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1% $Id$ %
2\screenshot{configure_rockbox/images/ss-sound-settings}{The sound settings screen}{}
3
4The sound settings menu offers a selection of sound settings you may
5change to customise your listening experience.
6
7\section{\label{ref:volume}Volume}
8 This setting adjusts the volume of your music. Like most professional
9 audio gear and many consumer audio products, Rockbox uses a decibel scale
10 where 0~dB is a reference that indicates the maximum volume that the \dap{}
11 can produce without possible distortion (clipping). All values lower than
12 this reference will be negative and yield a progressively softer volume.
13 \nopt{iriverh100,iriverh300,ondavx777}{%
14 Values higher than 0~dB are available and can be used to raise the
15 volume more than would otherwise be possible. These volume levels will
16 ordinarily lead to distorted sound, but might work nicely for music that has
17 an otherwise low volume level.
18 }
19 The volume can be adjusted from a
20 \opt{player}{minimum of -78~dB to a maximum of +18~dB.}%
21 \opt{recorder,recorderv2fm,ondio}{minimum of -100~dB to a maximum of +12~dB.}%
22 \opt{iriverh100,iriverh300}{minimum of -84~dB to a maximum of 0~dB.}%
23 \opt{iaudiom3,iaudiom5,iaudiox5,ipod3g,ipod4g,gigabeatf,mrobe100,mpiohd200}{%
24 minimum of -73~dB to a maximum of +6~dB.}%
25 \opt{ipodnano}{minimum of -72~dB to a maximum of +6~dB.}%
26 \opt{ipodvideo,cowond2}{minimum of -89~dB to a maximum of +6~dB.}%
27 \opt{ipodnano2g,ipodcolor,ipod1g2g,iriverh10,iriverh10_5gb,sansa,sansaAMS}{minimum of
28 -74~dB to a maximum of +6~dB.}%
29 \opt{gigabeats}{minimum of -90~dB to a maximum of +6~dB.}%
30 \opt{gigabeatf,vibe500}{minimum of -74~dB to a maximum of +6~dB.}%
31 \opt{fuzeplus}{minimum of -100~dB to a maximum of +6~dB.}
32 \opt{ipodvideo}{\\Remark: Lowering the volume below -57~dB will also affect the line-out
33 and the recording gain.}
34 \opt{cowond2}{\\Remark: Lowering the volume below -57~dB will also affect the line-out.}
35
36\nopt{gigabeats}{
37\section{Bass}
38 This setting emphasises
39 \nopt{iriverh100,iriverh300}{or suppresses}
40 the lower (bass) frequencies in the sound. A value of 0~dB means that bass
41 sounds are unaltered (flat response).
42 \opt{masd}{The minimum setting is -15~dB and the maximum is 15~dB.}%
43 \opt{masf}{The minimum setting is -12~dB and the maximum is 12~dB.}%
44 \opt{iriverh100,iriverh300}{The minimum setting is 0~dB and the maximum is 24~dB.}%
45 \opt{ipodnano,ipodnano2g,ipodcolor,mpiohd200}{%
46 The minimum setting is -6~dB and the maximum is 9~dB.}%
47 \opt{ipodvideo}{The minimum setting is -12~dB and the maximum is 12~dB.}%
48 \opt{iaudiom3,iaudiom5,iaudiox5,sansa,sansaAMS,iriverh10,iriverh10_5gb,vibe500,fuzeplus}{%
49 The minimum setting is -24~dB and the maximum is 24~dB.}
50
51\section{\label{ref:volume_limit}Volume Limit}
52 This setting adjusts the maximum volume of your music. The setting is by
53 default set to the maximum volume which equals to no limit. To set a volume
54 limit, select a volume from the list and the maximum volume will be limited to
55 the selected value all over the system.
56
57\opt{ipodvideo}{
58\section{Bass Cutoff}
59 This setting controls the frequency below which the bass adjustment applies.
60 The setting has a range from 1 to 4, where a bigger number affects a bigger
61 range of bass frequencies. The actual cutoff frequency used for each setting
62 value will vary with sample rate.
