MMC: DVD-RAM Format Type 00h description

David Burg dburg at nero.com
Mon Jun 6 05:56:47 PDT 2005


* From the T10 Reflector (t10 at t10.org), posted by:
* "David Burg" <dburg at nero.com>
*
Dear all,

Reading 5r01a draft again, I found the follow paragraph about DVD-RAM Format
Type 00h (format unit description):

"6.5.3.4.1.2 DVD-RAM

The defect list handling is specified by the combination of the CmpList bit
and the DCRT bit as shown
in Table 224. In the case that the CmpList bit is set to zero and the DCRT
bit is set to one, the
Number of Blocks field shall be ignored and the number of addressable blocks
shall be retained.
Otherwise, the Number of Blocks field specifies the number of addressable
blocks for the whole disc.
For DVD-RAM the Number of Blocks value shall be the value returned by the
READ FORMAT
CAPACITIES command. The Type Dependent Parameter field specifies the Block
Length."

I think the "the value returned by the READ FORMAT CAPACITIES command" is
either wrong or the description of Read Format Capacities needs to be
clarified (...and existing device firmware changed). The reason is that (at
least some) DVD-RAM devices return multiple format descriptors for format
type 00h with different number of blocks. "the value returned by the READ
FORMAT CAPACITIES command" suggests that only one number of blocks is
permitted for format descriptors of format type 00h.

I believe the DVD-RAM devices *need* the possibility to return multiple
format descriptors with different sizes for format type 00h in order to
signal the host the maximum user data area size possible (minimum spare area
size) and the ?default and recommended? user data area size (default because
the number of blocks from the format unit parameters may be ignored,
recommended because the hardware vendors know what spare area size they need
to perform good defect management, which I, software vendor, do not know).

I am wondering if a third format descriptor should be returned also to
indicate the minimum user data area size (maximum spare area size). I
believe DVD-RAM devices are not providing this value currently. Or maybe I
am confused because the maximum spare area size is the default and
recommended size.

Please let me know if my understanding of DVD-RAM devices is correct.

Best regards,

David Burg

----------------------------------------------------------------
David Burg
Software Development,
InCD and Low Level Drivers Project Leader

Nero AG               phone: +49 (0)7248 928 327 (room line) Internal VoIP
-363
Im Stoeckmaedle 18    fax:   +49 (0)7248 928 299
76307 Karlsbad        email: dburg at nero.com
Germany               http://www.nero.com
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