Add new section 'Optimising battery runtime' to the manual (FS#11148).

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25382 a1c6a512-1295-4272-9138-f99709370657

4 files changed, 101 insertions, 6 deletions

diff --git a/manual/advanced_topics/main.tex b/manual/advanced_topics/main.tex
index 47d4305f72..b13a76712b 100644
--- a/manual/advanced_topics/main.tex
+++ b/manual/advanced_topics/main.tex
@@ -580,3 +580,98 @@ current version.
 
 \opt{archos}{\input{advanced_topics/archos-flashing.tex}}
 
+\section{Optimising battery runtime}
+  Rockbox offers a lot of settings that have high impact on the battery runtime 
+  of your \dap{}. The largest power savings can be achieved through disabling
+  unneeded hardware components -- for some of those there are settings
+  available. 
+\opt{swcodec}{
+  Another area of savings is avoiding or reducing CPU boosting
+  through disabling computing intense features (e.g. sound processing) or 
+  using effective audio codecs. 
+} The following provides a short overview of the most relevant settings and 
+  rules of thumb.
+
+\nopt{ondio}{
+\subsection{Display backlight}
+  The active backlight consumes a lot of power. Therefore choose a setting that
+  disables the backlight after timeout (for setting \setting{Backlight} see 
+  \reference{ref:Displayoptions}). Avoid to have the backlight enabled all the 
+  time.
+}
+
+\opt{lcd_sleep}{
+\subsection{Display power-off}
+  Shutting down the display and the display controller saves a reasonable amount 
+  of power. Choose a setting that will put the display to sleep after timeout
+  (for setting \setting{Sleep} see \reference{ref:Displayoptions}). Avoid to 
+  have the display enabled all the time -- even, if the display is transflective
+  and is readable without backlight. Depending on your \dap{} it might be 
+  significantly more efficient to re-enable the display and its backlight for a 
+  glimpse a few times per hour than to keep the display enabled.
+}
+
+\opt{accessory_supply}{
+\subsection{Accessory power supply}
+  As default your \dap{}'s accessory power supply is always enabled to ensure
+  proper function of connected accessory devices. Disable this power supply, if 
+  -- or as long as -- you do not use any accessory device with your \dap{} while 
+  running Rockbox (see \reference{ref:AccessoryPowerSupply}).
+}
+
+\opt{lineout_poweroff}{
+\subsection{Line Out}
+  Rockbox allows to switch off the line-out on your \dap{}. If you do not need 
+  the line-out, switch it off (see \reference{ref:LineoutOnOff}).
+}
+
+\opt{spdif_power}{
+\subsection{Optical Output}
+  Rockbox allows to switch off the S/PDIF output on your \dap{}. If you do not 
+  need this output, switch it off (see \reference{ref:SPDIF_OnOff}).
+}
+
+\opt{disk_storage}{
+\subsection{Anti-Skip Buffer}
+  Having a large anti-skip buffer tends to use more power, and may reduce your
+  battery life. It is recommended to always use the lowest possible setting 
+  that allows correct and continuous playback (see \reference{ref:AntiSkipBuf}).
+}
+
+\opt{swcodec,disk_storage,flash_storage}{
+\subsection{Audio format and bitrate}
+\opt{swcodec}{
+  In general the fastest decoding audio format will be the best in terms of
+  battery runtime on your \dap{}. An overview of different codec's performance 
+  on different \dap{}s can be found at \wikilink{CodecPerformanceComparison}.
+}
+
+\opt{flash_storage}{
+  Your target uses flash that consumes a certain amount of power during access.
+  The less often the flash needs to be switched on for buffering and the shorter 
+  the buffering duration is, the lower is the overall power consumption. 
+  Therefore the bitrate of the audio files does have an impact on the battery 
+  runtime as well. Lower bitrate audio files will result in longer battery 
+  runtime.
+}
+\opt{disk_storage}{
+  Your target uses a hard disk which consumes a large amount of power while
+  spinning -- up to several hundred mA. The less often the hard disk needs to 
+  spin up for buffering and the shorter the buffering duration is, the lower is 
+  the power consumption. Therefore the bitrate of the audio files does have an 
+  impact on the battery runtime as well. Lower bitrate audio files will result 
+  in longer battery runtime.
+}
+
+  Please do not re-encode any existing audio files from one lossy format to 
+  another based upon the above mentioned. This will reduce the audio quality.
+  If you have the choice, select the best suiting codec when encoding the 
+  original source material.
+}
+
+\opt{swcodec}{
+\subsection{Sound settings}
+  In general all kinds of sound processing will need more CPU time and therefore
+  consume more power. The less sound processing you use, the better it is for 
+  the battery runtime (for options see \reference{ref:configure_rockbox_sound}).
+}
diff --git a/manual/configure_rockbox/display_options.tex b/manual/configure_rockbox/display_options.tex
index f416e8418e..23673e2482 100644
--- a/manual/configure_rockbox/display_options.tex
+++ b/manual/configure_rockbox/display_options.tex
@@ -60,8 +60,8 @@
         \item[Sleep (After Backlight Off).]
         This setting controls how long rockbox will wait before turning off the
         display after the backlight is turned off. Turning off the display
-        saves a little bit of battery power but turning on the display takes
-        noticeably longer than just turning on the backlight.
+        saves battery power but turning on the display takes noticeably longer 
+        than just turning on the backlight.
       }
       
