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<chapter id="usage">
<title>Usage</title>

<sect1 id="commandline">
<title>Command line</title>

<para>
<application>MPlayer</application> utilizes a complex playtree. It consists
of global options written as first, for example

<screen>mplayer -vfm 5</screen>

and options written after filenames, that apply only to the given
filename/URL/whatever, for example:

<screen>mplayer -vfm 5 <replaceable>movie1.avi</replaceable> <replaceable>movie2.avi</replaceable> -vfm 4</screen>
</para>

<para>
You can group filenames/URLs together using <literal>{</literal> and
<literal>}</literal>. It is useful with option <option>-loop</option>:

<screen>mplayer { 1.avi -loop 2 2.avi } -loop 3</screen>

The above command will play files in this order: 1, 1, 2, 1, 1, 2, 1, 1, 2.
</para>

<para>
Playing a file:
<synopsis>
<command>mplayer</command><!--
--> [<replaceable>options</replaceable>]<!--
--> [<replaceable>path</replaceable>/]<replaceable>filename</replaceable>
</synopsis>
</para>

<para>
Another way to play a file:
<synopsis>
<command>mplayer</command><!--
--> [<replaceable>options</replaceable>]<!--
--> <replaceable>file:///uri-escaped-path</replaceable>
</synopsis>
</para>

<para>
Playing more files:
<synopsis>
<command>mplayer</command><!--
--> [<replaceable>default options</replaceable>]<!--
--> [<replaceable>path</replaceable>/]<replaceable>filename1</replaceable><!--
--> [<replaceable>options for filename1</replaceable>]<!--
--> <replaceable>filename2</replaceable><!--
--> [<replaceable>options for filename2</replaceable>] ...
</synopsis>
</para>

<para>
Playing VCD:
<synopsis>
<command>mplayer</command> [<replaceable>options</replaceable>]<!--
--> vcd://<replaceable>trackno</replaceable><!--
--> [-cdrom-device <replaceable>/dev/cdrom</replaceable>]
</synopsis>
</para>

<para>
Playing DVD:
<synopsis>
<command>mplayer</command> [<replaceable>options</replaceable>]<!--
--> dvd://<replaceable>titleno</replaceable><!--
--> [-dvd-device <replaceable>/dev/dvd</replaceable>]
</synopsis>
</para>

<para>
Playing from the WWW:
<synopsis>
<command>mplayer</command> [<replaceable>options</replaceable>]<!--
--> http://<replaceable>site.com/file.asf</replaceable>
</synopsis>
(playlists can be used, too)
</para>

<para>
Playing from RTSP:
<synopsis>
<command>mplayer</command> [<replaceable>options</replaceable>]<!--
--> rtsp://<replaceable>server.example.com/streamName</replaceable>
</synopsis>
</para>

<para>
Examples:
<screen>
mplayer -vo x11 <replaceable>/mnt/Films/Contact/contact2.mpg</replaceable>
mplayer vcd://<replaceable>2</replaceable> -cdrom-device <replaceable>/dev/hdc</replaceable>
mplayer -afm 3 <replaceable>/mnt/DVDtrailers/alien4.vob</replaceable>
mplayer dvd://<replaceable>1</replaceable> -dvd-device <replaceable>/dev/hdc</replaceable>
mplayer -abs 65536 -delay -0.4 -nobps <replaceable>~/movies/test.avi</replaceable><!--
--></screen>
</para>
</sect1>


<sect1 id="subosd">
<title>Subtitles and OSD</title>

<para>
<application>MPlayer</application> can display subtitles along with movie files.
Currently the following formats are supported:
<itemizedlist>
<listitem><para>VOBsub</para></listitem>
<listitem><para>OGM</para></listitem>
<listitem><para>CC (closed caption)</para></listitem>
<listitem><para>MicroDVD</para></listitem>
<listitem><para>SubRip</para></listitem>
<listitem><para>SubViewer</para></listitem>
<listitem><para>Sami</para></listitem>
<listitem><para>VPlayer</para></listitem>
<listitem><para>RT</para></listitem>
<listitem><para>SSA</para></listitem>
<listitem><para>PJS (Phoenix Japanimation Society)</para></listitem>
<listitem><para>MPsub</para></listitem>
<listitem><para>AQTitle</para></listitem>
<listitem><para><ulink url="http://unicorn.us.com/jacosub/">JACOsub</ulink></para></listitem>
</itemizedlist>
</para>

<para>
<application>MPlayer</application> can dump the previously listed subtitle formats
(<emphasis role="bold">except the three first</emphasis>) into the following
destination formats, with the given options:
<itemizedlist>
<listitem><para>MPsub: <option>-dumpmpsub</option></para></listitem>
<listitem><para>SubRip: <option>-dumpsrtsub</option></para></listitem>
<listitem><para>MicroDVD: <option>-dumpmicrodvdsub</option></para></listitem>
<listitem><para>JACOsub: <option>-dumpjacosub</option></para></listitem>
<listitem><para>Sami: <option>-dumpsami</option></para></listitem>
</itemizedlist>
</para>

