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<P><B><A NAME=2.3.2>2.3.2. Audio output devices</A></P></B>
<P><B>MPlayer</B>'s audio interface is called <I>libao2</I>. It currently
contains these drivers :</P>
<TABLE BORDER=0>
<TD COLSPAN=4><P><B><FONT CLASS="text">General:</B></P></TD>
<TR><TD> </TD><TD VALIGN=top><FONT CLASS="text">oss</TD><TD> </TD><TD><FONT CLASS="text">OSS (ioctl) driver</TD></TR>
<TR><TD></TD><TD VALIGN=top><FONT CLASS="text">sdl</TD><TD></TD><TD><FONT CLASS="text">SDL driver (supports up/downsampling, <B>ESD</B>, <B>ARTS</B> etc)</TD></TR>
<TR><TD></TD><TD VALIGN=top><FONT CLASS="text">nas</TD><TD></TD><TD><FONT CLASS="text">NAS (Network Audio System) driver</TD></TR>
<TR><TD></TD><TD VALIGN=top><FONT CLASS="text">alsa5</TD><TD></TD><TD><FONT CLASS="text">native ALSA 0.5 driver</TD></TR>
<TR><TD></TD><TD VALIGN=top><FONT CLASS="text">alsa9</TD><TD></TD><TD><FONT CLASS="text">native ALSA 0.9 driver (works, but has problems -> use OSS)</TD></TR>
<TR><TD></TD><TD VALIGN=top><FONT CLASS="text">sun</TD><TD></TD><TD><FONT CLASS="text">SUN audio driver (/dev/audio) for BSD and Solaris8 users</TD></TR>
</TABLE>
<P>The fact is, Linux soundcard drivers are usually bad, and always as
incompatible as they can be. It MAY take a while to find your optimal settings.</P>
<P><UL>
<LI>if you have OSS as driver, first try with <I>-ao oss</I> (this is the default).
If you experience glitches, halts or anything out of the ordinary, have a
look at <I>-ao sdl</I> (NOTE: of course you'll have to have a new SDL library and its
devel pair installed). It helps in a lot of cases (it also supports ESD, ARTS, and
up/downsampling. /esd is GNOME's, arts is KDE's sound daemon/).</LI>
<LI>if you have ALSA version 0.5, then you ALMOST always have to use <I>-ao alsa5</I> ,
since 0.5 has buggy OSS emulation code, and will <B>crash MPlayer</B> with
a message like this:<BR>
<UL>
<CODE>DEMUXER: Too many (945 in 8390980 bytes) video packets in the buffer!</CODE></UL>
</LI>
<LI>if you have ALSA version 0.9, use <I>-ao oss</I> or <I>-ao sdl</I> as you
wish. You can also use <I>-ao alsa9</I> as it works now, however it has many
problems (losing sync, disappearing audio, etc).</LI>
</UL></P>
<P>On <B>Solaris/FreeBSD</B> systems, use the SUN audio driver with the
<I>-ao sun</I> option, otherwise you'll have no video, nor audio playing.</P>
<P><B><A NAME=2.3.2.1>2.3.2.1. Soundcard experiences, recommendations</A></B></P>
<P><TABLE BORDER=0 WIDTH=100%>
<TD COLSPAN=3><B><FONT CLASS="text">VIA onboard chipset (via82cxxx) 48Khz only</B></TD><TR>
<TD></TD><TD><FONT CLASS="text">Driver:</TD><TD><FONT CLASS="text"> from <A HREF="http://sourceforge.net/project/showfiles.php?group_id=3242&release_id=59602">here</A></TD><TR>
<TD COLSPAN=3><B><FONT CLASS="text">Aureal Vortex 2</B></TD><TR>
<TD> </TD><TD><FONT CLASS="text">OSS:</TD><TD><FONT CLASS="text">no driver</TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS/Pro:</TD><TD><FONT CLASS="text">OK</TD><TR>
