PI/PO scanning in DVD-ROM vs Burner

Thought I would start a thread for comparing PI/PO scans in a LiteOn DVD-ROM vs scanning in the burner. This is the same question that arose when C1/C2 error scanning first came to exist, when we noticed how differently the DVD-ROM drives would report errors. Looks like the same issue exists here.

this is a Ricoh DVD+RW, bundled with the LiteOn 401S drive.
Scanned in the burner:

Scanned in a 166S DVD-ROM drive:

Bundled Ricoh DVD+R 4x

Scanned in the 401 burner:

Scanned in the 166S:

Interesting. I’m glad to finally see some direct comparisons (I don’t have a DVD burner or I would have done so myself).

It is surely too early to say with any certainty, but it looks as if the differences may not be systematic like they were with the C1/C2 scans. Every C1/C2 scan performed on a DVD-ROM drive that I saw dramatically under-reported the error counts, leading me to conclude that the DVD-ROM drives have some systematic problem that prevents them from properly reporting C1/C2 error levels.

However, in your two examples the “better” reader changes positions with the two different discs, and although the average levels are fairly different, the maximums aren’t different by orders of magnitude. I would say it is possible that what you have shown may simply be attributable to the differing ability of each drive to read different discs. Thus, the DVD-ROM drives may be just as “accurate” as the burners for PI/PO testing: although they show different error levels, they may be showing the correct levels for each respective drive. In my mind this is different than the C1/C2 issue with respect to DVD-ROM drives where I feel that the reported numbers were lower than what the drive’s internals actually encountered.


Look here for scanning differences between Lite-on LTC-48161H and LTD-165H: http://club.cdfreaks.com/showthread.php?s=&threadid=75818

One interesting note is that the 401 slows way down when reading the Ricoh bundled DVD+R in CDSpeed, for the last 25% of the disc, the 166 does not slow at all. That would certainly support the notion that the 401 is not as +R friendly as the 166. More tests will follow.

Burned at 2.4x
Reading in the 401S:

Reading in the 166S:

Sold as Fuji DVD+R, no speed rating

Scanning in 401S:

Scanning in the 166S

It would appear that the relative error rates reported by the 2 drives very much depends on the particular media being scanned. Each drive seems to have it’s own preferences, which is very much the same thing I’ve seen with CDR scans. In other words, there’s no predicting how a drive will respond to a given media in comparison to another drive.

The biggest difference seems to be in the PI reporting, while the 166s seems to consistantly report lower PO max rates.

More scans will follow.

Scanned in the 401 drive:

Scanned in the 166:

The 401 reads this disc much slower than the 166, I can’t say why, but it has happened on a couple other discs also. The same thing happens in Kprobe with both drives set on “max” speed, 401 is slower, but the results are sure good!
Here’s a transfer rate test on both drives with the same +RW disc.

It’s starting to look as though one of the biggest differences between scans on the burner and scans on the 166 may be related to the reading speed. I’ve noted different reading speeds on many different media types. Here, the burner tops out at 6.3x, and the 166 tops out at 8.2x.
This is Memorex 4x DVD+RW media

In the 401S:

In the 166S:

Whether the difference in read speed will acount for all of the difference in the scans, I leave to you to decide. but certainly it would account for part of it.

Scanned in 401S:

Scanned in 166S:

Here again, the 166 reads the media at >8x max, while the 401 reads it at >6x max. The results are just as inconsistant as previous comparisons.
On +R discs, the 166s seems to be showing more PO but less PI than the 401s.
On +RW discs, the 166 has clearly higher PI, PO is also higher in total and average counts, but not really higher in the max values.

Bottom line seems to be that the 166 is somewhat consistent in it’s reporting, and so would be an adequate tool for scanning if no other drive is available. It will be a decent benchmark for comparing different media from the same burner. But it should not be used to compare results from different drives, and certainly you should not compare your own results to someone elses based on scans done in a DVD-ROM drive.

Those tests are not accurate. You are using speed “Max”, when the Max speed for this drives is completely different.

The Max speed in the LDW-401S is 12x.

The Max speed in the LTD-166S however is 16x.

Both drives will report very different results because of the different speeds. You need to test them both at 8x to get accurate results, and even then, we will still not know for sure which one is more accurate.

It doesn’t matter where you set the speed, each drive reads a given media at a given speed. It’s clearly stated in the thread what speeds they are actually reading at. The 401 will not read recordables at 8x. If you LOOK at the results, you will see that reading speed cannot account for all the differences.

In case anyone is wondering, Kprobe does not allow you to set read speed on the 166S, it’s locked at 8x on recordables (at least on DVD+).

The 401S will allow some speed adjustment:
Set below 3x, you get 1x.
Set at 3x, you get 2.4x.
Set at 4x, you get 4x.
Set at 6x, you get 6x.
Set anywhere above 6x, you get 6x.

Can you scan a disc in 1x and compare it with a scan in 6x on the LDW-401S?

Here’s the same DVD+R, Memorex 4x, that was tested in the last test post above. Scanned at 1x.