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New section: choosing the video codec for your encode: what to consider before picking it.

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DOCS/xml/en/encoding-guide.xml
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@ -1350,6 +1350,111 @@ Do not do this! Always use a file or CD/DVD/etc device as input.
</para>
</sect2>
<sect2 id="menc-feat-dvd-mpeg4-codec">
<title>Choosing the video codec</title>
<para>
Choosing the video codec to use depends on several factors, some of
which widely depend on personal taste and technical constraints.
</para>
<itemizedlist>
<listitem><para>
<emphasis role="bold">Compression efficiency</emphasis>:
It's quite easy to understand that newer-generation codecs are made
to yield better picture quality than previous generations.
Therefore, you cannot be wrong
<footnote id='fn-menc-feat-dvd-mpeg4-codec-cpu'>
<para>Be careful, however: decoding DVD-resolution MPEG-4 AVC videos
requires a fast machine (i.e. a Pentium 4 over 1.5Ghz or a Pentium M
over 1Ghz).
</para></footnote>
by choosing MPEG-4 AVC codecs like
<systemitem class="library">x264</systemitem> instead of MPEG-4 ASP codecs
such as <systemitem class="library">libavcodec</systemitem> MPEG-4 or
<systemitem class="library">XviD</systemitem>.
(To get a better grasp of what the fundamental differences between
MPEG-4 ASP and MPEG-4 AVC are, you would be well advised to read the entry
"<ulink url="http://guru.multimedia.cx/?p=10">15 reasons why MPEG4 sucks</ulink>"
from Michael Niedermayer's blog.)
Likewise, you should get better quality using MPEG-4 ASP instead
of MPEG-2 codecs.
</para>
<para>
However, newer codecs which are in heavy development can suffer from
bugs which have not yet been noticed and which can ruin an encode.
This is simply the tradeoff for using bleeding-edge technology.
</para>
<para>
What's more, beginning to use a new codec requires that you spend some
time becoming familiar with its available options, so that you know what
to adjust to achieve a desired picture quality.
</para></listitem>
<listitem><para>
<emphasis role="bold">Hardware compatibility</emphasis>:
It usually takes a long time for standalone video players to begin to
include support for the latest video codecs.
As a result, most only support MPEG-2 and MPEG-4 ASP
(beware: usually, not all MPEG-4 ASP features are supported).
Please refer to the technical specs of your player (if they are available),
or Google around for more information.
</para></listitem>
<listitem><para>
<emphasis role="bold">Best quality per encoding time</emphasis>:
Codecs that have been around for some time (such as
<systemitem class="library">libavcodec</systemitem> MPEG-4 and
<systemitem class="library">XviD</systemitem>) are usually heavily
optimized with all kinds of smart algorithms and SIMD assembly code.
That's why they tend to yield the best quality per fps.
However, they may have some very advanced options that, if enabled,
will make the encode really slow for marginal gains.
</para>
<para>
If you are after blazing speed you should stick around the default
settings of the video codec (which doesn't mean you should not experiment
with some of the options which are mentioned in other sections
of this guide).
</para>
<para>
You may also consider choosing a codec which can do multi-threaded
processing.
<systemitem class="library">libavcodec</systemitem> MPEG-4 does
allow that, resulting in small speed gains at the price of lower
picture quality.
<systemitem class="library">XviD</systemitem> has some experimental
patches available to boost encoding speed, by about 40-60% in typical
cases, with low picture degradation.
<systemitem class="library">x264</systemitem> also allows multi-threaded
encoding, which currently speeds-up encoding by 15-30% while lowering
PSNR by about 0.05dB.
</para></listitem>
<listitem><para>
<emphasis role="bold">Personal taste</emphasis>:
This is where it gets almost irrational: For the same reason that some
hung on to DivX&nbsp;3 for years when newer codecs were already doing wonders,
some folks will prefer <systemitem class="library">XviD</systemitem>
or <systemitem class="library">libavcodec</systemitem> MPEG-4 over
<systemitem class="library">x264</systemitem>.
</para>
<para>
Make your own judgment, and don't always listen to what some people will
tell you to do or think: The best codec is the one you master the best,
and the one that looks best to your eyes on your display
<footnote id='fn-menc-feat-dvd-mpeg4-codec-playback'>
<para>The same encode may not look the same on someone else's monitor or
when played back by a different decoder, so future-proof your encodes by
playing them back on different setups.</para></footnote>!
</para></listitem>
</itemizedlist>
<para>
Please refer to the section
<link linkend="menc-feat-selecting-codec">selecting codecs and container formats</link>
to get a list of supported codecs.
</para>
</sect2>
<sect2 id="menc-feat-dvd-mpeg4-audio">
<title>Audio</title>