zeb@endor:~/Videos$ avconv -ss 7 -r 20 -i rs2.mp4 -t 60 -c:v mpeg4 -r 20 rs2-clip.avi
avconv version 9.16-6:9.16-0ubuntu0.14.04.1, Copyright (c) 2000-2014 the Libav developers
  built on Aug 10 2014 18:19:26 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
[h264 @ 0x939a320] A non-intra slice in an IDR NAL unit.
[h264 @ 0x939a320] decode_slice_header error
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'rs2.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 0
    compatible_brands: mp41avc1qt
    creation_time   : 2014-10-21 02:51:05
    encoder         : vlc 2.1.4 stream output
    encoder-eng     : vlc 2.1.4 stream output
  Duration: 00:23:58.28, start: 0.000000, bitrate: 983 kb/s
    Stream #0.0(eng): Video: h264 (High), yuv420p, 1366x768, 981 kb/s, 20 fps, 1000k tbn, 50 tbc
    Metadata:
      creation_time   : 2014-10-21 02:51:05
Output #0, avi, to 'rs2-clip.avi':
  Metadata:
    major_brand     : isom
    minor_version   : 0
    compatible_brands: mp41avc1qt
    creation_time   : 2014-10-21 02:51:05
    encoder-eng     : vlc 2.1.4 stream output
    ISFT            : Lavf54.20.4
    Stream #0.0(eng): Video: mpeg4, yuv420p, 1366x768, q=2-31, 200 kb/s, 20 tbn, 20 tbc
    Metadata:
      creation_time   : 2014-10-21 02:51:05
Stream mapping:
  Stream #0:0 -> #0:0 (h264 -> mpeg4)
Press ctrl-c to stop encoding
[h264 @ 0x94de1e0] A non-intra slice in an IDR NAL unit.
[h264 @ 0x94de1e0] decode_slice_header error
frame= 1200 fps=166 q=31.0 Lsize=    7638kB time=60.00 bitrate=1042.9kbits/s
video:7604kB audio:0kB global headers:0kB muxing overhead 0.450418%
zeb@endor:~/Videos$