Question about video file tags: Duration, TrackDuration, MediaDuration

[Archive]

[Originally posted by akrk1986 on 2008-05-17 19:56:36-07]

I'm using ExifTool to read information from video files and ran into a file that has different values in some of those tags.

I have two questions:

1) What is the difference between the above 3 tags? Or, actually, between all six (those and their group 1 counterparts)?

2) What is the difference between 'MediaDuration' and 'MediaDuration (1)'? I understand that tags with '(1)' are from group 1, but I'm unclear what the distinction between Group 1 and non-Group 1 tags.

Thanks,
Amir

[Archive]

[Originally posted by exiftool on 2008-05-18 22:23:10-07]

"MediaDuration" and "MediaDuration (1)" are simply different tag keys
for the same tag name.  This happens whenever a duplicate tag name
is encountered.

Duration should be the length of the Movie.  If it has separate tracks,
each track may have its own duration.  The length of sequential tracks
should add to the total movie length provided they run for the entire
movie.  I'm not entirely sure what MediaDuration is, and would have
to consult the QuickTime or MP4 documentation to figure this out.

Sometimes it is useful to decode the file with -v, -v2 or -v3 to see
the structure.  This sometimes helps in understanding.

- Phil