path: root/manual
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authorThom Johansen <>2006-11-22 18:21:39 +0000
committerThom Johansen <>2006-11-22 18:21:39 +0000
commit7ec37778830d130c68572e1c6646fce4172e74b8 (patch)
tree87976ca17446d87e3cc2a14e6fcf7cb8bf4429c1 /manual
parent6675b64f468c14b8c3f2b426417485a6134ce4b2 (diff)
Small attempt at documenting the dithering option.
git-svn-id: svn:// a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'manual')
1 files changed, 28 insertions, 0 deletions
diff --git a/manual/configure_rockbox/sound_settings.tex b/manual/configure_rockbox/sound_settings.tex
index 2cf4c4e064..828bdacd5a 100755
--- a/manual/configure_rockbox/sound_settings.tex
+++ b/manual/configure_rockbox/sound_settings.tex
@@ -385,3 +385,31 @@ is similar to ``Q'' in the Graphical EQ).
filters, and High Shelf, the peaking filters are not currently operational.}
+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.