path: root/DOCS/xml/en/mencoder.xml

<?xml version="1.0" encoding="iso-8859-1"?>
<chapter id="mencoder">
<title>Encoding with MEncoder</title>

<para>
For the complete list of available <application>MEncoder</application> options
and examples, please see the man page. For a series of hands-on examples and
detailed guides on using several encoding parameters, read the
<ulink url="../../tech/encoding-tips.txt">encoding-tips</ulink> that were
collected from several mailing list threads on mplayer-users. Search the
<ulink url="http://mplayerhq.hu/pipermail/mplayer-users/">archives</ulink>
for a wealth of discussions about all aspects of and problems related to
encoding with <application>MEncoder</application>.
</para>

<sect1 id="menc-feat-divx4">
<title>Encoding 2 or 3-pass MPEG-4 (&quot;DivX&quot;)</title>

<formalpara>
<title>2-pass encoding</title>
<para>
The name comes from the fact that this method encodes the file <emphasis>twice</emphasis>.
The first encoding (dubbed pass) creates some temporary files
(<filename>*.log</filename>) with a size of few megabytes, do not delete
them yet (you can delete the AVI). In the second pass, the 2-pass output
file is created, using the bitrate data from the temporary files. The
resulting file will have much better image quality. If this is the first
time you heard about this, you should consult some guides available on the
Net.
</para>
</formalpara>

<para>
This example shows how to encode a DVD to a 2-pass MPEG-4 (&quot;DivX&quot;) AVI.
Just two commands are needed:
<screen>rm frameno.avi</screen>
remove this file, which can come from a previous 3-pass encoding (it interferes
with current one)
<screen>
mencoder -dvd 2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=1 -oac copy -o movie.avi
mencoder -dvd 2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2 -oac copy -o movie.avi
</screen>
</para>

<formalpara>
<title>3-pass encoding</title>
<para>
This is an extension of 2-pass encoding, where the audio encoding takes
place in a separate pass. This method enables estimation of recommended
video bitrate in order to fit on a CD. Also, the audio is encoded only
once, unlike in 2-pass mode. The schematics:
</para>
</formalpara>

<procedure>
<step><para>
  Remove conflicting temporary file:
  <screen>rm frameno.avi</screen>
  </para></step>
<step><para>
  <emphasis>First pass:</emphasis>

  <screen>mencoder <replaceable>file/DVD</replaceable> -ovc frameno -oac mp3lame -lameopts vbr=3 -o frameno.avi</screen>
  
  An audio-only avi file will be created, containing
  <emphasis role="bold">only</emphasis> the requested audio stream. Don't forget
  <option>-lameopts</option>, if you need to set it. If you were encoding a
  long movie, <application>MEncoder</application> prints the recommended
  bitrate values for 650Mb, 700Mb, and 800Mb destination sizes, after this
  pass finishes.
  </para></step>
<step><para>
  <emphasis>Second pass:</emphasis>
  <screen>
mencoder <replaceable>file/DVD</replaceable> -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vpass=1:vbitrate=<replaceable>bitrate</replaceable><!--
--></screen>
This is the first pass of video encoding. Optionally specify the video
bitrate MEncoder printed at the end of the previous pass.
  </para></step>
<step><para>
  <emphasis>Third pass:</emphasis>
<screen>
mencoder <replaceable>file/DVD</replaceable> -oac copy -pass 2 \
         -ovc divx4 -divx4opts br=<replaceable>bitrate</replaceable>
</screen>
This is the second pass of video encoding. Specify the same bitrate
as in the previous pass unless you really know what you are doing.
In this pass, audio from <filename>frameno.avi</filename> will be
inserted into the destination file...and it's all ready!
</para></step>
</procedure>

<example>
<title>Example of 3-pass encoding</title>
<para>
<screen>rm frameno.avi</screen>
remove this file, which can come from a previous 3-pass encoding
(it interferes with current one)
<screen>
mencoder -dvd 2 -ovc frameno -o frameno.avi -oac mp3lame -lameopts vbr=3
mencoder -dvd 2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=1 -oac copy -o movie.avi
mencoder -dvd 2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2 -oac copy -o movie.avi
</screen>
</para>
</example>
</sect1>

