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<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>7.2.Audio codecs</title><link rel="stylesheet" href="default.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.68.1"><link rel="start" href="index.html" title="MPlayer - The Movie Player"><link rel="up" href="codecs.html" title="Chapter7.Codecs"><link rel="prev" href="video-codecs.html" title="7.1.Video codecs"><link rel="next" href="codec-importing.html" title="7.3.Win32 codecs importing HOWTO"><link rel="preface" href="howtoread.html" title="How to read this documentation"><link rel="chapter" href="intro.html" title="Chapter1.Introduction"><link rel="chapter" href="install.html" title="Chapter2.Installation"><link rel="chapter" href="usage.html" title="Chapter3.Usage"><link rel="chapter" href="cd-dvd.html" title="Chapter4.CD/DVD usage"><link rel="chapter" href="faq.html" title="Chapter5.Frequently Asked Questions"><link rel="chapter" href="containers.html" title="Chapter6.Containers"><link rel="chapter" href="codecs.html" title="Chapter7.Codecs"><link rel="chapter" href="video.html" title="Chapter8.Video output devices"><link rel="chapter" href="audio.html" title="Chapter9.Audio output devices"><link rel="chapter" href="tv.html" title="Chapter10.TV"><link rel="chapter" href="radio.html" title="Chapter11.Radio"><link rel="chapter" href="ports.html" title="Chapter12.Ports"><link rel="chapter" href="mencoder.html" title="Chapter13.Basic usage of MEncoder"><link rel="chapter" href="encoding-guide.html" title="Chapter14.Encoding with MEncoder"><link rel="appendix" href="bugreports.html" title="AppendixA.How to report bugs"><link rel="appendix" href="bugs.html" title="AppendixB.Known bugs"><link rel="appendix" href="skin.html" title="AppendixC.MPlayer skin format"><link rel="appendix" href="history.html" title="AppendixD.History"><link rel="subsection" href="audio-codecs.html#swac3" title="7.2.1.Software AC3 decoding"><link rel="subsection" href="audio-codecs.html#hwac3" title="7.2.2.Hardware AC3 decoding"><link rel="subsection" href="audio-codecs.html#libmad" title="7.2.3.libmad support"><link rel="subsection" href="audio-codecs.html#hwmpa" title="7.2.4.Hardware MPEG audio codec"><link rel="subsection" href="audio-codecs.html#aac" title="7.2.5.AAC codec"><link rel="subsection" href="audio-codecs.html#amr" title="7.2.6.AMR codecs"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">7.2.Audio codecs</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="video-codecs.html">Prev</a></td><th width="60%" align="center">Chapter7.Codecs</th><td width="20%" align="right"><a accesskey="n" href="codec-importing.html">Next</a></td></tr></table><hr></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="audio-codecs"></a>7.2.Audio codecs</h2></div></div></div><div class="itemizedlist"><p class="title"><b>The most important audio codecs above all:</b></p><ul type="disc"><li>
MPEG layer 1/2/3 (MP1/2/3) audio (<span class="bold"><strong>native</strong></span>
code, with MMX/SSE/3DNow! optimization)
</li><li>
Windows Media Audio 7 and 8 (AKA WMAv1 and WMAv2) (<span class="bold"><strong>native</strong></span> code, with
<a href="video-codecs.html#ffmpeg" title="7.1.1.FFmpeg/libavcodec"><code class="systemitem">libavcodec</code></a>)
</li><li>
Windows Media Audio 9 (WMAv3) (using DMO DLL)
</li><li>
AC3 Dolby audio (<span class="bold"><strong>native</strong></span> code, with
MMX/SSE/3DNow! optimization)
</li><li>
AC3 passing through sound card hardware
</li><li>
AAC
</li><li>
Ogg Vorbis audio codec (<span class="bold"><strong>native</strong></span> library)
</li><li>
RealAudio: DNET (low bitrate AC3), Cook, Sipro and ATRAC3
</li><li>
QuickTime: Qualcomm and QDesign audio codecs
</li><li>
VIVO audio (g723, Vivo Siren)
</li><li>
Voxware audio (using DirectShow DLL)
</li><li>
alaw and ulaw, various gsm, adpcm and pcm formats and other simple old
audio codecs
</li><li>
Adaptive Multi-Rate (AMR) speech codecs
</li></ul></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="swac3"></a>7.2.1.Software AC3 decoding</h3></div></div></div><p>
This is the default decoder used for files with AC3 audio.
</p><p>
The AC3 decoder can create audio output mixes for 2, 4, or 6 speakers.
When configured for 6 speakers, this decoder provides separate output of
all the AC3 channels to the sound driver, allowing for full "surround
sound" experience without the external AC3 decoder required to use the
hwac3 codec.
</p><p>
Use the <tt class="option">-channels</tt> option to select the number of output
channels. Use <tt class="option">-channels 2</tt> for a stereo downmix. For a 4
channel downmix (Left Front, Right Front, Left Surround and Right Surround
outputs), use <tt class="option">-channels 4</tt>. In this case, any center
channel will be mixed equally to the front channels. <tt class="option">-channels
6</tt> will output all the AC3 channels as they are encoded - in the
order Left, Right, Left Surround, Right Surround, Center and LFE.
