Why DVD+R(W) is superior to DVD-R(W)

I just posted the article Why DVD+R(W) is superior to DVD-R(W).

Since the war between DVD+R(W) and DVD-R(W) started, several comparisons of the two formats have been published, but none of those I read did contain really accurate technical information. The goal of this paper is to present the technical details and see which format is the best.

Read the full article here:  [http://www.cdfreaks.com/article/203-Why-DVDRW-is-superior-to-DVD-RW/](http://www.cdfreaks.com/article/203-Why-DVDRW-is-superior-to-DVD-RW/)

Feel free to add your comments below. 

Please note that the reactions from the complete site will be synched below.

Hasn’t hardware based defect management been a feature of the DVD+RW format since day one?

the article says that while hardware based defect management is a feature of dvd+rw, it has not been implemented in any drive as of yet.

If thats the case, then every drive manufacturer out there has been falsely advertising this feature since the first DVD+RW drive was announced.

Indeed…I see a large gap between what dvd+rw is capable of, and what dvd+rw drives nowadays can do…

You would hope DVD+R is a better format, as they had the benefit of seeing what -R could do. This article is interesting and a start, but the bottom line on what it means to an end user isn’t clear. Not surprisingly, it’s probably not a compelling difference for many. The real issue is which things are relevant to an end user. Those get a little lost in the article, but they include: - Better ECC - Better power calibration info - Better linking - Less space lost in multiple writes The compelling item, defect management, isn’t all that relevant - who would really use RW? RW isn’t a stable medium. Unfortunately starting with the physical aspects (especially pits), no matter how much better you believe it to be, isn’t entirely convincing by itself - it’s only several processing stages later that data gets delivered from a drive. That is, you have to evaluate the net effect on the whole chain (from data to write to read to data). Looking at what happens at the physical level by itself isn’t all that informative, as ECC is there to offset the physical issues.
[edited by buzzy on 23.06.2003 23:39]

> That is, you have to evaluate the net effect on the whole chain > (from data to write to read to data). Looking at what happens at > the physical level by itself isn’t all that informative, as ECC > is there to offset the physical issues. The point here was to show that linking problems on - format can be caused by inferior design at two independent levels (logical and physical), whose bad effects are summed. I agree that it would have been more interesting with figures showing the impact of this physical effect, but I could not obtain those.

I don’t quite get this. Philips says its drives are Mt. Rainier compatible. Is this not the same thing as having defect management built in? Isn’t DVD-MRW just about that?

What Philips drives? What does not have built-in Defect Management? DVD-MRW or DVD+MRW?

Ain’t Pioneer A06 has Defect Management? I think it does.

What are technical disadvantages of DVD+ compared to DVD- format?

The way I heard it, DVD -R and -RW were designed to be most compatible with stand-alone DVD players. Precisely how are +R and +RW superior with regard to playback in stand-alone DVD players, if they are, compared to -R and -RW? :X

I don’t think this point should be underestimated. I think it is misleading for Spath to criticize compatibilty based on players barfing over unexpected reserved fields, but not mention that the reason that logical layer enhancements like defect management were deliberately avoided in DVD-R was to maintain compatibility with existing players (pre VD+.) Players that barf over unexpected values or non-zero reserved fields are likely to be in violation of the spec anyway. I don’t have the specs, but it is common for technical specs to recommend that reserved fields or unexpected values be ignored in most cases. The exception to this would be a field whose specific purpose is to declare an incompatible change. Can I also object to the “plus” and “minus” framing? It’s an unpronounced hyphen in DVD-R. Officially, the VD+ formats aren’t even DVDs, because the Forum does not endorse them. So the dual connonation of DVD+R as (a) a DVD and (b) better than a “minus” is highly misdirectional. It is only “better” if your evaluation criteria completely excludes compatibility.