<para>
<application>MEncoder</application> can dump DVD subtitles into
<link linkend="menc-feat-extractsub">VOBsub</link> format.
</para>

<para>
The command line options differ slightly for the different formats:
</para>

<formalpara>
<title>VOBsub subtitles</title>
<para>
VOBsub subtitles consist of a big (some megabytes) <filename>.SUB</filename> file,
and optional <filename>.IDX</filename> and/or <filename>.IFO</filename>
files.  If you have files like
<filename><replaceable>sample.sub</replaceable></filename>,
<filename><replaceable>sample.ifo</replaceable></filename> (optional),
<filename><replaceable>sample.idx</replaceable></filename> - you have to pass
<application>MPlayer</application> the <option>-vobsub sample
[-vobsubid <replaceable>id</replaceable>]</option> options
(full path optional). The <option>-vobsubid</option> option is like
<option>-sid</option> for DVDs, you can choose between subtitle tracks
(languages) with it. In case that <option>-vobsubid</option> is omitted,
<application>MPLayer</application> will try to use the languages given by the
<option>-slang</option> option and fall back to the <systemitem>langidx</systemitem>
in the <filename>.IDX</filename> file to set the subtitle language. If it fails,
there will be no subtitles.
</para>
</formalpara>

<formalpara>
<title>Other subtitles</title>
<para>
The other formats consist of a single text file containing timing,
placement and text information. Usage: If you have a file like
<filename><replaceable>sample.txt</replaceable></filename>,
you have to pass the option <option>-sub
<replaceable>sample.txt</replaceable></option> (full path optional).
</para>
</formalpara>

<variablelist>
<title>Adjusting subtitle timing and placement:</title>
<varlistentry>
  <term><option>-subdelay <replaceable>sec</replaceable></option></term>
  <listitem><simpara>
    Delays subtitles by <option><replaceable>sec</replaceable></option> seconds.
    Can be negative. The value is added to movie's time position counter.
    </simpara></listitem>
</varlistentry>
<varlistentry>
  <term><option>-subfps <replaceable>RATE</replaceable></option></term>
  <listitem><simpara>
    Specify frame/sec rate of subtitle file (float number).
    </simpara></listitem>
</varlistentry>
<varlistentry>
  <term><option>-subpos <replaceable>0-100</replaceable></option></term>
  <listitem><simpara>
    Specify the position of subtitles.
    </simpara></listitem>
</varlistentry>
</variablelist>

<para>
If you experience a growing delay between the movie and the subtitles when
using a MicroDVD subtitle file, most likely the framerate of the movie and
the subtitle file are different. Please note that the MicroDVD subtitle
format uses absolute frame numbers for its timing, but there is no fps
information in it, and therefore the <option>-subfps</option> option should
be used with this format. If you like to solve this problem permanently,
you have to manually convert the subtitle file framerate.
<application>MPlayer</application> can do this
conversion for you:

<screen>mplayer -dumpmicrodvdsub -fps <replaceable>subtitles_fps</replaceable> -subfps <replaceable>avi_fps</replaceable> -sub <replaceable>subtitle_filename</replaceable> <replaceable>dummy.avi</replaceable></screen>
</para>

<para>
About DVD subtitles, read the <link linkend="dvd">DVD</link> section.
</para>
</sect1>


<sect1 id="control">
<title>Control</title>

<para>
<application>MPlayer</application> has a fully configurable, command
driven, control layer which lets you control
<application>MPlayer</application> with keyboard, mouse, joystick or remote
control (using LIRC). See the man page for the complete list of keyboard controls.
</para>


<sect2 id="ctrl-cfg">
<title>Controls configuration</title>

<para>
<application>MPlayer</application> allows you bind any key/button to any
<application>MPlayer</application> command using a simple config file.
The syntax consist of a key name followed by a command. The default config file location is
<filename>$HOME/.mplayer/input.conf</filename> but it can be overridden
using the <option>-input <replaceable>conf</replaceable></option> option
(relative path are relative to <filename>$HOME/.mplayer</filename>).
</para>

<para>
You can get a full list of supported key names by running
<command>mplayer -input keylist</command>
and a full list of available commands by running
<command>mplayer -input cmdlist</command>.
</para>

<example id="input_control_file">
<title>A simple input control file</title>
<programlisting>
##
## MPlayer input control file
##

RIGHT seek +10
LEFT seek -10
- audio_delay 0.100
+ audio_delay -0.100
q quit
&gt; pt_step 1
&lt; pt_step -1
ENTER pt_step 1 1<!--
--></programlisting>
</example>
</sect2>


<sect2 id="lirc">
<title>Control from LIRC</title>

<para>
Linux Infrared Remote Control - use an easy to build home-brewn IR-receiver,
an (almost) arbitrary remote control and control your Linux box with it!
More about it on the <ulink url="http://www.lirc.org">LIRC homepage</ulink>.
</para>

