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

<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision$ -->
<chapter id="mencoder">
<title>Encoding with <application>MEncoder</application></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 <replaceable>movie.avi</replaceable>
mencoder dvd://2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2 -oac copy -o <replaceable>movie.avi</replaceable>
</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 <application>MEncoder</application> 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 <replaceable>movie.avi</replaceable>
mencoder dvd://2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2 -oac copy -o <replaceable>movie.avi</replaceable>
</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 <link linkend="ffmpeg">libavcodec</link>'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 <application>MEncoder</application> currently
cannot encode MPEG1 layer 2 (MP2) audio, which all other players expect in MPEG files.
</para>

<para>
To change <application>MEncoder's</application> 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> <replaceable>media.avi</replaceable> -o <replaceable>output.mpg</replaceable>
</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,
  WAV) 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 <application>MEncoder</application>
to append 2 (or more) AVI files:
</para>

<para>
Command:
<screen>cat 1.avi 2.avi | mencoder -noidx -ovc copy -oac copy -o <replaceable>output.avi</replaceable> -</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 (more or less up to date):

<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>ljpeg</entry><entry>
   Lossless 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>wmv2</entry><entry>
  Windows Media Video, version 2 (aka WMV8)
  </entry></row>
<row><entry>rv10</entry><entry>
  an old RealVideo codec
  </entry></row>
<row><entry>mpeg1video</entry><entry>
  MPEG1 video
  </entry></row>
<row><entry>mpeg2video</entry><entry>
  MPEG2 video
  </entry></row>
<row><entry>huffyuv</entry><entry>
  lossless compression
  </entry></row>
<row><entry>asv1</entry><entry>
  ASUS Video v1
  </entry></row>
<row><entry>asv2</entry><entry>
  ASUS Video v2
  </entry></row>
<row><entry>ffv1</entry><entry>
  FFmpeg's lossless video codec
  </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 <replaceable>output.avi</replaceable> \*.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 <replaceable>output.avi</replaceable> <replaceable>frame001.jpg,frame002.jpg</replaceable> <!--
--></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 <replaceable>output.avi</replaceable> \*.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 <replaceable>output.avi</replaceable> \*.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 <replaceable>output.avi</replaceable> \*.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 <replaceable>output.avi</replaceable> \*.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 formatted 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 <replaceable>movie.mpg</replaceable> -ifo <replaceable>movie.ifo</replaceable> -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 (DVD, SVCD) and H263 files. Regretfully, there are
<emphasis role="bold">no</emphasis> video players outside which support this
attribute of MPEG4, except <application>MPlayer</application>.
</para>

<para>
This feature can be used only with <link linkend="ffmpeg">libavcodec</link>'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>

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

<sect1 id="custommatrices"><title>Custom inter/intra matrices</title>

<para>
With this feature of <link linkend="ffmpeg">libavcodec</link> you are
able to set custom inter (I-frames/key frames) and intra (P-frames/predicted
frames) matrices. It is supported by many of the codecs:
<systemitem>mpeg1video</systemitem> and <systemitem>mpeg2video</systemitem>
are reported as working.
</para>

<para>
A typical usage of this feature is to set the matrices preferred by the
<ulink url="http://www.kvcd.net/">KVCD</ulink> specifications.
</para>

<para>
The <emphasis role="bold">KVCD &quot;Notch&quot; Quantization Matrix:</emphasis>
</para>

<para>
Intra:
<screen>
 8  9 12 22 26 27 29 34
 9 10 14 26 27 29 34 37
12 14 18 27 29 34 37 38
22 26 27 31 36 37 38 40
26 27 29 36 39 38 40 48
27 29 34 37 38 40 48 58
29 34 37 38 40 48 58 69
34 37 38 40 48 58 69 79
</screen>

Inter:
<screen>
16 18 20 22 24 26 28 30
18 20 22 24 26 28 30 32
20 22 24 26 28 30 32 34
22 24 26 30 32 32 34 36
24 26 28 32 34 34 36 38
26 28 30 32 34 36 38 40
28 30 32 34 36 38 42 42
30 32 34 36 38 40 42 44
</screen>
</para>

<para>
Usage:
<screen>
$ mencoder <replaceable>input.avi</replaceable> -o <replaceable>output.avi</replaceable> -oac copy -ovc lavc -lavcopts inter_matrix=...:intra_matrix=...
</screen>
</para>

