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

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<!-- $Revision$ -->
<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-mpeg4">
<title>Encoding two pass MPEG-4 (&quot;DivX&quot;)</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 two 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>

<example>
<title>copy audio track</title>
<para>
Two pass encode of a DVD to an MPEG-4 (&quot;DivX&quot;) AVI while copying
the audio track.
<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>
</example>

<example>
<title>encode audio track</title>
<para>
Two pass encode of a DVD to an MPEG-4 (&quot;DivX&quot;) AVI while encoding
the audio track to MP3.
<screen>
mencoder dvd://2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=1 -oac mp3lame -lameopts vbr=3 -o <replaceable>movie.avi</replaceable>
mencoder dvd://2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2 -oac mp3lame -lameopts vbr=3 -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"><systemitem class="library">libavcodec</systemitem></link>'s
<emphasis>mpeg1video</emphasis> codec, because players - except
<application>MPlayer</application> - expect MPEG-1 video, and MPEG-1 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 MPEG-1 layer 2 (MP2) audio, which all other players expect in MPEG files.
</para>

<para>
To change <application>MEncoder</application>'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> <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. If you wish to rescale,
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 2: bicubic.
</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
  MPEG-1 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 <replaceable>1.avi</replaceable> <replaceable>2.avi</replaceable> &gt; <replaceable>3.avi</replaceable>
mencoder -noidx -ovc copy -oac copy -o <replaceable>output.avi</replaceable> <replaceable>3.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 <systemitem class="library">libavcodec</systemitem>
  codec family</title>

<para>
<link linkend="ffmpeg"><systemitem class="library">libavcodec</systemitem></link>
provides simple encoding to a lot of interesting video and audio formats.
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>
  H.263
  </entry></row>
<row><entry>h263p</entry><entry>
  H.263+
  </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>
  MPEG-1 video
  </entry></row>
<row><entry>mpeg2video</entry><entry>
  MPEG-2 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 (JPEG, PNG, TGA, SGI)</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 is in the man page.

<informalexample>
<para>
Creating an MPEG-4 file from all the JPEG files in the current directory:
<screen>
mencoder mf://*.jpg -mf w=800:h=600:fps=25:type=jpg -ovc lavc -lavcopts vcodec=mpeg4 -oac copy -o <replaceable>output.avi</replaceable>
</screen>
</para>
</informalexample>

<informalexample>
<para>
Creating an MPEG-4 file from some JPEG files in the current directory:
<screen>
mencoder mf://<replaceable>frame001.jpg,frame002.jpg</replaceable> -mf w=800:h=600:fps=25:type=jpg -ovc lavc -lavcopts vcodec=mpeg4 -oac copy -o <replaceable>output.avi</replaceable>
</screen>
</para>
</informalexample>

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

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

<informalexample>
<para>
Creating a Motion TGA (MTGA) file from all the TGA files in the current
directory:
<screen>
mencoder mf://*.tga -mf w=800:h=600:fps=25:type=tga -ovc copy -oac copy -o <replaceable>output.avi</replaceable><!--
--></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 two pass encoding</title>
<screen>
rm subtitles.idx subtitles.sub
mencoder dvd://1 -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vpass=1 -vobsubout subtitles -vobsuboutindex 0 -sid 2
mencoder dvd://1 -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vpass=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. MPEG-1/2) 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>
MPEG-4 has an unique feature: the video stream can contain its needed aspect
ratio. Yes, just like MPEG-1/2 (DVD, SVCD) and H.263 files. Regretfully, there are
<emphasis role="bold">no</emphasis> video players outside which support this
attribute of MPEG-4, except <application>MPlayer</application>.
</para>

<para>
This feature can be used only with
<link linkend="ffmpeg"><systemitem class="library">libavcodec</systemitem></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"><systemitem class="library">libavcodec</systemitem></link>
you are able to set custom inter (I-frames/keyframes) 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 MPEG-4 (&quot;DivX&quot;) rip of a DVD movie</title>

<para>
  One frequently asked question is "How do I make the highest quality DVD
  rip possible?  I don't care about file size, I just want the best
  quality."
</para>

<para>
  This question is perhaps at least somewhat wrongly posed. After all, if
  you don't care about file size, why not simply copy the MPEG-2 video
  stream from the DVD whole? Sure, your AVI will end up being 5GB, give
  or take, but if you want the best quality and don't care about size,
  this is certainly your best option.
</para>

<para>
  In fact, the reason you want to transcode a DVD into MPEG-4 is
  specifically because you <emphasis role="bold">do</emphasis> care about
  file size.
</para>

<para>
  It's difficult to offer a cookbook recipe on how to create a very high
  quality DVD rip. There are several factors to consider, and you should
  understand these details or else you're likely to end up disappointed
  with your results. Below we'll investigate some of these issues, and
  then have a look at an example. We assume you're using
  <systemitem class="library">libavcodec</systemitem> to encode the video,
  although the theory applies to other codecs as well.
</para>

<para>
  The main assumption of this guide is that you have no specific file size
  constraints and have no problem giving up bits in exchange for quality.
  While much of the information presented here is useful in any case, some
  of it may work against you if you have a file size goal, such as fitting a
  video on a CD.
</para>

