Formatting a disc did not erase it
 

I had a DVD with a Jimi Hendrix concert and a Deep Purple concert on it. I decided to format the disc thereby erasing that stuff and using the disc again to record a guitar video which I recently bought. After I was done recording the guitar video I watched it and after the video was over you could see the Deep Purple video. So when I formatted the disc all of it's contents were not erased.

I thought that when you format a disc you are totally erasing it's contents. But here for some reason it didn't work that way. I'm using Sony DVD-RW discs and a Sony DVD Recorder.

Formatting does nothing but flag the content as data that can be erased. If you want to erase it would would need to record some data over it. Always been this way with any type of recordable media.

If that's true then the manufacturers of these DVD recorders(mine is a Sony) should not show you an on screen message saying that if you format all data will be erased. That's quite deceiving. It's too bad though that there is not a way to simply blank out the disc other than recording new stuff on top of the old stuff.

There is a way to blank out the disc ... delete all titles on it

I'll have to look in my owner's manual and hopefully they will give instructions on how to do that.

No offense, man. But this has been the issue for over 20 years on every sort of computer disc. Sorry you didn't know, yet. Now you do! Even overwriting the data doesn't always completely erase a disc. That's why the "safe" overwriting systems write over many times, not just once....4 is a common number of overwrites. If you really want an optical disc to be secure and deleted, break it in half and use a new one for new data.

I believe this will have the same effect as a quick format. A security/detective program that will simply read bits off the disc will still find the data, even if there is no disc structure to help. Overwriting is the only true way to delete computer discs. Or make them unreadable through physical damage, not a good choice for a $200 hard drive, maybe for a $.25 DVD.

I would say that normally this is not the case. I've burned and formatted and burned DVD-RWs over and over again, and never noticed bleed through from the previous title. I'm not even sure how that would work unless somehow the VTS title stopped and there was another VOB file with the next number in the series visible, but even then, I wouldn't expect the DVD player to be able to see it because the pointer to that old file should have been erased (all formatting does is clear the Table of Contents) when the TOC was read.

Were you burning ISOs or a VIDEO_TS folder? Assuming it was the VIDEO_TS are you positive you didn't mix in some old VTS_XX_X.VOBs from the Deep Purple concert in with your guitar video? That seems to me to be a much more likely scenario.

Hey, I wasn't even thinking about that aspect. This must be either a DVD-RAM or a DVD+RW, since those formats can do partial deletes. That is just how those 2 formats work. The Deep Purple wasn't erased, only Jimi. DVD-RW can only be deleted "whole disc" at a time.

Dude, you shouldn't be deleting Jimi anyway.

That makes a lot more sense, I hadn't thought about the partial delete idea.