<TD></TD><TD><FONT CLASS="text">ALSA:</TD><TD><FONT CLASS="text">no driver</TD><TR>
<TD></TD><TD><FONT CLASS="text">Max kHz:</TD><TD>48</TD><TR>
<TD></TD><TD><FONT CLASS="text">Driver:</TD><TD><FONT CLASS="text"><A HREF="http://aureal.sourceforge.net">aureal.sourceforge.net</A></TD><TR>
<TD></TD><TD><FONT CLASS="text">Driver2:</TD><TD><FONT CLASS="text"> from <A HREF="http://makacs.poliod.hu/~pontscho/aureal/au88xx-1.1.3.tar.bz2">here</A><BR>
(<I>buffer size increased to 32k</I>)</TD><TR>
<TD COLSPAN=3><B><FONT CLASS="text">GUS PnP</B></TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS:</TD><TD><FONT CLASS="text">no driver</TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS/Pro:</TD><TD><FONT CLASS="text">OK</TD><TR>
<TD></TD><TD><FONT CLASS="text">ALSA:</TD><TD><FONT CLASS="text">OK</TD><TR>
<TD></TD><TD><FONT CLASS="text">Max kHz:</TD><TD><FONT CLASS="text">48</TD><TR>
<TD COLSPAN=3><B><FONT CLASS="text">SB Live!</B></TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS:</TD><TD><FONT CLASS="text">HW AC3 won't work</TD><TR>
<TD></TD><TD><FONT CLASS="text">ALSA:</TD><TD><FONT CLASS="text">OK</TD><TR>
<TD></TD><TD><FONT CLASS="text">Max kHz:</TD><TD><FONT CLASS="text">48</TD><TR>
<TD COLSPAN=3><B><FONT CLASS="text">SB AWE 64</B></TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS:</TD><TD><FONT CLASS="text">max 44kHz</TD><TR>
<TD></TD><TD><FONT CLASS="text">ALSA:</TD><TD><FONT CLASS="text">48kHz sounds shit</TD><TR>
<TD></TD><TD><FONT CLASS="text">Max kHz:</TD><TD><FONT CLASS="text">48</TD><TR>
<TD COLSPAN=3><B><FONT CLASS="text">Gravis UltraSound ACE</B></TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS:</TD><TD><FONT CLASS="text">not OK</TD><TR>
<TD></TD><TD><FONT CLASS="text">ALSA:</TD><TD><FONT CLASS="text">OK</TD><TR>
<TD></TD><TD><FONT CLASS="text">Max kHz:</TD><TD><FONT CLASS="text">44</TD><TR>
<TD COLSPAN=3><B><FONT CLASS="text">Gravis UltraSound MAX</B></TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS:</TD><TD><FONT CLASS="text">OK</TD><TR>
<TD></TD><TD><FONT CLASS="text">ALSA:</TD><TD><FONT CLASS="text">OK (?)</TD><TR>
<TD></TD><TD><FONT CLASS="text">Max kHz:</TD><TD><FONT CLASS="text">48</TD><TR>
<TD COLSPAN=3><B><FONT CLASS="text">ESS 688</B></TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS:</TD><TD><FONT CLASS="text">OK</TD><TR>
<TD></TD><TD><FONT CLASS="text">ALSA:</TD><TD><FONT CLASS="text">OK (?)</TD><TR>
<TD></TD><TD><FONT CLASS="text">Max kHz:</TD><TD><FONT CLASS="text">48</TD><TR>
<TD COLSPAN=3><B><FONT CLASS="text">C-Media cards (which ones?)</B></TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS:</TD><TD><FONT CLASS="text">not OK (hissing) (?)</TD><TR>
<TD></TD><TD><FONT CLASS="text">ALSA:</TD><TD><FONT CLASS="text">OK (?)</TD><TR>
<TD></TD><TD><FONT CLASS="text">Max kHz:</TD><TD><FONT CLASS="text">?</TD><TR>