63}
64
65\section{Treble}
66 This setting emphasises
67 \nopt{iriverh100,iriverh300}{or suppresses}
68 the higher (treble) frequencies in the sound. A value of 0~dB means that
69 treble sounds are unaltered (flat response).
70 \opt{masd}{The minimum setting is -15~dB and the maximum is 15~dB.}%
71 \opt{masf}{The minimum setting is -12~dB and the maximum is 12~dB.}%
72 \opt{iriverh100,iriverh300}{The minimum setting is 0~dB and the maximum is 6~dB.}%
73 \opt{ipodnano,ipodnano2g,ipodcolor,mpiohd200}{%
74 The minimum setting is -6~dB and the maximum is 9~dB.}%
75 \opt{ipodvideo}{The minimum setting is -12~dB and the maximum is 12~dB.}%
76 \opt{iaudiom3,iaudiom5,iaudiox5,sansa,sansaAMS,iriverh10,iriverh10_5gb,vibe500,fuzeplus}{%
77 The minimum setting is -24~dB and the maximum is 24~dB.}
78
79\opt{ipodvideo}{
80\section{Treble Cutoff}
81 This setting controls the frequency above which the treble adjustment applies.
82 The setting has a range from 1 to 4, where a bigger number affects a smaller
83 range of treble frequencies. The actual cutoff frequency used for each setting
84 value will vary with sample rate.
85}
86}
87
88\opt{gigabeats}{
89\section{Tone Controls}
90 There is a five-band equalizer built into your \dap{} that allows you to
91 control various different parameters for each band. This equalizer is
92 implemented in hardware, and therefore does not tax the processor when in use.
93 Rockbox also features a more advanced five-band equalizer (see
94 \reference{ref:EQ}) that is implemented in software and allows more fine
95 grained control, but also requires more processor time.
96
97 \begin{description}
98 \item[Band 1 Gain.]
99 This band acts as a low shelf filter that boosts or lowers all
100 frequencies below a certain frequency limit, much as a ``bass''
101 control found on ordinary stereo systems does. The ``gain'' parameter
102 controls how much the loudness of the band is adjusted. Positive
103 numbers make the EQ band louder, while negative numbers make that EQ
104 band quieter.
105 \item[Bands 2-4 Gain.]
106 These bands act as peaking filters that boost or lower a frequency
107 range centered at a certain frequency. Graphic equalizers in home
108 stereos are usually peaking filters. The ``gain'' parameter controls
109 how much each band is adjusted as with the the low shelf filter.
110 \item[Band 5 Gain.]
111 Band 5 acts as a high shelf filter, boosting or lowering all
112 frequencies above a certain frequency limit, much like a ``treble''
113 control found on ordinary stereo systems does. As with the other bands,
114 ``gain'' controls how much each band is adjusted.
115 \item[Advanced Tone Control Settings.]
116 This submenu allows you to change advanced parameters for each band.
117 \end{description}
118
119 As a general guide, EQ band 1 should be used for low frequencies, EQ bands 2
120 to 4 should be used for mids, and EQ band 5 should be used for highs.\\*
121
122 \subsection{Advanced Tone Control Settings}
123 As in the previous menu, the ``gain'' setting controls how much the
124 loudness of the band is adjusted. In addition the following parameters
125 can be adjusted:
126
127 \begin{description}
128 \item[Band 1 Frequency.]
129 The ``frequency'' parameter sets where the shelving starts to take
130 effect. For example, a cutoff frequency of 80~Hz will adjust only very
131 low frequencies. A cutoff frequency of 175~Hz, on the other hand, will
132 adjust a much wider range of bass frequencies.
133 \item[Bands 2-4 Frequency.]
134 The ``frequency'' parameter for these bands sets the centre frequency of
135 the range that is affected by the gain set.
136 \item[Bands 2-4 Width.]
137 This parameter sets the width of the range around the centre frequency
138 that is affected by the tone control. The possible settings are
139 ``wide'' or ``narrow''.
140 \item[Band 5 Frequency.]
141 This works just as for band 1 frequency, except that it affects the
142 high frequency end of the spectrum instead of the low.
143 \end{description}
144
145}
146
147\section{Balance}
148 This setting controls the balance between the left and right channels. The
149 default, 0, means that the left and right outputs are equal in volume.
