Today, i've been merging logs from my guild's Sha of Fear yesterday's kill and got a strange result: adds on pagoda been damaged for 30 seconds after boss died. But i knew that it's not true. Well, i knew whats happened - merge process went wrong, but i didn't know why.
Spent some time trying to find a bug in my merge tool i found nothing. And, at last, found the root of the problem: Internet time.
As you may know, OS (at least windows) syncing your local time with internet services to keep your clocks right. It's pretty comfy, your comuter's clocks will never run too far ahead or fall behind the real clocks.
But... in our case this was fatal. 3 Tanks recorded a log in the 3 hours raid. And, at some point, OS of the one of them synced with time server and corrected local time. As a result: difference between two logs in the beginning of the raid was 1.5 mins, and in the end - just 30 seconds. Fatal desynchronisation, because merger can find and use only one confluence point and use time different in this point for a whole log (because of it's structure).
So, if you are going to record multi-PoV log and merge it, i recommend to disable internet time for a raid, or disable at all:
Next version of our log uploader will control merge process and check if logs starts to desynchronise.