What is "Set Output Path" ?

This  simple addon will automatically set all your scenes output path depending of your filename and your scene name, and render your image or video outputs in a subfolder where your file is saved. You can now change the different field to set up your outputs !

Where does the versioning come from ? 

If you have purchased and use my "Snapshot files addon" (https://blendermarket.com/products/snapshot-files), the output path will also use the current versioning of the file !

Why is it useful ?

It's a time saver, because your don't have to set up by hand all inputs. And time is important !