150 Negative numbers increase the volume of the left channel relative to the
151 right, positive numbers increase the volume of the right channel relative
152 to the left.
153
154\section{Channels}
155 A stereo audio signal consists of two channels, left and right. The
156 \setting{Channels} setting determines if these channels are to be combined in
157 any way, and if so, in what manner they will be combined.
158 Available options are:
159 %
160 \begin{description}
161 \item[Stereo.]
162 Leave the audio signal unmodified.
163 \item[Mono.]
164 Combine both channels and send the resulting signal to both stereo
165 channels, resulting in a monophonic output.
166 \item[Custom.]
167 Allows you to manually specify a stereo width with the
168 \setting{Stereo Width} setting described later in this chapter.
169 \item[Mono Left.]
170 Plays the left channel in both stereo channels.
171 \item[Mono Right.]
172 Plays the right channel in both stereo channels.
173 \item[Karaoke.]
174 Removes all sound that is common to both channels. Since most
175 music is recorded with vocals being equally present in both channels
176 to make the singer sound centrally placed, this often (but not
177 always) has the effect of removing the voice track from a song. This
178 setting also very often has other undesirable effects on the sound.
179 \end{description}
180
181\section{Stereo Width}
182 Stereo width allows you to manually specify the effect that is applied
183 when the \setting{Channels} setting is set to ``custom''.
184 All values below 100\% will progressively mix the contents of one channel
185 into the other. This has the effect of gradually centering the stereo image,
186 until you have monophonic sound at 0\%. Values above 100\% will progressively
187 remove components in one channel that is also present in the other. This has
188 the effect of widening the stereo field. A value of 100\% will leave the
189 stereo field unaltered.
190
191\opt{masf}{
192 \section{Loudness}
193 When listening at low volumes, the ear will tend to make bass and treble
194 frequencies sound quieter than they really are. To compensate for this,
195 \setting{Loudness} is an effect which emphasises bass and treble in a fashion
196 suited to the human ear. Frequencies in the vocal range are unaffected, since
197 the human ear picks these up very easily at any sound level.
198 It is of course also possible to use this effect at higher volumes for
199 enhanced bass and treble.
200}
201
202\opt{masf}{
203\section{Auto Volume}
204 Auto volume is a feature that automatically lowers the volume on loud parts,
205 and then slowly restores the volume to the previous level over a time
206 interval. This setting allows this time interval to be configured. Short
207 values like 20~ms are useful for ensuring a constant volume for in-car use and
208 other applications where background noise makes a constant loudness desirable.
209 A longer timeout means that the change in volume back to the previous level
210 will be smoother, so there will be fewer sharp changes in volume level.
211}
212
213\opt{masf}{
214\section{Super Bass}
215 This setting changes the threshold at which bass frequencies are affected by
216 the \setting{Loudness} setting, making the sound of drums and bass guitar
217 louder in comparison to the rest of the sound. This setting only has an
218 effect if \setting{Loudness} is set to a value larger than 0~dB.
219}
220
221\opt{masf}{
222\section{MDB {}-- Micronas Dynamic Bass}
223 The rest of the parameters in this menu relate to the Micronas Dynamic
224 Bass (MDB) function. MDB is designed to enable the user to hear bass
225 notes that the headphones and/or speakers are not capable of reproducing.
226 Every tone has a fundamental frequency (the ``main tone'') and also several
227 harmonics, which are related to that tone. The human brain has a mechanism
228 whereby it can actually infer the presence of bass notes from the higher
229 harmonics that they would generate.
230
231 The practical upshot of this is that MDB produces a more authentic sounding
232 bass by tricking the brain into believing it is hearing tones that the
233 headphones or speakers are not capable of reproducing.
234
235 The MDB parameters are as follows:
236 %
237 \begin{description}
238 \item[MDB enable.]
239 This turns the MDB feature on or off. For many users this will be the
240 only setting they need, since Rockbox picks sensible defaults for the
241 other parameters. MDB is turned off by default.
242 \item[MDB strength.]
243 How loud the harmonics generated by MDB will be.
244 \item[MDB Harmonics.]
