I find myself scratching my head as I know there are audit reports for the site collections, which is good, and I know there are third-party applications that can collate the audit data and present it nicely, but I want to collate all the data from each site collection and store it in a single csv file every 60 minutes... or even better, 'simply' store all SharePoint audit data(view, download, create, delete, etc) in a custom event log file (similar to system or application or setup for Windows Logs).

Is there anyone out there that uses custom code to do either of the above?
or do you have any advice? it's not that I don't want to use third-party solutions, I'm just looking for a way to capture it using the simplest possible method.

Thank you for your help.