[MEncoder-users] Can't cut GOP from source

[belcampo]

mencoder -ss 00:00:01.440 -endpos 00:00:00.480 
/md/8940_20100722004000.mpg.ts -o /md/tst.avi -vf 
softskip,scale=720:576:0,harddup -demuxer lavf -sws 10 -nosound -ovc 
x264 -x264encopts 
bitrate=1672:me=umh:me_range=24:nodct_decimate:nointerlaced:8x8dct:nofast_pskip:trellis=1:partitions=p8x8,b8x8,i8x8,i4x4:mixed_refs:keyint=250:keyint_min=25:psy_rd=0.8,0.2:frameref=3:bframes=3:b_adapt=2:b_pyramid=none:weight_b:weightp=2:direct_pred=auto:subq=7:mbtree:chroma_me:cabac:aud:aq_mode=1:deblock:threads=auto
MEncoder SVN-r31745-4.2.3 (C) 2000-2010 MPlayer Team
158 audio & 340 video codecs
success: format: 0  data: 0x0 - 0x83e43d5c
libavformat file format detected.
[h264 @ 0x94d8440] non-existing SPS 0 referenced in buffering period
     Last message repeated 1 times
[mpegts @ 0x94cbd30] max_analyze_duration reached
[lavf] stream 0: video (h264), -vid 0
LAVF: Program 1
VIDEO:  [H264]  1440x1080  0bpp  25.000 fps    0.0 kbps ( 0.0 kbyte/s)
[V] filefmt:35  fourcc:0x34363248  size:1440x1080  fps:25.000  ftime:=0.0400
Opening video filter: [expand osd=1]
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
Opening video filter: [harddup]
Opening video filter: [scale w=720 h=576 interlaced=0]
Opening video filter: [softskip]
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
[h264 @ 0x8887920]non-existing SPS 0 referenced in buffering period
Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264)
==========================================================================
[NULL @ 0x8887920]non-existing SPS 0 referenced in buffering period
Pos:   0.0s      1f ( 0%)  0.00fps Trem:   0min   0mb  A-V:0.000 [0:0]
Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
[swscaler @ 0x892e100]Bicubic spline scaler, from yuv420p to yuv420p 
using MMX2
x264 [info]: using SAR=64/45
x264 [info]: using cpu capabilities: MMX2 SSE2Slow SlowCTZ
x264 [info]: profile High, level 3.0
Pos:   0.0s      4f ( 0%)  0.00fps Trem:   0min   0mb  A-V:0.000 [0:0]

1 duplicate frame(s)!
Pos:   0.0s      6f ( 0%)  0.00fps Trem:   0min   0mb  A-V:0.000 [0:0]

1 duplicate frame(s)!
Pos:   0.0s      8f ( 0%)  0.00fps Trem:   0min   0mb  A-V:0.000 [0:0]

1 duplicate frame(s)!
Pos:   0.0s      9f ( 0%)  0.00fps Trem:   0min   0mb  A-V:0.000 [0:0]

1 duplicate frame(s)!
Pos:   0.0s     10f ( 0%)  0.00fps Trem:   0min   0mb  A-V:0.000 [0:0]

1 duplicate frame(s)!
Pos:   0.0s     11f ( 0%)  0.00fps Trem:   0min   0mb  A-V:0.000 [0:0]

1 duplicate frame(s)!
Pos:   0.0s     47f ( 0%) 15.15fps Trem:   0min   0mb  A-V:0.000 [0:0]
Writing header...
ODML: vprp aspect is 16:9.
Writing header...
ODML: vprp aspect is 16:9.
Pos:   0.5s     60f ( 0%) 12.33fps Trem:   0min   0mb  A-V:0.000 [0:0]

Flushing video frames.
Writing index...
Writing header...
ODML: vprp aspect is 16:9.

Video stream: 1909.668 kbit/s  (238708 B/s)  size: 563352 bytes  2.360 
secs  60 frames
x264 [info]: frame I:1     Avg QP:13.26  size:  3988
x264 [info]: frame P:36    Avg QP:17.93  size: 13029
x264 [info]: frame B:22    Avg QP:21.86  size:  4105
x264 [info]: consecutive B-frames: 24.1% 75.9%  0.0%  0.0%
x264 [info]: mb I  I16..4: 10.4% 88.8%  0.9%
x264 [info]: mb P  I16..4:  9.8%  9.1%  5.4%  P16..4: 31.3% 16.0% 12.2% 
  0.0%  0.0%    skip:16.2%
x264 [info]: mb B  I16..4:  0.9%  0.4%  0.8%  B16..8: 24.3%  3.5%  1.7% 
  direct:13.8%  skip:54.5%  L0:28.0% L1:47.6% BI:24.4%
x264 [info]: final ratefactor: 19.93
x264 [info]: 8x8 transform intra:41.5% inter:50.2%
x264 [info]: direct mvs  spatial:95.5% temporal:4.5%
x264 [info]: coded y,uvDC,uvAC intra: 43.8% 60.6% 39.8% inter: 28.8% 
35.3% 7.6%
x264 [info]: i16 v,h,dc,p: 57% 26% 10%  7%
x264 [info]: i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 32% 11% 39%  3%  3%  6%  2% 
  2%  2%
x264 [info]: i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 33% 20% 23%  4%  5%  7%  3% 
  3%  2%
x264 [info]: i8c dc,h,v,p: 60% 19% 19%  3%
x264 [info]: Weighted P-Frames: Y:27.8%
x264 [info]: ref P L0: 73.7% 10.7% 11.1%  4.2%  0.3%
x264 [info]: ref B L0: 92.4%  7.6%
x264 [info]: kb/s:1909.67

I get Pos: 0.5 and 60f

Removing -vf harddup -demuxer lavfs gives me 24f

ffmpeg with the same sourcefile gives me 12frames, BBC-HD 25fps 
material, what am I doing wrong ?

Henk