avconv dá erro ao tentar dividir um arquivo desde a atualização 14.04

Question

Eu uso o seguinte comando para dividir um arquivo, mas desde uma atualização de 12.04 para 14.04 ele gera um erro. O arquivo resultante contém apenas áudio, sem vídeo.

avconv -i cam.mp4 -ss 00:14:00 -t 00:28:00 -c:a copy -c:v copy output-clip.mp4

Alguma sugestão de como corrigir isso?

Saída completa:

 built on Aug 10 2014 18:16:02 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
[mov,mp4,m4a,3gp,3g2,mj2 @ 0xb6d000] multiple edit list entries, a/v desync might occur, patch welcome
[h264 @ 0xb74520] A non-intra slice in an IDR NAL unit.
[h264 @ 0xb74520] decode_slice_header error
[mov,mp4,m4a,3gp,3g2,mj2 @ 0xb6d000] max_analyze_duration reached
Guessed Channel Layout for  Input Stream #0.1 : stereo
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'cam.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 0
    compatible_brands: mp41avc1qt  
    creation_time   : 2014-08-26 08:07:33
    encoder         : vlc 2.0.8 stream output
    encoder-eng     : vlc 2.0.8 stream output
  Duration: 01:02:16.95, start: 0.000000, bitrate: 2023 kb/s
    Stream #0.0(eng): Video: h264, 720x576, PAR 16:15 DAR 4:3, 1001 tbn
    Metadata:
      creation_time   : 2014-08-26 08:07:33
    Stream #0.1(eng): Audio: mp2, 44100 Hz, stereo, s16p, 127 kb/s
    Metadata:
      creation_time   : 2014-08-26 08:07:33
    Stream #0.2(eng): Video: h264 (High), yuv420p, 720x576 [PAR 16:15 DAR 4:3], 1887 kb/s, 25 fps, 25 tbr, 1001 tbn, 50 tbc
    Metadata:
      creation_time   : 2014-08-26 08:07:33
Output #0, mp4, to 'output-clip.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 0
    compatible_brands: mp41avc1qt  
    creation_time   : 2014-08-26 08:07:33
    encoder-eng     : vlc 2.0.8 stream output
    encoder         : Lavf54.20.4
    Stream #0.0(eng): Video: libx264, 720x576 [PAR 16:15 DAR 4:3], q=2-31, 1001 tbn, 1001 tbc
    Metadata:
      creation_time   : 2014-08-26 08:07:33
    Stream #0.1(eng): Audio: mp2, 44100 Hz, stereo, 127 kb/s
    Metadata:
      creation_time   : 2014-08-26 08:07:33
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press ctrl-c to stop encoding
frame=    0 fps=  0 q=-1.0 size=       0kB time=10000000000.00 bitrate=   0.0kbiframe=    0 fps=  0 q=-1.0 size=       0kB time=10000000000.00 bitrate=   0.0kbiframe=    0 fps=  0 q=-1.0 size=       0kB time=10000000000.00 bitrate=   0.0kbiframe=    0 fps=  0 q=-1.0 size=       0kB time=10000000000.00 bitrate=   0.0kbiframe=    0 fps=  0 q=-1.0 size=       0kB time=10000000000.00 bitrate=   0.0kbiframe=    0 fps=  0 q=-1.0 size=       0kB time=1090.27 bitrate=   0.0kbits/s   frame=    0 fps=  0 q=-1.0 size=       0kB time=1455.51 bitrate=   0.0kbits/s   frame=    0 fps=  0 q=-1.0 size=       0kB time=1497.23 bitrate=   0.0kbits/s   frame=    0 fps=  0 q=-1.0 size=       0kB time=1680.01 bitrate=   0.0kbits/s   frame=    0 fps=  0 q=-1.0 size=       0kB time=1680.01 bitrate=   0.0kbits/s   frame=    0 fps=  0 q=-1.0 size=       0kB time=1680.01 bitrate=   0.0kbits/s   frame=    0 fps=  0 q=-1.0 Lsize=   26770kB time=1680.01 bitrate= 130.5kbits/s    
video:0kB audio:26190kB global headers:0kB muxing overhead 2.214985%