DVD-r/+r inquery

[james636]

Hello all. I have a couple of inquries about DVD plus and minus format. I have an Optorite DD1203 and I'm using Prodisc 8x dvd-r/+r media. The +r, at the start of a burning process, starts out at 6x and gradually ascends to 8x (about 25 sec.). Thats fine. But the -r starts out at 4x and jumps to 8x in a totally different manner. It burns about 1.6GB at 4x and then leap frogs to 8x. The funny thing about it, is that it seems the burning software that I use (Nero 6, DVD Decrypter, Alcohol 120%, and etc.) knows that the discs will burn this way. I say that because, when nero 6 (or whichever app I choose to use) calculates the time it will take the discs to burn, it factors in that there will be two different speeds that will be used instead of only 8x as it does with the +r. I'll try to explain more; when I use DVD Identifier to identify the disc, it only states that it is 8x. But when Nero 6 calculates the burning time, it doesn't calculate it as only 8x disc, it calculates it by using 4x speed for 1.6GB and the remaining at 8x. This would mean that if it only calculates the disc to burn at 8x and as I mentioned the disc burns 1.6 GB at 4x and then jumps to 8x, the then estimated burn time and the actual time it took to burn the disc would be off. But as I stated earlier, the burn time and the estimated burn time are both on point with each other. I first noticed this using Ritek G05 dvd-r 8x media, so I tried the prodisc 8x dvd-r media and they both performed the same way. Does anyone have any information as to why dvd+r and dvd-r burn different.

[garryheather]

The timing is derived in a different manner on + and -R discs. It's all to do with track wobble and pregrooves, and can get a little hairy.

Basically, it is not uncommon to see drives apparently "accelerate" at certain points on a disc. Some recorders in particular have "zones" where the drive will speed up, others maintain a constant velocity throughout the disc.

It's behaviour will probably change when you feed it CD-R's as well. Going between formats will show up the differences in write strategies that your recorder uses - this and maybe dynamic write control (which monitors the quality of the burn and media) will all have an impact on writing speed.

If you get into the phsyical differences between the formats, you will see how and why the timing changes between discs, and many recorders use this to their advantage to make more efficient burns as far as the effort it has to put into the recording phase. This helps lower end systems keep up and buffer under-runs down to a minimum, in addition to power savings and of course the burn quality by keeping the drive timing bang on.

[james636]

What? Pardon me for not being as knowledgable as you, but can you simplify your explanation just a tad Are you saying that it is nothing to worry about. Is it common that -r format does this. Is it safe to say that +r format is better or more advanced than -r format.

[pg55555]

I`m not an expert, but when you use DVDIdentifier to check your media, under the Drive Capabilities tab, you will find details about the "writing strategy" you drive can use in that mdia.

You`ll find the writing strategies of +R and -R are different. It is my undertanding these differents are at the heart of the +R and -R specifications.

[garryheather]

OK.

First of all, don't worry about it.

There is no right answer to which is better regarding + or -. I use both, +R for data (better error correction for data and slightly faster access times) and -R for video and knocabout projects where cost per blank is an issue. I also have compatibility issues on some hardware and can control -R more easily than +R on problematic hardware.

There are inherent differences between how your recorder will write to CD-R's, DVD-R's and DVD+R's. It's to do with the format, predominantly. CD-R's and DVD-R's use a tracking system based on a "wobble" on a tracking groove cut into the blank to identify where on the disc the optical block is looking at, where-as the +R format uses a different form of addressing based on timing pulses which are more accurate. This then leads into things like CAV and CLV, which determines whether of not the disc maintains a Constant Angular Velocity where the rotational speed of the disc stays the same therefore the data gets faster as it gets nearer the edge of the disc (most often seen in data +R) or Constant Linear Velocity, where the disc slows down as it nears the edge to keep the data transfer rate the same no matter where in the disc the block is. Think Audio CD and you're there - if you've ever seen one in say a portable player and can see the disc spinning and wondered why it appears to slow down as you skip to tracks near the end of the album, now you know !

When it comes to recording, a number of recorders use Partial CAV and Partial CLV. A lot of readers do to, these days - especially if faced with poor quality discs (although it is not as common as it is on the recorders).

The best example of this I saw was on a recent 52x CD writer. If I can find a speed graph I'll link to it, but basically it started off at something like 12x for the lead in and initial 100Mb or so, then stopped burning while the drive accelereated up to 24x for a while, say another 350Mb, and only then did the drive accelerate up to 52x. This would be an example of a Partial strategy.

Does that make it a little clearer ?

[garryheather]

As a footnote to my last post, here are some example graphs that show my point about partial (or zoned, as they call it) writing speeds:

http://www.cdrinfo.com/Sections/Articles/Specific.asp?ArticleHeadline=Sanyo+CRD%2DBP15...%2DRW&Series=0

http://www.cdrinfo.com/Sections/Articles/Specific.asp?ArticleHeadline=Mitsumi+CR%2D480...ries=0&index=4

http://www.cdrinfo.com/Sections/Articles/Sources/LiteOn%20LTR-24102B%20CD-RW/images/cd...write-test.gif

These generic examples may help you understand the principles a bit better.

[james636]

Thanks, That explanation was perfect; It really cleared my consious. I thought maybe it was either a problem with my discs or drive. As I stated earlier, I tried the Ritek G05's and then switched to the Prodiscs in hopes of a difference in prformance; Your information will keep me from searching for a solution in which there wasn't a problem present.

Thanks Again