245 The percentage of the low notes that is converted into harmonics.
246 If low notes are causing speaker distortion, this can be set to 100\%
247 to eliminate the fundamental completely and only produce harmonics in the
248 signal. If set to 0\% this is the same as turning the MDB feature off.
249 \item[MDB Centre Frequency.]
250 The cutoff frequency of your headphones or speakers. This is usually
251 given in the specification for the headphones/speakers.
252 \item[MDB shape.]
253 It is recommended that this parameter be set to 1.5 times the centre frequency.
254
255 This is the frequency up to which harmonics are generated. Some of the
256 lower fundamentals near the cut{}-off range will have their lower
257 harmonics cut, since they will be below the range of the speakers.
258 Fundamentals between the cut{}-off frequency and the lower frequency
259 will have their harmonics proportionally boosted to compensate and restore
260 the `loudness' of these notes.
261
262 For most users, the defaults should provide an improvement in sound
263 quality and can be safely left as they are. For reference, the defaults
264 Rockbox uses are:
265 %
266 \begin{table}[h!]
267 \begin{rbtabular}{0.5\textwidth}{Xc}{Setting & Value}{}{}
268 MDB Strength & 50~dB \\
269 MDB Harmonics & 48\% \\
270 MDB Centre Frequency & 60~Hz \\
271 MDB Shape & 90~Hz \\
272 \end{rbtabular}
273 \end{table}
274
275 \end{description}
276}
277
278\opt{swcodec}{
279\section{Crossfeed}
280 Crossfeed attempts to make the experience of listening to music on
281 headphones more similar to listening to music with stereo speakers. When you
282 listen to music through speakers, each ear will hear sound originating from
283 both speakers. However, the sound from the left speaker reaches your right
284 ear slightly later than it does your left ear, and vice versa.\\
285
286 The human ear and brain together are very good at interpreting the time
287 differences between direct sounds and reflected sounds and using that
288 information to identify the direction that the sound is coming from. On the
289 other hand, when listening to headphones, each ear hears only the stereo
290 channel corresponding to it. The left ear hears only the left channel and
291 the right ear hears only the right channel. The result is that sound from
292 headphones does not provide the same spatial cues to your ear and brain as
293 speakers, and might for that reason sound unnatural to some listeners.\\
294
295 The crossfeed function uses an algorithm to feed a delayed and filtered
296 portion of the signal from the right channel into the left channel and vice
297 versa in order to simulate the spatial cues that the ear and brain receive
298 when listening to a set of loudspeakers placed in front of the listener. The
299 result is a more natural stereo image that can be especially appreciated in
300 older rock and jazz records, where one instrument is often hard-panned to
301 just one of the speakers. Many people will find such records tiring to listen
302 to using earphones and no crossfeed effect.\\
303
304 Crossfeed has the following settings:
305 \begin{description}
306 \item[Crossfeed.]
307 Selects whether the crossfeed effect is to be enabled or not.
308 \item[Direct Gain.]
309 How much the level of the audio that travels the direct path from a speaker
310 to the corresponding ear is supposed to be decreased.
311 \item[Cross Gain.]
312 How much the level of the audio that travels the cross path from a speaker
313 to the opposite ear is to be decreased.
314 \item[High-Frequency Attenuation.]
315 How much the upper frequencies of the cross path audio will be dampened.
316 Note that the total level of the higher frequencies will be a combination
317 of both this setting and the \setting{Cross Gain} setting.
318 \item[High-Frequency Cutoff.]
319 Decides at which frequency the cross path audio will start to be cut
320 by the amount described by the \setting{High-Frequency Attenuation}
321 setting.
322 \end{description}
323
324 Most users will find the default settings to yield satisfactory results, but
325 for the more adventurous user the settings can be fine-tuned to provide a
326 virtual speaker placement suited to ones preference.
327 % TODO: adapt the guidelines for crossfeed settings found here?
328 % http://www.ohl.to/interests-in-audio/crossfeed-and-eq-for-headphones/
329 Beware that the crossfeed function is capable of making the audio distort
330 if you choose settings which result in a too high output level.
