[MEncoder-users] [BUG] a-v sync problems with pullup, softskip (only on some DVDs)

[Corey Hickey]

D Richard Felker III wrote:
> Duplicate frames occur when pullup outputs less than 24 fps, because
> it can't find valid matches for some fields. See the verbose output:
> 
> affinity: .0..1+.2+.3.+4.+5.
> breaks:   .0..1.|2..3..4|.5.
> duration: 1
> 
> This indicates that pullup thinks the second field of the
> 2-field-duration frame there matches better with the FOLLOWING frame
> than with its own partner, and so it refuses to output either one as a
> frame. (The internal pullup engine outputs both fields as lone fields,
> but the vf_pullup wrapper for mplayer drops these.) Notice that the
> same thing is happening with field 5 after the duration-3 frame.
> 
> The only reason the duration-3 frame looks so clean itself (breaks on
> both sides and ideal affinity between fields) is that pullup FORCES
> these attributes whenever it gets a perfect duplicate field due to
> soft telecine. Until the first patch I made earlier, it didn't force
> the affinities on the duration-3 frame, so even more fields were
> getting dropped...
> 

I'm doing my best to understand what you're saying here, but I haven't 
quite figured out how to interpret pullup's verbose output. Actually, I 
understand your description of what pullup is doing but I can't relate 
it to your example yet.

I suppose 0, 1, 2, 3, 4, and 5 are the fields pullup has in its buffer, 
the + sign indicates whether the field matches the previous or following 
field, and the breaks show which fields pullup thinks should be grouped 
into frames. Am I correct? This is the first time I've really looked at 
that output so I'm not really sure what to make of it.

If what I said above is correct, then I have a few more questions. If 
I'm wrong above then the questions may be irrelevant or way off-base.

1. Does mencoder print the line of frame details before or after it 
prints the corresponding output from pullup? "After" would make sense to 
me but I can't be sure.
2. What duration does "duration:" indicate?
3. Why are there sometimes two blocks of pullup output for one "frame 
details" line?
4. For each input frame, which field numbers (in pullup's output) are 
the fields that make up that frame? Or is the input pairing not really 
relevant?

> 
> It seems really difficult...something is EXTREMELY bogus about this
> file. ivtc seems to handle it better, but both ivtc and detc have
> problems with it as well. You might see if you have better luck with
> filmdint..
> 

I'll check it out when I have some time later on.

> My guess is that this DVD is badly mastered...that it was telecined
> first, and then an inverse-telecine'ing mpeg2 encoder was used to make
> it mostly into soft-telecine. Further, my guess is that it did a bad
> job and got some of these sequences with only very small motion
> out-of-sync.
> 

 From what I've read these new Star Wars DVDs have been "digitally 
restored". I don't know what that involved, but probably your guess is 
correct.

Thanks for all the help,
Corey