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author | Thom Johansen <thomj@rockbox.org> | 2006-11-22 18:21:39 +0000 |
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committer | Thom Johansen <thomj@rockbox.org> | 2006-11-22 18:21:39 +0000 |
commit | 7ec37778830d130c68572e1c6646fce4172e74b8 (patch) | |
tree | 87976ca17446d87e3cc2a14e6fcf7cb8bf4429c1 /manual/configure_rockbox | |
parent | 6675b64f468c14b8c3f2b426417485a6134ce4b2 (diff) | |
download | rockbox-7ec37778830d130c68572e1c6646fce4172e74b8.tar.gz rockbox-7ec37778830d130c68572e1c6646fce4172e74b8.zip |
Small attempt at documenting the dithering option.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@11575 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'manual/configure_rockbox')
-rwxr-xr-x | manual/configure_rockbox/sound_settings.tex | 28 |
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). | |||
385 | filters, and High Shelf, the peaking filters are not currently operational.} | 385 | filters, and High Shelf, the peaking filters are not currently operational.} |
386 | 386 | ||
387 | } | 387 | } |
388 | |||
389 | \opt{SWCODEC}{ | ||
390 | \section{Dithering} | ||
391 | This setting controls the dithering and noise shaping functionality of Rockbox. | ||
392 | |||
393 | Most of Rockbox' audio file decoders work at a higher bit depth than the 16 bits | ||
394 | used for output on the \daps{} audio connectors. The simplest way in which to | ||
395 | convert from one bit depth to another is simply discarding all the surplus bits. | ||
396 | This is the default behaviour, and adds distortion to the signal that will | ||
397 | vary in character along with the desired sound. | ||
398 | |||
399 | Dithering adds low-level noise to the signal prior to throwing away the surplus | ||
400 | bits, which gives the resulting signal a uniform noise floor which is | ||
401 | independent of the signal. Most people find this noise preferable to the | ||
402 | time-varying noise heard when not performing dithering. | ||
403 | |||
404 | After dithering, noise shaping is performed. This basically just pushes the | ||
405 | dithering noise to the parts of the frequency spectrum humans cannot hear so | ||
406 | easily. In Rockbox' case, some of the noise is pushed up to above 10 kHz. | ||
407 | |||
408 | This setting will be put to its best use when listening to dynamic music with | ||
409 | frequently occuring quiet parts, classical music being a typical example. It is | ||
410 | worth noting that the effects of dithering and noise shaping are very subtle, | ||
411 | and not easily noticable. | ||
412 | |||
413 | Rockbox uses highpass triangular distribution noise as the dithering noise | ||
414 | source, and a third order noise shaper. | ||
415 | } | ||