331}
332
333\opt{swcodec}{
334\section{\label{ref:EQ}Equalizer}
335 \screenshot{configure_rockbox/images/ss-equalizer}{The graphical equalizer}{}
336 Rockbox features a parametric equalizer (EQ). As the name suggests, a
337 parametric EQ lets you control several different parameters for each
338 band of the EQ. \nopt{gigabeats}{In some ways the EQ is similar to the
339 \setting{Bass} and \setting{Treble} settings described earlier, but the EQ
340 allows you to control the sound much more carefully. Note that the parameteric
341 EQ bands will be applied in addition to any bass or treble tone controls.
342 } \opt{gigabeats}{The EQ is similar to the \setting{Tone Controls} described
343 above, but allows more delicate control.}\\
344
345 \note{A maximum of 10 EQ bands are possible on most devices, but using more
346 than are required will waste battery and introduce additional rounding
347 noise. For best results, use the fewest number of bands required.}
348
349 Rockbox's parametric EQ is composed of five different bands:
350 \begin{description}
351 \item[Band 0: Low shelf filter.]
352 The low shelf filter boosts or lowers all frequencies below a certain
353 frequency limit, much as the ``bass'' control found on ordinary
354 stereo systems does.
355 Adjust the ``cutoff'' frequency parameter to decide where the shelving
356 starts to take effect. For example, a cutoff frequency of 50~Hz will
357 adjust only very low frequencies. A cutoff frequency of 200~Hz, on the
358 other hand, will adjust a much wider range of bass frequencies.
359 The ``gain'' parameter controls how much the loudness of the band is
360 adjusted. Positive numbers make the EQ band louder, while negative
361 numbers make that EQ band quieter.
362 The ``Q'' parameter should always be set to 0.7 for the shelving
363 filters. Higher values will add a small boost around the cutoff
364 frequency that is almost always undesirable.
365 \item[Bands 1-8: Peaking filters.]
366 Peaking EQ filters boost or lower a frequency range centered at the
367 centre frequency chosen.
368 Graphic equalizers in home stereos are usually peaking
369 filters. The peaking filters in Rockbox's EQ lets you adjust three
370 different parameters for EQ bands 1 through 8. The ``centre'' parameter
371 controls the centre frequency of the frequency range that is affected
372 as described above.
373 The ``gain'' parameter controls how much each band is adjusted, and
374 works as for the low shelf filter.
375 Finally, the ``Q'' parameter controls how wide or narrow the affected
376 frequency range is. Higher Q values will affect a narrower band of
377 frequencies, while lower Q values will affect a wider band of
378 frequencies.
379 \item[Band 9: High shelf filter.]
380 A high shelf filter boosts or lowers all frequencies above a certain
381 frequency limit, much as the ``treble'' control found on ordinary
382 stereo systems does.
383 The high shelf filter is adjusted the same way as the low shelf filter,
384 except that it works on the high end of the frequency spectrum rather
385 than the low end.
386 \end{description}
387 As a general guide, EQ band 0 should be used for low frequencies, EQ bands 1
388 through 8 should be used for mids, and EQ band 9 should be used for highs.
389
390\begin {description}
391 \item[Enable EQ.]
392 This option controls whether the EQ is on or off.
393
394 \item[Graphical EQ.]
395 This option brings up a graphic EQ screen, which allows adjustment of each of
396 the three parameters described above (gain, centre frequency, and Q) for each
397 of the five EQ bands.
398
399 \begin{btnmap}
400 \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,IAUDIO_X5_PAD,GIGABEAT_PAD%
401 ,GIGABEAT_S_PAD,SANSA_C200_PAD,IAUDIO_M3_PAD,MROBE100_PAD%
402 ,SANSA_CLIP_PAD,SANSA_FUZEPLUS_PAD}{\ButtonRight}
403 \opt{SANSA_E200_PAD,SANSA_FUZE_PAD,IPOD_4G_PAD,IPOD_3G_PAD}{\ButtonScrollFwd}