<para>
If you have the LIRC package installed, <filename>configure</filename> will
autodetect it. If everything went fine, <application>MPlayer</application>
will print &quot;<systemitem>Setting up LIRC support...</systemitem>&quot;
on startup. If an error occurs it will tell you. If there is no message about
LIRC there is no support compiled in. That's it :-)
</para>

<para>
The application name for <application>MPlayer</application> is - surprise -
<filename>mplayer</filename>. You can use any <application>MPlayer</application>
commands and even pass more than one command by separating them with
<literal>\n</literal>.
Do not forget to enable the repeat flag in <filename>.lircrc</filename> when
it makes sense (seek, volume, etc). Here is an excerpt from a sample
<filename>.lircrc</filename>:
</para>

<programlisting>
begin
     button = VOLUME_PLUS
     prog = mplayer
     config = volume 1
     repeat = 1
end

begin
    button = VOLUME_MINUS
    prog = mplayer
    config = volume -1
    repeat = 1
end

begin
    button = CD_PLAY
    prog = mplayer
    config = pause
end

begin
    button = CD_STOP
    prog = mplayer
    config = seek 0 1\npause
end<!--
--></programlisting>

<para>
If you do not like the standard location for the lirc-config file
(<filename>~/.lircrc</filename>) use the <option>-lircconf
<replaceable>filename</replaceable></option> switch to specify another
file.
</para>
</sect2>


<sect2 id="slave-mode">
<title>Slave mode</title>
<para>
The slave mode allows you to build simple frontends to
<application>MPlayer</application>. When run with the
<option>-slave</option> option <application>MPlayer</application> will
read commands separated by a newline (\n) from stdin.
The commands are documented in the
<ulink url="../../tech/slave.txt">slave.txt</ulink> file.
</para>
</sect2>
</sect1>


<sect1 id="streaming">
<title>Streaming from network or pipes</title>

<para>
<application>MPlayer</application> can play files from the network, using the
HTTP, FTP, MMS or RTSP/RTP protocol.
</para>

<para>
Playing works simply by passing the URL on the command line.
<application>MPlayer</application> honors the <envar>http_proxy</envar>
environment variable, using a proxy if available. Proxies can also be forced:
<screen>mplayer <replaceable>http_proxy://proxy.micorsops.com:3128/http://micorsops.com:80/stream.asf</replaceable></screen>
</para>

<para>
<application>MPlayer</application> can read from stdin
(<emphasis>not</emphasis> named pipes). This can for example be used to
play from FTP:
<screen>wget <replaceable>ftp://micorsops.com/something.avi</replaceable> -O - | mplayer -</screen>
</para>

<note><para>
It is also recommended to enable <option>-cache</option> when playing
from the network:
<screen>wget <replaceable>ftp://micorsops.com/something.avi</replaceable> -O - | mplayer -cache 8192 -</screen>
</para></note>

<sect2 id="streaming-save">
<title>Saving streamed content</title>
<para>
  Once you succeed in making <application>MPlayer</application> play
  your favorite internet stream, you can use the option
  <option>-dumpstream</option> to save the stream into a file.
  For example:
<screen>
  mplayer <replaceable>http://217.71.208.37:8006</replaceable> -dumpstream -dumpfile <replaceable>stream.asf</replaceable>
</screen>
  will save the content streamed from
  <replaceable>http://217.71.208.37:8006</replaceable> into
  <replaceable>stream.asf</replaceable>.
  This works with all protocols supported by
  <application>MPlayer</application>, like MMS, RSTP, and so forth.
</para>
</sect2>

</sect1>

<sect1 id="mpst" xreflabel="Remote streams">
<title>Remote streams</title>

<para>
Remote streams allow you to access most <application>MPlayer</application>
stream type from a remote host. The main purpose of this feature is to make
it possible to directly use the CD or DVD drive of another computer on the
network (provided you have the required bandwidth). On the downside some
stream type (currently TV and MF) are not usable remotely because they are
implemented at the demuxer level. It is sad for MF but TV stream would anyway
require an insane amount of bandwidth.
</para>

<sect2 id="compile_mpst_server">
<title>Compiling the server</title>
<para>
After having compiled <application>MPlayer</application> go to the
<filename>TOOLS/netstream</filename> directory and enter
<application>make</application> to build the server binary.
You can then copy the <application>netstream</application> binary
to the right place on your system (usually
<filename class="directory">/usr/local/bin</filename> on Linux).
</para>
</sect2>

