FFMPEG -mbd parameter

[Klagar]

Hi !

I'm trying to understand FFMPEG as best I can, but some parameters still seem to elude both deduction and research.
For instance, does anyone know what the -mbd parameter is supposed to do ?

I read somewhere that setting it to "2" or "rd" makes the encoding go slower but creates a slightly less heavy output file, but that's about it. Also a lot of discussions about -mbd being supposedly related in some way to -cmp and its relatives, but most people seem to discredit this theory.

Thoughts, anyone ?

Thanks !!!

[bat999]

Hi
This is the info that I have from man ffmpeg:-

-mbd <int> E.V.. macroblock decision algorithm (high quality mode)
simple E.V.. use mbcmp (default)
bits E.V.. use fewest bits
rd E.V.. use best rate distortion

And this is from the online documentation (3.4 Advanced Video Options):-
From here:-http://www.ffmpeg.org/ffmpeg-doc.html

`-mbd mode'
macroblock decision

`0'
FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).
`1'
FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
`2'
FF_MB_DECISION_RD: rate distortion

It looks like:-
If you don't use the -mbd parameter or if you use -mbd 0 then you get FF_MB_DECISION_SIMPLE.
If you use -mbd 1 you get FF_MB_DECISION_BITS.
If you use -mbd 2 you get FF_MB_DECISION_RD.

I've never knowingly used this parameter, so presumably it's always been 0 (FF_MB_DECISION_SIMPLE) by default.
Maybe someone else will be able to explain just what this parameter does.
I've attached the man_ffmpeg file, though I think the online documentation is sufficient.

[Klagar]

Hi,

Thanks for the reference, unfortunately I had already figured out what settings were available and I have read both the documentations you pointed...

What the parameter does exactly is what I want to know ; though from what I've seen, even top developers and video experts cannot tell precisely what purpose it serves. I believe it more than probable that this is the kind of setting that is just not that important to use, or maybe it was meant to fix a problem that died long ago, or even never arose !

But I still hope someone out there understands the geomancy behind it !