Moon aka Sun (moon_aka_sun) wrote,

Taking care of CDs

Полезные советы отсюда:

Do:

  1. Handle discs by the outer edge or the center hole.
  2. Use a non-solvent-based felt-tip permanent marker to mark the label side of the disc.
  3. Keep dirt or other foreign matter from the disc.
  4. Store discs upright (book style) in plastic cases specified for CDs and DVDs.
  5. Return discs to storage cases immediately after use.
  6. Leave discs in their packaging (or cases) to minimize the effects of environmental changes.
  7. Open a recordable disc package only when you are ready to record data on that disc.
  8. Store discs in a cool, dry, dark environment in which the air is clean.
  9. Remove dirt, foreign material, fingerprints, smudges, and liquids by wiping with a clean cotton fabric in a straight line from the center of the disc toward the outer edge.
  10. Use CD/DVD-cleaning detergent, isopropyl alcohol, or methanol to remove stubborn dirt or material.
  11. Check the disc surface before recording.

Do not:

  1. Touch the surface of the disc.
  2. Bend the disc.
  3. Use adhesive labels.
  4. Store discs horizontally for a long time (years).
  5. Open a recordable optical disc package if you are not ready to record.
  6. Expose discs to extreme heat or high humidity.
  7. Expose discs to extremely rapid temperature or humidity changes.
  8. Expose recordable discs to prolonged sunlight or other sources of ultraviolet light.
  9. Write or mark in the data area of the disc (the area the laser “reads”).
  10. Clean by wiping in a direction going around the disc.

For CDs especially do not:

  1. Scratch the label side of the disc.
  2. Use a pen, pencil, or fine-tip marker to write on the disc.
  3. Write on the disc with markers that contain solvents.
  4. Try to peel off or reposition a label.


... there is consensus that, under recommended storage conditions, CD-R, DVD-R, and DVD+R discs should have a life expectancy of 100 to 200 years or more; CD-RW, DVD-RW, DVD+RW, and DVD-RAM discs should have a life expectancy of 25 years or more. Little information is available for CD-ROM and DVD-ROM discs (including audio and video), resulting in an increased level of uncertainty for their life expectancy. Expectations vary from 20 to 100 years for these discs.

... CD-R and DVD-R discs have a shelf life of 5 to 10 years before recording.

... the life expectancy for RW and RAM discs will be less than that of R discs.

...The data on the phase-changing metal alloy film layer can be erased and rewritten to a limited number of times (about 1,000 times for RW discs and about 100,000 times for RAM discs).


Для полноты картины, добавлю ещё ссылки про диски и всё что с ними связано:

What is DVDR?
DVD FAQ
CD-Recordable FAQ


Ну и чтоб далеко не ходить, таблица размеров:

                 2^20         2^10         10^3             bits

1x CD                   150   KB/s   153.6 kB/s   1,228,800 bps
1x DVD    1.3208 MB/s  1352.5 KB/s  1385   kB/s  11,080,000 bps

2352/2048 = 1.1484375

21 min   94,500 secs        10^3        2^10  184.6 MB  (212.0 MB)
63 min  283,500 secs        ~~~~        ~~~~  553.7 MB  (635.9 MB)
74 min  333,000 secs  681,984 kB  666,000 KB  650.3 MB  (746.9 MB)
80 min  360,000 secs  737,280 kB  720,000 KB  703.1 MB  (807.4 MB)
90 min  405,000 secs              810,000 KB  791.0 MB  (908.4 MB)
99 min  445,500 secs              891,000 KB  870.1 MB  (999.3 MB)

              12cm                        8cm

DVD-5  2+  hrs SS/SL  4.37 GB  (4.70 BB)  DVD-1 ~1/2 hr  SS/SL 1.36 GB (1.46 BB) 
DVD-9  4   hrs SS/DL  7.95 GB  (8.54 BB)  DVD-2 ~1.3 hrs SS/DL 2.47 GB (2.66 BB)
DVD-10 4.5 hrs DS/SL  8.74 GB  (9.40 BB)  DVD-3 ~1.4 hrs DS/SL 2.72 GB (2.92 BB)
DVD-14 6.5 hrs DS/ML 12.32 GB (13.24 BB) 
DVD-18 8   hrs DS/DL 15.90 GB (17.08 BB)  DVD-4 ~2.5 hrs DS/DL 4.95 GB (5.32 BB)

DVD-R     1.0  SS/SL  3.68 GB (3.95 BB)
DVD-R,+R  2.0  SS/SL  4.37 GB (4.70 BB)   DVD-RAM 2.0    SS/SL 1.36 GB (1.46 BB)
DVD-R,+R  2.0  DS/SL  8.75 GB (9.40 BB)   DVD-RAM 2.0    DS/SL 2.47 GB (2.65 BB)

DVD-RW,+RW 2.0 SS/SL  4.37 GB (4.70 BB)
DVD-RW,+RW 2.0 DS/SL  8.75 GB (9.40 BB)

CD-ROM         SS/SL  0.635 GB (0.650 BB) CD-ROM         SS/SL 0.180 gig (0.194 BB)
DDCD-ROM       SS/SL  1.270 GB (1.364 BB) DDCD-ROM       SS/SL 0.360 gig (0.387 BB)


Why is DVD larger than CD?

  1. smaller pit length (~2.08x)
  2. tighter tracks (~2.16x)
  3. slightly larger data area (~1.02x)
  4. more efficient channel bit modulation (~1.06x)
  5. more efficient error correction (~1.32x)
  6. less sector overhead (~1.06x)
Total increase for a single layer is about 6.8 times a standard CD-ROM
Tags: facts, links
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