       \opt{backlight_brightness}{
diff --git a/manual/configure_rockbox/playback_options.tex b/manual/configure_rockbox/playback_options.tex
index 8ac9548eaf..5f61b0b0e2 100644
--- a/manual/configure_rockbox/playback_options.tex
+++ b/manual/configure_rockbox/playback_options.tex
@@ -62,7 +62,7 @@ you to configure settings related to audio playback.
   The setting \setting{FF/RW Min Step} controls the initial speed and \setting{FF/RW Accel} controls the acceleration.
 
 \opt{disk_storage}{
-  \section{Anti-Skip Buffer}
+  \section{\label{ref:AntiSkipBuf}Anti-Skip Buffer}
     This setting controls how early Rockbox starts refilling the music buffer
     from the hard drive when playing. A longer Anti-Skip Buffer helps prevent
     skips in music playback if Rockbox has trouble reading from the disk.
@@ -204,7 +204,7 @@ you to configure settings related to audio playback.
 }%\opt{swcodec}
 
 \opt{spdif_power}{
-  \section{Optical Output}
+  \section{\label{ref:SPDIF_OnOff}Optical Output}
     Enables or disables the optical S/PDIF output to 
     allow a digital connection to a suitable external decoder.  To enable
     optical output, set to \setting{Yes}
diff --git a/manual/configure_rockbox/system_options.tex b/manual/configure_rockbox/system_options.tex
index d2eb992b89..af7695ed48 100644
--- a/manual/configure_rockbox/system_options.tex
+++ b/manual/configure_rockbox/system_options.tex
@@ -152,7 +152,7 @@ This sub menu relates to limits in the Rockbox operating system.
 }
 
 \opt{accessory_supply}{
-\subsection{Accessory Power Supply}
+\subsection{\label{ref:AccessoryPowerSupply}Accessory Power Supply}
 This option turns the accessory power supply \setting{On} and \setting{Off}.
 The Apple accessory protocol has been partially implemented in Rockbox, and
 thus there is a reasonable chance that your favourite accessory will work.
@@ -162,7 +162,7 @@ this option \setting{On}. If it is not required, then turning this setting
 }
 
 \opt{lineout_poweroff}{
-\subsection{Line Out}
+\subsection{\label{ref:LineoutOnOff}Line Out}
 This option turns the \dap{}'s line-out \setting{On} and \setting{Off}. On some 
 devices an enabled line-out will consume some power even if not used. If it is 
 not required, then turning this setting \setting{Off} will save battery and