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Wrote down what i learned from implementing support for overwriteable DVD

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Thomas Schmitt 2007-01-18 13:55:28 +00:00
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Overwriteable DVD Cookbook
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Inspired by Andy Polyakov's http://fy.chalmers.se/~appro/linux/DVD+RW/tools ,
backed by reading mmc5r03c.pdf from http://www.t10.org/ftp/t10/drafts/mmc5/
and by experiments with drives NEC ND-4570A and LG GSA-4082B.
For libburnia.pykix.org by Thomas Schmitt <scdbackup@gmx.net>
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Media type can be recognized by Current Profile from 46h GET CONFIGURATION.
(mmc5r03c.pdf 6.6.2.1)
DVD-RAM 0012h
DVD-RW Restricted Overwrite 0013h
DVD-RW Sequential Recording 0014h (i.e. unformatted)
DVD+RW 001Ah
A short compilation of the write model:
- Overwriting in general
The recipes described here are depending on formatting state:
- DVD-RAM, fully formatted DVD+RW or DVD-RW
- Unformatted DVD+RW
- Partly formatted DVD+RW
- Unformatted DVD-RW
- Partly formatted DVD-RW
- Intermediate state DVD-RW
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Overwriting in general :
No Write Parameters mode page 05h is to be sent. Speed can be influenced by
B6h SET STREAMING , speed capabilities can be inquired by ACh GET PERFORMANCE.
It is advised to set only speeds and sizes which are returned by ACh.
(mmc5r03c.pdf 6.39 SET STREAMING, 6.8 GET PERFORMANCE)
Optimal performance is promised without any speed setting. But my experiments
showed that SET STREAMING values persist after media change.
In formatted areas of the media, coarse random access is possible.
For DVD-RAM and DVD+RW write addresses and data size need to be aligned
to 2 KiB. For DVD-RW alignment has to be 32 KiB. Within these limitations
the write address is at the discretion of the sending program.
Just use 2Ah WRITE to send data.
(mmc5r03c.pdf, 6.44)
Not yet formatted areas may be completely forbidden or they may be allowed
for sequential writing (DVD-RW Intermediate state) or they may be allowed
for random access only after the necessary waiting time for formatting to reach
the desired address (DVD+RW with background formatting active).
Already written areas can be overwritten without special precaution.
Blanking a DVD-RW actually destroys its formatting.
When writing is done, it is mandatory to force the drive's buffer to media by
35h SYNCHRONIZE CACHE.
(mmc5r03c.pdf, 6.41)
Most of the concepts usually expressed in Write Parameters mode page 05h do not
apply to the recipes here: Test-Write, Buffer Underrun protection,
Multi-session, Write Type, Block Type, Track Mode, ...
There are hints for multi-session formats with DVD-RW but both of my drives
do not offer "Add Session" Format Types 12h or 14h.
(mmc5r03c.pdf 6.5.4.2.7 , 6.5.4.2.9)
Caution: Drive and media compatibility seems still to be quite an adventure.
If you experience problems, especially problems with readability, then try
different drives and media brands. Failure does not necessarily mean that the
software did anything wrong.
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DVD-RAM, fully formatted DVD+RW or DVD-RW :
There is no need for any finalizing other than forcing the drive's buffer to
media by 35h SYNCHRONIZE CACHE (which is mandatory for writing, anyway).
(mmc5r03c.pdf, 6.41)
(It seems to do no harm to send to DVD+RW or DVD-RW a 5Bh CLOSE TRACK SESSION
with Close Function 010b despite there is no session open in this scenario.)
Full format is the natural state of DVD-RAM.
DVD+RW reaches this state if Background Formatting is allowed to finish without
being stopped by 5Bh CLOSE TRACK SESSION.
(mmc5r03c.pdf, 6.5 FORMAT UNIT, 6.5.4.2.14 Format Type = 26h)
The formatting state of a DVD+RW may be inquired by 51h READ DISC INFORMATION
requiring Data Type 000b "Standard Disc Information". In the reply, BG Format 3
indicates fully formatted media.