<TD COLSPAN=3><B><FONT CLASS="text">Yamaha cards (*ymf*)</B></TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS:</TD><TD><FONT CLASS="text">not OK (?) (maybe -ao sdl)</TD><TR>
<TD></TD><TD><FONT CLASS="text">ALSA:</TD><TD><FONT CLASS="text">OK only with ALSA 0.5 with OSS emulation <B>AND</B> <I>-ao sdl</I> (!) (?)</TD><TR>
<TD></TD><TD><FONT CLASS="text">Max kHz:</TD><TD><FONT CLASS="text">?</TD><TR>
<TD COLSPAN=3><B><FONT CLASS="text">Cards with envy24 chips (like Terratec EWS88MT)</B></TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS:</TD><TD><FONT CLASS="text">?</TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS/Pro:</TD><TD><FONT CLASS="text">OK</TD><TR>
<TD></TD><TD><FONT CLASS="text">ALSA:</TD><TD><FONT CLASS="text">?</TD><TR>
<TD></TD><TD><FONT CLASS="text">Max kHz:</TD><TD><FONT CLASS="text">?</TD><TR>
<TD COLSPAN=3><B><FONT CLASS="text">PC Speaker or DAC</B></TD><TR>
<TD></TD><TD><FONT CLASS="text">OSS:</TD><TD><FONT CLASS="text">OK (<I>use the SDL driver : -ao sdl</I>)</TD><TR>
<TD></TD><TD><FONT CLASS="text">ALSA:</TD><TD><FONT CLASS="text">no driver</TD><TR>
<TD></TD><TD><FONT CLASS="text">Max kHz:</TD><TD><FONT CLASS="text">the driver emulates 44.1 maybe more</TD><TR>
<TD></TD><TD><FONT CLASS="text">Driver:</TD><TD><FONT CLASS="text"><A HREF="ftp://ftp.infradead.org/pub/pcsp">ftp://ftp.infradead.org/pub/pcsp</A></TD><TR>
</TABLE></P>
<P><UL>
<LI>on Linux, use at least kernel 2.4 if possible, 2.2 isn't tested
<LI>if sound clicks when playing from CD-ROM, turn on IRQ unmasking !
for example "hdparm -u1 /dev/cdrom" (see "man hdparm" !!!)
This is recommended anyways... (for XMMS, etc...)
Read section <A HREF="cd-dvd.html#4.1">4.1</A>.
<LI>don't use your soundcard by other application ( for ex. XMMS ) !
if you use ESD, start MPlayer with the '-vo sdl:esd' option !
<LI>Please tell us how MPlayer and your soundcard(s) worked together!
</UL></P>
<P><B><A NAME=2.3.2.2>2.3.2.2. Audio plugins</A></B></P>
<P><B>MPlayer</B> has support for audio plugins. Audio plugins can be used for
changing the properties of the audio data before the sound reaches the sound
card. They are enabled using the <CODE>-aop</CODE> switch followed by the
<CODE>list=plugin1,plugin2,...</CODE> switch. The <CODE>list</CODE> switch is
required and determines which plugins that should be used and in which order
they should be executed, example:
</P>
<P> <CODE>mplayer media.avi -aop list=resample,format</CODE></P>
<P>would run the sound through the resampling plugin followed by the format
plugin.
</P>
<P>The plugins can also have switches that changes their behaviour. These
switches are explained in detail in the sections below. A plugin will execute
using default settings if it's switches are omitted. Example of how to use
plugins in combination with plugin specific switches:
</P>
<P> <CODE>mplayer media.avi -aop
list=resample,format:fout=48000:format=0x8</CODE>
</P>
<P>would set the output frequency of the resample plugin to 44100Hz and the
output format of the format plugin to AFMT_U8.
