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Old 17th December 2010, 16:05   #1  |  Link
spotter
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Does DVD Structural Protection make a disk more prone to scratch defects?

Somehting I'm wondering after developing my tool (see this forum), but does anyone know if DVD structual protection mechanisms (i.e. invalid sectors) make a disk more susceptible to errors?

the reason I'm thinking this is that isn't a DVD's ECC codes done by certain blocks, so if one has both invalid and valid data within one ECC block, one has to hope that both

a) the amount of blocks the ECC can correct for is more than just the invalid sectors (if its less, than any scratch in the valid data in that shared ECC block will never be recoverable)

b) that even if the invalid blocks are less, that one doesn't go over with errors to valid sectors.

Is this a correct assumption? or am I misunderstanding how the ECC works?

Just seems that if my assumptions are right it would take the invalid sectors approach beyond just a copy protection mechanism to selling a defective product (ignoring the argument that copy protection itself makes the product defective)
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Old 20th December 2010, 06:13   #2  |  Link
spotter
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so to answer my own question,

from: http://e-articles.info/e/a/title/Handling-DVD-Errors/ (amongst others)

it appears that DVD error correction basically takes place at the 2048 bit block level, which is the DVD block size and udf/iso block size. Therefore as the invalid sectors are always full blocks, it probably doesn't impact error correction.
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Old 20th December 2010, 07:27   #3  |  Link
xenex
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@spotter

For further reference, this "ECMA Standard" PDF document has more information on DVD physical structure, ECC format, etc., than you probably care to know:

http://www.ecma-international.org/pu...T/Ecma-267.pdf
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