<sect2 id="menc-feat-dvd-mpeg4-2pass">
<title>Constant Quantizer vs. two pass</title>

<para>
  There are three approaches to encoding the video: constant bitrate
  (CBR), constant quantizer, and two pass (ABR, or average bitrate).
</para>

<para>
  In each of these modes, <systemitem class="library">libavcodec</systemitem>
  breaks the video frame into 16x16 pixel macroblocks and then applies a
  quantizer to each macroblock. The lower the quantizer, the better the
  quality and higher the bitrate. The method
  <systemitem class="library">libavcodec</systemitem> uses to determine
  which quantizer to use for a given macroblock varies and is highly
  tunable. (This is an extreme over-simplification of the actual
  process, but the basic concept is useful to understand.)
</para>

<para>
  When you specify a constant bitrate, <systemitem
  class="library">libavcodec</systemitem> will encode the video, discarding
  detail as much as necessary and as little as possible in order to remain
  lower than the given bitrate. If you truly don't care about file size,
  you could as well use CBR and specify a bitrate of infinity. (In
  practice, this means a value high enough so that it poses no limit, like
  10000Kbit.) With no real restriction on bitrate, the result is that
  <systemitem class="library">libavcodec</systemitem> will use the lowest
  possible quantizer for each macroblock (as specified by
  <option>vqmin</option>, which is 2 by default). As soon as you specify a
  low enough bitrate that <systemitem class="library">libavcodec</systemitem>
  is forced to use a higher quantizer, then you're almost certainly ruining
  the quality of your video. In general, you should avoid CBR altogether if
  you care about quality.
</para>

<para>
  With constant quantizer, <systemitem
  class="library">libavcodec</systemitem> uses the same quantizer, as
  specified by the <option>vqscale</option> option, on every macroblock. If
  you want the highest quality rip possible, again ignoring bitrate, you can
  use <option>vqscale=2</option>. This will yield the same bitrate and PSNR
  (peak signal-to-noise ratio) as CBR with
  <option>vbitrate</option>=infinity and the default <option>vqmin</option>
  of 2.
</para>

<para>
  The problem with constant quantizing is that it uses the given quantizer
  whether the macroblock needs it or not. That is, it might be possible
  to use a higher quantizer on a macroblock without sacrificing visual
  quality. Why waste the bits on an unnecessarily low quantizer? Your
  CPU has as many cycles as there is time, but there's only so many bits
  on your hard disk.
</para>

<para>
  With a two pass encode, the first pass will rip the movie as though it
  were CBR, but it will keep a log of properties for each frame. This
  data is then used during the second pass in order to make intelligent
  decisions about which quantizers to use. During fast action or low
  detail scenes, higher quantizers will likely be used, and during
  slow moving or high detail scenes, lower quantizers will be used.
</para>

<para>
  If you use <option>vqscale=2</option>, then you're wasting bits. If you
  use <option>vqscale=3</option>, then you're not getting the highest
  quality rip. Suppose you rip a DVD at <option>vqscale=3</option>, and
  the result is 1800Kbit. If you do a two pass encode with
  <option>vbitrate=1800</option>, the resulting video will have <emphasis
  role="bold">higher quality</emphasis> for the <emphasis role="bold">same
  bitrate</emphasis>.
</para>

<para>
  Since you're now convinced that two pass is the way to go, the real
  question now is what bitrate to use? The answer is that there's no
  single answer. Ideally you want to choose a bitrate that yields the
  best balance between quality and file size. This is going to vary
  depending on the source video.
</para>

<para>
  A good starting point for a very high quality rip is about 2000Kbit plus
  or minus 200Kbit. For fast action or high detail source video, or if
  you just have a very critical eye, you might decide on 2400 or 2600.
  For some DVDs, you might not notice a difference at 1400Kbit. It's a
  good idea to experiment with scenes at different bitrates to get a feel.
</para>

</sect2>

<sect2 id="menc-feat-dvd-mpeg4-crop">
<title>Cropping and Scaling</title>

<para>
  Native DVD resolution is 720x480 for NTSC, and 720x576 for PAL, but
  there's an aspect flag that specifies whether it's full-screen (4:3) or
  wide-screen (16:9). Many (if not most) widescreen DVDs are not strictly
  16:9, and will be either 1.85:1 or 2.35:1 (cinescope). This means that
  there will be black bands in the video that will need to be cropped out.
</para>

<para>
  <application>MPlayer</application> provides a crop detection filter that
  will determine the crop rectangle (<option>-vf cropdetect</option>).
  Because MPEG-4 uses 16x16 macroblocks, you'll want to make sure that each
  dimension of the video you're encoding is a multiple of 16 or else you
  will be degrading quality, especially at lower bitrates. You can do this
  by rounding the width and height of the crop rectangle down to the nearest
  multiple of 16. When cropping, you'll want to increase the y-offset by
  half the difference of the old and the new height so that the resulting
  video is taken from the center of the frame. And because of the way DVD
  video is sampled, make sure the offset is an even number. (In fact, as a
  rule, never use odd values for any parameter when you're cropping and
  scaling video.) If you're not comfortable throwing a few extra pixels
  away, you might prefer instead to scale the video instead. We'll look
  at this in our example below.
</para>

