[MEncoder-users] Inverse telecine? framerate from 120000/1001 to 24000/1001

[Rich Felker]

On Thu, Aug 31, 2006 at 05:04:29AM +0400, Evgeniy Stepanov wrote:
> On Thursday 31 August 2006 05:07, Rich Felker wrote:
> > Yes, what you said is nonsense. The reason the file uses 120 tick/sec
> > timebase is that it's not all 24 fps but some 30 fps, and the smallest
> > common timebase that can represent timestamps correctly for both is
> > 1/120 sec. If you try to make it 1/24 sec timebase, you will have to
> > discard one in every five frames from the 30 fps parts. If you want to
> > make it 1/30 sec timebase, you will have to show every 4th frame in
> > the 24 fps parts for double duration. Both choices will look very
> > ugly and choppy.
> 
> It might be a good idea to somehow locate the parts of original video that are 
> 24 fps and the parts that are 30 fps, and encode them separately. Then, 
> either leave the resulting videos as they are, or mux them

Concatenating streams with different encoding parameters produces
_invalid_ files except with a few stupid containers that try to
support more than they should or that simply don't care about
brokenness (the latter is more likely, e.g. mpeg containers).

> into some vfr 
> container.

They're already in a VFR container, that's the whole point..

> AFAIK, there is no good way of converting 30 <-> 24 fps.

Yes, there is no way and never will be. You can't resample
undersampled signals. (Converting between 3000 fps and 2400 fps would
be easy on the other hand. :)

Rich