The recognized time attributes include any per-vertex time for a line
or the following attributes:
1) TIMECODE - attributes for Hour,
Minute, Second and Frame (optional):
Hour - 'TIMECODE (H)'
Minute - 'TIMECODE (M)'
Second - 'TIMECODE (S)'
Frame - 'TIMECODE (F)' .
These are recognized as a timestamp during a day in the format HH:MM:SS
or HH:MM:SS.FF just broken up in to separate attributes.
The beginning time of the video is determined from the earliest time
in the file and that is subtracted away to get the video-relative time.
A single TIMECODE attribute in the format 'HH:MM:SS' or 'HH:MM:SS:FF'
is also supported.
2) VTR_TIME - This attribute is the number of seconds from the beginning of the video. It is rarely used, and added as part of a custom project.
3) Absolute date/time values in attributes TIMESTAMP, UTCDATE/UTCTIME,
or TIME. If any of those are present with a recognized time format they
are used as the absolute time and the earliest recognized time in the
file is treated as the time for the video start.