[MPlayer-DOCS] suggestions for main/docs/xml/en/encoding-guide.xml

[compn]

sorry i missed the first couple threads on this, i think its a well written
guide and just needs a bit more polishing.


> <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

like size, quality, streamability, usability and popularity as well as...

(popularity meaning that even if x264 is the greatest current codec,
not everyone has the h264 decoding library installed, just like it took
a while for everyone to get divx3 and then to get xvid...)

>   which widely depend on personal taste and technical constraints.
> </para>
> <itemizedlist>
>   <listitem><para>
>   <emphasis role="bold">Compression efficiency</emphasis>:
>   It is quite easy to understand that newer-generation codecs are made
>   to yield better picture quality than previous generations.

how about just 'most newer-generation codecs are made to increase quality
and compression'

>   Therefore, you cannot go wrong

therefor, the authors of this guide, and many other people (doom9, others?)
suggest you use an mpeg-4 avc codec like...

>   <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>
>   when 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.)

imo, that blog post is horribly inefficient at telling the average user
the differences between mp4 asp and mp4 avc... the user does not care about the
framework of the codec. either a guide showing the difference should be
linked to or this part removed. or maybe 'advanced codec developers maybe
interested in reading michael ni's opinion on why mpeg4 asp codecs suck'


>   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.

bleeding edge? do non-native english people know this word?
how about 'newest technology' ?

>   </para>
>   <para>
>   What is more, beginning to use a new codec requires that you spend some
>   time becoming familiar with its 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 is why they tend to yield the best quality quality per
>   encoding time ratio.
>   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 does not mean you should not experiment


double negative.
-(which does not mean you should not experiment
+(you should still try the other options which are mentioned in other sections


>   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>


err, where does using threads affect picture quality? this needs to be
rephrased... and where did you get those statistics? 40-60% speedup
using what? an smp box? if so, say so..

> 
>   <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>

hmm, this makes little sense unless you were around during those divx3 days...
how about:

Back when the majority of people were using divx3 and newer codecs started
emerging, some people chose to stick with divx3. they might have been afraid
of change. this meant that they lost out on better quality codecs and got stuck
with old divx3 bugs. this is also happening today with libavcodec and xvid
vs the newer codecs like x264.

>   <para>
>   Make your own judgment, and do not always listen to what some people will
>   tell you to do or think: The best codec is the one you master the best,

doesnt this then invalidate the guide? :) how about something like:

Make your own judgement, do not take advice from people who swear by one
codec. take a few sample clips from raw sources and compare 
different encoding options/codecs to find one that suits you 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>