# cat *.mp4|ffmpeg -i - -vcodec copy -acodec copy output.mp4
ffmpeg version 1.0 Copyright (c) 2000-2012 the FFmpeg developers
  built on Oct 11 2012 12:41:30 with gcc 4.4.6 (GCC) 20120305 (Red Hat 4.4.6-4)
  configuration:
  libavutil      51. 73.101 / 51. 73.101
  libavcodec     54. 59.100 / 54. 59.100
  libavformat    54. 29.104 / 54. 29.104
  libavdevice    54.  2.101 / 54.  2.101
  libavfilter     3. 17.100 /  3. 17.100
  libswscale      2.  1.101 /  2.  1.101
  libswresample   0. 15.100 /  0. 15.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0xaa88500] stream 0, offset 0x30: partial file
[mov,mp4,m4a,3gp,3g2,mj2 @ 0xaa88500] Could not find codec parameters for stream 0 (Video: h264 (avc1 / 0x31637661), 420x350, 204 kb/s): unspecified pixel format
Consider increasing the value for the 'analyzeduration' and 'probesize' options
pipe:: could not find codec parameters