[MPlayer-users] mencoder lavcopts for decreasing filesize

[Jeff Clagg]

On Sat, Feb 11, 2006 at 11:13:30PM +0100, Ellis Whitehead wrote:
> Hi Jeff.
> 
> > 1. Read
> > http://mplayerhq.hu/DOCS/HTML/en/menc-feat-enc-libavcodec.html#menc-feat-dvd-mpeg4-lavc-encoding-options
> 
> Thanks for the link.  I'll do some experimenting with the "Options to
> adjust" section.
> 
> > 2. I think you should consider the relationship between vbitrate and
> > filesize.
> 
> I should have written explicitly that I'm interested in reducing
> filesize without visibly reducing quality.  So the given vbitrate was
> just meant as a fill-in.  For my own encoding I use three different
> vbitrate values (3000, 1500, 800) for different purposes, and the
> filesize reduction ratio is similar with all of them.  Or am I
> misunderstanding what you meant?

vbitrate directly determines file size. After all, filesize = bitrate *
time. If changing other options causes changes in bitrate (filesize),
this doesn't necessarily tell you ANYTHING about those other options, it
just tells you something about libavcodec's ratecontrol. The correct way
to deal with this is to isolate either quality or bitrate in your testing.
Isolating bitrate is much easier. And in that case, you should also
probably be using 2-pass encoding.

Also, please do not tell people to use vhq or mbd=1. mbd=0 is fast but
less quality; mbd=2 is slower but better quality. mbd=1 is not generally
considered a good speed/quality tradeoff so you should probably just
never use it. The only reason anyone EVER suggests vhq or mbd=2 is
because they got the idea from yet another outdated guide, or worse,
they got it from some lame guide that got it from some lame guide that
got it from some lame guide that hasn't been updated in about 3 years.
Frankly I don't think I've seen a single good guide out there other than
the one I linked above.