[MPlayer-DOCS] encoding guide draft

[Guillaume Poirier]

Hi,

On Apr 4, 2005 2:46 AM, Diego Biurrun <diego at biurrun.de> wrote:
> Rich, I like this very much, we need to find a way to integrate it into
> our MEncoder documentation finally.  Guillaume, does this sound like a
> task for you?

Yes, I can certainly do that. We'll have to make some decision on how
to organize the new guide as it will be substantially bigger than the
old one (if the outputted HTML could be spread across several files, I
think it would help readability).
Also, some of Rich's paragraphs are pretty much a rewrite of the old
guide, and I'm not sure how I should deal with those issues as Rich
told me that he started to work on his guide when MEncoder's doc was
crappy.
I guess the best thing would be to take the best of both worlds, but
that'll require a little more work than a simple copy/paste + XML
formating.
Here's what I think I'm gonna do:
Merge Rich's guide into the XML section by section, starting with the
ones that I'm comfortable with (like cropping, scaling...).
The one(s) I'm not comfortable with is the section about pulldown, as
to the best of my knowledge, there's already a fairly big explanation
of proper pulldown on the docs, so I'm not sure I'm gonna be able to
extract the relevant new informations to put only those on the XML.
I'll see how it goes.

> I have just reread the guide again and found a few more typos and minor
> glitches, here it goes:

Would you append to have a corrected draft on hand that you could send
me (on private mail for example)? If you don't that's fine too, it's
just that whenever you might save some of my time, it means more time
I can put toward working on the guide.

> On Fri, Apr 01, 2005 at 02:13:49PM -0500, D Richard Felker III wrote:

> > The so-called "three-pass" encoding which MEncoder supports has been
> > reported to cause A/V desync. This will definitely happen if it is
> > used in conjunction with certain filters, therefore, it is now
> > recommended NOT to use three-pass mode. This feature is only left for
> > compatibility purposes and for expert users who understand when it is
> > safe to use and when it is not. If you have never heard of three-pass
> > mode before, forget that we even mentioned it!
> 
> Is this still valid?  I remember Loren doing a lot of n-pass work, but
> probably it only applies to x264, dunno.

Loren's 3 (and up) pass encode is for lavc and x264. Depending on the
movie material, it really can improve PSNR (also I must say raising
PSNR by 0.5-0.7dB at the best isn't something you can see at first
glance at the encoded movie.

Regards,
Guillaume