[MPlayer-dev-eng] [RFC] preliminary x264 encoding help text

[Guillaume Poirier]

Hi,

On Apr 10, 2005 1:00 AM, Jeff Clagg <snacky at ikaruga.co.uk> wrote:
> Hi, I'm doing some preliminary work on a document that will provide
> encoding tips for users of x264. Here are my ideas for topics that
> should be addressed:
> 
> 1) Intro stuff
> 2) Getting x264 and getting it to work with mencoder
> 3) Suggestions about what options to use, and why
> 4) muxing issues (what container format to use, and why)

Nice work Jeff. I'll read it thoroughly tomorrow, when I'm awake.
It's really nice to see that several people are interested in
improving the encoding doc (I am, and so is Rich).

> In the attached document, I think I have items 1 and 2 fairly well
> covered. 3 is partly covered. I'm disappointed by how long this section
> is, but I'm also unhappy with how incomplete it is. Frankly I'm beginning
> to think my rant against the deblocking filter tinkerers might belong
> elsewhere.

I'd like to hear Loren's thought about that, but you made a point.


> As for section 4, I don't feel very commited to it and I would
> appreciate it if someone else would offer to address it.

I am. I know I should add this section, which is all the more
important now that we will have x264 in the docs, and now that I
broadened the spectrum of codec that are advised to be used for encode
and that are not compatible with avi.

> I know there are some people around here who have done a lot of benchmarks
> that I haven't, which is why my write-up below only covers the frameref
> and subq options in any kind of serious detail. I would be grateful if
> someone could submit more benchmarks involving the partition-related
> options and the bframe related options. And a special prize is deserved
> by anyone who can show a PSNR gain by adjusting the deblocking parameters
> by -2 or more.


You can use Romain Dolbeau's mencgen to make an automatic test of all
kinds of combinations of codecs options.
http://www.caps-entreprise.com/private/dolbeau/lavcGenetic/lavcGenetic.html


> When this document is in decent shape, I will adapt it for inclusion
> in DOCS/xml/en/mencoder.xml (which, btw, rocks, and should probably
> be referenced multiple times in the man page).

Good to know that. I'm still working on it as it lacks, as I said the
muxing part at least, and it also lacks the tips from the guide that
Rich wrote.
I don't know XML too much, so it takes me time to format it properly.
(plus, like everyone else, I also have a real life outside of MPlayer ;-) )


> Meanwhile I'd be very
> grateful for any comments or contributions.

I'll do that. Tell you what, here's on attachment a compilation of
tips that Loren gave on Doom9 forum about Snow and x264 that I
gathered for future use.
This might be helpful.


> And on a semi-related note, can anyone give a convincing justification for
> why the man page still states that increasing frameref is more effective
> on anime vs. live material? I fear this comment may have its origins in
> some poorly-considered and half-assed tests I did way back last fall.

That's very possible. But Loren is maintaining x264's section of the
manpage himself, so I never bothered to question those statements.
But since Loren encodes mainly animes AFAIK, I'm not sure he had
tested that thoroughly. I guess mencgen could be of a great help here
too.

Thanks for the work,

Regards,
Guillaume
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