[MPlayer-DOCS] r21861 - trunk/DOCS/xml/en/encoding-guide.xml
gpoirier
subversion at mplayerhq.hu
Wed Jan 10 01:08:17 CET 2007
Author: gpoirier
Date: Wed Jan 10 01:08:16 2007
New Revision: 21861
Modified:
trunk/DOCS/xml/en/encoding-guide.xml
Log:
explain how to use MEncoder to create QuickTime-compatible files
Mainly based on a patch by Mark Pilgrim % pilgrim A gmail P com %
Original thread:
Date: Oct 19, 2006 9:50 PM
Subject: [MPlayer-DOCS] Interested in contributing case studies
Modified: trunk/DOCS/xml/en/encoding-guide.xml
==============================================================================
--- trunk/DOCS/xml/en/encoding-guide.xml (original)
+++ trunk/DOCS/xml/en/encoding-guide.xml Wed Jan 10 01:08:16 2007
@@ -2898,11 +2898,12 @@
<option>filmdint</option>.
</para>
-<para>
+<para id="menc-feat-dvd-mpeg4-example-crop">
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
+Make sure you seek to a fully filled frame (such as a bright scene,
+past the opening credits and logos), and
you will 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:
@@ -4082,6 +4083,321 @@
<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
+<sect1 id="menc-feat-quicktime-7">
+<title>Using <application>MEncoder</application> to create
+<application>QuickTime</application>-compatible files</title>
+
+
+<sect2 id="menc-feat-quicktime-7-why-use-it">
+<title>Why would one want to produce <application>QuickTime</application>-compatible Files?</title>
+
+<para>
+ There are several reasons why producing
+ <application>QuickTime</application>-compatible files can be desirable.
+</para>
+<itemizedlist>
+<listitem><para>
+ You want any computer illiterate to be able to watch your encode on
+ any major platform (Windows, Mac OSX, Unices …).
+</para></listitem>
+<listitem><para>
+ <application>QuickTime</application> is able to take advantage of more
+ hardware and software acceleration features of Mac OSX than
+ platform-independent players like <application>MPlayer</application>
+ or <application>VLC</application>.
+ That means that your encodes have a chance to be played smoothly by older
+ G4-powered machines.
+</para></listitem>
+<listitem><para>
+ <application>QuickTime</application> 7 support the next-generation codec H.264,
+ which yields significantly better picture quality than previous codec
+ generations (MPEG-2, MPEG-4 …).
+</para></listitem>
+</itemizedlist>
+</sect2>
+
+<sect2 id="menc-feat-quicktime-7-constraints">
+<title><application>QuickTime</application> 7 limitations</title>
+
+<para>
+ <application>QuickTime</application> 7 supports H.264 video and AAC audio,
+ but it does not support them muxed in AVI container format.
+ However, you can use <application>MEncoder</application> to encode
+ the video and audio, and then use an external program such as
+ <application>mp4creator</application> (part of the
+ <ulink url="http://mpeg4ip.sourceforge.net/">MPEG4IP suite</ulink>)
+ to remux the video and audio tracks into an MP4 container.
+</para>
+
+<para>
+ <application>QuickTime</application>'s support for H.264 is limited,
+ so you will need to drop some advanced features.
+ If you encode your video with features that
+ <application>QuickTime</application> 7 does not support,
+ <application>QuickTime</application>-based players will show you a pretty
+ white screen instead of your expected video.
+</para>
+
+<itemizedlist>
+<listitem><para>
+ <emphasis role="bold">B-frames</emphasis>:
+ <application>QuickTime</application> 7 supports a maximum of 1 B-frame, i.e.
+ <option>-x264encopts bframes=1</option>. This means that
+ <option>b_pyramid</option> and <option>weight_b</option> will have no
+ effect, since they require <option>bframes</option> to be greater than 1.
+</para></listitem>
+<listitem><para>
+ <emphasis role="bold">Macroblocks</emphasis>:
+ <application>QuickTime</application> 7 does not support 8x8 DCT macroblocks.
+ This option (<option>8x8dct</option>) is off by default, so just be sure
+ not to explicitly enable it. This also means that the <option>i8x8</option>
+ option will have no effect, since it requires <option>8x8dct</option>.
+</para></listitem>
+<listitem><para>
+ <emphasis role="bold">Aspect ratio</emphasis>:
+ <application>QuickTime</application> 7 does not support SAR (sample
+ aspect ratio) information in MPEG-4 files; it assumes that SAR=1. Read
+ <link linkend="menc-feat-quicktime-7-scale">the section on scaling</link>
+ for a workaround.
+</para></listitem>
+</itemizedlist>
+
+</sect2>
+
+<sect2 id="menc-feat-quicktime-7-crop">
+<title>Cropping</title>
+<para>
+ Suppose you want to rip your freshly bought copy of "The Chronicles of
+ Narnia" Your DVD is region 1,
+ which means it is NTSC. The example below would still apply to PAL,
+ except you would omit <option>-ofps 24000/1001</option> and use slightly
+ different <option>crop</option> and <option>scale</option> dimensions.
