[MPlayer-DOCS] CVS: main/DOCS/xml/en mencoder.xml,1.11,1.12
Diego Biurrun CVS
diego at mplayerhq.hu
Sat Jan 3 00:07:09 CET 2004
Update of /cvsroot/mplayer/main/DOCS/xml/en
In directory mail:/tmp/cvs-serv953/DOCS/xml/en
Modified Files:
mencoder.xml
Log Message:
DVD ripping section added courtesy of Samuli Kärkkäinen with some
improvements made by me.
Index: mencoder.xml
===================================================================
RCS file: /cvsroot/mplayer/main/DOCS/xml/en/mencoder.xml,v
retrieving revision 1.11
retrieving revision 1.12
diff -u -r1.11 -r1.12
--- mencoder.xml 1 Jan 2004 14:43:46 -0000 1.11
+++ mencoder.xml 2 Jan 2004 23:07:07 -0000 1.12
@@ -62,7 +62,7 @@
<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
@@ -515,7 +515,7 @@
</para>
<para>
-A typical usage of this feature is to set the matrices preferred by the
+A typical usage of this feature is to set the matrices preferred by the
<ulink url="http://www.kvcd.net/">KVCD</ulink> specifications.
</para>
@@ -569,4 +569,183 @@
</para>
</sect1>
+<sect1 id="menc-feat-dvd-mpeg4">
+<title>Making a high quality MPEG4 ("DivX") 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 "telecine field 23.976"</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>
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