[Libburn] Drive data/properties gathering

[Stéphane LOEUILLET]

hello libburn ML readers,

i decided to give libburn a try to see what needed work

so, i gathered latest CVS, plenty of SCSI docs (MMC-1 std to 4 draft,
SPC, ...), and a few burners.

i "heard" that Todd from Optimystic was working on improving libisofs by
addind Rock Ridge, libburn maintainers working on TAO support but i saw
noone working actively on communication with the drive.

what seems to need work :

Error handling when using MODE_SELECT_10 to test TAO/SAO/...
availability (is there a better way to do it ? like a page mode that
describe this kind of capability)

Enhanced MODE_SENSE_10 probing : actually, only few informations are
extracted from page mode 2Ah. (basic MMC-1 i would say but nothing like
MMC2 or MMC3 info like available write speed list)

Handling of future MMC-4 drives : for now, MMC-4 is still a draft but i
suppose there are already some drives around that support early MMC-4.

The problem with MMC-4 is that page mode 2Ah is deprecated, in favour of
a feature/capability list. (which is far clearer that this infinite ugly
bit-field that 2Ah is)

i'd like your feedback on a few points :
  - how should capabilities be presented ?

extending the drive_info structure infinitly would make it as ugly as
page mode 2Ah is.

or should we provide a feature list like what MMC-4 (and perhaps even
earlier versions) provide, as a linked list ? (recreating it from 2Ah in
the case that the drive is too old and does not provide it) 

or even several lists :
one for accepted media types
(DVD-R/DVD+R/DVD-RW/DVD+RW/DVD+R9/CD-R/CD-RW/DD-CD/CD-MO/DVD+R DL/....)

one for writing modes :
(Packet writting, SAO 96R, DAO 16, TAO, ...)

and what does not fit in a list going to a structure like we have
actually

  - what info are really needed ?

few would need to know their drive supports bar-code reading, CD+G, CD
Extra, CD-I/Photo CD, VCD/SVCD, ...


i already implemented "available write speed list" (for MMC-3 drives
only) even if actually i don't know where to store those speeds.

i did it at the end of the MODE_SENSE_10/2Ah call. i don't yet know why
but it seems this list is sensitive to the type of media which has last
been inserted :

on my combo CD/DVD burner, the reported available speeds aren't the same
depending on the media type. i need to find a way to query those either
on demand, specifying a fake media type as parameter to query each speed
list or only just before burn time.


that's all for now

++

-- 
Stéphane LOEUILLET <stephane.loeuillet at tiscali.fr>