[MPlayer-dev-eng] [RFC] change lacv's MPEG-4 encoding options defaults

[Ivan Kalvachev]

2005/12/28, Guillaume Poirier <docmaintainerwannabe at laposte.net>:
> Hi there,
> Wouldn't it be nice if lavc's default's were the best speed/quality
> tradeoff?
>
> Currently, lavc's defaults are pretty much "blazing speed at all costs",
> which I don't think is a good idea since it doesn't help promoting lavc
> as a high quality codec, but just "good very fast codec".
>
> I'd like lavc to default to vcodec=mpeg4:mbd=2:trell:v4mv:turbo
>
> In my experience
> (http://tuxrip.free.fr//MPlayer-DOCS-HTML/en/menc-feat-enc-libavcodec.html#menc-feat-mpeg4-lavc-example-settings),
> it was only 0.74dB below optimal quality while being several times
> faster than optimal quality.
>
> I'd like to consider adding vmax_b_frames=1, vb_strategy=2 and dia=-1,
> but I have not made any recent speed/quality tests recently.
>
> Maybe with latest Michael's commits, further tests should be done to
> find the new best speed/quality tradeoff, but until then, what do you
> guys think?

I must say that i am also against this change.

1. 'turbo' overrides 'mbd' and set it to 0. It also disables v4mv,
qpel, trellis,cbp,mv0,qprd and makes search diamand really small. In
short the given line have only benefith because 'turbo' sets mb_cmp=2
(hadamand).
I think mbd=2 is not good default because (AFAIK) it is supposed to
work for bitrate only.

2. ATM there aren't no-options. It meas that for every enabled option
there must have no-option that disables it. There is thread that tries
to use ffmpeg options directly in mencoder, that I consider good idea,
but it will make even harder to implement the no-options.

It would be much better to have presets.