(mmc5r03c.pdf 6.22.3.1.13)
DVD-RW reaches this state either by Format Type 00h (or 10h) with maximum
size given as Number Of Blocks, or by writing sequentially until the disc is
completely full into an intermediate session opened by format 15h resp. 13h.
(mmc5r03c.pdf, 6.5 FORMAT UNIT, 6.5.4.2.1, 6.5.4.2.10, 6.5.4.2.8)
A fully formatted DVD-RW can be recognized by 23h READ FORMAT CAPACITIES. The
Descriptor Type of the Current/Maximum Capacity Descriptor is 10b ("Formatted
Media") and 0 blocks are offered with Format Types 13h or 11h.
(mmc5r03c.pdf, 6.24.3.2.1, 6.24.3.3)
See also discussion of unformatted or partially formatted DVD-RW below.
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Unformatted DVD+RW
This is the state of previously unused DVD+RW media.
The formatting state of a DVD+RW may be inquired by 51h READ DISC INFORMATION
requiring Data Type 000b "Standard Disc Information".
In the reply, BG Format 0 indicates unformatted media (or unsuitable media).
(mmc5r03c.pdf 6.22.3.1.13)
Formatting has to be started by command 04h FORMAT UNIT, Format Type 26h.
Different from other format types, 26h allows to send a fantasy size of
0xffffffff blocks and does not require the caller to know the exact maximum
size offered with that format.
(mmc5r03c.pdf, 6.5 FORMAT UNIT, 6.5.4.2.14 Format Type = 26h)
As its name suggests, one has not to wait for background formatting to end
but may very soon start writing as on formatted media. Random access to
yet unformatted areas can last long, though.
If backup formatting has been started at the beginning of the session, then
it may get stopped after the final cache sync by 5Bh CLOSE TRACK SESSION
with Close Function 010b.
(mmc5r03c.pdf 6.3.3.6)
Formatting of DVD+RW is called "de-icing" because unformatted areas offer
no hold for random access addressing and are thus slippery like ice. One can
also see a color change from shiny unformatted to more dull formatted media.
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Partly formatted DVD+RW :
This state is achieved by stopping background formatting before the media
was completely formmatted.
The formatting state of a DVD+RW is obtained by 51h READ DISC INFORMATION
requiring Data Type 000b "Standard Disc Information".
In the reply, BG Format 1 indicates partly formatted media.
(mmc5r03c.pdf 6.22.3.1.13)
If the data of the session surely fit into the formatted area, then it would
be unnecessary to restart background formatting.
But in order to make the DVD+RW surely accept its maximum number of bytes,
formatting may be restarted by command 04h FORMAT UNIT, Format Type 26h,
with the Restart bit set and Number of Blocks set to 0xffffffff.
(mmc5r03c.pdf, 6.5 FORMAT UNIT, 6.5.4.2.14 Format Type = 26h)
From then on, the same rules apply as for previously unformatted DVD+RW.
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Unformatted DVD-RW (media profile is 0014h) :
This state is present with previously unused media. It is also present with
media blanked by programs cdrecord, wodim or dvd+rw-format and with media which
were sequentially written from blank state.
Profile transition from formatted 0013h to unformatted 0014h is done by
A1h BLANK.
(mmc5r03c.pdf, 6.2)
For becoming overwriteable such media need to be treated by command 04h FORMAT
UNIT.
(mmc5r03c.pdf, 6.5)
The Format Type has to be chosen from the list replied by 23h READ FORMAT
CAPACITIES. Suitable are Format Types 00h, 10h, 15h.
(mmc5r03c.pdf 6.24)
Format Types 00h and 10h provide a writeable area of a size given by Number of
Blocks. Type 00h seems to be the most traditional and complete one. It needs
no closing of a session at the end of writing.
