DVD track length

Peter Van Hove Peter at Smart-Projects.net
Wed Dec 21 16:29:21 PST 2005


* From the T10 Reflector (t10 at t10.org), posted by:
* "Peter Van Hove" <Peter at Smart-Projects.net>
*
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Hi,
=20
Is there any reason why a drive,=20
based on any command,=20
would return a track length (or data from which a track length can be
calculated),
that would be different from an *exact* multiple of 16 (2K blocks) ?
=20
(this is on DVD, any kind of DVD, of course)
=20
In other words, can drives return a value that is not ECC block aligned
?
=20
I sometimes encounter such situations where I wonder if I cannot simply
adjust the value and assume the drive is *wrong*
=20
I'm looking at such a situation right now.
A couple of drives return, what I assume is, a correct length (based on
the Read Track Info commands).
One drive return, as length, 17 blocks more ... (instead of 16 or 32)
Obviously this one drive is wrong, because all the other drives return
the same value, but in the field one doesn't have the luxury of
comparison,
so I wonder if I cannot simply adjust this length to a more suitable
one. (Not that I don't face the question then of adding or removing =
...)
Or should I keep in account that not-ECC-aligned lengths are correct
sometimes ?  (not taken in account that on lower level *of course* the
data is ECC aligned)
=20
Peter

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 Hi,
  
 Is there any reason why a drive, = 
based on any command, 
would return a track length (or data = from which a=20 track length can be calculated),
 that would be different from an = *exact* multiple of=20 16 (2K blocks) ?
  
 (this is on DVD, any kind of DVD, of=20 course)
  
 In other words, can drives return a = value that is=20 not ECC block aligned ?
  
 I sometimes encounter such situations = where I=20 wonder if I cannot simply adjust the value and assume the drive is=20 *wrong*
  
 I'm looking at such a situation right=20 now.
 A couple of drives return, what I = assume is, a=20 correct length (based on the Read Track Info commands).
 One drive return, as length, 17 blocks = more ...=20 (instead of 16 or 32)
 Obviously this one drive is wrong, = because all the=20 other drives return the same value, but in the field one doesn't have = the luxury=20 of comparison,
 so I wonder if I cannot simply adjust = this length=20 to a more suitable one. (Not that I don't face the question then of = adding or=20 removing ...)
 Or should I keep in account that = not-ECC-aligned=20 lengths are correct sometimes ?  (not taken in account that on = lower level=20 *of course* the data is ECC aligned)
  
 Peter


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