<para>
<screen>
$ mencoder <replaceable>input.avi</replaceable> -ovc lavc -lavcopts
vcodec=mpeg2video:intra_matrix=8,9,12,22,26,27,29,34,9,10,14,26,27,29,34,37,
12,14,18,27,29,34,37,38,22,26,27,31,36,37,38,40,26,27,29,36,39,38,40,48,27,
29,34,37,38,40,48,58,29,34,37,38,40,48,58,69,34,37,38,40,48,58,69,79
:inter_matrix=16,18,20,22,24,26,28,30,18,20,22,24,26,28,30,32,20,22,24,26,
28,30,32,34,22,24,26,30,32,32,34,36,24,26,28,32,34,34,36,38,26,28,30,32,34,
36,38,40,28,30,32,34,36,38,42,42,30,32,34,36,38,40,42,44 -oac copy -o svcd.mpg
</screen>
</para>
</sect1>

<sect1 id="menc-feat-dvd-mpeg4">
<title>Making a high quality MPEG4 (&quot;DivX&quot;) rip of a DVD movie</title>

<para>
  Ripping a DVD title into a maximally high quality MPEG4 (DivX) file
  involves many considerations. Below is an example of the process when
  there is no file size goal (other than perhaps fitting the result into 2GB).
  <systemitem class="library">libavcodec</systemitem> will be used for the video,
  and the audio will be copied as is without any changes.
</para>

<sect2 id="menc-feat-dvd-mpeg4-crop">
<title>Cropping</title>
<para>
  Play the DVD and run the crop detection filter
  (<option>-vf cropdetect</option>) on it. This gives you a crop rectangle
  to use for encoding. The reason for cropping is that many movies are
  not shot in a standard DVD aspect ratio (16/9 or 4/3), or, for whatever
  reason, the picture does not properly fill the frame. So you want to crop
  out the pointless black bars when you rip. It also improves the quality
  of the rip since the sharp edge of the black bars wastes a lot of bits.
  A common aspect is 2.35, which is cinescope. Most big blockbuster
  movies have this aspect ratio.
</para>
</sect2>

<sect2 id="menc-feat-dvd-mpeg4-quality">
<title>Quality level</title>
<para>
  Next you need to choose the desired quality level. When there is no
  need to fit the resulting file on CDs or the like, using constant
  quantizing AKA constant quality is a good choice. That way each frame
  is given as much bits as its needs to keep the quality at the desired
  level, but multiple encoding passes are not needed. With
  <systemitem class="library">libavcodec</systemitem>, you get constant
  quality by using
  <option>-lavcopts vqscale=<replaceable>N</replaceable></option>.
  <option>vqscale=3</option> should give you a file below 2GB in size,
  depending mainly on the movie length and video noisiness (the more
  noise, the harder it is to compress.)
</para></sect2>

<sect2 id="menc-feat-dvd-mpeg4-2gb">
<title>Files over 2GB</title>
<para>
  If the file resulting from constant quality encoding is over 2GB big,
  you will have to create an index to be able to view it properly.
  Either

<itemizedlist>
<listitem><para>
  play the file with <option>-forceidx</option> to create an index
  on the fly or
  </para></listitem>
<listitem><para>
  use <option>-saveidx</option> to write an index to a file once and
  <option>-loadidx</option> to use it when playing the file.
  </para></listitem>
</itemizedlist>

  If this bothers you, you may want to keep the file size below 2GB.
</para>

<para>
  There are two ways to avoid this. You can try encoding again using
  <option>vqscale=4</option> and see if both the resulting file size
  and picture quality are acceptable. You can also use
  <link linkend="menc-feat-divx4">2 pass encoding</link>.
  As you will be copying the audio track as is and hence know its
  bitrate, and you know the running time of the movie, you can
  compute the required bitrate to give to the
  <option>-lavcopts vbitrate=<replaceable>bitrate</replaceable></option>
  option without using
  <link linkend="menc-feat-divx4">3 pass encoding</link>.
</para></sect2>