The Number Of Blocks may be at most the value reported by 23h READ FORMAT
CAPACITIES in the entry for the desired format type. Full format is achieved
by sending exactly the reported value.
(mmc5r03c.pdf, 6.5.4.2.1 Format Type = 00h, 6.5.4.2.5 Format Type = 10h)
Format Type 15h provides a writeable area of given size too, but this area can
be expanded by sequential writing and afterwards marked as overwriteable by
closing the session. It is even allowed to format with size 0 and to leave
the size claim entirely to a sequential write process beginning at LBA 0.
(mmc5r03c.pdf, 6.5.4.2.10 Format Type = 15h)
When writing is done and cache is synced, one should send 5Bh CLOSE TRACK
SESSION with Close Function 010b in order to bring the session out of
Intermediate state.
(mmc5r03c.pdf 6.3.3.2.3)
If not written up to the last 32 KiB block, the DVD-RW is only partly formatted
after that.
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Partly formatted DVD-RW (media profile is 0013h) :
This state is achieved by formatting a DVD-RW with a number of blocks which
is less than offered for the Format Type by the drive's reply to 23h READ
FORMAT CAPACITIES. If the media was most recently formatted by Format Types
015h or 013h then it must have got written some bytes and afterwards treated
by 5Bh CLOSE TRACK SESSION, 010b in order to be partly formatted.
(mmc5r03c.pdf 6.3.3.2.3 CLOSE TRACK SESSION 010b, 6.24 READ FORMAT CAPACITIES)
Elsewise the media is in Intermediate state. See below.
If the data of the session surely fit into the formatted area, then it would
be unnecessary to do any further formatting.
But in order to make the DVD-RW surely accept its maximum number of bytes,
partial formatting may be expanded by command 04h FORMAT UNIT, Format Type 13h,
which is supposed to be offered by the drive in this state. This brings the
session again into Intermediate state and thus allows expansion by sequential
writing. As with Format Type 15h it is ok to set Number Of Blocks to 0, so that
no fixed size formatting work is done and writing can begin soon after.
(mmc5r03c.pdf, 6.5.4.2.8 Format Type = 13h)
A fully formatted DVD-RW offers 0 blocks with format 13h. It makes not much
sense to bring such a full session into Intermediate state because no gain in
size is possible any more. Rather apply recipe "DVD-RAM, fully formatted DVD+RW
or DVD-RW" above.
When writing is done and cache is synced, one should send 5Bh CLOSE TRACK
SESSION with Close Function 010b in order to bring the session out of
Intermediate state.
(mmc5r03c.pdf 6.3.3.2.3)
If not written up to the last 32 KiB block, the DVD-RW is only partly formatted
after that.
Format Type 13h has been tested only with expanding sessions formatted by 15h.
Nevertheless it is offered with sessions from 00h and 10h, too.
According to the specs, Format Type 11h would expand a session by a fixed
size. This has not been tested yet because it is less appealing than 13h.
(mmc5r03c.pdf, 6.5.4.2.6 Format Type = 11h)
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Intermediate state DVD-RW (media profile is 0013h) :
This state is achieved by formatting a DVD-RW with Format Type 15h or 13h
without subsequentially writing data and sending 5Bh CLOSE TRACK SESSION
with Close Function 010b.
Such media behave very unpleasing with my DVD-ROM drive under Linux 2.4 ide-cd.
One should therefore better avoid to release media in this state.
This state can be recognized by 23h READ FORMAT CAPACITIES. The Descriptor Type
of the Current/Maximum Capacity Descriptor is 11b ("Unknown Capacity") and
no formats 13h or 11h are offered.
(mmc5r03c.pdf, 6.24.3.2.1, 6.24.3.3)
One may treat such media as if Format Type 15h or 13h had been freshly applied.
I.e. sequential writing from LBA 0. After cache sync bring the session out
of Intermediate state by 5Bh CLOSE TRACK SESSION with Close Function 010b.
(mmc5r03c.pdf 6.3.3.2.3)
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