How can I recreate this encoder and what settings in OBS?

[LTGonline]

I found something interesting. I had one session that went 9 hrs with no errors and green across the board on twitch inspector. Normally under encoder or streaming tool, it says OBS -output module. However for the only session that went error free it said Lavf57.71.100 any idea what that is and why it is not obs module? also, it seemed to work.