[MEncoder-users] Skipping frame! and duplicate frame(s)! problems

[Jonathan]

Corey Hickey wrote:
> Jonathan wrote:
> 
>>>> While trying to encode some of my DVDs for portability purposes
>>>>I've run into problems with a lot of skipped and duplicated frames.
>>>
>>>
>>>I see that you've got a few duplicate frames, and skiped frames,
>>>but I don't see a problem.
>>
>>
>>In the areas where this happens the output is horribly 
>>interlaced/telecined and farther into the source it starts skipping 
>>frames every 5-10 frames and went on doing so for over 500 frames before 
>>I killed the encode.
>>
> Try using filmdint. In my experience it does better than pullup (and
> ivtc) with regard to skipped frames in telecined video. If your video
> isn't telecined, though, the skipping is pretty much unavoidable.
> 
Having tested pullup more it seems to do a very good job considering the 
material I am giving it to work with!  The frames it is skipping are 
parts of the opening credits where a bunch of very short (5-10 frames) 
telecined clips from throughout the series are played back in rapid 
succession.  It appears it is skipping the telecined frames where one of 
the interlaced frames appears at the beginning or end of the clip so it 
can't find the matching frame.  I've also pretty much resigned myself to 
seeing these messages no matter what at this point.  Some of the pans 
outside of the credits where pullup stitched frames together jerk now 
though.

> NTSC DVD video can have either 24000/1001 fps or 30000/1001, and is
> allowed to switch at any time. This usually happens during the DVD
> mastering process when sections of video with different framerates are
> spliced together.
> 
This appears to happen for no apparent reason at several points during 
the episode.  Why can't they be consistent putting this stuff together :P
> 
> When encoding a mixed-framerate dvd to a single-framerate container such
> as avi, 30000/1001 fps video must be reduced to 24000/1001 somehow.
> Pullup and filmdint inverse-telecine telecined video, thus reducing the
> framerate as desired. If the 30000/1001 fps material is not telecined,
> however, the only way to get 24000/1001 fps out of it is by skipping a
> frame now and then. Mencoder can't just slow it down because then the
> video would lag behind the audio.
> 
This seems to be happening anyway, as near as I can tell the audio is 
ahead although I'm not very good at judging that.  I can tell for sure 
it is off annoyingly much though.  One of the commands I have tried 
using to encode the video is

mencoder -oac pcm -vf pullup,softskip -ofps 24000/1001 -ovc x264 
-x264encopts pass=1:bitrate=952:bframes=3 -o test.test stream.dump

stream.dump was produced by this command

mplayer -dumpstream -alang en dvd://1

Does anyone have any suggestions on how to correct this, I've read the 
man page and the website docs but neither of them say anything about 
sound sync problems when using the pullup filter.  I would prefer to 
extract and encode the audio separately if anyone knows a way to do that 
and have it stay in sync because I plan to mux multiple tracks (original 
stream and commentaries) into Matroska with Ogg Vorbis.
> 
>>>mencoder doesn't really change the framerate per-se, it's just informing
>>>you that the framerate of the source video has changed.
>>>
>>
>>Is that hardcoded into the video stream or is it just something mencoder 
>>figures out?
>>
> 
> 
> Yes, the different fps values are within the video stream. When
> mencoder/mplayer notices a change it prints a message.
That is also a little frustrating because as I mentioned above the 
framerate changes for no obvious reason for several minutes in some 
portions of the video.

> 
[snip]
>>H.264 is *really* nice but a bit slow!
> 
> 
> Just for fun, try out snow. On my tests, it retains considerably more
> detail than x264. Snow is not finished yet, but I like it already.
> 
I might try snow at some future point but because I plan to keep these 
for a quite long time I want to stay with something that will not change 
incompatibly.

If someone would like to have a go at encoding some of this themselves I 
can put part of stream.dump or whatever other files would be useful on 
my site but I'm on 40KB/s SDSL so please be patient if you decide to 
download them.

Thanks a bunch,
Jonathan