<sect1 id="menc-feat-mpeg">
<title>Encoding to MPEG format</title>
<para>
<application>MEncoder</application> can create MPEG (MPEG-PS) format output
files. It's probably useful only with libavcodec's <emphasis>mpeg1video</emphasis>
codec, because players - except <application>MPlayer</application> - expect MPEG1
video, and MPEG1 layer 2 (MP2) audio streams in MPEG files.
</para>

<para>
this feature is not very useful right now, aside that it probably has many bugs,
but the more importantly because MEncoder currently cannot encode MPEG1 layer 2
(MP2) audio, which all other players expect in MPEG files.
</para>

<para>
To change MEncoder's output file format, use the <option>-of mpeg</option> option.
</para>

<para>
Example:
<screen>
mencoder -of mpeg -ovc lavc -lavcopts vcodec=mpeg1video -oac copy <replaceable>other options</replaceable> media.avi -o output.mpg
</screen>
</para>
</sect1>


<sect1 id="menc-feat-rescale">
<title>Rescaling movies</title>

<para>
Often the need to resize movie images' size emerges. Its reasons can be
many: decreasing file size, network bandwidth,etc. Most people even do
rescaling when converting DVDs or SVCDs to DivX AVI. This is <emphasis role="bold">bad</emphasis>.
Instead of even you doing so, read the <link linkend="aspect">Preserving aspect ratio</link>
section.
</para>

<para>
The scaling process is handled by the <literal>scale</literal> video filter:
<option>-vf scale=<replaceable>width</replaceable>:<replaceable>height</replaceable></option>.
Its quality can be set with the <option>-sws</option> option.
If it's not specified, <application>MEncoder</application> will use 0: fast
bilinear.
</para>

<para>
Usage:
<screen>
mencoder <replaceable>input.mpg</replaceable> -ovc lavc -lavcopts vcodec=mpeg4 -vf scale=640:480-o <replaceable>output.avi</replaceable>
</screen>
</para>
</sect1>


<sect1 id="menc-feat-streamcopy">
<title>Stream copying</title>

<para>
<application>MEncoder</application> can handle input streams in two ways:
<emphasis role="bold">encode</emphasis> or <emphasis role="bold">copy</emphasis>
them. This section is about <emphasis role="bold">copying</emphasis>.
</para>

<itemizedlist>
<listitem><para>
  <emphasis role="bold">Video stream</emphasis> (option <option>-ovc copy</option>):
  nice stuff can be done :) Like, putting (not converting!) FLI or VIVO or
  MPEG1 video into an AVI file!  Of course only
  <application>MPlayer</application> can play such files :) And it probably
  has no real life value at all. Rationally: video stream copying can be
  useful for example when only the audio stream has to be encoded (like,
  uncompressed PCM to MP3).
  </para></listitem>
<listitem><para>
  <emphasis role="bold">Audio stream</emphasis> (option <option>-oac copy</option>):
  straightforward.  It is possible to take an external audio file (MP3,
  Vorbis) and mux it into the output stream. Use the
  <option>-audiofile <replaceable>filename</replaceable></option> option
  for this.
  </para></listitem>
</itemizedlist>
</sect1>


<sect1 id="menc-feat-fix-avi">
<title>Fixing AVIs with broken index or interleaving</title>

<para>
Easiest thing. We simply copy the video and audio streams, and
<application>MEncoder</application> generates the index. Of course this cannot fix possible bugs in
the video and/or audio streams. It also fixes files with broken interleaving,
thus the <option>-ni</option> option won't be needed for them anymore.
</para>

<para>
Command:
<screen>
mencoder -idx <replaceable>input.avi</replaceable> -ovc copy -oac copy -o <replaceable>output.avi</replaceable><!--
--></screen>
</para>


<sect2 id="menc-feat-appending">
<title>Appending multiple AVI files</title>

<para>
As a side-effect, the broken AVI fixer function enables MEncoder to append
2 (or more) AVI files:
</para>

<para>
Command:
<screen>cat 1.avi 2.avi | mencoder -noidx -ovc copy -oac copy -o output.avi -</screen>
</para>

<note><para>
This expects <filename>1.avi</filename> and <filename>2.avi</filename> to use
the same codecs, resolution, stream rate etc, and at least <filename>1.avi</filename>
must not be broken. You may need to fix your input AVI files first, as described
<link linkend="menc-feat-fix-avi">above</link>.
</para></note>
</sect2>
</sect1>

