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Diffstat (limited to '')
| -rw-r--r-- | doc/user.xml | 144 |
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> |