Re: [Dvdrtools-users] unable to write dvd-r with linux kernel 1.6

[Bryan J. Smith]

On Thu, 2005-05-12 at 20:52 -0400, Larry Siden wrote:
> Concerning dvdrecord and growisofs, is one prefered over the other for
> burning music/video?

For maximum player compatibility, you want a single-groove media
recorded in disc-at-once (DAO) mode.  DVD+R cannot do this, and its
organization is not physically the same as DVD-R (or CD-R for that
matter).

Magneto-optical (MO) media, such as CD-RW, DVD-RAM, DVD-RW, DVD+RW and,
a variant, DVD+R looks like a hard drive, physically -- pie-slice.
Single-groove media, such as CD-ROM, CD-R, DVD-ROM (including DVD-Video)
and DVD-R look like a record -- one entry, one exit.

On MO media, when you do a full revolution, the head does not move
outside _until_ the full revolution is complete, and then it immediately
and discretely moves one cylinder up.  On single-groove media, the laser
follows one, long, linear track from the inside of the CD outward.

The former is not what most -ROM/-Video players were designed to do
until more recently.  That's why using a single-groove media with a
program that can record as such, in a single, linear stroke, is used.

Sure, CAV, direct access, pie-slice formats are great for data access.
But they are not great for consumer compatibility.  And sometimes the
use of the media or drives, or the wrong media in drives (especially
rewriting drives) can reduce writer (or even reader) drive longevity.

E.g., I've seen people seriously reduce the life of both their writers
and readers by using CLV MO CD-RW media in a CAV MO CD-RW drive (what I
like to call "CD+RW" retroactively) -- commonplace because CLV media
tended to be cheaper than CAV (this has since changed).  Not only is the
MO head trying to modify "unfinished" positions of the CLV, but the
reader could attempt to do the same.

CAV v. CLV is a major issue for MO because spacing is different, hence
why Sony/Philips just created an entirely new designation for it with
DVD+RW (instead of causing the issues we had with CD"+"RW).  It's very
different than single-groove, because the spacing is the same for -ROM/-
R media.

It's a long story that I'm going to eventually put into a FAQ, with lots
of pictures to show not only how DVD-R and DVD+R/RW are physically
different, but how CAV v. CLV becomes an issue with MO.


-- 
Bryan J. Smith                                 address@hidden 
----------------------------------------------------------------- 
Beware of those who define their preference in terms of hate of
another option, and not on the positive merits of their selection