How do I get the timecode of the first frame using a command-line tool?

[Simon_Haddad]

If I convert a video to h.264 using FFmpeg or Handbrake, and then open the resultant file in Avidemux, the first frame is timed at like 00:00:00.034 or 00:00:00.050 or so.
(Handbrake also marks the first chapter there.) Is there any way to get this number using FFmpeg or something? I'm writing some conversion scripts and would prefer to not babysit the computer by pointing and clicking all day.