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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422  % $Id$ % \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}{ 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}{minimum of -\fixme{??} dB to a maximum of +\fixme{??} dB.} \opt{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) 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 emphasises 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,sansa}{\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 emphasises 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,sansa}{\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{\label{ref:EQ}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{table} \begin{center} \begin{tabularx}{\textwidth}{lX}\toprule \textbf{EQ Band(s)} & \textbf{Description} \\\midrule 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.. \\ % 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. \\ % Band 4: Hi 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.\\ \bottomrule \end{tabularx} \end{center} \end{table} 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. \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}{\ButtonScrollUp} & 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}{\ButtonScrollDown} & 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 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{ipodvideo}{ \section{Hardware EQ} This function controls the EQ that is built into the hardware of your \playerman{}. The hardware EQ functions similarly to the Graphical EQ in that it allows adjustment of several parameters. However, unlike the Graphical EQ, the Hardware EQ allows the user to choose from a limited number of settings for Center Frequency'' and Bandwidth'' (Bandwidth'' in the Hardware EQ is similar to Q'' in the Graphical EQ). \note{While the \setting{Hardware EQ} menu shows Low Shelf, three peaking filters, and High Shelf, the peaking filters are not currently operational.} } \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 in which 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. } `