[MEncoder-users] DVD with vfr av-sync problem

[Peter Cordes]

Munzuk wrote:
>mencoder -fps 30000/1001 -aid 129 -ovc lavc -oac copy -lavcopts vcodec=mpeg4 1.VOB -o 1.AVI
>
>The problems come after this (the duplicated frames con be avoided with ofps 
>24000/1001), about 0,5 seconds at 30fps
>.
>.
>.
>Pos: 166.3s   3998f ( 2%) 59.54fps Trem:  38min 1675mb  A-V:-0.009 [818:1536]
>1 duplicate frame(s)!
>Pos: 166.5s   4002f ( 2%) 59.57fps Trem:  38min 1675mb  A-V:-0.018 [817:1536]
>1 duplicate frame(s)!
>Pos: 166.6s   4004f ( 2%) 59.58fps Trem:  38min 1673mb  A-V:-0.019 [817:1536]
>demux_mpg: 30000/1001fps NTSC content detected, switching framerate.
>Warning! FPS changed 23.976 -> 29.970  (-5.994005) [4]  A-V:-0.018 [817:1536]
>Pos: 166.9s   4014f ( 2%) 59.64fps Trem:  38min 1673mb  A-V:0.003 [815:1536]]
>1 duplicate frame(s)!
>Pos: 167.1s   4019f ( 2%) 59.65fps Trem:  38min 1672mb  A-V:0.020 [815:1536]
>1 duplicate frame(s)!
>Pos: 167.2s   4021f ( 2%) 59.65fps Trem:  38min 1672mb  A-V:0.026 [814:1536]
>demux_mpg: 24000/1001fps progressive NTSC content detected, switching 
>framerate.
>
>1 duplicate frame(s)!
>Pos: 167.5s   4028f ( 2%) 59.66fps Trem:  38min 1673mb  A-V:0.018 [814:1536]
>1 duplicate frame(s)!
>Pos: 167.7s   4032f ( 2%) 59.66fps Trem:  38min 1672mb  A-V:0.027 [814:1536]
>1 duplicate frame(s)!

 If you want to inverse-telecine the whole thing, and output a ~24fps video,
try -vf filmdint=io=30:24:verbose=1:dint_thres=256,softskip -fps 30000/1001 -ofps 24000/1001

 filmdint looks at the MPEG field flags, so it see the switches from hard to
soft telecine.  (If it's not actually telecined, but rather interlaced, you
should decrease the deinterlace threshold, so the output won't look combed.
It will lose some fields, but that's unavoidable converting 60i or 30p to
24p framerate.)  I think some DVDs makers often hard TC on all-black frames,
so losing fields there won't matter.  (I have a DVD that has 2s of black
frames at the beginning and end of one of the bonus features that are hard
TCed.)

 -vf pullup might be useful instead.

  Since you're outputting to avi, mencoder should be able to correct the A/V
sync if an odd frame creeps in anywhere.  (If it eventually recovers the way
you were doing it before, maybe -mc 1 would let it get back in sync faster.)

-- 
#define X(x,y) x##y
Peter Cordes ;  e-mail: X(peter at cor , des.ca)

"The gods confound the man who first found out how to distinguish the hours!
 Confound him, too, who in this place set up a sundial, to cut and hack
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