</P>
<P>Currently audio plugins can not be used in <B>MEncoder</B>.</P>
<P><B><A NAME=2.3.2.2.1>2.3.2.2.1. Up/Downsampling</A></B></P>
<P><B>MPlayer</B> fully supports up/down sampling of the sound. This plugin can
for example be used if you have a fixed frequency sound card or if you are
stuck with an olqd sound card that is only capable of max 44.1kHz.
Limitations in your hardware are not auto detected, so you have to specify
the sample frequency explicitly. This plugin has one switch:
<CODE>fout</CODE> which is used for setting the desired output sample
frequency, it defaults to 48kHz, and is given in
<Hz>.
</P>
<P>Usage :<BR>
<CODE>mplayer media.avi -aop list=resample:fout=<required
frequency in Hz, like 44100></CODE></P>
<P><B><A NAME=2.3.2.2.2>2.3.2.2.2. Surround Sound decoding</A></B></P>
<P><B>MPlayer</b> has an audio plugin that can decode matrix encoded
surround sound. Dolby Surround is an example of a matrix encoded format.</p>
<P>Many files with 2 channel audio actually contain matrixed surround
sound.</p>
<P>To use this feature, you will need a sound-card supporting at least 4 channels.</P>
<P>Usage :<BR>
<CODE>mplayer media.avi -aop list=surround</CODE></P>
<P><B><A NAME=2.3.2.2.3>2.3.2.2.3. Sample format converter</A></B></P>
<P>If your sound card driver doesn't support signed 16bit int, this plugin can
be used to change the format to one which your sound card can understand. It
has one switch <CODE>format</CODE> which can be set to one of the numbers
found in libao2/afmt.h. This plugin is hardly ever needed and is intended for
advanced users. Observe that this plugin only changes the sample format and
not the sample frequency or the number of channels.
</P>
<P>Usage :<BR>
<CODE>mplayer media.avi -aop
list=format:format=<required output format></CODE>
</P>
<P><B><A NAME=2.3.2.2.4>2.3.2.2.4. Delay</A></B></P>
<P>This plugin delays the sound and is intended as an example of how to develop
new plugins. It can not be used for anything useful from users perspective
and is mentioned here for the sake of completeness only. Do not use this
plugin unless you are a developer.</P>
<P><B><A NAME=2.3.2.2.5>2.3.2.2.5. Software volume control</A></B></P>
<P>This plugin is a software replacement for the volume control, and
can be used in machines with broken mixer device. It can also be
used if one wants to change the output volume from <B>MPlayer</B>
without changing the PCM volume setting in the mixer. It has one
switch <CODE>volume</CODE> that is used for setting the initial
sound level. The initial sound level can be set to values between 0
and 255 and defaults to 255. Use this plugin with caution since it
can reduce the signal to noise ratio of the sound. In most cases it
is best to set the level for the PCM sound to max, leave this plugin
out and control the output level to your speakers with the mixers
master volume control. If there is an external amplifier connected
to the computer (this is almost always the case), the noise level
can be minimized by adjusting the master level and the volume knob
on the amplifier until the hissing noise in the background is gone.
</P>
<P>Usage :<BR>
<CODE>mplayer media.avi -aop
list=volume:volume=<0-255></CODE>
</P>
<P><B><A NAME=2.3.2.2.6>2.3.2.2.6. Extrastereo</A></B></P>
<P>This plugin increases (linearly) the difference between left and right
channels (as the XMMS extrastereo plugin) which has some of "live" effect
on playback.
</P>
<P>Usage :<BR>
<CODE>mplayer media.avi -aop list=extrastereo</CODE><BR>
<CODE>mplayer media.avi -aop list=extrastereo:mul=3.45</CODE></P>
<P>The default coefficient (<CODE>mul</CODE>) is a float number that defaults
to 2.5. If you set it to 0.0, you will have a mono sound (average of both
channels), if you set it to 1.0, sound will be unchanged.</P>
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