[FFmpeg-user] Negative start

[Marcus Engene]

Hi list,

[root at ip-10-149-69-183 apa]# ffmpeg -i 041336917.mov
ffmpeg version 2.3.1 Copyright (c) 2000-2014 the FFmpeg developers
   built on Aug  6 2014 09:11:22 with gcc 4.8.2 (GCC) 20131212 (Red Hat 
4.8.2-7)
   configuration: --sws-max-filter-size=512 --enable-gpl 
--enable-libmp3lame --enable-shared --enable-nonfree --enable-libx264 
--enable-libfaac --enable-filter=movie --enable-libvpx --enable-pthreads 
--enable-libtheora --enable-libvorbis
   libavutil      52. 92.100 / 52. 92.100
   libavcodec     55. 69.100 / 55. 69.100
   libavformat    55. 48.100 / 55. 48.100
   libavdevice    55. 13.102 / 55. 13.102
   libavfilter     4. 11.100 /  4. 11.100
   libswscale      2.  6.100 /  2.  6.100
   libswresample   0. 19.100 /  0. 19.100
   libpostproc    52.  3.100 / 52.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '041336917.mov':
   Metadata:
     major_brand     : qt
     minor_version   : 537199360
     compatible_brands: qt
     creation_time   : 2008-03-31 00:22:31
   Duration: 00:00:19.62, start: -6.607608, bitrate: 35168 kb/s
     Stream #0:0(eng): Video: mpeg2video (Main) (xdvf / 0x66766478), 
yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 26226 kb/s, 29.97 fps, 
29.97 tbr, 2997 tbn, 59.94 tbc (default)
     Metadata:
       creation_time   : 2008-03-31 00:22:31
       handler_name    : Apple Alias Data Handler
       encoder         : XDCAM EX 1080p30 (35 Mb/s VBR)
       timecode        : 01:00:00;00
     Stream #0:1(eng): Data: none (tmcd / 0x64636D74), 0 kb/s (default)
     Metadata:
       creation_time   : 2008-03-31 00:24:15
       handler_name    : Apple Alias Data Handler
       timecode        : 01:00:00;00
At least one output file must be specified
[root at ip-10-149-69-183 apa]#


So we have this clip. If I
ffmpeg -i 041336917.mov out.mov
...then...
[root at ip-10-149-69-183 apa]# ffmpeg -i out.mov
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'out.mov':
   Metadata:
     major_brand     : qt
     minor_version   : 512
     compatible_brands: qt
     encoder         : Lavf55.48.100
   Duration: 00:00:26.29, start: 0.000000, bitrate: 2185 kb/s
     Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 
1920x1080 [SAR 1:1 DAR 16:9], 2183 kb/s, 29.97 fps, 29.97 tbr, 11988 
tbn, 59.94 tbc (default)
     Metadata:
       handler_name    : DataHandler
       encoder         : Lavc55.69.100 libx264
       timecode        : 01:00:00;00
     Stream #0:1(eng): Data: none (tmcd / 0x64636D74), 0 kb/s
     Metadata:
       handler_name    : DataHandler
       timecode        : 01:00:00;00

The only way around it seems to be...
ffmpeg -i 041336917.mov -ss 00:00:06.6 out.mov
...
   Duration: 00:00:19.62, start: 0.000000, bitrate: 2908 kb/s

This is a user submitted file and I don't know how the user produced it. 
exiftool says nothing in particular except for
"Com Apple Finalcutstudio Media Uuid"

Is the metadata broken? Can it be fixed? Googling around, adding -async 
1 is suggested. But here's no audio here, so an badly aligned audio does 
not seem to be the cause.

Thanks,
Marcus