+</para>
+
+<para>
+ After running <option>mplayer dvd://1</option>, you 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 is
+ 24000/1001 fps progressive video. This simplifies the process somewhat,
+ since you do not need to use an inverse telecine filter such as
+ <option>pullup</option> or a deinterlacing filter such as
+ <option>yadif</option>.
+</para>
+
+<para>
+ Next, you need to crop out the black bars from the top and bottom of the
+ video, as detailed in <link linkend="menc-feat-dvd-mpeg4-example-crop">this</link>
+ previous section.
+</para>
+
+</sect2>
+
+<sect2 id="menc-feat-quicktime-7-scale">
+<title>Scaling</title>
+
+<para>
+ The next step is truly heartbreaking.
+ <application>QuickTime</application> 7 does not support MPEG-4 videos
+ with a sample aspect ratio other than 1, so you will need to upscale
+ (which wastes a lot of disk space) or downscale (which loses some
+ details of the source) the video to square pixels.
+ Either way you do it, this is highly inefficient, but simply can not
+ be avoided if you want your video to be playable by
+ <application>QuickTime</application> 7.
+ <application>MEncoder</application> can apply the appropriate upscaling
+ or downscaling by specifying respectively <option>-vf scale=-10:-1</option>
+ or <option>-vf scale=-1:-10</option>.
+ This will scale your video to the correct width for the cropped height,
+ rounded to the closest multiple of 16 for optimal compression.
+ Remember that if you are cropping, you should crop first, then scale:
+
+ <screen>-vf crop=720:352:0:62,scale=-10:-1</screen>
+</para>
+
+</sect2>
+
+<sect2 id="menc-feat-quicktime-7-avsync">
+<title>A/V sync</title>
+
+<para>
+ Because you will be remuxing into a different container, you should
+ always use the <option>harddup</option> option to ensure that duplicated
+ frames are actually duplicated in the video output. Without this option,
+ <application>MEncoder</application> will simply put a marker in the video
+ stream that a frame was duplicated, and rely on the client software to
+ show the same frame twice. Unfortunately, this "soft duplication" does
+ not survive remuxing, so the audio would slowly lose sync with the video.
+</para>
+
+<para>
+ The final filter chain looks like this:
+ <screen>-vf crop=720:352:0:62,scale=-10:-1,harddup</screen>
+</para>
+
+</sect2>
+
+<sect2 id="menc-feat-quicktime-7-bitrate">
+<title>Bitrate</title>
+
+<para>
+ As always, the selection of bitrate is a matter the technical properties
+ of the source, as explained
+ <link linkend="menc-feat-dvd-mpeg4-resolution-bitrate">here</link>, as
+ well as a matter of taste.
+ This movie has a fair bit of action and lots of detail, but H.264 video
+ looks good at much lower bitrates than XviD or other MPEG-4 codecs.
+ After much experimentation, the author of this guide chose to encode
+ this movie at 900kbps, and thought that it looked very good.
+ You may decrease bitrate if you need to save more space, or increase
+ it if you need to improve quality.
+</para>
+
+</sect2>
+
+<sect2 id="menc-feat-quicktime-7-example">
+<title>Encoding example</title>
+
+<para>
+ You are now ready to encode the video. Since you care about
+ quality, of course you will be doing a two-pass encode. To shave off
+ some encoding time, you can specify the <option>turbo</option> option
+ on the first pass; this reduces <option>subq</option> and
+ <option>frameref</option> to 1. To save some disk space, you can
+ use the <option>ss</option> option to strip off the first few seconds
+ of the video. (I found that this particular movie has 32 seconds of
+ credits and logos.) <option>bframes</option> can be 0 or 1.
+ The other options are documented in <link
+ linkend="menc-feat-x264-encoding-options-speedvquality">Encoding with
+ the <systemitem class="library">x264</systemitem> codec</link> and
+ the man page.
+
+ <screen>mencoder dvd://1 -o /dev/null -ss 32 -ovc x264 \
+-x264encopts pass=1:turbo:bitrate=900:bframes=1:\
+me=umh:4x4mv:trellis=1:qp_step=4:qcomp=0.7:direct_pred=3:keyint=300 \
+-vf crop=720:352:0:62,scale=-10:-1,harddup \
+-oac faac -faacopts br=192:mpeg=4:object=1 -channels 2 -srate 48000 \
+-ofps 24000/1001</screen>
+
+ If you have multi-processor machine, you can add
+ <option>threads=auto</option>. This increases encoding speed by about
+ 94% per CPU core, with very little quality penalty (about 0.005dB for
+ dual processor, about 0.01dB for a quad processor machine).
