[MEncoder-users] low quality decrypt

[Pete Davis]

> > the marvelous MPlayer documentation found at
> > http://www.mplayerhq.hu/DOCS/HTML/en/index.html .
> > Pay special attention to chapters 7 and 8, which go into detail on the
> > mysteries of video encoding using MEncoder.
> 
> Really, I tried to do so. But i simply couldnt understand much. My
> problem is that i know nothing about image/video processing. To be
> honest, i tried with the spanish version, but i see now it is some out
> of date. And i get lost with the english version.
> 
> However, the real problem _for me_ is, imho, the high level (or not
> for novice) of the help. I think it requires a previous knowledge of
> video stream, formats, etc etc
> 
> Newcommers, like me, just pretend to decryp a dvd without having a
> deep knowledge of all the posibilities that mencoder provides.
> 
> As time goes by, i will try to impruve my output files, once i get a
> deeper knowledge and practice with mencoder.
> 

Miguel, I agree, as a beginner, I found the documentation very hard to
follow because you do really need to understand quite a bit about video. 

I found that simply trying to encode a bunch of different things, reading
about and trying different parameters, and looking at the results, thing
slowly started to make more sense to me. It does take a while to start
feeling comfortable with all the terminology and different things you need
to know.

For encoding DVDs, you really need to read through Chapter 8 (unfortunately
it hasn't been translated into the Spanish version!). It's very important to
understand how the DVD is encoded so that you can properly re-encode it.
Many DVDs will require certain filters depending on how the DVD was encoded,
otherwise you could end up with a poor quality rip.

In addition, you'll find that two pass encodings will produce much better
results than a single pass. They'll also be somewhat smaller (about 10-20%,
I find).

Unfortunately, the example in the Spanish docs (7.1 Codificacion MPEG-4 en 2
or 3 pasadas) is not a particularly good example. It does a 2 pass encoding
but does a 3rd pass for audio which isn't necessary.

Modifying their example, I would do something like this instead:

Pass #1:

mencoder dvd://2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=1 -oac copy -o
/dev/null

Pass #2

mencoder dvd://2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2 -oac mp3lame
-lameopts vbr=3 -o pelicula.avi


The first pass sends the output to /dev/null because the AVI output isn't
needed. What's needed is the divx2pass.log file that's generated.

The second pass encodes both audio and video. It will use the information
from divx2pass.log to further refine the encoding which will produce higher
quality output and a smaller .avi.

This is simply a generic example, though. Depending on the original DVD, you
made need to apply certain filters.

Hope this helps.

Buena suerte.

Pete