<sect2 id="use_mpst">
<title>Using remote streams</title>
<para>
First you have to start the server on the computer you intend to remotely
access. Currently the server is very basic and does not have any commands
line arguments so just enter <filename>netstream</filename>. Now you can
for example play the second track of a VCD on the server with :
<screen>
mplayer -cache 5000 <replaceable>mpst://servername/vcd://2</replaceable>
</screen>
You can also access files on this server :
<screen>
mplayer -cache 5000 <replaceable>mpst://servername//usr/local/movies/lol.avi</replaceable>
</screen>
Note that paths which aren't starting with a / will be relative to
the directory where the server is running. The <option>-cache</option> option is not
needed but highly recommended.
</para>

<para>
Be aware that currently the server is not secure at all. So do not complain
about the numerous exploits which are possible through this. Instead send
some (good) patch to make it better or start writing your own server.
</para>

</sect2>

</sect1>

<sect1 id="edl" xreflabel="Edit Decision Lists (EDL)">
<title>Edit Decision Lists (EDL)</title>

<para>
The edit decision list (EDL) system allows you to automatically skip
or mute sections of videos during playback, based on a movie specific
EDL configuration file.
</para>

<para>
This is useful for those who may want to watch a film in "family-friendly"
mode. You can cut out any violence, profanity, Jar-Jar Binks .. from a movie
according to your own personal preferences. Aside from this, there are other
uses, like automatically skipping over commercials in video files you watch.
</para>

<para>
The EDL file format is pretty bare-bones. There is one command per line that
indicates what to do (skip/mute) and when to do it (using pts in seconds).
</para>

<sect2 id="edl_using">
<title>Using an EDL file</title>
<para>
Include the <option>-edl &lt;filename&gt;</option> flag when you run
<application>MPlayer</application>, with the name of the EDL file you
want applied to the video.
</para>
</sect2>

<sect2 id="edl_making">
<title>Making an EDL file</title>
<para>
The current EDL file format is:
<programlisting>
[begin second] [end second] [action]
</programlisting>
Where the seconds are floating-point numbers and the action is either
<literal>0</literal> for skip or <literal>1</literal> for mute. Example:
<programlisting>
5.3   7.1    0
15    16.7   1
420   422    0
</programlisting>
This will skip from second 5.3 to second 7.1 of the video, then mute at
15 seconds, unmute at 16.7 seconds and skip from second 420 to second 422
of the video. These actions will be performed when the playback timer
reaches the times given in the file.
</para>

<para>
To create an EDL file to work from, use the <option>-edlout &lt;filename&gt;</option>
flag. During playback, just hit <keycap>i</keycap> to mark the beginning and 
end of a skip block. A corresponding entry will be written to the file for
that time. You can then go back and fine-tune the generated EDL file as well as
change the default operation which is to skip the block described by each line.
</para>
</sect2>

</sect1>


<sect1 id="advaudio" xreflabel="Advanced Audio">
<title>Advanced audio</title>

<sect2 id="advaudio-surround">
<title>Surround/Multichannel playback</title>

<sect3 id="advaudio-surround-DVD">
<title>DVDs</title>
<para>
Most DVDs and many other files include surround sound.
<application>MPlayer</application> supports surround playback but does not
enable it by default because stereo equipment is by far more common. To play a
file that has more than two channels of audio use <option>-channels</option>.
For example, to play a DVD with 5.1 audio:

<screen>mplayer dvd://1 -channels 6</screen>

Note that despite the name "5.1" there are actually six discrete channels.
If you have surround sound equipment it is safe to put the
<option>channels</option> option in your <application>MPlayer</application>
configuration file <filename>~/.mplayer/config</filename>. For example, to make
quadraphonic playback the default, add this line:

<programlisting>channels=4</programlisting>

<application>MPlayer</application> will then output audio in four channels when
all four channels are available.
</para>
</sect3>


<sect3 id="advaudio-surround-stereoinfour">
<title>Playing stereo files to four speakers</title>

<para>
<application>MPlayer</application> does not duplicate any channels by default,
and neither do most audio drivers. If you want to do that manually:

<screen>mplayer <replaceable>filename</replaceable> -af channels=2:2:0:1:0:0</screen>

See the section on
<link linkend="advaudio-channels-copying">channel copying</link> for an
explanation.
</para>

</sect3>


<sect3 id="advaudio-surround-passthrough">
<title>AC3/DTS Passthrough</title>

<para>
DVDs usually have surround audio encoded in AC3 (Dolby Digital) or DTS
(Digital Theater System) format. Some modern audio equipment is capable of
decoding these formats internally. <application>MPlayer</application> can be
configured to relay the audio data without decoding it. This will only work if
you have a S/PDIF (Sony/Philips Digital Interface) jack in your sound card.
</para>

<para>
If your audio equipment can decode both AC3 and DTS, you can safely enable
passthrough for both formats. Otherwise, enable passthrough for only the format
your equipment supports.
</para>

<itemizedlist>
<title>To enable passthrough on the command line:</title>
<listitem><para>
For AC3 only, use <option>-ac hwac3</option>
</para></listitem>
<listitem><para>
For DTS only, use <option>-ac hwdts</option>
</para></listitem>
<listitem><para>
For both AC3 and DTS, use <option>-afm hwac3</option>
</para></listitem>
</itemizedlist>