<para>
  Also, be careful about "half black" pixels at the edges. Make sure you
  crop these out too, or else you'll be wasting bits there that
  are better spent elsewhere.
</para>

<para>
  After all is said and done, you'll probably end up with video whose pixels
  aren't quite 1.85:1 or 2.35:1, but rather something close to that. You
  could calculate the new aspect ratio manually, but
  <application>MEncoder</application> offers an option for <systemitem
  class="library">libavcodec</systemitem> called <option>autoaspect</option>
  that will do this for you. Absolutely do not scale this video in order to
  square the pixels unless you like to waste your hard disk space. Scaling
  should be done on playback, and the player will use the aspect stored in
  the AVI to determine the correct resolution.
</para>

</sect2>

<sect2 id="menc-feat-dvd-mpeg4-audio">
<title>Audio</title>

<para>
  Audio is a much simpler problem to solve: just leave it as is. Even AC3
  5.1 streams are at most 448Kbit/s, and they're worth every bit. You
  might be tempted to transcode the audio to high quality Ogg Vorbis, but
  just because you don't have an A/V receiver for AC3 pass-through today
  doesn't mean you won't have one tomorrow. Future-proof your DVD rips by
  preserving the AC3 stream.
</para>


</sect2>

<sect2 id="menc-feat-dvd-mpeg4-interlacing">
<title>Interlacing and Telecine</title>

<para>
  Almost all movies are shot at 24 fps. Because NTSC is 29.97 fps, some
  processing must be done to this 24 fps video to make it run at the correct
  NTSC framerate. The process is called 3:2 pulldown, commonly referred to
  as telecine (because pulldown is often applied during the telecine
  process), and, naively described, it works by slowing the film down to
  23.976 fps, and repeating every fourth frame.
</para>

<para>
  No special processing, however, is done to the video for PAL DVDs, which
  run at 25 fps. (Technically, PAL can be telecined, called 2:2 pulldown,
  but this doesn't become an issue in practice.) The 24 fps film is simply
  played back at 25 fps. The result is that the movie runs slightly faster,
  but unless you're an alien, you probably won't notice the difference.
  Most PAL DVDs have pitch-corrected audio, so when they're played back at
  25 fps things will sound right, even though the audio track (and hence the
  whole movie) has a running time that's 4% less than NTSC DVDs.
</para>

<para>
  Because the video in a PAL DVD hasn't been altered, you needn't worry
  much about frame rate. The source is 25 fps, and your rip will be 25
  fps. However, if you're ripping an NTSC DVD movie, you may need to
  apply inverse telecine.
</para>

<para>
  For movies shot at 24 fps, the video on the NTSC DVD is either telecined
  29.97 fps, or else it is progressive 24 fps and intended to be telecined
  on-the-fly by a DVD player. On the other hand, TV series are usually
  only interlaced, not telecined. This is not a hard rule: some TV series
  are interlaced (such as Buffy the Vampire Slayer) whereas some are a
  mixture of progressive and interlaced (such as Angel, or 24).
</para>

<para>
  It's highly recommended that you read the section on <link
  linkend="menc-feat-telecine">How to deal with telecine and interlacing
  in NTSC DVDs</link> to learn how to handle the different possibilities.
</para>

<para>
  However, if you're mostly just ripping movies, likely you're either
  dealing with 24 fps progressive or telecined video, in which case you can
  use the <option>pullup</option> filter <option>-vf
  pullup,softskip</option>.
</para>

</sect2>


<sect2 id="menc-feat-dvd-mpeg4-filtering">
<title>Filtering</title>

<para>
  In general, you want to do as little filtering as possible to the movie
  in order to remain close to the original DVD source. Cropping is often
  necessary (as described above), but do not scale the video. Although
  scaling down is sometimes preferred to using higher quantizers, we want
  to avoid both these things: remember that we decided from the start to
  trade bits for quality.
</para>

<para>
  Also, do not adjust gamma, contrast, brightness, etc. What looks good
  on your display may not look good on others. These adjustments should
  be done on playback only.
</para>

<para>
  One thing you might want to do, however, is pass the video through a
  very light denoise filter, such as <option>-vf hqdn3d=2:1:2</option>.
  Again, it's a matter of putting those bits to better use: why waste them
  encoding noise when you can just add that noise back in during playback?
  Increasing the parameters for <option>hqdn3d</option> will further
  improve compressibility, but if you increase the values too much, you
  risk degrading the image visibily. The suggested values above
  (<option>2:1:2</option>) are quite conservative; you should feel free to
  experiment with higher values and observe the results for yourself.
</para>

</sect2>


<sect2 id="menc-feat-dvd-mpeg4-example">
<title>Example</title>

<para>
  So, you've just bought your shiny new copy of Harry Potter and the Chamber
  of Secrets (widescreen edition, of course), and you want to rip this DVD
  so that you can add it to your Home Theatre PC. This is a region 1 DVD,
  so it's NTSC. The example below will still apply to PAL, except you'll
  omit <option>-ofps 23.976</option> (because the output framerate is the
  same as the input framerate), and of course the crop dimensions will be
  different.
</para>

