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Please note that the "+RW" format, also known as DVD+RW was neither developed nor approved by the DVD Forum. The approved recordable formats are DVD-R, DVD-RW and DVD-RAM.

DVD-RAM seems to be pretty much incompatible with anything else.

The others are a mix of "it might work, depending on your player or DVD-ROM drive".

Check out VCDHelp for a nice, concise summary. (Despite several typos and grammatical errors.) In particular they make the DVDForum vs. DVD+RW Alliance division clear.

The Forum has been resistant to significant changes due to consumer confusion and cost issues. Until then, none of the companies can say they are developing a DVD product. They can only say they are developing additional technology that they will submit to the DVD Forum for consideration.

For example, you'll notice that blank DVD+RW cannot legally display the DVD Logo, as the DVD Forum declined to integrate it in to the DVD spec. They control this the same way Phillips controls the CD format.

Heaven only knows why, since manufacturers won't be required to support the format in order to get the DVD logo licensed (unless and until the DVD Forum is persuaded to adopt an additional write/rewrite standard which is highly unikely). Ie., the discs may play in PC drives, but won't necessarily work in licensed players (particularly set top). If I'm only worried about backups, then DVD+RW has a couple of features that help, but if I'm interested in making standard video DVDs that play on the widest possible range of players, then DVD-R and DVD-RW are the way to go.

DVD-RAM is an even worse proposition, since it is designed for forward compatibility only and concentrates on data storage.

I own DVD Studio Pro and I have access to all of the features that Gilmore says aren't available.

The main difference between the DVD-R for General and DVD-R for Authoring drives is that the DVD-R for Authoring writes an additional lead-in that is required at the duplication plant. With this extra info on the DVD, a DVD-R can be used as the master rather than a DLT.

Note also that Apple did the right thing by using the Pioneer drive as DVD-R and DVD-RW are the only writeable formats endorsed by the DVD Forum. DVD+R and DVD+RW are not sanctioned.

The licences are obtained from the DVD Forum (formerly the DVD Consortium) which originally consisted of 10 big electronics companies (Hitachi, Matsushita, Mitsubishi, Philips, Pioneer, Sony, Thomson Multimedia, Time Warner, Toshiba and Victor).

There's definately some licenced DVD players for Linux in development (e.g. PowerDVD-Linux), but I don't see how any open-sourced version could ever be legal under the terms of the licence; disclosing the decryption source code is not allowed, as any and all information that you get with the licence is covered under an NDA.

This snippet from the site linked above shows the prices involved:

3. License Fees are now required for the right to use the Format Books. The License Fee is US$10,000 per DVD Format for each Product Category, as specified in Schedule A-1 of the Definitive License.

Example: If a licensee wishes to manufacture DVD-Video players, the licensee shall pay US$20,000 since it needs to obtain licenses for DVD-Video Book and DVD-ROM Book, both to be used for Product Category II (DVD Players).

Example: If a licensee wishes to manufacture DVD-RAM drives and DVD-RAM discs, the licensee shall pay US$40,000 since it needs to obtain licenses for DVD-RAM and DVD-ROM Books, to be used for Category I Products (DVD discs) and Category II Products (DVD drives).


Here's a link to the text of the licence (PDF format).

I've been working with the Linux Video group where we've been trying to make an open source player for DVD discs. The ONLY problem that we're fighting right now is not the know-how to get it done, but rather trying to obtain the file format documents for DVD-Video and being able to use them legally. Indeed, the recent deCSS program is another really good example of how file format specifications can be illegal to implement, even if you have obtained the specifications legally.

The way that the DVD Fourm (formerly known as the DVD Consortium, with oversees the DVDCCA... this is the group of companies that cross-license each other's patents and shares information regarding DVD development) currenly requires you to sign a non-disclosure agreement (NDA) to obtain the specifications, and that NDA also prohibits you from even discussing the specifications with anybody unless they have also signed the same NDA. Since this is covered under the trade secret laws, this particular bit of intellectual property is theirs theoretically forever. At least until you can hire a bunch of lawyers to demonstrate that a DVD is no longer a trade secret.

I've also set up a seperate mailing list from the main Linux Video group that is in the process of developing an Open Video Disc specification which is trying to allow people to develop products without having to pay royalties or deal with patent infringments. Fees for most of the current video formats range from over $10,000 (for the DVD specs.... license fees are on top of that) to the MPEG Licensing Authority who is being quite reasonable for most close-source projects, but if you read the details of what you must do to license a product, is contrary to the nature of most open-source projects. It is still possible to write a GPL'ed MPEG player, but it would only be free as in speech and not free as in beer. In fact, you would probabally have to charge somebody to download the software. Shareware MPEG players are probabally skating on some very thin ice legally, and certainly part of the registration costs would have to go to the MPEGLA.

One of the things that is so nice about HTML is the fact that this standard is open, patent and royalty free. If CERN had tried to put a patent on HTML I doubt that the web would have developed nearly so quickly. Or rather imagine if Apple's hypercard system had been developed with the GPL and file formats were made open for anybody on any platform to use.

One of the things that I believe is killing the Unicode character encoding is that all kinds of intellectual property restrictions are placed on it, and you need to pay royalties to develop much software that uses it. Again, think what would have happened with ASCII had it been kept closed up, and why EBDIC isn't being used for character encoding.

More importantly, open and free specifications are critical to data preservation, and a point that really hasn't been brought up by Calc (the author of the original post on /.)