404 \opt{IRIVER_H10_PAD}{\ButtonScrollUp}
405 \opt{PBELL_VIBE500_PAD}{\ButtonUp}
406 \opt{MPIO_HD200_PAD}{\ButtonVolUp}
407 \opt{MPIO_HD300_PAD}{\ButtonScrollUp}
408 \opt{touchscreen}{\TouchMidRight}
409 &
410 \opt{HAVEREMOTEKEYMAP}{
411 \opt{GIGABEAT_RC_PAD}{\ButtonRCFF}
412 \opt{IAUDIO_RC_PAD}{\ButtonRCRight}
413 &}
414 Raises the highlighted parameter.
415 \\
416 %
417 \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,IAUDIO_X5_PAD,GIGABEAT_PAD%
418 ,GIGABEAT_S_PAD,SANSA_C200_PAD,IAUDIO_M3_PAD,MROBE100_PAD%
419 ,SANSA_CLIP_PAD,SANSA_FUZEPLUS_PAD}{\ButtonLeft}
420 \opt{SANSA_E200_PAD,SANSA_FUZE_PAD,IPOD_4G_PAD,IPOD_3G_PAD}{\ButtonScrollBack}
421 \opt{IRIVER_H10_PAD}{\ButtonScrollDown}
422 \opt{PBELL_VIBE500_PAD}{\ButtonDown}
423 \opt{MPIO_HD200_PAD}{\ButtonVolDown}
424 \opt{MPIO_HD300_PAD}{\ButtonScrollDown}
425 \opt{touchscreen}{\TouchMidLeft}
426 &
427 \opt{HAVEREMOTEKEYMAP}{
428 \opt{GIGABEAT_RC_PAD}{\ButtonRCRew}
429 \opt{IAUDIO_RC_PAD}{\ButtonRCLeft}
430 &}
431 Lowers the highlighted parameter.
432 \\
433 %
434 \opt{IPOD_4G_PAD,IPOD_3G_PAD,PBELL_VIBE500_PAD}{\ButtonLeft}
435 \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,IAUDIO_X5_PAD,SANSA_E200_PAD,SANSA_C200_PAD%
436 ,SANSA_FUZE_PAD,GIGABEAT_PAD,GIGABEAT_S_PAD,IAUDIO_M3_PAD,MROBE100_PAD%
437 ,SANSA_CLIP_PAD,SANSA_FUZEPLUS_PAD}{\ButtonUp}
438 \opt{IRIVER_H10_PAD,MPIO_HD200_PAD,MPIO_HD300_PAD}{\ButtonRew}
439 \opt{touchscreen}{\ActionStdPrev}
440 &
441 \opt{HAVEREMOTEKEYMAP}{
442 \opt{IRIVER_RC_H100_PAD}{\ButtonRCRew}
443 \opt{GIGABEAT_RC_PAD}{\ButtonRCVolUp}
444 \opt{IAUDIO_RC_PAD}{\ButtonRCUp}
445 &}
446 Moves to the previous EQ band.
447 \\
448 %
449 \opt{IPOD_4G_PAD,IPOD_3G_PAD,PBELL_VIBE500_PAD}{\ButtonRight}
450 \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,IAUDIO_X5_PAD,SANSA_E200_PAD,SANSA_C200_PAD%
