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

[Corey Hickey]

D Richard Felker III wrote:
> On Tue, Mar 15, 2005 at 12:41:48PM -0800, Corey Hickey wrote:
> 
>>I've been seeing an elusive a-v sync problem recently with a few DVDs
>>and have finally tracked it down to a reproducible test case.
>>
>>Using pullup,softskip on the (recently released) Star Wars DVD results
>>in audio that plays about 0.3 seconds early.
> 
> 
> Interesting. Can you tell me if strange frame skips or duplicates
> happen at the beginning (with or without pullup loaded). Unfortunately
> mencoder doesn't like filters that buffer a few frames ahead, so
> pullup has to do a nasty hack to hide that it's doing this.. If the
> first few frames are supposed to be skipped it could mess things up
> rather badly, perhaps...?
> 

I don't know exactly what you mean by strange, but there certainly are a
lot more of them when I use pullup. I just made a couple logs of the
first part of the movie:

mencoder starwars.vob -v -aid 128 \
-vf pullup,softskip,crop=714:352:2:62,scale=688:288 \
-ovc lavc -oac copy -ofps 24000/1001 -endpos 530

...with and without pullup,softskip.

bugfood at bugfood:~/mpbug$ grep 'Skipping frame!' big-nopullup.log | wc -l
2
bugfood at bugfood:~/mpbug$ grep 'duplicate frame(s)' big-nopullup.log | wc -l
3
bugfood at bugfood:~/mpbug$ grep 'Skipping frame!' big-pullup.log | wc -l
1
bugfood at bugfood:~/mpbug$ grep 'duplicate frame(s)' big-pullup.log | wc -l
115

big-pullup.log and big-nopullup.log are uploaded:
mpqh incoming/desync2/
http://fatooh.org/files/mpbug/desync2/

I also just noticed something I hadn't before: when using pullup
mencoder reports "Could not get buffer from pullup!" four times. I just
checked the logs of the cut section I uploaded earlier, though, and I
don't see that message (even though the cut section has the same desync).

The messages appear after a long series of duplicate frames, between
about 84 and 88 MB into the file. I tried encoding just that portion,
and pullup doesn't give me an error - just lots of duplicate frames. If
you're interested, you can download just that portion:

dd if=bigpart.vob of=test.vob bs=8192 count=512 skip=10240
--> http://fatooh.org/files/mpbug/desync2/test.vob

Thanks again,
Corey