<itemizedlist>
<title>To enable passthrough in the <application>MPlayer</application>
configuration file: </title>
<listitem><para>
For AC3 only, use <option>ac=hwac3,</option>
</para></listitem>
<listitem><para>
For DTS only, use <option>ac=hwdts,</option>
</para></listitem>
<listitem><para>
For both AC3 and DTS, use <option>afm=hwac3</option>
</para></listitem>
</itemizedlist>

<para>
Note that there is a comma (",") at the end of
<option>ac=hwac3,</option> and <option>ac=hwdts,</option>. This will make
<application>MPlayer</application> fall back on the codecs it normally uses when
playing a file that does not have AC3 or DTS audio. <option>afm=hwac3</option>
does not need a comma; <application>MPlayer</application> will fall back anyway
when an audio family is specified.
</para>

</sect3>

<sect3 id="hwmpa-surround-passthrough">
<title>MPEG audio Passthrough</title>

<para>
Digital TV transmissions (such as DVB and ATSC) and some DVDs usually have 
MPEG audio streams (in particular MP2).
Some MPEG hardware decoders such as full-featured DVB cards and DXR2 
adapters can natively decode this format. 
<application>MPlayer</application> can be configured to relay the audio data 
without decoding it.
</para>

<para>
To use this codec:
<screen> mplayer -ac hwmpa </screen>
</para>
</sect3>

<sect3 id="advaudio-surround-matrix">
<title>Matrix-encoded audio</title>

<para>
<emphasis>***TODO***</emphasis>
</para>
<para>
This section has yet to be written and cannot be completed until somebody
provides sample files for us to test. If you have any matrix-encoded audio
files, know where to find some, or have any information that could be helpful,
please send a message to the
<ulink url="http://lists.mplayerhq.hu/mailman/listinfo/mplayer-docs">MPlayer-DOCS</ulink>
mailing list. Put "[matrix-encoded audio]" in the subject line.
</para>
<para>
If no files or further information are forthcoming this section will be dropped.
</para>

<para>
Good links:
<itemizedlist>
<listitem><para>
<ulink url="http://electronics.howstuffworks.com/surround-sound5.htm">http://electronics.howstuffworks.com/surround-sound5.htm</ulink>
</para></listitem>
<listitem><para>
<ulink url="http://www.extremetech.com/article2/0,1697,1016875,00.asp">http://www.extremetech.com/article2/0,1697,1016875,00.asp</ulink>
</para></listitem>
</itemizedlist>
</para>

</sect3>


<sect3 id="advaudio-surround-hrtf">
<title>Surround emulation in headphones</title>

<para>
<application>MPlayer</application> includes an HRTF (Head Related Transfer
Function) filter based on an
<ulink url="http://sound.media.mit.edu/KEMAR.html">MIT project</ulink>
wherein measurements were taken from microphones mounted on a dummy human head.
</para>

<para>
Although it is not possible to exactly imitate a surround system,
<application>MPlayer</application>'s HRTF filter does provide more spatially
immersive audio in 2-channel headphones. Regular downmixing simply combines all
the channels into two; besides combining the channels, <option>hrtf</option>
generates subtle echoes, increases the stereo separation slightly, and alters
the volume of some frequencies. Whether HRTF sounds better may be dependent on
the source audio and a matter of personal taste, but it is definitely worth
trying out.
</para>

<para>
To play a DVD with HRTF:

<screen>mplayer dvd://1 -channels 6 -af hrtf</screen>

</para>

<para>
<option>hrtf</option> only works well with 5 or 6 channels. Also,
<option>hrtf</option> requires 48 kHz audio. DVD audio is already 48 kHz, but if
you have a file with a different sampling rate that you want to play using
<option>hrtf</option> you must resample it:

<screen>mplayer <replaceable>filename</replaceable> -channels 6 -af resample=48000,hrtf</screen>

</para>

</sect3>


<sect3 id="advaudio-surround-troubleshooting">
<title>Troubleshooting</title>

<para>
If you do not hear any sound out of your surround channels, check your mixer
settings with a mixer program such as <application>alsamixer</application>;
audio outputs are often muted and set to zero volume by default.
</para>

</sect3>

</sect2>


<sect2 id="advaudio-channels">
<title>Channel manipulation</title>

<sect3 id="advaudio-channels-general">
<title>General information</title>

<para>
Unfortunately, there is no standard for how channels are ordered. The orders
listed below are those of AC3 and are fairly typical; try them and see if your
source matches. Channels are numbered starting with 0.

