TN118 - Writable CD/DVD Media

118.1    Summary

        The reliability, compatibility, and longevity of recordable CD and DVD
        media varies a great deal. Using low quality or non-standard media risks
        problems reading the discs in other computers and/or the ability to
        recover the data in any computer after the media is old.

        Choosing quality media with maximum compatibility is not expensive
        compared to the value of the data and value of the time lost when the
        disc is not readable.

118.2    Types of Optical Media

        There are several categories of current optical media:

        CD-ROM, DVD-ROM   Not recordable. Read only. Manufactured with the data
                          molded onto the disc using a mechanical process.
                          Suitable only for high volume duplication.

        CD-R, DVD-R,      Write once, then read only. Organic dye coating on the
        DVD+R             disk permanently changes from transparent to opaque
                          when exposed to intense laser light. Data is written
                          sequentially like a tape drive.

        CD-RW, DVD-RW,    Rewritable (write, erase, re-write). Phase changing
        DVD+RW            metallic coating on the disk becomes more or less
                          reflective when exposed to various intensities of
                          laser light. Data is written sequentially like a tape
                          drive. Not as stable as the organic dye disks, used
                          only when rewritability is required.

        DVD-RAM           Read/write. Same phase change technology as DVD-R
                          except instead of writing sequentially like a DVD-R,
                          data can be written in random sectors like a hard
                          disk. Much less compatible with drives supporting
                          other CD and DVD formats, used only when random
                          write access is required.

        DVD-R(A), or      Variation of typical DVD-R media. Originally intended
        Authoring         for professional use, has devolved into an obscure
                          format supported by virtually no current recording
                          technology.

118.3    Standards for Optical Media, DVD-R vs. DVD+R

        The standards for the CD-ROM, CD-R, and CD-RW were defined by Sony and
        Phillips and published in a series referred to as the "Rainbow Books."
        These standards are well understood and followed by most of the
        industry.

        The standards for DVD's are more convoluted. The DVD Forum
        (http://www.dvdforum.org/), a large consortium of industry vendors
        founded by the collective owners of the DVD intellectual property
        rights, publishes the standards for DVD-ROM, DVD-R, DVD-RW, and DVD-RAM.

        A competing consortium, the DVD+RW Alliance (http://www.dvdrw.com/)
        published alternative standards called DVD+R and DVD+RW.

        It is important to note that DVD-R and DVD+R are different formats from
        different organizations and are NOT compatible with each other. The
        DVD+RW Alliance claims their standard is technically superior, but in
        reality it is about money. The DVD Forum has higher license fees and
        more rigid certification standards, so it costs less to make DVD+R and
        DVD+RW media. In this author's opinion the DVD+RW Alliance is not about
        delivering better media, but all about delivering cheaper, less
        compatible media.

        DVD-R format has been in use since 1997, and has had a five-year lead on
        DVD+R. While many computer drives can read both types, not all drives
        can read the "plus" formats, but all can read the "dash" formats.

118.4    CD Capacity

        For CD's, if you care about compatibility, the safest option is to stick
        with the 74 minute (650 Megabyte) disc. The 80 minute (700 Meg) CD was
        originally defined for a specialized product and while common today, may
        not be supported by all CD drives. The 90 minute (800 meg) and 99 minute
        (870 Meg) CDs are not defined in any standard and likely to have
        significant compatibility problems.

118.5    Media Brand/Quality

        Most brands of media the consumer can find for sale in the typical
        office supply store are not actually manufactured by the brand name on
        the package. Usually the brand name contracts the manufacture of the
        media to any number of overseas companies. Further, the brands change
        the manufacturer depending on who wins the next bid and can be quite
        inconsistent over a period of time. IBM, HP, Memorex, Fuji, and Imation
        are all brands that either outsource their manufacturing of media or
        worse yet, just sell the use of their brand name to the highest bidder.

        The quality of media varies widely from one manufacturer to the next.
        Not all manufacturers have licensed the same intellectual property
        rights. There at least three different organic dyes that can be used and
        numerous variations in manufacturing techniques resulting in countless
        permutations of media type and quality.  Drive manufacturers do not test
        their drives with the large variety of low-end media sold by discount
        retailers, they test with high-end media from reputable vendors. Low
        quality media will produce much less consistent results and have more
        compatibility problems between drives.

        Reputable media manufacturers include Taiyo Yuden, MAM-A (Mitsui), Sony,
        Verbatim (Mitsubishi), Maxell (Hitachi) and TDK. Unfortunately, to
        confuse everyone, all of the manufacturers except Taiyo Yuden and MAM-A
        have also used their brand on lower quality products manufactured by
        other companies so they can have a "low price point" product in the
        market.

        The actual manufacturer can be determined by using special software to
        read the media ID code from an unrecorded disk.

            http://www.dvdinfopro.com/
            http://dvd.identifier.cdfreaks.com/

118.6    What to Buy

        With the difficulty of determining quality from brand markings on most
        products, the author finds it easier to stick with Taiyo Yuden or MAM-A
        who seem to deliver consistent results. The following are part numbers
        and URLs for purchase:

           MAM-A Mitsui CD-R GOLD 74 min 52x
           Super White for Color Thermal
           Part# 40902
           http://www.datamediastore.com/mam-a-gold-cd-r-40355.html

           MAM-A Mitsui DVD-R GOLD Archival 4.7G 8X
           Thermal printable / White EDGE-2-EDGE
           Part# 83439
           http://www.datamediastore.com/mam-a-gold-dvd-r-83439.html

           Other distributors:
             http://www.meritline.com/
             http://www.supermediastore.com/
             http://www.rima.com/