[MPlayer-users] mencoder lavcopts for decreasing filesize

[Guillaume POIRIER]

Hi,

On 2/11/06, Ellis Whitehead <lists at ellisw.net> wrote:
> Quick summary:
> If you take a simple lavcopts of:
>  vcodec=mpeg4:vbitrate=1500:keyint=125:vqmax=5:vhq
> and add:
>  mbd=1:vmax_b_frames=2:vi_qfactor=-0.8:preme=0:vqsquish=0:vrc_strategy=0
> then you'll get about a 5% filesize reduction.  Add "-vf hqdn3d" to
> the mencoder command line and you'll get another 5% (approximately, of
> course, depending on video source).

here http://www.nowiswhen.net/public/mencoder_lavcopts_size/ you say
that hqdn3d is a noise filter. It's not. It's a DEnoise filter.


> A bit longer:
> Last April I submitted bug report #276 about poor mpeg4 encoding
> quality in mencoder.
>   http://bugzilla.mplayerhq.hu/show_bug.cgi?id=276
> I think the problem may have been resolved now,

I just went through you bug report and closed it. Read what I wrote
there for the explanation.


> For the last year I've been working with mplayer and mencoder for a
> couple of large club projects, and gained quite of bit of experience
> with them for many different tasks.  I've had to keep extensive notes
> (since there's too much to remember), and I started organizing them so
> that others might benefit in some little ways.  In particular, I think
> I'll try to write up several "tips" pages for some of the more
> difficult stuff:
>
> 1. mencoder lavcopts for decreasing filesize
> 2. programming overlay video for mplayer/mencoder
> 3. splitting and combining DV files
> 4. high-quality real-time filters
> 5. using makefiles to handle batch video conversions
>
> I have no idea how much of this I'll really get around to writing up,
> but I did a write-up for #1 so far.  I put up a few screenshots on a
> webpage for visual comparison.  It's not a rigorous comparison by any
> means, but it might help someone who needs to get a few more minutes
> of video into a certain amount of space:
>  http://www.nowiswhen.net/public/mencoder_lavcopts_size/


I strongly advise you to read this section of the doc
http://tuxrip.free.fr//MPlayer-DOCS-HTML/en/menc-feat-enc-libavcodec.html#menc-feat-dvd-mpeg4-lavc-encoding-options
as long as the ones following. If you're after quality, there seem to
be several things you're missing.

As a side note, I'd really prefer if you could contribute doc patches,
in the form of encoding examples or things that you have the feeling
seem to be missing in the official doc. That way the information is
not spread all across the net, which leaves the n00bs clueless.

I've tried to improve mencoder's doc with my own experience of
mencoder, but there are lots of things possible with mencoder that
I've never done because I don't have any use for it. Therefore, more
exotic usages of mencoder aren't covered, and that's why users
contributions are more than welcome.

Guillaume

--
Just because code is syntactically "valid" GNU C doesn't mean gcc can
always compile it.
  Steven Bosscher - 2005-01-01
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11203#c14
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