I worked together with Hawkpat to create a tool that can analyze chat logs generated by Minecraft and figure out your total play time with that information.
Due to the text encoding used, this will likely only work on Windows. There are 3 modes:

[1] Automatic (default) [2] Enter path(s) [3] Enter glob

1: Automatic trys to detect your logs in the normal minecraft folder C:/Users/USER/AppData/Roaming/.minecraft/logs

2: With this mode you can enter your own file paths Separate multiple paths with pipes (vertical bar: | ).

3: With glob you can enter a glob to select multiple folders in a directory Glob will basicly select your path but also all the paths of any subdirectories that might exist in your spicified path and that match the glob Separate multiple globs with pipes (vertical bar: | ). Make sure files don't overlap

Folders that start with period must be explicitly specified (AppData/Roaming/.*/logs)

Glob-Example: To find all logs folders in all folders that start with . in AppData, C:/Users/USER/AppData/Roaming/.*/** This would select all the logs in .minecraft but also in .technic for instance

Globs can take a bit to load if your selection is large

You can read more about globs here.

Github link:[url=Github link: github.com/tintin10q/minecraft-logs-analyzer] github.com/tintin10q/minecraft-logs-analyzer[/url]

Gui: https://i.imgur.com/LICap0E.png
My playtime Graph: https://i.imgur.com/Og3PXvG.png