slow burn speed for quality?

[Robert Bobson]

I've found a lot of people online that "think" that burning a disc at slow speed improves the quality, but I can't find any definitive, "expert" proof that this is the case.

anyone?

[Emre Safak]

There is a point of diminishing returns; I don't hesitate to burn my DVD+Rs at 8x (i.e., not slower). The best way to find out the burn quality is to scan your disc with a utility like Nero CD/DVD Speed. Use good media (Japanese) with a good burner and all will be well.

[Paul Doherty]

I was told by a friend whose opinion I respect that burning at 6x or above increased the risk of a bad burn (I think he said that was because the change in burning speeds near the start or end increased the risk of errors).

I tend to stick to burning at 4x, and after extensive testing with Nero DVD Speed I have found no evidence that burning at 1x improves the quality.

[Giroud Francois]

if you look at the burn with a microscope, you can see that the burn look like a spot (the dot burn) with a tail (when the laser switch off).
if the laser is badly calibrated (it is a complex match between the disc and burner and firmware). the tail is too big or long and can link two spots.
in that case using lower speed give more time to the laser to switch off and minimize the tail.
another problem could be that to create the spot fast enough, the laser use a big pulse, and in some case there is an overburn (spot too big than can overlap with other track). again low speed allows the laser to work better (more time to control power) and could give better result.
But fact is that if there is a bad match between the disc and the firmware or a bad calibration, you could get bad result at any speed.
That is why changing the media or the burner can sometime give a real different score between success and failure.
The calibration is roughly the process to emit the laser beam to the disc at different power and see how it is absorbed by the disc layer, this is done accordingly to the firmware table (containing all the generic disc models and the profile for a correct laser burn (time and power).

Personally when i want a reliable disc (master) i always use the slowest speed possible.
Strangely, you have to observe that 2X speed is not an official standard speed for DVD. The book that listed DVD specification sets 1X and 4X.
You have to know that writing information on a CD or DVD is not as simple as aligning dot on a track.
the information is written by packet, each packet contains redundant information. The packet is written as a cloud of dot, so they are not located all at the same place.
This way you can have a scratch on the disc and still be able to find the information you need.
This can lead to strange behaviour, since not all reader are tolerant to the loss of information.
Usually, even a badly scratched DVD can be seen on a video DVD player, while the same disc could be unreadable on a PC.
That is why a disc you can test as perfect on your equipement can show
macro blocks, picture freeze on a less tolerant reader.
Again , personally, i kept an old sony reader, very finicky about DVD-R as test machine. If it works here, it works everywhere.
But i have to say that many discs i tested, just give a "no disc" message on my sony or play only few seconds, while working perfectly on my no-name cheap taiwanese DVD player at home.
All the cartoons for my kids are backuped on cheap DVD-R (the original kept out of their hands) and even heavily scratched and full of fingerprints (cheese, chocolate etc...) still works on this cheap player.

[Vic Owen]

Here's another cut on this issue by the owner of the editorsbin.com website:
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"Regarding media:

Burning at 4x on 16x media isn't always as a good thing. There is a lot of confusion over this in the industry, so let me clear this up once and for all.

Recording at 2x or 1x should be done with 2x media.
Recording at 4x should be done with 4x media.
Recording at 2x should be done with either 4x or 2x media.
Recording ar 8x should be done with 8x or 16x media (footnote 1).
Recordiing at 16x should only be done with 16x media.
Recording at 2.4x should be done with 2.4x +R DL Media.
Recording ar 4x on 4x rated +R 4x DL should be avoided. Record at 2.4x.

Footnote 1

Each "x" rating described a layer process specific for that speed of recording. The higher speed processes are not always good for lower speeds. They are different, and should be avoided. You will often find you get better results recording at 4x on actual 4x media.

The higher the speed you record, the more likely you are going to create a situation where the player may be required to re-pass a sector, and this can cause distortion which will look like data rates are too high. In effect, they are too high, because the sector must re-read them and thus it cannot do its job fast enough. That is essentially what happens when bit rates are too high. So as you can see, there is more than one way to arrive at a particular symptom.

Additionals:

If it is a one-off I want to give to a client, and all I have are 8x or 16x media, I would just go with an 8x burn myself. Though I would rather use 4x media for clients. It's also a good idea to inform any client, that burned discs are not close to 100% on all players. At best, I tell viewers that easily 80% of the players will be fine, but that 20% is still a large number. Lot's of players will skip, pixelate, or act strange when playing DVD-R media. There is no shortage of el-cheap-o players out there.

Using Toast v6 with DVD+R media will not set the book type properly. Avoid using +R media for video unless you are sure you understand how to set book type."

-Alex Alexzander

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Your mileage may vary....

[Paul Doherty]

Thanks for that interesting post Vic. It seems reasonable enough and I had some discs to burn, so I used it as a test.

I took some 8x Ritek A grade DVD-Rs and burned 12 of them in a Pioneer 107 (up to date with the latest official firmware). I burnt 4 at 2x, 4 at 4x and 4 at 8x. Then I tested them all with Nero DVD Speed Disc Quality test. The results were (marks out of 100).

2x burning. Average score 51. Burning time 30 minutes.
4x burning. Average score 54. Burning time 15 minutes.
8x burning. Average score 54. Burning time 9 minutes.

Clearly it's not a big enough sample to be statistically significant, but basically it suggests that with these discs and this burner, it doesn't make much difference qualitywise whether you burn at 2, 4 or 8x.

[Vic Owen]

Yeah, that's been my experience, as well. I used to burn everything at 1X, but some time back, I just let Toast do its own thing (Best mode). When I make the dupes in my 1X7 tower, I also let it choose the speed ("Optimum" on my unit, I think). Out of several hundred DVDs burned, I've had only one reject and I think that was due to a client's combo player that should have been trashed long ago. I use Ridata & Taiyo exclusively, depending what's on sale at the moment. Both have worked well. I once preferred the Ridata 4Xs, but since they are typically no longer available, I've been using the 8X Taiyo stuff with virtually 100% success rates. My burn times have dropped to 6 minutes.

Over time, I've found Alex's info to be dependable and I think he hits it on this one.

[Paul Doherty]

Slight update I've just burnt 4 discs at 1x speed using the same media and burner as in my post above. The result was:-

1x burning. Average score 50. Burn time 59 minutes.

So very little difference in burn quality - big difference in burn time.