Visit length via nginx server logs

Hi guys! :slight_smile:
I’m slowly importing my nginx access logs in Piwik. I was wondering: is it possible to get the visit length via access logs? I now have 0s for all requests.

Maybe combining “enter” and “exit” time? Is it possible to make nginx print that data?
Anyone managed to do something about this?

Ops maybe this would be better in Support section?