<orderedlist spacing="compact">
<title>mono</title>
<listitem override="0"><simpara>center</simpara></listitem>
</orderedlist>

<orderedlist spacing="compact">
<title>stereo</title>
<listitem override="0"><simpara>left</simpara></listitem>
<listitem><simpara>right</simpara></listitem>
</orderedlist>

<orderedlist spacing="compact">
<title>quadraphonic</title>
<listitem override="0"><simpara>left front</simpara></listitem>
<listitem><simpara>right front</simpara></listitem>
<listitem><simpara>left rear</simpara></listitem>
<listitem><simpara>right rear</simpara></listitem>
</orderedlist>

<orderedlist spacing="compact">
<title>surround 4.0</title>
<listitem override="0"><simpara>left front</simpara></listitem>
<listitem><simpara>right front</simpara></listitem>
<listitem><simpara>center rear</simpara></listitem>
<listitem><simpara>center front</simpara></listitem>
</orderedlist>

<orderedlist spacing="compact">
<title>surround 5.0</title>
<listitem override="0"><simpara>left front</simpara></listitem>
<listitem><simpara>right front</simpara></listitem>
<listitem><simpara>left rear</simpara></listitem>
<listitem><simpara>right rear</simpara></listitem>
<listitem><simpara>center front</simpara></listitem>
</orderedlist>

<orderedlist spacing="compact">
<title>surround 5.1</title>
<listitem override="0"><simpara>left front</simpara></listitem>
<listitem><simpara>right front</simpara></listitem>
<listitem><simpara>left rear</simpara></listitem>
<listitem><simpara>right rear</simpara></listitem>
<listitem><simpara>center front</simpara></listitem>
<listitem><simpara>subwoofer</simpara></listitem>
</orderedlist>

</para>

<para>
The <option>-channels</option> option is used to request the number of
channels from the audio decoder. Some audio codecs use the number of specified
channels to decide if downmixing the source is necessary. Note that this does
not always affect the number of output channels. For example, using
<option>-channels 4</option> to play a stereo MP3 file will still result in
2-channel output since the MP3 codec will not produce the extra channels.
</para>

<para>
The <option>channels</option> audio filter can be used to create or remove
channels and is useful for controlling the number of channels sent to the sound
card. See the following sections for more information on channel manipulation.
</para>

</sect3>


<sect3 id="advaudio-channels-mono">
<title>Playing mono with two speakers</title>

<para>
Mono sounds a lot better when played through two speakers - especially when
using headphones. Audio files that truly have one channel are automatically
played through two speakers; unfortunately, most files with mono sound are
actually encoded as stereo with one channel silent. The easiest and most
foolproof way to make both speakers output the same audio is the
<option>extrastereo</option> filter:

<screen>mplayer <replaceable>filename</replaceable> -af extrastereo=0</screen>

</para>

<para>
This averages both channels, resulting in both channels being half as loud as
the original. The next sections have examples of other ways to do this without a
volume decrease, but they are more complex and require different options
depending on which channel to keep. If you really need to maintain the volume,
it may be easier to experiment with the <option>volume</option> filter and find
the right value. For example:

<screen>mplayer <replaceable>filename</replaceable> -af extrastereo=0,volume=5</screen>

</para>

</sect3>


<sect3 id="advaudio-channels-copying">
<title>Channel copying/moving</title>

<para>
The <option>channels</option> filter can move any or all channels.
Setting up all the suboptions for the <option>channels</option>
filter can be complicated and takes a little care.

<orderedlist spacing="compact">
<listitem><para>
Decide how many output channels you need. This is the first suboption.
</para></listitem>
<listitem><para>
Count how many channel moves you will do. This is the second suboption. Each
channel can be moved to several different channels at the same time, but keep in
mind that when a channel is moved (even if to only one destination) the source
channel will be empty unless another channel is moved into it. To copy a
channel, keeping the source the same, simply move the channel into both the
destination and the source. For example:
<programlisting>
channel 2 --> channel 3
channel 2 --> channel 2
</programlisting>
</para></listitem>
<listitem><para>
Write out the channel copies as pairs of suboptions. Note that the first channel
is 0, the second is 1, etc. The order of these suboptions does not matter as
long as they are properly grouped into
<replaceable>source:destination</replaceable> pairs.
</para></listitem>
</orderedlist>

</para>


<bridgehead>Example: one channel in two speakers</bridgehead>

<para>
Here is an example of another way to play one channel in both speakers. Suppose
for this example that the left channel should be played and the right channel
discarded. Following the steps above:
<orderedlist>
<listitem><para>
In order to provide an output channel for each of the two speakers, the first
suboption must be "2".
</para></listitem>
<listitem><para>
The left channel needs to be moved to the right channel, and also must be moved
to itself so it won't be empty. This is a total of two moves, making the second
suboption "2" as well.
</para></listitem>
<listitem><para>
To move the left channel (channel 0) into the right channel (channel 1), the
suboption pair is "0:1", "0:0" moves the left channel onto itself.
</para></listitem>
</orderedlist>
Putting that all together gives:

<screen>mplayer <replaceable>filename</replaceable> -af channels=2:2:0:1:0:0</screen>
</para>

