Format Video Length in HH:MM:SS from Command Line

In my experimentation with audio and video manipulation, I've found that most tools prefer to handle time in HH:MM:SS (hour:minute:second) format.  I always presumed that using seconds would be easier but I'm barely a novice media tool user, much less a tool creator.

When I wrote the Create Short Preview from Video post, I calculated the video length in seconds with the following command:

length=$(ffprobe $sourcefile  -show_format 2>&1 | sed -n 's/duration=//p' | awk '{print int($0)}')]

That was helpful in detecting if a video was long enough to generate a preview for, but I then needed to get that length in HH:MM:SS format:

formattedlength=$(printf "%02d:%02d:%02d\n" $(($length/3600)) $(($length%3600/60)) $(($length%60)))

In the end you need to evaluate loads of individual statements to get your final HH:MM:SS format!