DVD Burn Speed

Dan Sherman wrote on 11/10/2005, 12:19 PM

In the midst of burning a run of DVDs.
Have been in the habit of burning discs at 4X.
But using Taio Yuden 8X.
So thought I'd try an 8X burn.
Now I notice the burn area on the disc is much smaller than on the ones I burned at 4X.
1) Why is that?
2) Is there any reason to burn at 4X if media can be burned at 8X,---any difference in quality?

Comments

riredale wrote on 11/10/2005, 4:41 PM

The burn speed relates to the speed of the disk when playing back a bitrate of about 1.3MB/sec ("1X"). A DVD contains a continuous spiral-wound track that starts near the hub and ends at the outer edge. Since the inner circumference is shorter than the outer circumference, this means that a DVD will spin at high rpms at the beginning, then gradually slow down as it reaches the outer portion of the track.

A desktop DVD burner can spin a disk up to about six times the initial default playback speed safely. Any more and some disks run the risk of exploding (it happened to me in my CD burner a few months back; an impressively-loud noise) due to the very high forces generated. So if you tell the burner to burn at 6x, it will spin very fast at the beginning, then gradually slow down as the outer track area is reached.

But if you tell the burner to burn at 8x, it can't--not initially, anyway. So it will burn the first 25% of the track at, say, 6x, and then at that point the rpms will be low enough that the burner can shift gears and finish the rest of the disk at 8x. Oftentimes you can see the point where the burner shifted gears, since the burn density on the disk will be different for 6x and 8x.

The same thing happens if you burn at 16x--the burner starts at 6x, then 8x, then 12x, then 16x (but only for the last portion of the whole burn). The result is that you get diminishing returns. A full disk will burn at 8x in about 8 minutes, so you would think a 16x burn would take 4 minutes. Not so; it still needs about 6 minutes, because only the very last part of the burn can proceed at "16x."

By the way, laptop burners take far longer, even if rated for 8x, because they can't draw as much power from the system. They are thus severely handicapped in the maximum rpms they can spin. It's not uncommon to start out an "8x" burn at just 2x. You can see this for yourself by using a burning program that shows the actual burn rate, not the proposed burn rate. I use Nero, and have downloaded a registry patch that allows Nero to show the actual burn rate while burning. Very interesting.

Dan Sherman wrote on 11/10/2005, 7:13 PM

Now that is very interesting.
Thanks for the detailed answer.
I use both DVD-A to author and to burn.
Do you feel Nero would be better?
I ran into problems with Nero,---compatibility issues in the days of Vegas 4.
I have that too,---but use it mostly to copy or rip stuff.

johnmeyer wrote on 11/11/2005, 8:44 AM

Now I notice the burn area on the disc is much smaller than on the ones I burned at 4X.

Even with the difference in burn speeds, it seems very unlikely to me that there would be any difference at all in the area that is burned. Playback speed and total storage capacity is, of course, completely unaffected by what speed you burn at. Therefore, if you see a different diameter burned, then you must be burning a different amount of stuff on one disk vs. the other disk.

I suppose that the leadout might be a different length at different speeds, but I'd be surprised if it would be a big enough difference that you could actually see it.

If your DVDA version os 1.0 or 2.0, then I would recommend using Nero to burn. With 3.0, at least with my Pioneer burners, it seems to work just fine. I've never had any problems with Nero. The only compatibility issues I ever saw discussed that I felt were real were a problem with one of the game boxes. That was fixed a long time ago.

riredale wrote on 11/11/2005, 9:05 AM

John:

My assumption was that Sherman was seeing the "ring" of the 6x burn, but that the overall burn area was the same as before. That's why I launched into a backgrounder (hopefully accurate) about burn speeds.

I wonder if we'll ever see reduced burn times through the use of multiple lasers. Didn't someone have a CD reader a few years back that worked on this principle?

Dan Sherman wrote on 11/11/2005, 3:56 PM

Keep in mind the project is only 2:39 in length.
There is NO doubt that the area burned differs.
Both play back fine,---but the one burned at 8x takes up less than half of the space taken up by the 4x burn.

johnmeyer wrote on 11/11/2005, 5:47 PM

I wonder if we'll ever see reduced burn times through the use of multiple lasers. Didn't someone have a CD reader a few years back that worked on this principle?

I think I remember something about that. Multiple lasers sounds like an excellent idea, although for burning, getting everything to line up would be pretty difficult.

Tinle wrote on 11/12/2005, 5:59 AM

"Didn't someone have a CD reader a few years back that worked on this principle?"

Kenwood did for a while (using a single laser split into seven beams).

"Built around Zen Research's multibeam technology, this 72-speed TrueX CDRom is a very fast drive - at least when it comes to reading very large files. A standard CDRom drive consists of a single, narrow laser beam that reads the data on the disk. Zen's technology splits the reading laser into seven beams, allowing seven tracks to be read at once. The gathered information is interpreted by a custom chip that processes the information in parallel, as opposed to the serial chips in other CDRoms.

We tested the drive's ability to perform various read tasks against a 52-speed Creative CD5220, with mixed results. In a large single file read test, the drive performed miraculously, with 507Mb transferred in a mere 54 seconds. The Creative, by contrast, completed the same task in one minute 35 seconds. Transferring mixed small files, however, revealed a more mediocre performance: 214Mb took two minutes 17 seconds, compared with the Creative's one minute 16 seconds.

Browsing 44 Paint Shop Pro images, with file sizes totalling 203Mb, highlighted a less marked performance deficit, with the Kenwood completing the task in one minute 24 seconds compared with one minute seven seconds from the Creative."

riredale wrote on 11/12/2005, 12:11 PM

Sherman:

All I can think of is that, with some burning programs such as Nero, you are given the option of burning an "official" DVD-R, which apparently requires a burn out to I think a 70mm radius, or an "illegal" DVD-R, which uses just a short leadout and thus burns a much smaller area on the disk.

A couple of years ago I was mystified as to why burning a segment of just a few minutes took as long as burning a 30-minute program. This was the reason--the burner was filling in all the unused space out to 70mm with an enormous leadout.