How does one calculate half life time (AKA,
"Playback"
Time: 35.85 s.
Frames: 8912
Size: 554
into a hh:ss:mm time?
This probably isn’t a popular method but I actually do the math in my head (I pretty much failed math in high school so no you don’t need to be good at it).
I just count in multiples of 60 until I reach the closest time and then add/subtract from there, though I’m sure there’s a much better and more efficient way of doing it. Unfortunately Googling it just provides you with a decimal answer 
I’d gladly help you, but I don’t know what you mean. 35 seconds is 0 hours 0 minutes and 35 seconds.
Some do it by timing it during post-production in Vegas. Like quad showed here.
Or you can use this easy tool:
http://www.tools4noobs.com/online_tools/seconds_to_hh_mm_ss/
oh thanks arianon, im going to do it post production I just want to see how fast my run is at the moment,
so far its 03:44
Wow that pic shows alot on how HL21 was rendered
Only problem for me is I dont have sony vegas, I have Vegas Movie Studio HD Platinum