<sect1 id="menc-feat-enc-libavcodec">
<title>Encoding with the libavcodec codec family</title>

<para>
<link linkend="ffmpeg">libavcodec</link> provides simple encoding to a lot
of interesting video and audio formats (currently its audio codecs are
unsupported). You can encode to the following codecs:

<informaltable frame="all">
<tgroup cols="2">
<thead>
<row><entry>Codec name</entry><entry>Description</entry></row>
</thead>
<tbody>
<row><entry>mjpeg</entry><entry>
   Motion JPEG
  </entry></row>
<row><entry>h263</entry><entry>
  H263
  </entry></row>
<row><entry>h263p</entry><entry>
  H263 Plus
  </entry></row>
<row><entry>mpeg4</entry><entry>
  ISO standard MPEG-4 (DivX 5, XVID compatible)
  </entry></row>
<row><entry>msmpeg4</entry><entry>
  pre-standard MPEG-4 variant by MS, v3 (aka DivX3)
  </entry></row>
<row><entry>msmpeg4v2</entry><entry>
  pre-standard MPEG-4 by MS, v2 (used in old asf files)
  </entry></row>
  <row><entry>wmv1</entry><entry>
  Windows Media Video, version 1 (aka WMV7)
  </entry></row>
<row><entry>rv10</entry><entry>
  an old RealVideo codec
  </entry></row>
<row><entry>mpeg1video</entry><entry>
  MPEG1 video :)
  </entry></row>
<row><entry>huffyuv</entry><entry>
  lossless compression
  </entry></row>
</tbody>
</tgroup>
</informaltable>

The first column contains the codec names that should be passed after the
<literal>vcodec</literal> config, like: <option>-lavcopts vcodec=msmpeg4</option>
</para>

<informalexample>
<para>
An example, with MJPEG compression:
<screen>mencoder -dvd 2 -o title2.avi -ovc lavc -lavcopts vcodec=mjpeg -oac copy</screen>
</para>
</informalexample>
</sect1>


<sect1 id="menc-feat-enc-images">
<title>Encoding from multiple input image files (JPEGs,PNGs or TGAs)</title>

<para>
<application>MEncoder</application> is capable of creating movies from one
or more JPEG, PNG or TGA files.  With simple framecopy it can create MJPEG
(Motion JPEG), MPNG (Motion PNG) or MTGA (Motion TGA) files.
</para>

<orderedlist>
<title>Explanation of the process:</title>
<listitem><para>
  <application>MEncoder</application> <emphasis>decodes</emphasis> the input image(s) with
  <systemitem class="library">libjpeg</systemitem> (when decoding PNGs, it
  will use <systemitem class="library">libpng</systemitem>).
  </para></listitem>
<listitem><para>
  <application>MEncoder</application> then feeds the decoded image to the
  chosen video compressor (DivX4, Xvid, ffmpeg msmpeg4, etc.).
  </para></listitem>
</orderedlist>

<formalpara>
<title>Examples</title>
<para>
The explanation of the <option>-mf</option> option can be found below in
the man page.

<informalexample>
<para>
Creating a DivX4 file from all the JPEG files in the current dir:
<screen>
mencoder -mf on:w=800:h=600:fps=25 -ovc divx4 -o output.avi \*.jpg<!--
--></screen>
</para>
</informalexample>

<informalexample>
<para>
Creating a DivX4 file from some JPEG files in the current dir:
<screen>
mencoder -mf on:w=800:h=600:fps=25 -ovc divx4 -o output.avi frame001.jpg,frame002.jpg <!--
--></screen>
</para>
</informalexample>

<informalexample>
<para>
Creating a Motion JPEG (MJPEG) file from all the JPEG files in the current
dir:
<screen>
mencoder -mf on:w=800:h=600:fps=25 -ovc copy -o output.avi \*.jpg<!--
--></screen>
</para>
</informalexample>

<informalexample>
<para>
Creating an uncompressed file from all the PNG files in the current dir:
<screen>
mencoder -mf on:w=800:h=600:fps=25:type=png -ovc raw -o output.avi \*.png<!--
--></screen>
</para>
</informalexample>

<note><para>
Width must be integer multiple of 4, it's a limitation of the RAW RGB AVI format.
</para></note>

