> > >The page in question was updated with following two paragraphs:
Updated write-up is online and reads now as following: What does plus in DVD+RW/+R stand for? Originally this paragraph started as following: The key feature of DVD+RW/+R media is high [spatial] frequency wobbled [pre-]groove with addressing information modulated into it. This makes it possible to resume interrupted [or deliberately suspended] burning process with accuracy high enough for DVD[-ROM] player not to "notice" anything at playback time. Recovery from buffer underrun condition in DVD-RW/-R case in turn is way less accurate procedure, and the problem is that the provided accuracy is very much what average player can tolerate. Now given that both provided and tolerated inaccuracies are proportional to respectively writing and reading velocities there basically no guarantee that DVD-RW/-R recording that suffered from buffer underrun will be universally playable. Well, it turned out that I was wrong about one thing. Even though DVD-RW/-R groove is wobbling at [apparently] 6 times lower spatial frequency, it does provide for equally accurate recovery from buffer underrun condition/loss-less linking. However! You apparently have to choose between buffer underrun protection and DVD-ROM/-Video compatibility. The catch is that the latter is achieved only in Disk-at-once Recording mode which requires: a. prior knowledge of data-set size, b. uninterrupted data-stream [buffer underruns are not tolerated]. While the former is defined only in Incremental Recording mode which implies explicit support by player unit(*). DVD+RW/+R are free from this limitation and provide both DVD-ROM/-Video compatibility and [unconditional] buffer underrun protection/loss-less linking. As already mentioned, DVD+RW(**) [pre-]groove has "addressing information modulated into it." This gives you an advantage of writing in truly arbitrary order [even to virgin surface and practically instantly, after ~40 seconds long initial format procedure]. In addition DVD+RW can be conveniently [over-]written with 2KB granularity(***). DVD-RW in turn can only be overwritten in arbitrary order. Meaning that it either has to be completely formatted first [takes 1/2 hour or so] or initially written to in sequential manner. And it should also be noted that arbitrary overwrite is never an option if DVD-RW media was recorded in [compatible] Disc-at-once mode, disc blanking is. Sometimes DVD+RW/+R recording strategy is erroneously referred to as packet writing. I write "erroneously" for following reason. Despite the fact that DVD-RW/-R provide for loss-less linking [within the packet only?], packets are still denoted with certain linking information which distinguishes it [recording mode in question] from e.g. Disk-at-once. Now the point is that written DVD+RW/+R media [well, its Data Zone] does not contain any linking information and is logically indistinguishable from one written in DVD-RW/-R Disc-at-once mode [or DVD-ROM for that matter]. Which is why I'm reluctant to call DVD+RW/+R recording method for packet writing. Or TAO/SAO/DAO for that matter... (*) I'm no longer 100% sure that it's absolutely required... At least linking sectors [if any] are assigned with LBA so that address space remains contiguous... If anybody can clarify, I would definitely appreciate a note... At least it looks like if explicit support is not actually required, it's not necessarily trivial to master compatible filesystem layout. On the other hand most DVD-ROM units support it nowadays. (**) DVD+R also has address in pre-groove [ADIP], but it's not clear what is it used for, as DVD+R provides for sequential recording only. (***) DVD "native" blocksize is 32KB, so that 2KB granularity is just a trick, but you're excused from playing it, i.e. reading 32KB, replacing corresponding 2KB and writing 32KB back. A. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
