
| & Raises the highlighted parameter.\\ |
| % |
| \opt{IPOD_4G_PAD,IPOD_3G_PAD,IPOD_VIDEO_PAD}{\ButtonScrollBack} |
| \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,IAUDIO_X5_PAD}{\ButtonDown} |
| \opt{SANSA_E200_PAD}{\ButtonScrollFwd} |
| & Lowers the highlighted parameter.\\ |
| % |
| \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,IAUDIO_X5_PAD}{\ButtonLeft} |
| \opt{IPOD_4G_PAD,IPOD_3G_PAD,IPOD_VIDEO_PAD}{\ButtonLeft} |
| \opt{SANSA_E200_PAD}{\ButtonUp} |
| & Moves to the previous EQ band. \\ |
| % |
| \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,IAUDIO_X5_PAD}{\ButtonRight} |
| \opt{IPOD_4G_PAD,IPOD_3G_PAD,IPOD_VIDEO_PAD}{\ButtonRight} |
| \opt{SANSA_E200_PAD}{\ButtonDown} |
| & Moves to the next EQ band. \\ |
| % |
| \opt{IRIVER_H100_PAD,IRIVER_H300_PAD}{\ButtonSelect} |
| \opt{IAUDIO_X5_PAD,IPOD_4G_PAD,IPOD_3G_PAD,IPOD_VIDEO_PAD,SANSA_E200_PAD}{\ButtonSelect} |
| & Toggles the cursor among the three parameters (gain, center frequency, |
| Q) for the selected EQ band.\\ |
| % |
| \opt{IRIVER_H100_PAD,IRIVER_H300_PAD}{\ButtonMode} |
| \opt{IPOD_4G_PAD,IPOD_3G_PAD,IPOD_VIDEO_PAD}{\ButtonMenu} |
| \opt{IAUDIO_X5_PAD}{\ButtonPower/\ButtonRec} |
| \opt{SANSA_E200_PAD}{\ButtonPower/\ButtonRight} |
| & Exits the graphic EQ screen.\\ |
| \end{btnmap} |
| \end{table} |
| |
| \item[Pre-cut:] |
| If too much gain is added through the graphical EQ, your music may distort. |
| The \setting{Precut} setting allows you to adjust the overall gain of the EQ. |
| |
| If your music distorts when using the EQ, trying changing this setting to a |
| negative value. |
| |
| \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. |
| } |