Can you really "Undo" destructive effect edits?

[mixsit]

When you use "edit-undo" after processing an audio file with an effect (or eq), are you really getting back exactly to the original file?
I notice that when you apply the effect it takes some time to process, but when you 'undo', it seem instantaneous.
So far I've been using a copy of the source track(s) for the processing just in case.
Anybody know for sure?
Thanks in advance.

 

[heinz]

absolutely yes you get the original back.

when you perform an operation and undo is enabled, it backs up the original data into RAM, then performs the operation. when you 'undo', it immediately flushes the original data back from RAM, which is why it's nearly instantaneous.

 

[mixsit]

Ok, I think I got this figured out with some tests and explorer. (Thanks for pointing me in the right direction Heinz, you can tell this is new teritory for me here.

When you run a track through an effect, it writes a new file (marked 'Fx'), and the old file is still there.
You can still tell cake to use the old file instead, with undo (with or without doing a save- that doesn't seem to mater), which is why it doesn't need to re-process it again.
The only thing apparently kept in ram is the undo history. If you close the project or crash, all those track files are still on the drive, but except for the last keeper version, you have no way to tell cake to play them. (Any body figure out how to play old .wa~ files?) These become the 'orphaned' tracks you see in 'clean audio disk', including your original source tracks if they weren't backed up.
This is ok, now that I know what the rules are. (Assuming I actually DID get it right!) I'll always hopefully have at least a bun' of the original audio for safety, and multiple passes trying to get the effect right is a fresh, one time processing of the original, not stacked up over and over. These were my two main concerns.

Thanks everyone.