Determining the certified write speeds of DVD-R/-RW discs by interpretingpre-recorded lead-in information.

Kris.Schoofs at pimc.be Kris.Schoofs at pimc.be
Tue Oct 14 02:35:05 PDT 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* Kris.Schoofs at pimc.be
*
I am attempting to determine the certified write speeds of DVD-R/-RW media
by interpreting the pre-recorded information in the lead-in (by using READ
DVD STRUCTURE : Format code 0x0Eh (Pre-recorded information in Lead-in)).
My goal is that even on older writers it will be possible to identify all
of the disc's certified write speeds (albeit they will be unable to write
the higher speed discs).

I've already done this successfully for DVD+R/+RW (by interpreting the
ADIP) but I'm struggling with DVD-R/-RW.

My current approach is counting the FIELD IDs in the 'pre-recorded
information of the lead-in'-structure (as returned by READ DVD STRUCTURE).

So :
Field ID=5 present (located at offset 32, excluding the
ReadDVDStructure-header)
=> only 1X write supported by the disc

Field ID=7 present
=> also 2X write supported by the disc

Field ID=9 present
=> also 4X write supported by the disc

Field ID=11 present
=> also 6X write supported by the disc

Field ID=13 present
=> also 8X write supported by the disc


But after analysing a few discs I noticed that this approach doesn't work.
Example#1 :
=> A Pioneer DVD-R labeled as 2x disc only reports up to FieldID=5 (the
same as a 1x disc does)
Example#2 :
=> A Pioneer DVD-R labeled as 4x disc reports up to FieldID=13. Which,
according to my (obviously wrong) assumptions would lead to the concluision
that this disc also supports 8X write (which it clearly doesn't).

Is it at all possible to establish a disc's certified write speeds by
interpreting returndata from MMC commands ?

If so, can somebody help me out by clarifying which fields need to be
examined in order to obtain the information I need.

Thanks,

Kris


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