Dark purple spot after burning

[kenmo]

I noticed after burning (via Nero) on the bottom of one of my Maxell DVD-Rs [Ritek made in Taiwan] there was two small dark purple spots in the burn area. What causes this ? Is it something I should be concerned about ?

Thanks in advance

Kenmo

[Kingnog]

Was it there before the burn?

You can run tests with nero cd/dvd speed (scandisk, for example) and see if any errors show up. If not, and if you can read the disk, it should be fine.

[kenmo]

It was there after the burn.

I believe it was caused by dust as I just burnt another Maxell and noticed small dust underneath. When I blew the dust partiicle away there was a small purplish spot.

I then looked at another Maxell still on the spindle and unburnt. When I removed it on the underside there was small dust particles.

[kenmo]

Just ran a Nero scandisc and the media is fine. So what happens when Nero is buring a dvd or cd and Nero encounters a bit of dust during the burn ?

Does it bypass the dust or write to media covered by dust ?

(I hope I'm making sense).

[Capmaster]

Just ran a Nero scandisc and the media is fine. So what happens when Nero is buring a dvd or cd and Nero encounters a bit of dust during the burn ?

Does it bypass the dust or write to media covered by dust ?

(I hope I'm making sense).

It doesn't know the dust is there while it's burning. There will maybe be a spot of bad data, but if you're burning DVD video, the player is tolerant of a small number of errors. Gross errors will cause it to freeze or skip, but small errors you might not even notice on playback.

I would say give it a try in a standalone player. It may play fine

[kenmo]

I take it there is some redunancy built into DVDs incase data gets corrupted. Something like a Raid5 hard disk system.?

[Capmaster]

I take it there is some redunancy built into DVDs incase data gets corrupted. Something like a Raid5 hard disk system.?

No. Not like a hard disk, unless you're using DVD-RAM that is.

The player will interpolate missing data based on the previous trend for that image position. It'll "guess" what goes where the missing data is. It actually works very well.

But after a certain point when the disc corruption is so bad large chunks are missing, it can't fill in the blanks anymore and it will start to skip or freeze or cause macro blocks in those spots.

The 1st gen. CD players in the early 1980s didn't have this function. The slightest spec of dust on a CD and it'd stop playing or skip all over :P Now you can have a fair amount of dirt and scratches and it'll still play.

Take a CD and use it in your car for a while ....say a year. Then take it inside and run an analysis, or use CDex to rip it back off to HD. Count the errors it finds, and you'll be amazed that it still plays. Same thing with DVDs