Burning DVD's... still at a low speed?

[Claymonkey]

DVD burners have come a long way. However, I still know a lot of die hards that insist you don't want to burn a dvd-video beyond 2x. Mind you media is generally 16x these days and nero doesn't let you burn below 4x generally.

Do you still burn at a low speed for a video dvd or do you say "the heck with it" and burn at 8-16x these days. I've noticed that I have burned at 16x with verify and it says its fine.. but you still get the occasional skip. Does that have more to do with me using the computer during the burn process or because I'm burning at a fast speed?

[LvR]

16X on Verbatim MCC004 +R media with a LiteOn LH-20SIP.

Been doing it this way since I got KProbe, Nero CD speed and DVDInfo Pro to agree that the combination of writer and media results in excellent error-free burns

[Brian Ellis]

I recommend you burn at ½ max speed or less, but not necessarily at the lowest possible.

A couple of years ago, I looked at disks burned on the same equipment at 8x and 2x through a metallurgical microscope and the "burn bits" were much more sharply defined in the slow burn, so I concluded there was at least a technical difference. This may be a reason for speculating that slow burns are better than fast ones.

I always burn at <½ max.

[wkulecz]

In my experience as long as the disk passes verification (I use Nero) no issues. But I usually burn 16X media at 8X because the verification failures seem to go away.

I use whatever media Fry's has on sale when I need more.

--wally.

[Paul79UF]

I always burn at <½ max.

Ditto.

Doing that just makes me feel more confident that the disc will burn properly. Besides, with a core duo processor, I can still work on other things while the dvd burns.

[Brian Ellis]

I posted the following in another forum. FYI

OK, here's an explanation WHY you should burn at lower than max speed.

With a pressed non-pirated disk containing a Hollywood blockbuster, the bits are pressed into one or two layer(s). I forget whether it's an 0 or a 1 bit that is actually pressed. This means that the profile of the layer looks like a series of pits, one for each bit. This is done from a carefully etched and polished master. If there is no pit, the collimated laser beam, focussed on the layer, goes through without interference, is reflected back by the metal coating (usually vacuum-evaporated aluminium), again without interference, to be picked up by the photodetector and so to the electronics. If there is a pit, then the light is refracted twice and the photodetector sees almost no light being returned. The contrast between a pit and no pit is therefore very high. Furthermore, the pits are very sharply defined, because they are mechanical. The size of each pit is less than 1 μm, much less than the thickness of a hair. These factors make reading such a disc easy.

A DVD±R is not at all like this. The inner layer(s) consist of solid polymer loaded with photoinitiators. During "burning", the photoinitiator detects when a relatively high power laser beam is present and causes the polymer to change its chemical structure and, in doing so, becomes slightly more opaque. During subsequent reading, the laser beam, which is continuous, has to either traverse the virgin polymer layer, which is not fully transparent (the photoinitiators are usually dyes) or the photopolymerised bits, which are less transparent. The contrast between a 1 and 0 bit is therefore much lower, making accurate reading more difficult. However, this is not all. Unlike during reading, the burning laser beam is switched on and off for the different bits. Typically, if burnt at 1x speed, we are talking about 5 - 9 million bits in each second. If you burn at 16x, this would be 80 - 144 million bits/s and each bit may last about only 1.7 nanoseconds. But it takes the laser a significant fraction of a nS to reach full power and switch off. This means that the pseudo-pit does not have sharply defined leading and trailing edges and the slower the burning speed, so the edges are better defined, increasing the chances of accurate reading. Once again, it doesn't stop there. The photoinitiators release free radicals which cause the photopolymerisation. The latter will also, under some circumstances, release a few free radicals, so that the "burnt pit" will spread randomly some nanometres beyond the limits subjected to the laser beam, causing the fuzziness of the "pit" to be extended (on some cheap discs, this can continue in time, especially in warm environments, so that the disc becomes totally unreadable after a number of years).

On DVD±RW discs, the process is different. The sensitive layer is a quaternary metal alloy which has three complex phase states. These change with temperature. These are designated with Greek letters but I'll call them a, b and c. States a and b are stable at room temperature. State a is reflective and state b is less so. The change from a to b is a matter of temperature. The IR light energy in the laser beam is converted to heat energy which raises the temperature sufficiently to change the phase from a to b, giving less reflective bits. Erasing uses a continuous higher power which raises the temperature sufficiently to change the phase of a and b to c. However phase c is unstable and reverts directly to a on cooling.

Whatever, for best burning results, and especially for archival purposes, burn at the slowest speed possible to get the sharpest "pits". I always burn at ½ the maximum or less.

While on the subject of burning, there is a mechanical limit to burning speed, corresponding roughly to 48x for a CD and 16x for a DVD. Above that, the centrifugal force on the periphery of the disc itself will flow it outwards sufficiently to render burning/reading problematic. In fact, if the disc is slightly unbalanced, for any reason, it will even shatter in the drive at high speeds (I think there is a video on YouTube demonstrating such shattering). So the limit is physical.

Finally, did you know that high speeds apply only towards the centre of the disc? A DVD which is being burnt at 16x will start at 16x, but will slow down as the laser moves outwards and may be only 4x towards the edge. This maintains a sensibly constant peripheral speed at the laser radius.

[KRSESQ]

Odd. My pioneer DVR-108 won't let me select a DVD burn speed higher than 4x in Nero. Don't know about DVD Workshop, but it takes about the same amount of time to burn. All my DVDs are perfectly readable except for a few frustrating glitches. CDs burn up to 48x, but I always select 8x no matter what.

Kevin

[LvR]

Some sense there Brian but

Finally, did you know that high speeds apply only towards the centre of the disc? A DVD which is being burnt at 16x will start at 16x, but will slow down as the laser moves outwards and may be only 4x towards the edge. This maintains a sensibly constant peripheral speed at the laser radius.

I guess that theory has never seen my LliteOn LH-20AIP in real life then - most burners/readers I see have a CAV burn/read strategy and therefore exhibits exactly the opposite characteristic - ie - burning/reading speed increases the further the laser sled is positioned from the center of the disk

[ND66]

I do it at 4X max.

10 years from now if my DVD is not readable anymore, I'll know I did all I could to prevent it from it. Also using Premium DVD blanks for it too.



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[Technoid]

Normally I tend to burn my 16x media at 8x since it produces the best results....
tho I got 2 cakeboxes of awfull DL media that overheats at lower than the max speed ( 8x)