[MPlayer-users] Performing 29.97->23.976 conversion for badly inv.telecined movie

[Vladimir Mosgalin]

I'm trying to make a copy of ntsc dvd with 29.97->23.976 fps conversion,
but I have problems. The movie (Beautiful Mind) doesn't seems to be
interlaced or telecined the usual way; instead, it looks like it was
telecined and then deinterlaced before mastering. So frame pattern seems
to be "1 2 3 4 4 5 ...". Quality of frames is acceptable, but I want to
get rid of this framerate and produce mpeg4 file with 23.976 fps.

ivtc & detc filters don't work for this case, so I tried decimate
filter. With default settings it produces awful results, however; the
problem is, the frames aren't really "4 4", but something like "4 4'" -
the second frame sometimes has visible difference in one or several
macroblocks - some small detail appears somewhere in the picture for one
frame. It seems like a bug, but it breaks conversion. Also, sometimes
interlacing pattern is visible, although it is very subtle, and motion
in the movie is mostly slow, too.

I'm experimenting with decimate parameters, but it doesn't help much.
One of the combination that works relatively good is
decimate=-4:4096:2048:0.0005

The result differs from scene to scene; on some of them, up to minute of
video can be converted without problems; however, on different scenes I
get "duplicate frame" message every second or two. In average, it
produces about 200 duplicated frames for 10 minutes of video.

Can someone suggest parameters for decimate (or some other filter) that
produces better results?

Exact encoding string:
mencoder /mnt/media/dvd2/video_ts/vts_01_1.vob -vf
pp=md,decimate=-4:4096:2048:0.0005,crop=720:460:0:4 -oac copy -ovc lavc
-lavcopts vqscale=2 -o /tmp/test.avi -ofps 23.976 -ss 5:00

An excerpt from log:
Pos:  12,9s    393f (35%)  53fps Trem:   0min  13mb  A-V:0,024 [2553:448]
1 duplicate frame(s)!
Pos:  13,6s    413f (35%)  53fps Trem:   0min  13mb  A-V:0,029 [2485:448]
1 duplicate frame(s)!
Pos:  14,3s    433f (35%)  53fps Trem:   0min  13mb  A-V:0,020 [2428:448]
1 duplicate frame(s)!
Pos:  14,9s    453f (35%)  53fps Trem:   0min  14mb  A-V:0,019 [2379:448]
1 duplicate frame(s)!
Pos:  15,6s    473f (35%)  53fps Trem:   0min  14mb  A-V:0,029 [2324:448]
1 duplicate frame(s)!
Pos:  16,3s    493f (35%)  53fps Trem:   0min  14mb  A-V:0,020 [2272:448]
1 duplicate frame(s)!
Pos:  16,9s    513f (35%)  53fps Trem:   0min  15mb  A-V:0,019 [2225:448]
1 duplicate frame(s)!
Pos:  17,6s    533f (35%)  54fps Trem:   0min  15mb  A-V:0,032 [2191:448]
1 duplicate frame(s)!
Pos:  76,0s   2283f (39%)  50fps Trem:   1min 135mb  A-V:0,026 [5495:448]
1 duplicate frame(s)!
Pos:  87,3s   2623f (40%)  50fps Trem:   1min 157mb  A-V:0,025 [5678:448]
1 duplicate frame(s)!
Pos:  88,0s   2643f (40%)  50fps Trem:   1min 158mb  A-V:0,032 [5677:448]
1 duplicate frame(s)!
Pos:  93,2s   2798f (40%)  51fps Trem:   1min 162mb  A-V:0,027 [5551:448]
1 duplicate frame(s)!
Pos:  97,5s   2928f (41%)  51fps Trem:   1min 165mb  A-V:0,032 [5421:448]
1 duplicate frame(s)!
Pos: 100,2s   3008f (41%)  51fps Trem:   1min 167mb  A-V:0,022 [5343:448]
1 duplicate frame(s)!
Pos: 107,7s   3233f (41%)  51fps Trem:   1min 170mb  A-V:0,022 [5118:448]
1 duplicate frame(s)!

-- 

Vladimir