<para>
  After running <option>mplayer dvd://1</option>, we follow the process
  detailed in the section <link linkend="menc-feat-telecine">How to deal
  with telecine and interlacing in NTSC DVDs</link> and discover that it's
  24 fps progressive video, which means that we needn't use an inverse
  telecine filter, such as <option>pullup</option> or
  <option>filmdint</option>.
</para>

<para>
  Next, we want to determine the appropriate crop rectangle, so we use the
  cropdetect filter:

  <screen>mplayer dvd://1 -vf cropdetect</screen>

  Make sure you seek to a fully filled frame (such as a bright scene), and
  you'll see in <application>MPlayer</application>'s console output:

  <screen>crop area: X: 0..719  Y: 57..419  (-vf crop=720:362:0:58)</screen>

  We then play the movie back with this filter to test its correctness:

  <screen>mplayer dvd://1 -vf crop=720:362:0:58</screen>

  And we see that it looks perfectly fine. Next, we ensure the width and
  height are a multiple of 16. The width is fine, however the height is
  not. Since we didn't fail 7th grade math, we know that the nearest
  multiple of 16 lower than 362 is 352.
</para>

<para>
  We could just use <option>crop=720:352:0:58</option>, but it'd be nice
  to take a little off the top and a little off the bottom so that we
  retain the center. We've shrunk the height by 10 pixels, but we don't
  want to increase the y-offset by 5-pixels since that's an odd number and
  will adversely affect quality. Instead, we'll increase the y-offset by
  4 pixels:

  <screen>mplayer dvd://1 -vf crop=720:352:0:62</screen>

  Another reason to shave pixels from both the top and the bottom is that we
  ensure we've eliminated any half-black pixels if they exist. Note that if
  your video is telecined, make sure the <option>pullup</option> filter (or
  whichever inverse telecine filter you decide to use) appears in the filter
  chain before you crop. If it is interlaced, deinterlace before cropping.
  (If you choose to preserve the interlaced video, then make sure your
  vertical crop offset is a multiple of 4.)
</para>

<para>
  If you're really concerned about losing those 10 pixels, you might
  prefer instead to scale the dimensions down to the nearest multiple of 16.
  The filter chain would look like:

  <screen>-vf crop=720:362:0:58,scale=720:352</screen>

  Scaling the video down like this will mean that some small amount of
  detail is lost, though it probably won't be perceptible. Scaling up will
  result in lower quality (unless you increase the bitrate). Cropping
  discards those pixels altogether. It's a tradeoff that you'll want to
  consider for each circumstance. For example, if the DVD video was made
  for television, you might want to avoid vertical scaling, since the line
  sampling corresponds to the way the content was originally recorded.
</para>

<para>
  On inspection, we see that our movie has a fair bit of action and high
  amounts of detail, so we pick 2400Kbit for our bitrate.
</para>

<para>
  We're now ready to do the two pass encode. Pass 1:

  <screen>mencoder dvd://1 -ofps 23.976 -oac copy -vf crop=720:352:0:62,hqdn3d=2:1:2 -ovc lavc \
-lavcopts vcodec=mpeg4:vbitrate=2400:v4mv:mbd=2:trell:cmp=3:subcmp=3:mbcmp=3:autoaspect:vpass=1 \
-o Harry_Potter_2.avi</screen>

  And pass 2 is the same, except that we specify <option>vpass=2</option>:

  <screen>mencoder dvd://1 -ofps 23.976 -oac copy -vf crop=720:352:0:62,hqdn3d=2:1:2 -ovc lavc \
-lavcopts vcodec=mpeg4:vbitrate=2400:v4mv:mbd=2:trell:cmp=3:subcmp=3:mbcmp=3:autoaspect:vpass=2 \
-o Harry_Potter_2.avi</screen>
</para>

<para>
  The options <option>v4mv:mbd=2:trell</option> will greatly increase the
  quality at the expense of encoding time. There's little reason to leave
  these options out when the primary goal is quality. The options
  <option>cmp=3:subcmp=3:mbcmp=3</option> select a comparison function that
  yields higher quality than the defaults. You might try experimenting with
  this parameter (refer to the man page for the possible values) as
  different functions can have a large impact on quality depending on the
  source material. For example, if you find
  <systemitem class="library">libavcodec</systemitem> produces too much
  blocky artifacting, you could try selecting the experimental NSSE as
  comparison function via <option>*cmp=10</option>.
</para>

<para>
  For this movie, the resulting AVI will be 138 minutes long and nearly
  3GB. And because you said that file size doesn't matter, this is a
  perfectly acceptable size. However, if you had wanted it smaller, you
  could try a lower bitrate. Increasing bitrates have diminishing
  returns, so while we might clearly see an improvement from 1800Kbit to
  2000Kbit, it might not be so noticeable above 2000Kbit. Feel
  free to experiment until you're happy.
</para>

<para>
  Because we passed the source video through a denoise filter, you may want
  to add some of it back during playback. This, along with the
  <option>spp</option> post-processing filter, drastically improves the
  perception of quality and helps eliminate blocky artifacts in the video.
  With <application>MPlayer</application>'s <option>autoq</option> option,
  you can vary the amount of post-processing done by the spp filter
  depending on available CPU. Also, at this point, you may want to apply
  gamma and/or color correction to best suit your display. For example:

  <screen>mplayer Harry_Potter_2.avi -vf spp,noise=9ah:5ah,eq2=1.2 -autoq 3</screen>

</para>
</sect2>

</sect1>

<sect1 id="menc-feat-telecine">
<title>How to deal with telecine and interlacing within NTSC DVDs</title>

<formalpara>
<title>Introduction</title>
<para>
  I suggest you visit this page if you don't understand much of what
  is written in this document:
  <ulink url="http://www.divx.com/support/guides/guide.php?gid=10">http://www.divx.com/support/guides/guide.php?gid=10</ulink>
  This URL links to an understandable and reasonably comprehensive
  description of what telecine is.
</para></formalpara>

<para>
  For technical reasons pertaining to the limitations of early
  television hardware, all video intended to be displayed on an NTSC
  television set must be 59.94 fields per second. Made-for-TV movies
  and shows are often filmed directly at 59.94 fields per second, but
  the majority of cinema is filmed at 24 or 23.976 frames per
  second. When cinematic movie DVDs are mastered, the video is then
  converted for television using a process called telecine.
</para>

<para>
  On a DVD, the video is never actually stored as 59.94 fields per
  second. For video that was originally 59.94, each pair of fields is
  combined to form a frame, resulting in 29.97 frames per
  second. Hardware DVD players then read a flag embedded in the video
  stream to determine whether the odd- or even-numbered lines should
  form the first field.
</para>

<para>
  Usually, 23.976 frames per second content stays as it is when
  encoded for a DVD, and the DVD player must perform telecining
  on-the-fly. Sometimes, however, the video is telecined
  <emphasis>before</emphasis> being stored on the DVD; even though it
  was originally 23.976 frames per second, it becomes 59.94 fields per
  second, and is stored on the disk as 29.97 frames per second.
</para>

<para>
  When looking at individual frames formed from 59.94 fields per
  second video, telecined or otherwise, interlacing is clearly visible
  wherever there is any motion, because one field (say, the
  even-numbered lines) represents a moment in time 1/59.94th of a
  second later than the other. Playing interlaced video on a computer
  looks ugly both because the monitor is higher resolution and because
  the video is shown frame-after-frame instead of field-after-field.
</para>

<para>
Notes:
</para>
<itemizedlist>
<listitem><para>
  This section only applies to NTSC DVDs, and not PAL.
  </para></listitem>
<listitem><para>
  The example <application>MEncoder</application> lines throughout the
  document are <emphasis role="bold">not</emphasis> intended for
  actual use. They are simply the bare minimum required to encode the
  pertaining video category. How to make good DVD rips or fine-tune
  <systemitem class="library">libavcodec</systemitem> for maximum
  quality is not within the scope of this document.
  </para></listitem>
<listitem><para>
  There are a couple footnotes specific to this guide, linked like this:
  <link linkend="menc-feat-telecine-footnotes">[1]</link>
  </para></listitem>
</itemizedlist>

<sect2 id="menc-feat-telecine-ident">
<title>How to tell what type of video you have</title>

<sect3 id="menc-feat-telecine-ident-progressive">
<title>Progressive</title>
<para>
  Progressive video was originally filmed at 23.976 fps, and stored
  on the DVD without alteration.
</para>

<para>
  When you play a progressive DVD in <application>MPlayer</application>,
  <application>MPlayer</application> will print the following line as
  soon as the movie begins to play:

  <screen> demux_mpg: 24fps progressive NTSC content detected, switching framerate.</screen>

  From this point forward, demux_mpg should never say it finds
  &quot;30fps NTSC content.&quot;
</para>

<para>
  When you watch progressive video, you should never see any
  interlacing. Beware, however, because sometimes there is a tiny bit
  of telecine mixed in, where you wouldn't expect. I've encountered TV
  show DVDs that have one second of telecine at every scene change, or
  at seemingly random places. I once watched a DVD that had a
  progressive first half, and the second half was telecined. If you
  want to be <emphasis>really</emphasis> thorough, you can scan the
  entire movie:

  <screen>mplayer dvd://1 -nosound -vo null -benchmark</screen>

  Using <option>-benchmark</option> makes
  <application>MPlayer</application> play the movie as quickly as it
  possibly can; still, depending on your hardware, it can take a
  while. Every time demux_mpg reports a framerate change, the line
  immediately above will show you the time at which the change
  occurred.
</para>

<para>
  Sometimes progressive video is referred to as &quot;soft-telecine&quot;
  because it is intended to be telecined by the DVD player.
</para>
</sect3>

<sect3 id="menc-feat-telecine-ident-telecined">
<title>Telecined</title>
<para>
  Telecined video was originally filmed at 23.976, but was telecined
  <emphasis>before</emphasis> it was written to the DVD.
</para>

<para>
  <application>MPlayer</application> does not (ever) report any
  framerate changes when it plays telecined video.
</para>