<para>
The advantage this example has over <option>extrastereo</option> is that the
volume of each output channel is the same as the input channel. The disadvantage
is that the suboptions must be changed to "2:2:1:0:1:1" when the desired audio
is in the right channel. Also, it is more difficult to remember and type.
</para>

<bridgehead>Example: left channel in two speakers shortcut</bridgehead>

<para>
There is actually a much easier way to use the <option>channels</option> filter
for playing the left channel in both speakers:

<screen>mplayer <replaceable>filename</replaceable> -af channels=1</screen>

The second channel is discarded and, with no further suboptions, the single
remaining channel is left alone. Sound card drivers automatically play
single-channel audio in both speakers. This only works when the desired channel
is on the left.
</para>

<bridgehead>Example: duplicate front channels to the rear</bridgehead>
<para>
Another common operation is to duplicate the front channels and play them back
on the rear speakers of a quadraphonic setup.
<orderedlist>
<listitem><para>
There should be four output channels. The first suboption is "4".
</para></listitem>
<listitem><para>
Each of the two front channels needs to be moved to the corresponding rear
channel and also to itself. This is four moves, so the second suboption is "4".
</para></listitem>
<listitem><para>
The left front (channel 0) needs to moved to the left rear (channel 2): "0:2".
The left front also needs to be moved to itself: "0:0". The right front (channel
1) is moved to the right rear (channel 3): "1:3", and also to itself: "1:1".
</para></listitem>
</orderedlist>
Combine all the suboptions to get:

<screen>mplayer <replaceable>filename</replaceable> -af channels=4:4:0:2:0:0:1:3:1:1</screen>

</para>

</sect3>


<sect3 id="advaudio-channels-mixing">
<title>Channel mixing</title>

<para>
The <option>pan</option> filter can mix channels in user-specified proportions.
This allows for everything the <option>channels</option> filter can do and
more. Unfortunately, the suboptions are much more complicated.
<orderedlist>
<listitem><para>
Decide how many channels to work with. You may need to specify this with
<option>-channels</option> and/or <option>-af channels</option>. Later examples
will show when to use which.
</para></listitem>
<listitem><para>
Decide how many channels to feed into <option>pan</option> (further decoded
channels are discarded). This is the first suboption, and it also controls how
many channels to employ for output.
</para></listitem>
<listitem><para>
The remaining suboptions specify how much of each channel gets mixed into each
other channel. This is the complicated part. To break the task down, split the
suboptions into several sets, one set for each output channel. Each suboption
within a set corresponds to an input channel. The number you specify will be the
percentage of the input channel that gets mixed into the output channel.
</para>
<para>
<option>pan</option> accepts values from 0 to 512, yielding 0% to 51200% of the
original volume. Be careful when using values greater than 1. Not only can this
give you very high volume, but if you exceed the sample range of your sound card
you may hear painful pops and clicks. If you want you can follow
<option>pan</option> with <option>,volume</option> to enable clipping, but it is
best to keep the values of <option>pan</option> low enough that clipping is not
necessary.
</para></listitem>
</orderedlist>
</para>

<bridgehead>Example: one channel in two speakers</bridgehead>

<para>
Here is yet another example for playing the left channel in two speakers. Follow
the steps above:
<orderedlist>
<listitem><para>
<option>pan</option> should output two channels, so the first
suboption is "2".
</para></listitem>
<listitem><para>
Since we have two input channels, there will be two sets of suboptions.
Since there are also two output channels,
there will be two suboptions per set.
The left channel from the file should go with full volume to
the new left and the right channels.
Thus the first set of suboptions is "1:1".
The right channel should be discarded, so the second would be "0:0".
Any 0 values at the end can be left out, but for ease of
understanding we will keep them.
</para></listitem>
</orderedlist>
Putting those options together gives:

<screen>mplayer <replaceable>filename</replaceable> -af pan=2:1:1:0:0</screen>

If the right channel is desired instead of the left, the suboptions to
<option>pan</option> will be "2:0:0:1:1".
</para>


<bridgehead>Example: left channel in two speakers shortcut</bridgehead>

<para>
As with <option>channels</option>, there is a shortcut that only works with the
left channel:

<screen>mplayer <replaceable>filename</replaceable> -af pan=1:1</screen>

Since <option>pan</option> has only one channel of input (the other channel is
discarded), there is only one set with one suboption, which specifies that the
only channel gets 100% of itself.
</para>