The only advantage of - over + that I could find is copyright management : thanks to its pre-embossed informations, DVD-R(W) discs can be made much more difficult to copy. I asked Pioneer for more ideas but did not get any answer ; anyone who knows such advantage of - over + is welcome to mail me.

Mainly because of linking and bit-settings (see the corresponding parts of the aticle). Note that DVD+R(W) have been created after their - counterpart, and they were certainly not designed to be less compatible.

> I don’t think this point should be underestimated. I think it is misleading for > Spath to criticize compatibilty based on players barfing over unexpected reserved > fields, but not mention that the reason that logical layer enhancements like > defect management were deliberately avoided in DVD-R was to maintain compatibility > with existing players (pre VD+.) It’s easy to claim afterwards that you willingly did not include a feature you did not think about AT THAT TIME. Besides, which compatibility problems are you talking about ? > Players that barf over unexpected values or non-zero reserved fields are likely > to be in violation of the spec anyway. I don’t have the specs, but it is common for > technical specs to recommend that reserved fields or unexpected values be ignored > in most cases. The exception to this would be a field whose specific purpose is to > declare an incompatible change. With these disc specs, reserved usually mean “must be filled with zeroes”. The book type definition Oof DVD-ROM standard gives a number of authorized values but does not explicitely say what to do when other values are read. > Can I also object to the “plus” and “minus” framing? It’s an unpronounced hyphen in > DVD-R. Officially, the VD+ formats aren’t even DVDs, because the Forum does not > endorse them. So the dual connonation of DVD+R as (a) a DVD and (b) better than > a “minus” is highly misdirectional. It is only “better” if your evaluation criteria > completely excludes compatibility. Luckily I’m typing and not talking, so you cannot know how I pronounce “DVD-R” :slight_smile:

A Wobble frequency for DVD+RW is too close to the channel bit frequency. 14T is the longest signal in the 8-16 modulation (EFM plus) and DVD+RW wobble is 16T in its half period. They are so close that the circuit has difficulty to separate them clearly. That is, the wobble signal can be distorted easily after writing on the DVD+RW disc. On the other hand, wobble frequency of DVD-R/RW is 93T in its half period and it’s far from the 14T channel bit signal. It’s easier to separate the main channel signal and the wobble signal from the signals from an optical pickup. The quality of the wobble signal is very crucial when the drive starts writing from the link point (at the gap). The wobble signal has to be so clear, without distortion and little jitter as possible, because it generates the writing channel bit clock via a PLL. But in the DVD+RW specification, it employs the lossless linking as a mandatory function. This allows only very small linking position error of the gap tolerance, i.e. so severe. It seems so harder to meet the required error/gap length of the link position than the DVD-R/RW system, especially when it comes to higher writing speed environment. Do you agree?

Hmmm, Philips (DVDRW416K, I believe it’s the latest product at present) nor Ricoh don’t seem to support DVD+MRW or EasyWrite for DVD+RW, supports only Mt Rainier for CD-RW. On the other hand, current Pioneer DVR-A06-J already supports DRT-DM : Destributed Real-time Defect Management that achives Prescision Recording Technology. Anyway, Microsoft already announced that the defect management would be supported in the Device Driver level in the coming Windows OS Longhorn due in 2005, for any of DVD-RW, DVD+RW and DVD-RAM defect management.

The wobble quality is important indeed, but noy that much for the writing clock, which can be nicely generated even from a damaged wobble by adding a few tricks to the standard PLL. From my experience the most difficult part is address (LPP/ADIP) tracking, and I always found that reading LPP on a burned part or while burning a - disc was much more difficult than reading ADIP on a + one. And from my own tests + linking is still in practice much more precise than the 8 bits allowed by the standard, even at 8x. But in the end it all depends on the chipsets, and yours may behave differently from those I have tested.

Yes, until +MRW is actually used in a drive DRT-DM is the best defect management system you can get. Note, however, that nothing in theory prevents + format to use DRT-DM/UDF2.0 too, while Mount Rainier will always be forbidden to - drives.