+</para>
+
+<para>
+ The second pass is the same, except that you specify the output file
+ and set <option>pass=2</option>.
+
+ <screen>mencoder dvd://1 <emphasis role="bold">-o narnia.avi</emphasis> -ss 32 -ovc x264 \
+-x264encopts <emphasis role="bold">pass=2</emphasis>:turbo:bitrate=900:frameref=5:bframes=1:\
+me=umh:4x4mv:trellis=1:qp_step=4:qcomp=0.7:direct_pred=3:keyint=300 \
+-vf crop=720:352:0:62,scale=-10:-1,harddup \
+-oac faac -faacopts br=192:mpeg=4:object=1 -channels 2 -srate 48000 \
+-ofps 24000/1001</screen>
+</para>
+
+<para>
+ The resulting AVI should play perfectly in
+ <application>MPlayer</application>, but of course
+ <application>QuickTime</application> can not play it because it does
+ not support H.264 muxed in AVI.
+ So the next step is to remux the video into an MP4 container.
+</para>
+</sect2>
+
+<sect2 id="menc-feat-quicktime-7-remux">
+<title>Remuxing as MP4</title>
+
+<para>
+ There are several ways to remux AVI files to MP4. You can use
+ <application>mp4creator</application>, which is part of the
+ <ulink url="http://mpeg4ip.sourceforge.net/">MPEG4IP suite</ulink>.
+</para>
+
+<para>
+ First, demux the AVI into separate audio and video streams using
+ <application>MPlayer</application>.
+
+ <screen>mplayer narnia.avi -dumpaudio -dumpfile narnia.aac
+mplayer narnia.avi -dumpvideo -dumpfile narnia.h264</screen>
+
+ The filenames are important; <application>mp4creator</application>
+ requires that AAC audio streams be named <systemitem>.aac</systemitem>
+ and H.264 video streams be named <systemitem>.h264</systemitem>.
+</para>
+
+<para>
+ Now use <application>mp4creator</application> to create a new
+ MP4 file out of the audio and video streams.
+
+ <screen>mp4creator -create=narnia.aac narnia.mp4
+mp4creator -create=narnia.h264 -rate=23.976 narnia.mp4</screen>
+
+ Unlike the encoding step, you must specify the framerate as a
+ decimal (such as 23.976), not a fraction (such as 24000/1001).
+</para>
+
+<para>
+ This <systemitem>narnia.mp4</systemitem> file should now be playable
+ with any <application>QuickTime</application> 7 application, such as
+ <application>QuickTime Player</application> or
+ <application>iTunes</application>. If you are planning to view the
+ video in a web browser with the <application>QuickTime</application>
+ plugin, you should also hint the movie so that the
+ <application>QuickTime</application> plugin can start playing it
+ while it is still downloading. <application>mp4creator</application>
+ can create these hint tracks:
+
+ <screen>mp4creator -hint=1 narnia.mp4
+mp4creator -hint=2 narnia.mp4
+mp4creator -optimize narnia.mp4</screen>
+
+ You can check the final result to ensure that the hint tracks were
+ created successfully:
+
+ <screen>mp4creator -list narnia.mp4</screen>
+
+ You should see a list of tracks: 1 audio, 1 video, and 2 hint tracks.
+
+<screen>Track Type Info
+1 audio MPEG-4 AAC LC, 8548.714 secs, 190 kbps, 48000 Hz
+2 video H264 Main at 5.1, 8549.132 secs, 899 kbps, 848x352 @ 23.976001 fps
+3 hint Payload mpeg4-generic for track 1
+4 hint Payload H264 for track 2
+</screen>
+</para>
+
+</sect2>
+
+<sect2 id="menc-feat-quicktime-7-metadata">
+<title>Adding metadata tags</title>
+
+<para>
+ If you want to add tags to your video that show up in iTunes, you can use
+ <ulink url="http://atomicparsley.sourceforge.net/">AtomicParsley</ulink>.
+
+ <screen>AtomicParsley narnia.mp4 --metaEnema --title "The Chronicles of Narnia" --year 2005 --stik Movie --freefree --overWrite</screen>
+
+ The <option>--metaEnema</option> option removes any existing metadata
+ (<application>mp4creator</application> inserts its name in the
+ "encoding tool" tag), and <option>--freefree</option> reclaims the
+ space from the deleted metadata.
+ The <option>--stik</option> option sets the type of video (such as Movie
+ or TV Show), which iTunes uses to group related video files.
+ The <option>--overWrite</option> option overwrites the original file;
+ without it, <application>AtomicParsley</application> creates a new
+ auto-named file in the same directory and leaves the original file
+ untouched.
+</para>
+
+</sect2>
+
+</sect1>
+
+
+<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
+
+
<sect1 id="menc-feat-video-for-windows">
<title>
Encoding with the <systemitem class="library">Video For Windows</systemitem>
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