[MEncoder-users] a-v synchronization problems of some NTSC DVDs with -oac copy

[David Soukal]

Hello,

I was trying to reencode the problematic movies with a newly synced  CVS
version of MPlayer but I was still having the same problems.

I wanted to ask you guys whether there's anything more I could do about
my problems or whether there's something being worked on. The responses
I got were inconclusive, at least for me, as to what to do next.

I also asked the same question on XVid mailing list but I never got any
response...

Do you have any idea what I might try before I give up XVid completely?

Thank you again,

David


> David Soukal wrote:
> Hello,
> 
> I have recently ran into A-V synchronization problems while encoding
> some NTSC DVDs. I looked at the mailing list archive and found very
> similar symptoms in a thread by Corey Hickey on March 15th ("a-v sync
> problems with pullup, softskip (only on some DVDs)"). I have studied the
> answers but I was unable to fix the problem. It seems that the problem
> was a bug in the code that has been fixed. But I didn't find a reference
> to the version of MPlayer that has the bug fixed. I'm using version
> 1.0pre6 compiled from sources on a Gentoo system (For Gentoo users: I
> had to recompile MPlayer recently with the dts flag to get FFMPEG
> support again.)
> 
> To reiterate the problems. I have noticed a short sync delay (of order
> of ms) with some DVDs that I converted while there was no sync problem
> with other DVDs. All the DVDs are in the NTSC format. The original DVDs
> show no sync problems, of course.
> 
> The problematic DVDs are stored progressive with exception of a couple
> of short scenes with telecined content. I used the following command
> line for the encoding:
> 
> mencoder -vf pullup=2:2:4:4,softskip,crop=704:368:8:60 -ofps 23.976 -oac
>  copy -ovc xvid -xvidencopts pass=1:${xvidencopts} -o movie.avi
> 
> where $xvidencopts is
> 
> xvidencopts="bitrate=1800:me_quality=6:nointerlacing:noqpel:gmc:trellis:quant_type=mpeg:
> vhq=4:autoaspect:chroma_opt:hq_ac:min_iquant=1:min_pquant=1:min_bquant=1".
> 
> I use the same commands (with exception of the cropping parameters and
> bitrate) for all DVDs, with some it works with other I get the problem.
> So it seems that the problem must be in the DVDs themselves.
> 
> Some observations that I made:
> 
> 1) the sync problem would be there even if I omitted pullup and softskip
> filters. One DVD that I have has first telecined content in the middle
> of the movie, however the sync problems would be there from the very
> beginning (with or without pullup,softskip)
> 
> 2) there would be no sync problem if I compressed the audio stream with
> lame instead of just copying it.
> 
> 3) MEncoder issues "1 duplicte frame(s) found" warning now and then. A
> small fragment of the log:
> 
> Pos:   0.0s      2f ( 0%)   0fps Trem:   0min   0mb  A-V:0.000 [0:0]
> 1 duplicate frame(s)!
> ODML: vprp aspect is 16384:7220.
> ODML: vprp aspect is 16384:7220. Trem:   0min   0mb  A-V:0.000 [0:0]
> 
> 1 duplicate frame(s)!
> Pos:   0.3s     10f ( 0%)   0fps Trem:   0min   0mb  A-V:0.000 [0:0]
> demux_mpg: 24fps progressive NTSC content detected, switching framerate.
> Pos:  17.4s    421f ( 0%)  53fps Trem:  48min 2133mb  A-V:0.000 [2801:0]
> 1 duplicate frame(s)!
> Pos: 230.8s   5539f ( 4%)  45fps Trem:  44min 1007mb  A-V:0.000 [1631:0]
> 1 duplicate frame(s)!
> Pos: 255.5s   6131f ( 4%)  45fps Trem:  43min 964mb  A-V:0.000 [1554:0]]
> 1 duplicate frame(s)!
> Pos: 268.3s   6437f ( 5%)  45fps Trem:  43min 944mb  A-V:0.000 [1518:0]
> 1 duplicate frame(s)!
> Pos: 269.2s   6459f ( 5%)  45fps Trem:  43min 943mb  A-V:0.000 [1515:0]
> 1 duplicate frame(s)!
> Pos: 270.8s   6497f ( 5%)  45fps Trem:  43min 940mb  A-V:0.000 [1509:0]
> 1 duplicate frame(s)!
> Pos: 275.4s   6607f ( 5%)  45fps Trem:  43min 933mb  A-V:0.000 [1497:0]
> ...
> 
> Is the message "duplicate frame(s)" a good or a bad thing? (I wasn't
> able to make out the right answer in the responses in Corey's thread)
> Why does it appear in progressive content?
> 
> 4) I use Windows Smartripper to backup the DVDs and MPlayer seems to
> have wrong information about the length of the movie (checked on the OSD
> display). However the result is always OK (as far as length is
> concerned). I'm including this observation here only for completeness.
> (BTW: I have a very small Linux partition (3GB) so I have to grab the
> DVD on a Windows partition)
> 
> 5) the sync problems exist only for some mixed-content DVDs not all of them.
> 
> 
> I'm using MEncoder only for a couple of months now. So I'm no expert. If
> I overlooked something obvious, I apologize in advance!
> 
> Thank you for your thoughts/comments.
> 
> David
> 
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