<para>
  Watching a telecined video, you will see interlacing artifacts that
  seem to &quot;blink&quot;: they repeatedly appear and disappear.
  You can look closely at this by
  <orderedlist>
  <listitem>
    <screen>mplayer dvd://1 -speed 0.1</screen>
    </listitem>
  <listitem><para>
    Seek to a part with motion.
    </para></listitem>
  <listitem><para>
    Look at the pattern of interlaced-looking and progressive-looking
    frames. If the pattern you see is PPPII,PPPII,PPPII,... then the
    video is telecined. If you see some other pattern, then the video
    may have been telecined using some non-standard method and
    <application>MEncoder</application> cannot losslessly convert it
    to progressive. If you don't see any pattern at all, then it is
    most likely interlaced.
    </para></listitem>
  </orderedlist>
</para>

<para>
  Sometimes telecined video is referred to as &quot;hard-telecine&quot;.
</para>
</sect3>

<sect3 id="menc-feat-telecine-ident-interlaced">
<title>Interlaced</title>
<para>

  Interlaced video was originally filmed at 59.94 fields per second,
  and stored on the DVD as 29.97 frames per second. The interlacing is
  a result of combining pairs of fields into frames, because within
  each frame, each field is 1/59.94 seconds apart.
</para>

<para>
  As with telecined video, <application>MPlayer</application> should
  not ever report any framerate changes when playing interlaced content.
</para>

<para>
  When you view an interlaced video closely with <option>-speed 0.1</option>,
  you will see that every single frame is interlaced.
</para>
</sect3>

<sect3 id="menc-feat-telecine-ident-mixedpt">
<title>Mixed progressive and telecine</title>
<para>
  All of a &quot;mixed progressive and telecine&quot; video was originally
  23.976 frames per second, but some parts of it ended up being telecined.
</para>

<para>
  When <application>MPlayer</application> plays this category, it will
  (often repeatedly) switch back and forth between &quot;30fps
  NTSC&quot; and &quot;24fps progressive NTSC&quot;. Watch the bottom of
  <application>MPlayer</application>'s output to see these messages.
</para>

<para>
  You should check the &quot;30fps NTSC&quot; sections to make sure
  they are actually telecine, and not just interlaced.
</para>
</sect3>

<sect3 id="menc-feat-telecine-ident-mixedpi">
<title>Mixed progressive and interlaced</title>
<para>
  In &quot;mixed progressive and interlaced&quot; content, progressive
  and interlaced video have been spliced together.
</para>

<para>
  This category looks just like &quot;mixed progressive and telecine&quot;,
  until you examine the 30fps sections and see that they don't have the
  telecine pattern.
</para>
</sect3>

</sect2>

<sect2 id="menc-feat-telecine-encode">
<title>How to encode each category</title>
<para>
  As I mentioned in the beginning, example <application>MEncoder</application>
  lines below are <emphasis role="bold">not</emphasis> meant to actually be used;
  they only demonstrate the minimum parameters to properly encode each category.
</para>

<sect3 id="menc-feat-telecine-encode-progressive">
<title>Progressive</title>
<para>
  Progressive video requires no special filtering to encode. The only
  parameter you need to be sure to use is
  <option>-ofps 23.976</option>. Otherwise, <application>MEncoder</application>
  will try to encode at 29.97 fps and duplicate frames.
</para>

<para>
  <screen>mencoder dvd://1 -nosound -ovc lavc -ofps 23.976</screen>
</para>
</sect3>

<sect3 id="menc-feat-telecine-encode-telecined">
<title>Telecined</title>
<para>
  Telecine can be reversed to retrieve the original 23.976 content,
  using a process called inverse-telecine.
  <application>MPlayer</application> contains two filters to
  accomplish this: <option>detc</option> and
  <option>ivtc</option>. You can read the manual page to see their
  differences, but for DVDs I've never had a problem with
  <option>ivtc</option>. Note that you should
  <emphasis role="bold">always</emphasis> inverse-telecine before any
  rescaling; unless you really know what you're doing,
  inverse-telecine before cropping, too
  <link linkend="menc-feat-telecine-footnotes">[1]</link>. Again,
  <option>-ofps 23.976</option> is needed, too.
</para>

<para>
  <screen>mencoder dvd://1 -nosound -vf ivtc=1 -ovc lavc -ofps 23.976</screen>
</para>
</sect3>

<sect3 id="menc-feat-telecine-encode-interlaced">
<title>Interlaced</title>
<para>
  For most practical cases it is not possible to retrieve a complete
  progressive video from interlaced content. The only way to do so
  without losing half of the vertical resolution is to double the
  framerate and try to &quot;guess&quot; what ought to make up the
  corresponding lines for each field (this has drawbacks - see method
  3).
</para>

<orderedlist>
<listitem><para>

  Encode the video in interlaced form. Normally, interlacing wreaks
  havoc with the encoder's ability to compress well, but
  <systemitem class="library">libavcodec</systemitem> has two
  parameters specifically for dealing with storing interlaced video a
  bit better: <option> ildct</option> and <option>ilme</option>. Also,
  using <option>mbd=2</option> is strongly recommended
  <link linkend="menc-feat-telecine-footnotes">[2] </link> because it
  will encode macroblocks as non-interlaced in places where there is
  no motion. Note that <option>-ofps</option> is NOT needed here.