</p><p>
The default number of output channels is 2.
</p><p>
To use more than 2 output channels, you will need to use OSS, and have a
sound card that supports the appropriate number of output channels via the
SNDCTL_DSP_CHANNELS ioctl. An example of a suitable driver is emu10k1
(used by Soundblaster Live! cards) from August 2001 or newer (ALSA CVS is
also supposed to work).
</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="hwac3"></a>7.2.2.Hardware AC3 decoding</h3></div></div></div><p>
You need an AC3 capable sound card, with digital out (S/PDIF). The card's
driver must properly support the AFMT_AC3 format (C-Media does). Connect
your AC3 decoder to the S/PDIF output, and use the <tt class="option">-ac
hwac3</tt> option. It is experimental but known to work with C-Media
cards and Soundblaster Live! + ALSA (but not OSS) drivers and DXR3/Hollywood+
MPEG decoder cards.
</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="libmad"></a>7.2.3.libmad support</h3></div></div></div><p>
<a href="http://www.underbit.com/products/mad/" target="_top">libmad</a> is a multiplatform,
integer (internally 24bit PCM) only
MPEG audio decoding library. It does not handle broken files well, and it
sometimes has problems with seeking, but it may perform better on FPU-less
(such as <a href="linux.html#arm" title="12.1.3.ARM">ARM</a>) platform than mp3lib.
</p><p>
If you have a proper installation of libmad, <tt class="filename">configure</tt>
will notice and support for MPEG audio decoding via
<code class="systemitem">libmad</code> will be built automatically.
</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="hwmpa"></a>7.2.4.Hardware MPEG audio codec</h3></div></div></div><p>
This codec (selected by -ac hwmpa) passes through MPEG audio packets
to hardware decoders, such as the ones found in full-featured DVB cards
and DXR2 adapters.
Don't use it in combination with any other audio output device
(such as OSS and ALSA) that isn't able to decode it (you will hear
only white noise).
</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="aac"></a>7.2.5.AAC codec</h3></div></div></div><p>
AAC (Advanced Audio Coding) is an audio codec sometimes found in MOV and MP4
files. An open source decoder called FAAD is available from
<a href="http://www.audiocoding.com" target="_top">http://www.audiocoding.com</a>.
<span class="application">MPlayer</span> includes a CVS snapshot of libfaad 2.1
beta, so you do not need to get it separately.
</p><p>
If you use gcc 3.2 which fails to compile our internal FAAD or want to use
the external library for some other reason, download the library from the
<a href="http://www.audiocoding.com/modules/mydownloads/" target="_top">download page</a>
and pass <tt class="option">--enable-faad-external</tt> to <tt class="filename">configure</tt>.
You do not need all of faad2 to decode AAC files, libfaad is enough. Build
it like this:
</p><pre class="screen">
cd faad2/
sh bootstrap
./configure
cd libfaad
make
make install
</pre><p>
Binaries are not available from audiocoding.com, but you can (apt-)get Debian
packages from <a href="http://www.debian-multimedia.org/" target="_top">Christian Marillat's homepage</a>,
Mandrake/Mandriva RPMs from the <a href="http://plf.zarb.org" target="_top">P.L.F</a> and RedHat RPMs
from <a href="http://greysector.rangers.eu.org/" target="_top">Grey Sector</a>.
</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="amr"></a>7.2.6.AMR codecs</h3></div></div></div><p>
Adaptive Multi-Rate speech codec is used in third generation (3G) mobile
phones.
Reference implementation is available from
<a href="http://www.3gpp.org" target="_top">The 3rd Generation Partnership Project</a>
(free for private use).
</p><p>
To enable support, download the sources for
<a href="http://www.3gpp.org/ftp/Specs/latest/Rel-6/26_series/26104-610.zip" target="_top">AMR-NB</a>
and
<a href="http://www.3gpp.org/ftp/Specs/latest/Rel-6/26_series/26204-600.zip" target="_top">AMR-WB</a>
codecs, put them in the directory where you unpacked the
<span class="application">MPlayer</span> source and run the following commands:
</p><pre class="screen">
unzip 26104-610.zip
unzip 26104-610_ANSI_C_source_code.zip
mv c-code libavcodec/amr_float
unzip 26204-600.zip
unzip 26204-600_ANSI-C_source_code.zip
mv c-code libavcodec/amrwb_float
</pre><p>
After that, follow the usual <span class="application">MPlayer</span>
<a href="features.html" title="2.4.Features">build procedure</a>.
</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="video-codecs.html">Prev</a></td><td width="20%" align="center"><a accesskey="u" href="codecs.html">Up</a></td><td width="40%" align="right"><a accesskey="n" href="codec-importing.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">7.1.Video codecs</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">7.3.Win32 codecs importing HOWTO</td></tr></table></div></body></html>
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