In the early days of non-linear editing, offline (rough cut/fine cut) edits were created with low res files. And then once an edit was locked the low-res timeline would be swapped out for the online quality files and all of the unused media would be removed from the project through media management.
Today the offline to online edit process is still alive but the offline process has been merged with the online process through the creation of proxies.
But in both of these scenarios, the edit starts with having all of the media available in order to determine what will work best. And its’s only after a timeline becomes locked that media management comes into play.
I Hate Television. I Hate It As Much As Peanuts. But I Can’t Stop Eating Peanuts.
– Orson Welles