451 ,SANSA_FUZE_PAD,GIGABEAT_PAD,GIGABEAT_S_PAD,IAUDIO_M3_PAD,MROBE100_PAD%
452 ,SANSA_CLIP_PAD,SANSA_FUZEPLUS_PAD}{\ButtonDown}
453 \opt{IRIVER_H10_PAD,MPIO_HD200_PAD,MPIO_HD300_PAD}{\ButtonFF}
454 \opt{touchscreen}{\ActionStdNext}
455 &
456 \opt{HAVEREMOTEKEYMAP}{
457 \opt{IRIVER_RC_H100_PAD}{\ButtonRCFF}
458 \opt{GIGABEAT_RC_PAD}{\ButtonRCVolDown}
459 \opt{IAUDIO_RC_PAD}{\ButtonRCDown}
460 &}
461 Moves to the next EQ band.
462 \\
463 %
464 \opt{IRIVER_H100_PAD,IRIVER_H300_PAD,GIGABEAT_PAD,GIGABEAT_S_PAD,IAUDIO_X5_PAD%
465 ,SANSA_C200_PAD,IPOD_4G_PAD,IPOD_3G_PAD,IPOD_VIDEO_PAD,SANSA_E200_PAD%
466 ,SANSA_FUZE_PAD,MROBE100_PAD,SANSA_CLIP_PAD,SANSA_FUZEPLUS_PAD}{\ButtonSelect}
467 \opt{MPIO_HD200_PAD}{\ButtonFunc}
468 \opt{MPIO_HD300_PAD}{\ButtonEnter}
469 \opt{PBELL_VIBE500_PAD}{\ButtonOK}
470 \opt{IRIVER_H10_PAD}{\ButtonRight}
471 \opt{IAUDIO_M3_PAD}{\ButtonPlay}
472 \opt{touchscreen}{\TouchCenter
473 \opt{COWON_D2_PAD}{/ \ButtonMenu}}
474 &
475 \opt{HAVEREMOTEKEYMAP}{
476 \opt{IRIVER_RC_H100_PAD}{\ButtonRCSelect}
477 \opt{GIGABEAT_RC_PAD,IAUDIO_RC_PAD}{\ButtonRCPlay}
478 &}
479 Toggles the cursor among the three parameters (gain, centre frequency,
480 Q) for the selected EQ band
481 \\
482 %
483 \opt{IRIVER_H100_PAD,IRIVER_H300_PAD}{\ButtonMode}
484 \opt{IPOD_4G_PAD,IPOD_3G_PAD,MPIO_HD300_PAD}{\ButtonMenu}
485 \opt{IAUDIO_X5_PAD}{\ButtonPower/\ButtonRec}
486 \opt{IAUDIO_M3_PAD,MPIO_HD200_PAD}{\ButtonRec}
487 \opt{SANSA_E200_PAD,SANSA_FUZE_PAD,IRIVER_H10_PAD}{\ButtonLeft}
488 \opt{GIGABEAT_PAD,GIGABEAT_S_PAD,SANSA_C200_PAD,MROBE100_PAD,SANSA_CLIP_PAD}{\ButtonPower}
489 \opt{PBELL_VIBE500_PAD}{\ButtonCancel}
490 \opt{SANSA_FUZEPLUS_PAD}{\ButtonBack}
491 \opt{touchscreen}{\TouchTopLeft
492 \opt{COWON_D2_PAD}{/ \ButtonPower}}
493 &
494 \opt{HAVEREMOTEKEYMAP}{
495 \opt{IRIVER_RC_H100_PAD}{\ButtonRCStop}
496 \opt{GIGABEAT_RC_PAD}{\ButtonRCDsp}
497 \opt{IAUDIO_RC_PAD}{\ButtonRCRec}
498 &}
499 Exits the graphic EQ screen.
500 \\
501 \end{btnmap}
502
503 \item[Pre-cut.]
504 If too much positive gain is added through the graphical EQ, your music may
505 distort. The \setting{Precut} setting allows you to apply a global negative
506 gain to decoded audio, cancelling out positive gain from the EQ. This will
507 prevent distortion when boosting certain frequency ranges, at the expense of
508 making audio quieter.
509
510 Alternatively, precut can be used with a flat EQ curve to implement a volume
511 cap. For example, on a player that allows overdriving the headphone output
512 to +6dB, maximum volume can be capped to +0dB by applying 6dB of precut. Note
513 that precut is not applied if EQ is disabled.
514
515\item[Simple EQ.]
516This option provides an easier alternative for those who are daunted by all of
517the parameters that can be adjusted using the graphical EQ. With the
518\setting{Simple EQ}, the only parameter that can be adjusted is the gain.
519
520\item[Advanced EQ.]
521This sub menu provides options for adjusting the same parameters as the
522\setting{Graphical EQ}. The only difference is that the parameters are
523adjusted through textual menus rather than through a graphic interface.
524
525\item[Save EQ Preset.]
526This option saves the current EQ configuration in a \fname{.cfg} file.
527
528\item[Browse EQ Presets.]
529This menu displays a list of EQ presets, as well as any EQ configurations saved
530using the \setting{Save EQ Preset} option. Users unfamiliar with the
531operation of a parametric EQ may wish to use the presets instead of trying to
532configure the EQ, or use the presets for designing their own custom EQ
533settings.
