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

[David Soukal]

Hello,

I wanted to add another piece of information. I tried to compress the
same movie with newest MPlayer (05/01 CVS snapshot) and with XVid 1.1
beta 2 hoping that the problem would be gone.

Unfortunatelly, the problem is still there. I'll try VirtualDub with
newest XVid to see whether the problem might be in the movie itself or XVid.

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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