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 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281  % $Id$ % \screenshot{configure_rockbox/images/ss-sound-settings}{}{} The Sound Settings menu offers a selection of sound properties you may change to customize your listening experience. \section{Volume} This control 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 distortion (clipping). Because the volume control is basically a comparison of the volume level you set to a reference maximum volume of 0 dB, the usable range of the volume setting is shown as a negative number. 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,x5}{\fixme{TODO - platform specific description.}} \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,x5}{\fixme{TODO - platform specific 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 channels function controls how much of the left channel signal is mixed into the right channel signal, and vice versa. \opt{MASCODEC}{This option controls the on{}-board mixing facilities of the \dap.} \opt{SWCODEC}{This option controls the mixing facilities of the \dap.} Available options are: % \begin{table} \begin{center} \begin{tabularx}{\textwidth}{lX}\toprule \textbf{Setting} & \textbf{Description} \\\midrule Mono Left & Plays the left channel in both stereo channels. \\ % Mono Right & Plays the right channel in both stereo channels. \\ % Mono & Mix both channels down to mono and send the mixed signal back to both. \\ % Stereo & Do not mix the signal. \\ % Stereo Narrow & Mixes small amounts of the opposite channel into the left and right channels, thus making the sound seem closer together. \\ % Stereo Wide & Elements of one channel that are present in the opposite channel are removed from the latter. This results in the sound seeming further apart. \\ % Karaoke & Removes all sound that is the same in both channels. Since most vocals are recorded in this way to make the artist sound central, this often (but not always) has the effect of removing the voice track from a song. \\ \bottomrule \end{tabularx} \end{center} \end{table} \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 \emph{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 \emph{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 stereo speakers. When you listen to music through speakers, your right ear hears sound from the left speaker and vice versa. However, the sound from the left speaker reaches your left ear slightly later than the sound from your right ear, and vice versa. Moreover, when listening to speakers, you hear the direct sound from the speakers, but you also hear reflections of that sound as the sound waves bounce off of walls, floors, ceilings, etc. These reflections reach your ears slightly after the direct sound. The human ear and brain 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, your ear hears only the direct sounds, and not reflections. Moreover, your 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. 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 \emph{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 \emph{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. } `