  <screen>mencoder dvd://1 -nosound -ovc lavc -lavcopts ildct:ilme:mbd=2</screen>
  </para></listitem>
<listitem><para>
  Use a deinterlacing filter before encoding. There are several of
  these filters available to choose from, each with its own advantages
  and disadvantages. Consult <option>mplayer -pphelp</option> to see
  what's available (grep for &quot;deint&quot;), and search the
  <ulink url="http://www.mplayerhq.hu/homepage/design6/info.html#mailing_lists">
  MPlayer mailing lists</ulink> to find many discussions about the
  various filters. Again, the framerate is not changing, so no
  <option>-ofps</option>. Also, deinterlacing should be done after
  cropping <link linkend="menc-feat-telecine-footnotes">[1]</link> and
  before scaling.

  <screen>mencoder dvd://1 -nosound -vf pp=lb -ovc lavc</screen>
  </para></listitem>
<listitem><para>
  Unfortunately, this option is buggy with
  <application>MEncoder</application>; it ought to work well with
  <application>MEncoder G2</application>, but that isn't here yet. You
  might experience crahes. Anyway, the purpose of <option> -vf
  tfields</option> is to create a full frame out of each field, which
  makes the framerate 59.94. The advantage of this approach is that no
  data is ever lost; however, since each frame comes from only one
  field, the missing lines have to be interpolated somehow. There are
  no very good methods of generating the missing data, and so the
  result will look a bit similar to when using some deinterlacing
  filters. Generating the missing lines creates other issues, as well,
  simply because the amount of data doubles. So, higher encoding
  bitrates are required to maintain quality, and more CPU power is
  used for both encoding and decoding. tfields has several different
  options for how to create the missing lines of each frame. If you
  use this method, then Reference the manual, and chose whichever
  option looks best for your material. Note that when using
  <option>tfields</option> you
  <emphasis role="bold">have to</emphasis> specify both
  <option>-fps</option> and <option>-ofps</option> to be twice the
  framerate of your original source.

  <screen>mencoder dvd://1 -nosound -vf tfields=2 -ovc lavc -fps 59.94 -ofps 59.94</screen>
  </para></listitem>
<listitem><para>
  If you plan on downscaling dramatically, you can excise and encode
  only one of the two fields. Of course, you'll lose half the vertical
  resolution, but if you plan on downscaling to at most 1/2 of the
  original, the loss won't matter much. The result will be a
  progressive 29.97 frames per second file. The procedure is to use
  <option>-vf field</option>, then crop
  <link linkend="menc-feat-telecine-footnotes">[1]</link> and scale
  appropriately. Remember that you'll have to adjust the scale to
  compensate for the vertical resolution being halved.
  <screen>mencoder dvd://1 -nosound -vf field=0 -ovc lavc</screen>
  </para></listitem>
</orderedlist>
</sect3>

<sect3 id="menc-feat-telecine-encode-mixedpt">
<title>Mixed progressive and telecine</title>
<para>
  In order to turn mixed progressive and telecine video into entirely
  progressive video, the telecined parts have to be
  inverse-telecined. There are two filters that accomplish this
  natively, but a better solution most of the time is to use two
  filters in conjunction (read onward for more detail).
</para>

<itemizedlist>
<listitem><para>
  Currently the most reliable method to deal with this type of video
  is to, rather than inverse-telecine the telecined parts, telecine
  the non-telecined parts and then inverse-telecine the whole
  video. Sound confusing? softpulldown is a filter that goes through
  a video and makes the entire file telecined. If we follow
  softpulldown with either <option>detc</option> or
  <option>ivtc</option>, the final result will be entirely
  progressive. Cropping and scaling should be done after the
  inverse-telecine operations, and <option> -ofps 23.976</option> is
  needed.

  <screen>mencoder dvd://1 -nosound -vf softpulldown,ivtc=1 -ovc lavc -ofps 23.976</screen>
  </para>
  </listitem>
<listitem><para>
  <option>-vf pullup</option> is designed to inverse-telecine
  telecined material while leaving progressive data alone. Pullup
  doesn't really work well with the current
  <application>MEncoder</application>, though, and is really intended
  for use with <application>MEncoder G2</application> (whenever it's
  ready). It works fine without <option>-ofps</option>, but
  <option>-ofps</option> is needed to prevent choppy output. With
  <option>-ofps</option>, it sometimes fails. The problems arise from
  <application>MEncoder</application>'s behavior of dropping frames to
  maintain synchronization between the audio and video: it drops
  frames before sending them through the filter chain, rather than
  after. As a result, <option>pullup</option> is sometimes deprived
  of the data it needs.
  </para>

  <para>
  If <application>MEncoder</application> drops too many frames in a
  row, it starves <option>pullup</option>'s buffers and causes it to
  crash.
  </para>

  <para>
  Even if <application>MEncoder</application> only drops one frame,
  <option> pullup</option> still doesn't get to see it, and will end
  up operating on an incorrect sequence of frames. Even though this
  doesn't cause a crash, <option> pullup</option> won't be able to
  make correct decisions on how to reassemble progressive frames, and
  will either match fields together incorrectly or drop several fields
  to compensate.
  </para>
  </listitem>

<listitem><para>
  I haven't used <option>-vf filmdint</option> myself, but here's what
  D Richard Felker III has to say:

  <blockquote><para>It's OK, but IMO it tries to deinterlace rather
    than doing inverse telecine too often (much like settop DVD
    players &amp; progressive TVs) which gives ugly flickering and
    other artefacts. If you're going to use it, you at least need to
    spend some time tuning the options and watching the output first
    to make sure it's not messing up.</para></blockquote>
  </para></listitem>
</itemizedlist>
</sect3>

<sect3 id="menc-feat-telecine-encode-mixedpi">
<title>Mixed progressive and interlaced</title>
<para>
  There are two options for dealing with this category, each of
  which is a compromise. You should decide based on the
  duration/location of each type.
</para>

<itemizedlist>
<listitem><para>
  Treat it as progressive. The interlaced parts will look interlaced,
  and some of the interlaced fields will have to be dropped, resulting
  in a bit of uneven jumpiness. You can use a postprocessing filter if
  you want to, but it may slightly degrade the progressive parts.
  </para>

  <para>
  This option should definitely not be used if you want to eventually
  display the video on an interlaced device (with a TV card, for
  example). If you have interlaced frames in a 23.976 frames per
  second video, they will be telecined along with the progressive
  frames. Half of the interlaced "frames" will be displayed for three
  fields' duration (3/59.94 seconds), resulting in a flicking
  &quot;jump back in time&quot; effect that looks quite bad. If you
  even attempt this, you <emphasis role="bold">must</emphasis> use a
  deinterlacing filter like <option>lb</option> or
  <option>l5</option>.
  </para>

  <para>
  It may also be a bad idea for progressive display, too. It will drop
  pairs of consecutive interlaced fields, resulting in a discontinuity
  that can be more visible than with the second method, which shows
  some progressive frames twice. 29.97 frames per second interlaced
  video is already a bit choppy because it really should be shown at
  59.94 fields per second, so the duplicate frames don't stand out as
  much.
  </para>

  <para>
  Either way, it's best to consider your content and how you intend to
  display it. If your video is 90% progressive and you never intend to
  show it on a TV, you should favor a progressive approach. If it's
  only half progressive, you probably want to encode it as if it's all
  interlaced.
  </para>
  </listitem>

<listitem><para>
  Treat it as interlaced. Some frames of the progressive parts will
  need to be duplicated, resulting in uneven jumpiness. Again,
  deinterlacing filters may slightly degrade the progressive parts.
  </para></listitem>

</itemizedlist>
</sect3>

</sect2>

<sect2 id="menc-feat-telecine-footnotes">
<title>Footnotes</title>
<orderedlist>
<listitem><formalpara>
  <title>About cropping:</title>
  <para>
  Video data on DVDs are stored in a format called YUV 4:2:0. In YUV
  video, luma (&quot;brightness&quot;) and chroma (&quot;color&quot;)
  are stored separately. Because the human eye is somewhat less
  sensitive to color than it is to brightness, in a YUV 4:2:0 picture
  there is only one chroma pixel for every four luma pixels. In a
  progressive picture, each square of four luma pixels (two on each
  side) has one common chroma pixel. You must crop progressive YUV
  4:2:0 to even resolutions, and use even offsets. For example,
  <option>crop=716:380:2:26</option> is OK but
  <option>crop=716:380:3:26 </option> is not.
  </para>
  </formalpara>

  <para>
  When you are dealing with interlaced YUV 4:2:0, the situation is a
  bit more complicated. Instead of every four luma pixels in the
  <emphasis>frame</emphasis> sharing a chroma pixel, every four luma
  pixels in each <emphasis> field</emphasis> share a chroma
  pixel. When fields are interlaced to form a frame, each scanline is
  one pixel high. Now, instead of all four luma pixels being in a
  square, there are two pixels side-by-side, and the other two pixels
  are side-by-side two scanlines down. The two luma pixels in the
  intermediate scanline are from the other field, and so share a
  different chroma pixel with two luma pixels two scanlines away. All
  this confusion makes it necessary to have vertical crop dimensions
  and offsets be multiples of four. Horizontal can stay even.
  </para>

  <para>
  For telecined video, I recommend that cropping take place after
  inverse telecining. Once the video is progressive you only need to
  crop by even numbers. If you really want to gain the slight speedup
  that cropping first may offer, you must crop vertically by multiples
  of four or else the inverse-telecine filter won't have proper data.
  </para>

  <para>
  For interlaced (not telecined) video, you must always crop
  vertically by multiples of four unless you use <option>-vf
  field</option> before cropping.
  </para>
  </listitem>

<listitem><formalpara>
  <title>About encoding parameters and quality:</title>
  <para>
  Just because I recommend <option>mbd=2</option> here doesn't mean it
  shouldn't be used elsewhere. Along with <option>trell</option>,
  <option>mbd=2</option> is one of the two
   <systemitem class="library">libavcodec</systemitem> options that
  increases quality the most, and you should always use at least those
  two unless the drop in encoding speed is prohibitive (e.g. realtime
  encoding). There are many other options to
  <systemitem class="library">libavcodec</systemitem> that increase
  encoding quality (and decrease encoding speed) but that is beyond
  the scope of this document.
  </para>
  </formalpara>
  </listitem>

</orderedlist>

</sect2>

</sect1>

</chapter>