Logo	Scheme	Capacity	Rotation Speed relative to an audio CD	Notes	Cost
	Blu-Ray	25 GB/54 GB	1	high capacity. Used for High Definition movies. Uses a blue laser to read them. The dual layer disks hold 54 GB. That is equivalent to 20 hours of standard video. Heavily encrypted to prevent copying. This is the format Microsoft, Sony, Lion’s Gate, MGM, Columbia, Fox, Disney and Wal-Mart are backing. Blu-Ray DVDs allow interactivity controlled by Java programs, though I have not heard the details of how this is supposed to work. The scheme is called BD-J (Blu-ray Disc Java). They come in R and RW versions.	$22.00 CAD each. Last revised 2007-10-09.
	HD DVD	15 GB/30 GB	1	Paramount supports only this format. Heavily encrypted to prevent copying. Developed by Toshiba and NEC. You buy them pre-recorded with movies in encrypted format. You don’t record your own material on them. Only proprietary hardware that prevents copying can read them. Provides sufficient resolution for full HDTV. Like Blu-ray, it uses a short wavelength blue laser. Players cost half as much as Blu-ray, and is more reliable, yet oddly it lost the format wars. On 2008-02-18 Toshiba threw in the towel and discontinued manufacturing players and discs. I think the Blu-Ray people won by repeatedly telling a small lie, that you needed Blu-Ray to get high definition. Naive users thought Blu-Ray was the only choice for HD. I think also Blu-Ray was a more distinctive name. HDDVD did not sound like a distinct product.
	DVD-Video, DVD5/DVD9	4.7 GB/9.2 GB	?	Time-Warner, Disney, MGM/UA etc. backing. read only. Created by mass duplication. The dual layer disks hold 9.2 GB.	Blanks are not generally available since is illegal to duplicate movies.
	DVD-R	4.7 GB	8-48	write once	$.45 CAD each. Last revised 2007-10-09.
	DVD-RW	4.7 GB	2.4	write many times	$1.20 CAD each. Last revised 2007-10-09.
	DVD+R	was 3.0 GB/side, now 4.7 per side. With double layer 8.5.	18	compatible with DVD-RAM. writeable once. dvd+r has a slightly more robust tracking system than DVD-R. My 16x drive writes 11.4 megabytes a second, considerably faster thana CDW drive.	$.26 CAD each. Last revised 2007-10-09.
	DVD+RW	was 3.0 GB/side, now 4.7 per side. With double layer 8.5.	8	compatible with DVD-RAM. rewritable.	$1.20 CAD each. Last revised 2007-10-09.
	DivX	n/a	?	scheme to allow game or video rental	Not available to the public.
	DVD-RAM	2.6 GB/side	?	used in Hitachi camcorders	$43.00 USD each. Last revised 2007-04-16.

The rotation speed is not really the statistic you want. You want the transfer rate in megabytes per second. However, those numbers were not readily available. The main thing you can learn from these numbers in that RW disks are much slower than R disks to record. Further, you need an extra erase pass.

Use a red Sharpie fine tip permanent marker to write the password/serial number/key on the top side of the DVD where you can’t lose it. Don’t apply any sort of sticky label since it may come off inside the drive, unless it is specially designed for DVDs.