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-rw-r--r--doc/user.xml144
1 files changed, 143 insertions, 1 deletions
diff --git a/doc/user.xml b/doc/user.xml
index 5c810dc70..a74c1ce27 100644
--- a/doc/user.xml
+++ b/doc/user.xml
@@ -393,7 +393,7 @@ systemctl start mpd.socket</programlisting>
a name registered in the PULSE server.
</entry>
</row>
- <row>
+ <row id="ao_format">
<entry>
<varname>format</varname>
</entry>
@@ -607,6 +607,148 @@ systemctl start mpd.socket</programlisting>
</tgroup>
</informaltable>
</section>
+
+ <section>
+ <title>Audio Format Settings</title>
+
+ <section>
+ <title>Global Audio Format</title>
+
+ <para>
+ The setting <varname>audio_output_format</varname> forces
+ MPD to use one audio format for all outputs. Doing that is
+ usually not a good idea. The values are the same as in
+ <link linkend="ao_format"><varname>format</varname> in the
+ <varname>audio_output</varname> section</link>.
+ </para>
+ </section>
+
+ <section>
+ <title>Resampler</title>
+
+ <para>
+ Sometimes, music needs to be resampled before it can be
+ played; for example, CDs use a sample rate of 44,100 Hz
+ while many cheap audio chips can only handle 48,000 Hz.
+ Resampling reduces the quality and consumes a lot of CPU.
+ There are different options, some of them optimized for high
+ quality and others for low CPU usage, but you can't have
+ both at the same time. Often, the resampler is the
+ component that is responsible for most of MPD's CPU usage.
+ Since MPD comes with high quality defaults, it may appear
+ that MPD consumes more CPU than other software.
+ </para>
+
+ <para>
+ The following resamplers are available (if enabled at
+ compile time):
+ </para>
+
+ <itemizedlist>
+ <listitem>
+ <para>
+ <ulink
+ url="http://www.mega-nerd.com/SRC/">libsamplerate</ulink>
+ a.k.a. Secret Rabbit Code (SRC).
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ internal: low CPU usage, but very poor quality. This is
+ the fallback if MPD was compiled without an external
+ resampler.
+ </para>
+ </listitem>
+ </itemizedlist>
+
+ <para>
+ The setting <varname>samplerate_converter</varname> controls
+ how MPD shall resample music. Possible values:
+ </para>
+
+ <informaltable>
+ <tgroup cols="2">
+ <thead>
+ <row>
+ <entry>
+ Value
+ </entry>
+ <entry>
+ Description
+ </entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>
+ "<parameter>internal</parameter>"
+ </entry>
+ <entry>
+ The internal resampler. Low CPU usage, but very
+ poor quality.
+ </entry>
+ </row>
+
+ <row>
+ <entry>
+ "<parameter>Best Sinc Interpolator</parameter>" or
+ "<parameter>0</parameter>"
+ </entry>
+ <entry>
+ libsamplerate: Band limited sinc interpolation, best
+ quality, 97dB SNR, 96% BW.
+ </entry>
+ </row>
+
+ <row>
+ <entry>
+ "<parameter>Medium Sinc Interpolator</parameter>" or
+ "<parameter>1</parameter>"
+ </entry>
+ <entry>
+ libsamplerate: Band limited sinc interpolation,
+ medium quality, 97dB SNR, 90% BW.
+ </entry>
+ </row>
+
+ <row>
+ <entry>
+ "<parameter>Fastest Sinc Interpolator</parameter>" or
+ "<parameter>2</parameter>"
+ </entry>
+ <entry>
+ libsamplerate: Band limited sinc interpolation,
+ fastest, 97dB SNR, 80% BW.
+ </entry>
+ </row>
+
+ <row>
+ <entry>
+ "<parameter>ZOH Sinc Interpolator</parameter>" or
+ "<parameter>3</parameter>"
+ </entry>
+ <entry>
+ libsamplerate: Zero order hold interpolator, very
+ fast, very poor quality with audible distortions.
+ </entry>
+ </row>
+
+ <row>
+ <entry>
+ "<parameter>Linear Interpolator</parameter>" or
+ "<parameter>4</parameter>"
+ </entry>
+ <entry>
+ libsamplerate: Linear interpolator, very fast, poor
+ quality.
+ </entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ </section>
+ </section>
</chapter>
<chapter>