| % $Id$ % |
| \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. |
| } |