[MEncoder-users] Choppy video when changing framerate

[Phil Ehrens]

Stanley wrote:
> Manuel Carro wrote:
> >     Using the -ofps option makes the video to definitely look choppy.
> > And it is not a question of the player itself: the same video (after
> > reducing the framerate) looks choppy when using mplayer, xine, totem,
> > etc.  I assume that, to go e.g. from 25 to 20 (my current benchmark)
> > -ofps could remove one out of each five frames.  But, when playing
> > back, it looks as if those removals were not happening evenly, but
> > rather in groups every second or so.  I do not think mencoder is doing
> > that (is it?).  Any hint of what could be the problem (and the
> > solution)?
> >   
> I have the same feeling too. The video does look choppy more or less 
> after changing FPS, especially reducing FPS a little bit (e.g. 25fps to 
> 24fps).
> I think this is somehow unavoidable without rendering all frames again 
> which will bring much computation. As the interval of frames changes, 
> the content of frames must be changed in order to look really smooth.

Exactly. Except in cases where ivtc works perfectly, reducing framerate
is a lossy process. Transcode's modfps clonetype 3 (pixel interpolation)
can produce very good results, however, and is a clever and elegant
solution.