<sect2 id="menc-feat-dvd-mpeg4-deinterlacing">
<title>Deinterlacing</title>
<para>
  If the movie is interlaced, you may want to deinterlace it as part of
  the ripping. It is debatable whether deinterlacing should be done at
  this stage. The benefit is that deinterlacing when converting to
  MPEG4 makes compression better, and viewing easier and less CPU
  intensive on computer monitors as no deinterlacing is required at
  that stage.
</para>

<para>
  If deinterlacing at the ripping stage is a good idea depends on
  the DVD. If the DVD is made from film, which was shot at 24 fps, you
  can as well deinterlace while ripping. If, however, the original was
  50/60 fps video, converting into deinterlaced 23.976/25 fps video
  will lose information. If you do decide to interlace, you can further
  experiment with different deinterlacing filters. See
  <ulink url="http://www.wieser-web.de/MPlayer/">http://www.wieser-web.de/MPlayer/</ulink>
  for examples. A good starting point is <option>-vf pp=fd</option>.
</para>

<para>
  If you are both cropping and deinterlacing, deinterlace
  <emphasis>before</emphasis> cropping. Actually, this is not necessary
  if the crop offset is vertically a multiple of 2 pixels. However with
  some other filters like dering you should always crop last, so it's a
  good habit to put the crop filter last.
</para></sect2>

<sect2 id="menc-feat-dvd-mpeg4-telecine">
<title>Inverse telecine</title>
<para>
  If you are ripping a PAL DVD, which is 25 fps, you do not need to
  think about the fps. Just use 25 fps. NTSC DVDs on the other hand are
  29.97 fps (often rounded to 30 fps, but that is not what they are).
  If the movie was shot for TV, you again do not need to touch the fps.
  But if the movie was shot on film, and hence at (exactly) 24 fps,
  it has been converted to 29.97 fps when making the DVD. That
  conversion where 12 fields are added to each 24 frames of film is
  called telecine. For more info about telecine, see a
  <ulink url="http://www.google.com/search?q=telecine+field+23.976">
  Google search for &quot;telecine field 23.976&quot;</ulink>.
</para>

<para>
  In case you have such a telecined DVD, you will want to do inverse
  telecine, that is convert the movie to 23.976 fps (29.97*4/5).
  Otherwise camera panning will look jerky and awful. You can use
  <option>-ofps 23.976</option> for this. Anything that is shown in
  theatres is shot on film and needs inverse telecine, TV shows do not.
</para></sect2>

<sect2 id="menc-feat-dvd-mpeg4-scaling">
<title>Scaling and aspect ratio</title>
<para>
  For best quality, do not scale the movie while ripping. Scaling
  causes artifacts and makes the file larger. Pixels in DVD movies
  are not square, so DVD movies include info about the correct aspect
  ratio. It is possible to store the aspect ratio in the MPEG4 header
  of the output file. Most video players ignore this info, but
  <application>MPlayer</application> honors it. So if you are only
  going to use <application>MPlayer</application> for viewing the
  ripped file, you do not need to scale the movie, just pass
  <option>-lavcopts autoaspect</option> to
  <application>MEncoder</application> and things will
  automagically work right. If you must scale the movie, be
  careful about getting the size right especially if you do cropping.
</para>
</sect2>

<sect2 id="menc-feat-dvd-mpeg4-summary">
<title>Summing it up</title>
<para>
  With all of the above mentioned in mind, a suitable encoding command
  might be

  <screen>
mencoder dvd://1 -aid 128 -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vqscale=3:vhq:v4mv:trell:autoaspect \
  -ofps 23.976 -vf crop=720:364:0:56 -o Harry_Potter_2.avi
  </screen>

  Here <option>dvd://1</option> gives the DVD title to rip. Option
  <option>-aid 128</option> says to use audio track 128, and
  <option>-oac copy</option> to copy it as is. You'll have to use
  <application>MPlayer</application> to find out the right values for
  these options.
</para>

<para>
  Options <option>vhq:v4mv:trell</option> for
  <option>-lavcopts</option> improve quality versus bitrate, but make
  encoding take longer. Especially <option>trell</option> slows
  encoding down but also increases quality visibly. If you want to
  deinterlace, add a <option>pp</option> filter to
  <option>-vf</option>, for example
  <option>-vf pp=fd,crop=720:364:0:56</option> (in that order). If you don't need
  inverse telecine, leave out the <option>-ofps 23.976</option>.
</para>
</sect2>

</sect1>

</chapter>