[MPlayer-users] Stabilizer filter in MEncoder?

[D Richard Felker III]

On Thu, Sep 02, 2004 at 12:40:29AM -0500, Stephen Stocker wrote:
> >>   Hi,
> >>
> >>   I'm wondering if there's a filter in MEncoder which could be used as a
> >>   stabilizer in some way? What I'm looking for is something which can
> >>   stabilize old home movies, to lessen the jerkiness caused by the
> >>   movements of the cameraman.
> >>
> >>   If this isn't possible, does anyone know of a command-line utility or
> >>   something of that nature for Linux which will do this? Thanks.
> >>
> >>   Steve
> >
> >there's no such feature right now, and actually it's a very difficult
> >task, stabilizing video. it would be a cool filter for someone to
> >write eventually, but don't expect to see it soon.
> >
> >rich
> 
>   Thanks Rich. Yeah, it would be nice, but I got the impression from
>   searching for such a thing that it wasn't an easy thing to do.
> 
>   I know almost nothing about the technology involved. For that matter,
>   I know very little about video in general. :)

i think the basic idea would be to buffer several frames ahead and do
motion estimation on them all, then throw out small, 'localized'
motion that doesn't match the overall motion direction of the frame,
and finally analyze the global motion of several consecutive frames to
decide whether it's jerking (back-and-forth) or actual panning
(consistent motion in one direction). then you have to shift the
jerked frames to compensate, and finally crop all the frames a little
bit to make up for the fact that you're missing pixels at the edges of
compensated frames.

the hard steps are distinguishing between local&global motion (a
person moving in the frame vs the camera panning), and between
jerking&panning (requires analyzing several frames as a group rather
than each one individually).

rich