534
535\end{description}
536}
537
538\opt{swcodec}{
539\section{Dithering}
540This setting controls the dithering and noise shaping functionality of Rockbox.
541
542Most of Rockbox' audio file decoders work at a higher bit depth than the 16 bits
543used for output on the \daps{} audio connectors. The simplest way to
544convert from one bit depth to another is simply discarding all the surplus bits.
545This is the default behaviour, and adds distortion to the signal that will
546vary in character along with the desired sound.
547
548Dithering adds low-level noise to the signal prior to throwing away the surplus
549bits, which gives the resulting signal a uniform noise floor which is
550independent of the signal. Most people find this noise preferable to the
551time-varying noise heard when not performing dithering.
552
553After dithering, noise shaping is performed. This basically just pushes the
554dithering noise to the parts of the frequency spectrum humans cannot hear so
555easily. In Rockbox' case, some of the noise is pushed up to above 10~kHz.
556
557This setting will be put to its best use when listening to dynamic music with
558frequently occuring quiet parts, classical music being a typical example. It is
559worth noting that the effects of dithering and noise shaping are very subtle,
560and not easily noticable.
561
562Rockbox uses highpass triangular distribution noise as the dithering noise
563source, and a third order noise shaper.
564}
565
566\opt{swcodec}{%
567\opt{pitchscreen}{%
568\section{Timestretch}
569Enabling \setting{Timestretch} allows you to change the playback speed without
570it affecting the pitch of the recording. After enabling this feature and
571rebooting, you can access this via the \setting{Pitch Screen}. This function is
572intended for speech playback and may significantly dilute your listening
573experience with more complex audio. See \reference{sec:pitchscreen} for more
574details about how to use the feature.
575}
576}
577
578\opt{swcodec}{
579\section{Compressor}
580The \setting{Compressor} reduces, or compresses, the dynamic range of the audio
581signal. This makes the quieter and louder sections closer to the same volume
582level by progressively reducing the gain of louder signals. When subsequently
583amplified, this has the effect of making the quieter sections louder while
584keeping the louder sections from clipping. This allows listening to the quiet
585sections of dynamic material in noisy environments while preventing sudden loud
586sections from being overbearing.
587
588There are several settings associated with the compressor. The first, and most
589important, is the \setting{Threshold}. The threshold is the audio input level
590at which the compressor begins to act. Any level louder than the threshold
591will be compressed to some extent. The maximum amount of compression, or the
592quietest level at which the compressor will operate, is -24~dB. The default of
593Off disables the compressor.
594
595The \setting{Makeup Gain} setting has two options: Off and Auto. Off means
596that the compressed audio will not be amplified after compression. The default
597of Auto will amplify the signal so that the loudest possible signal after
598compression will be just under the clipping limit. This is desirable because
599the compressed signal without makeup gain is quieter than the input signal.
600Makeup Gain in Auto restores the signal to the maximum possible level and
601brings the quieter audio up with it. This is what makes it possible to hear
602the quieter audio in noisy environments.
603
604The \setting{Ratio} setting determines how aggressively the compressor reduces
605gain above the threshold. For example, the 2:1 setting means that for each
606two decibels of input signal above the threshold, the compressor will only
607allow the output to appear as one decibel. The higher the ratio, the harder
608the signal is compressed. The ratio setting of Limit means essentially a ratio
609of infinity to one. In this case, the output signal is not allowed to exceed
610the threshold at all.
611
612The \setting{Knee} setting determines how abrupt the transition is from a
613non-compressed signal to a compressed signal. Hard Knee means that the
614transition occurs precisely at the threshold. The Soft Knee setting smoothes
615the transition from plus or minus three decibels around the threshold.
616
617The \setting{Attack Time} setting sets the delay in milliseconds between the
618input signal exceeding the activation threshold and acting upon it.
619
620The \setting{Release Time} setting sets the recovery time after the signal is
621compressed. Once the compressor determines that compression is necessary,
622the input signal is reduced appropriately, but the gain isn't allowed to
623immediately return to normal levels. This is necessary to reduce artifacts
624such as ``pumping.'' Instead, the gain is allowed to return to normal at the
625chosen rate. Release Time is the time for the gain to recover by 10~dB.
626}
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