<bridgehead>Example: downmixing 6-channel PCM</bridgehead>
<para>
<application>MPlayer</application>'s decoder for 6-channel PCM is not capable of
downmixing. Here is a way to downmix PCM using <option>pan</option>:
<orderedlist>
<listitem><para>
The number of output channels is 2, so the first suboption is "2".
</para></listitem>
<listitem><para>
With six input channels there will be six sets of options. Fortunately,
since we only care about the output of the first two channels, we only need to
make two sets; the remaining four sets can be omitted. Beware that not all
multichannel audio files have the same channel order! This example
demonstrates downmixing a file with the same channels as AC3 5.1:
<programlisting>
0 - front left
1 - front right
2 - rear left
3 - rear right
4 - center front
5 - subwoofer
</programlisting>
The first set of suboptions lists the percentages of the original volume, in
order, which each output channel should receive from the
front left channel: "1:0".
The front right channel should go into the right output: "0:1".
The same for the rear channels: "1:0" and "0:1".
The center channel goes into both output channels with half volume:
"0.5:0.5", and the subwoofer goes into both with full volume: "1:1".
</para></listitem>
</orderedlist>
Put all that together, for:

<screen>mplayer <replaceable>6-channel.wav</replaceable> -af pan=2:1:0:0:1:1:0:0:1:0.5:0.5:1:1</screen>

The percentages listed above are only a rough example. Feel free to tweak them.
</para>

<bridgehead>Example: Playing 5.1 audio on big speakers without a subwoofer</bridgehead>

<para>
If you have a huge pair of front speakers you may not want to waste any money on
buying a subwoofer for a complete 5.1 sound system. If you use
<option>-channels 5</option> to request that liba52 decode 5.1 audio in 5.0,
the subwoofer channel is simply discarded. If you want to distribute the
subwoofer channel yourself you need to downmix manually with
<option>pan</option>:

<orderedlist>
<listitem><para>
Since <option>pan</option> needs to examine all six channels, specify
<option>-channels 6</option> so liba52 decodes them all.
</para></listitem>
<listitem><para>
<option>pan</option> outputs to only five channels, the first suboption is 5.
</para></listitem>
<listitem><para>
Six input channels and five output channels means six sets of five suboptions.
  <itemizedlist spacing="compact">
  <listitem><simpara>
  The left front channel only replicates onto itself:
  "1:0:0:0:0"
  </simpara></listitem>
  <listitem><simpara>
  Same for the right front channel:
  "0:1:0:0:0"
  </simpara></listitem>
  <listitem><simpara>
  Same for the left rear channel:
  "0:0:1:0:0"
  </simpara></listitem>
  <listitem><simpara>
  And also the same for the right rear channel:
  "0:0:0:1:0"
  </simpara></listitem>
  <listitem><simpara>
  Center front, too:
  "0:0:0:0:1"
  </simpara></listitem>
  <listitem><simpara>
  And now we have to decide what to do with the subwoofer,
  e.g. half into front right and front left:
  "0.5:0.5:0:0:0"
  </simpara></listitem>
  </itemizedlist>
</para></listitem>
</orderedlist>
Combine all those options to get:

<screen>mplayer <replaceable>dvd://1</replaceable> -channels 6 -af pan=5:1:0:0:0:0:0:1:0:0:0:0:0:1:0:0:0:0:0:1:0:0:0:0:0:1:0.5:0.5:0:0:0</screen>

</para>

</sect3>

</sect2>


<sect2 id="advaudio-volume">
<title>Software Volume adjustment</title>

<para>
Some audio tracks are too quiet to be heard comfortably without amplification.
This becomes a problem when your audio equipment cannot amplify the signal for
you. The <option>-softvol</option> option directs
<application>MPlayer</application> to use an internal mixer. You can then use
the volume adjustment keys (by default <keycap>9</keycap> and
<keycap>0</keycap>) to reach much higher volume levels. Note that this does not
bypass your sound card's mixer; <application>MPlayer</application> only
amplifies the signal before sending it to your sound card.

The following example is a good start:

<screen>mplayer <replaceable>quiet-file</replaceable> -softvol -softvol-max 300</screen>

The <option>-softvol-max</option> option specifies the maximum allowable output
volume as a percentage of the
original volume. For example, <option>-softvol-max 200</option> would allow the
volume to be adjusted up to twice its original level.
It is safe to specify a large value with
<option>-softvol-max</option>; the higher volume will not be used until you
use the volume adjustment keys. The only disadvantage of a large value is that,
since <application>MPlayer</application> adjusts volume by a percentage of the
maximum, you will not have as precise control when using the volume adjustment
keys. Use a lower value with <option>-softvol-max</option> and/or specify
<option>-volstep 1</option> if you need higher precision.
</para>

<para>
The <option>-softvol</option> option works by controlling the
<option>volume</option> audio filter. If you want to play a file at a certain
volume from the beginning you can specify <option>volume</option> manually:

<screen>mplayer <replaceable>quiet-file</replaceable> -af volume=10</screen>

This will play the file with a ten decibel gain. Be careful when using the
<option>volume</option> filter - you could easily hurt your ears if you use
too high a value. Start low and work your way up gradually until you get a feel
for how much adjustment is required. Also, if you specify excessively high
values, <option>volume</option> may need to clip the signal to avoid sending your
sound card data that is outside the allowable range; this will result in
distorted audio.
</para>

</sect2>

</sect1>

</chapter>
