Did you ever wonder what the difference between DVD-R and DVD+R is? Each time I was buying blank DVDs I wondered… and then ignored it. Both standards are equally expensive and my DVD writer can write both.

Copy protection ring

This week, I had to write a DVD for a project delivery. I opened a fresh pack of blank DVDs and examined them a bit closer than usual. I noticed a strange ring on the data layer. At first I thought of a fault in the material and was quite frustrated with the thought of trashing all those DVDs.

Then I decided to ask the Internet first – and found out I was wrong. This strange ring is a copy protection. It is a small area where the encryption keys of video DVDs are stored. On DVD-Rs, this area is pre-recorded, so you can’t copy this key.

It’s not a bug, it’s a feature.

Identification code and higher production costs

There is no such limitation on DVD+Rs. DVD+R writers also do not write an unique identification code on the DVDs, like DVD-R writers do.

Producing DVD-Rs is also more expensive than producing DVD+Rs. The copy protection ring and another unique identification number have to be written on each DVD. This takes more time and therefore results in higher costs. Additionally, DVD-R producers have to pay more license fees to the DVD-Forum.

There are no real big disadvantages for DVD+Rs. DVD+R is not supported by the official DVD-Forum, so these DVDs are not allowed to carry the official DVD logo. Since this great DVD-Forum is also responsible for the limitations on DVD-Rs, the infamous region codes and CSS copy protection on video DVDs, this does not appear to be much of a loss. It’s also not a problem for compatibility – both types are about equally compatible to standalone players.

To make it short: DVD-R is evil and has only disadvantages compared to DVD+R.

Update 26.8.2006

Commenters here and at reddit.com said that DVD+R are less compatible to standalone players. According to the German c’t magazine, the difference is marginal:

At the last test, 93 percent of the DVD players worked with DVD+R. That’s 2 percent less than with DVD-R. Using a ‘compatibility tool’ to change the bit for media identification to DVD-ROM, both formats were equally recognized by 95 percent of the players. (translation by me)

Update 26.8.2006, II

Sorry for posting yet another update, but I feel I need to clarify something: Many postings that refer to me indicate that I propose DVD+R because you can copy original video DVDs with it. That is not the case.

In fact, most DVDs are simply too big to copy on a single layer DVD anyway. It is also very likely that there are additional copy protection mechanisms in the firmware of your DVD writer, so that it’ll refuse to copy DVDs on DVD+R even though it would be physically possible. (Haven’t tried, yet. If anyone did, please leave a comment)

My point is more an idealistic one: The DVD-R has intentionally been limited in its capabilities just to make the movie industry happy. Not only was this little successful – we all know how easy it is to completely strip the copy protection off a DVD – it also made the process of producing them more complicated. Additionally, those identification codes are yet another unnecessary privacy invasion.

That is why I think that DVD-Rs are morally inferior to DVD+R. In practice, the difference isn’t that big.