Have you ever gone to a store to buy blank recording media and wondered what all the letters and symbols mean? I decided that it might be interesting to look at all the different types and discuss their uses.
In 1985 Sony and Philips developed a standard for writing data to compact optical disks previously developed for the music industry. The media became widely known as CD-ROM or compact disk read only media as it could be read by an optical drive, but no data could be added. Since the capacity of these disks were many times the capacity of floppy disks, manufacturers quickly began distributing their software on CD-ROM. These disks were created by stamping a reflective sheet with a glass master similar to the process used to make vinyl records in the days before audio CDs.
As technology continued to develop, new CD-R or CD Recordable media became available where data could be written to a disk with a CD “burner”. The new CD-R media had a dye film instead of a reflective film and the CD burner used a laser to alter the reflective properties of the media. The changes, once made, were permanent making it a good format for permanent backups and small run software distribution.
Later CD-RW or CD ReWritable media and burners were developed allowing usage similar to a floppy disk with much greater capacity. The rewritable media would allow data to be written, erased, and modified.
In a similar evolution to CDs, DVD media also made the transition to the computing world. Originally developed as a medium to store and distribute video, the potential for data storage was quickly recognized and a consortium of computer manufacturers agreed on a standard format. The purpose of this agreement was to help avoid a format war similar to the VHS/Betamax battle of the early 80’s. Unfortunately after the initial DVD-R standard was created the war was started anyway with the creation of a DVD+R format which is similar to, but incompatible with, the DVD-R format. This means that you need to make sure your burner is compatible with both formats or choose the correct media.
Like CD’s, DVD’s have a RW version and media is available for both formats; DVD-RW and DVD+RW. These disks have a storage capacity that is 6.4 times that of a CD.
Another innovation in this technology was the creation of dual layer media. Introducing a second dye layer to the disk allows almost twice the amount of data to be stored on a single disk. Dual layer media is available in both write once and rewritable format. This media is identified by adding DL to the end of the name such as DVD-RW DL or DVD+R DL.
The latest addition to this media family is Blu-Ray. As the next generation of storage technology was being developed a “media format war” of types began again. This time the battle was short lived and the proponents of HD-DVD conceded in February 2008 that Blu-Ray would be the new standard. With single layer disks storing up to 25 Gb of data and dual layer storing 50 Gb, this format is suited for storing high definition video or large quantities of data. This media is labelled BD-R for recordable media, BD-R DL for dual layer recordable media and BD-RE for erasable media that can be written to over and over.
Here’s a summary:
Media Data capacity Music/Video capacity (Minutes)*
CD-R, CD-RW 700 Mb 80
DVD-R, DVD+R, 4.7 Gb 535/60
DVD-RW, DVD+RW
DVD-R DL, DVD+R DL, 8.5 Gb 970/120
DVD-RW DL, DVD+RW DL
BD-R, BD-RE 25 Gb 2850/350
BD-R DL 50 Gb 5700/700
*Note that video capacity is approximate and assumes no compression. Compression increases the video capacity with some sacrifice in picture quality. HD video uses considerably more space.
One last technology on note is LightScribe. Using LightScribe media in a compatible burner, a label or design can be etched into the top of the media. LightScribe enabled burners will be labelled on the front and include software to design the label.
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