<informalexample>
<para>
Creating a Motion PNG (MPNG) file from all the PNG files in the current
dir:
<screen>
mencoder -mf on:w=800:h=600:fps=25:type=png -ovc copy -o output.avi \*.png<!--
--></screen>
</para>
</informalexample>

<informalexample>
<para>
Creating a Motion TGA (MTGA) file from all the TGA files in the current
dir:
<screen>
mencoder -mf on:w=800:h=600:fps=25:type=tga -ovc copy -o output.avi \*.tga<!--
--></screen>
</para>
</informalexample>

</para>
</formalpara>
</sect1>


<sect1 id="menc-feat-extractsub">
<title>Extracting DVD subtitles to Vobsub file</title>

<para>
<application>MEncoder</application> is capable of extracting subtitles from
a DVD into Vobsub fomat files. They consist of a pair of files ending in
<filename>.idx</filename> and <filename>.sub</filename> and are usually
packaged in a single <filename>.rar</filename> archive.
<application>MPlayer</application> can play these with the
<option>-vobsub</option> and <option>-vobsubid</option> options.
</para>

<para>
You specify the basename (i.e without the <filename>.idx</filename> or
<filename>.sub</filename> extension) of the output files with
<option>-vobsubout</option> and the index for this subtitle in the
resulting files with <option>-vobsuboutindex</option>.
</para>

<para>
If the input is not from a DVD you should use <option>-ifo</option> to
indicate the <filename>.ifo</filename> file needed to construct the
resulting <filename>.idx</filename> file.
</para>

<para>
If the input is not from a DVD and you do not have the
<filename>.ifo</filename> file you will need to use the
<option>-vobsubid</option> option to let it know what language id to put in
the <filename>.idx</filename> file.
</para>

<para>
Each run will append the running subtitle if the <filename>.idx</filename>
and <filename>.sub</filename> files already exist. So you should remove any
before starting.
</para>

<example>
<title>Copying two subtitles from a DVD while doing 3-pass encoding</title>
<screen>
rm subtitles.idx subtitles.sub
mencoder -dvd 1 -vobsubout subtitles -vobsuboutindex 0 -sid 2 -o frameno.avi -ovc frameno
mencoder -dvd 1 -oac copy -ovc divx4 -pass 1
mencoder -dvd 1 -oac copy -ovc divx4 -pass 2 -vobsubout subtitles -vobsuboutindex 1 -sid 5<!--
--></screen>
</example>

<example>
<title>Copying a french subtitle from an MPEG file</title>
<screen>
rm subtitles.idx subtitles.sub
mencoder movie.mpg -ifo movie.ifo -vobsubout subtitles -vobsuboutindex 0 -vobsuboutid fr -sid 1<!--
--></screen>
</example>

</sect1>

<sect1 id="aspect">
<title>Preserving aspect ratio</title>
<para>
DVDs and SVCDs (i.e. MPEG1/2) files contain an aspect ratio value, which
describes how the player should scale the video stream, so humans won't
have egg heads (ex.: 480x480 + 4:3 = 640x480). However when encoding to AVI
(DivX) files, you have be aware that AVI headers don't store this value.
Rescaling the movie is disgusting and time consuming, there has to be a better
way!
</para>

<para>There is</para>

<para>
MPEG4 has an unique feature: the video stream can contain its needed aspect
ratio. Yes, just like MPEG1/2 files (DVD, SVCD). Regretfully, there are
<emphasis role="bold">no</emphasis> video players outside which support this
attribute. Except <application>MPlayer</application>.
</para>

<para>
This feature can be used only with <emphasis role="bold">libavcodec</emphasis>'s
<systemitem>mpeg4</systemitem> codec. Keep in mind: although <application>MPlayer</application>
will correctly play the created file, other players will use the wrong aspect
ratio.
</para>

<para>
You seriously should crop the black bands over and below the movie image.
See the man page for the usage of the <systemitem>cropdetect</systemitem> and
<systemitem>crop</systemitem> filters.
</para>

<formalpara>
<title>Usage</title>
<para>
<screen>mencoder sample-svcd.mpg -ovc lavc -lavcopts vcodec=mpeg4:autoaspect -vf crop=714:548:0:14 -oac copy -o output.avi</screen>
</para>
</formalpara>
</sect1>

</chapter>