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CD quality scans slow down intermittently on BenQ/Philips

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CD quality scans slow down intermittently on BenQ/Philips

Postby MediumRare on Sat Dec 02, 2006 8:46 am

I cross-flashed my recently purchased Philips DVDR 1660K with BenQ 1650 firmware to take advantage of the diagnostics available with CD-Speed.

Today I tried a disc quality scan of a couple of CDs and found that the drives slows down to just about 0 at various positions (as shown in the attached graph). This isn't a display artifact- you can har the thing slow down and the first time it happened, I though the program had died. :o

Also, it plays havoc with the jitter statistics because the jitter value goes up at each dip (it goes to 0 on the advanced quality test).

Is this normal behaviour with BenQ drives?

G
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627_@16x_qual_BCIC_max.png
intermittent dips in scanning rate with CDs
627_@16x_qual_BCIC_max.png (21.69 KiB) Viewed 1214 times
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Postby [buck] on Sat Dec 02, 2006 8:58 am

For the DW1650, yes. You'll usually get those slowdowns when you're scanning CD-Rs, DVD+RDLs, scanning at high speed, and sometimes even DVD±R(W) at 8x depending on the drive/firmware/media combination. Fortunately, my drive doesn't have a problem with DVD±R(W) at 8x.

The DW1640 with BSLB doesn't have any of these troubles, though :D
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Postby DrageMester on Sat Dec 02, 2006 1:09 pm

It's the same problem with BenQ DW1655 drives.

How many dips you get can vary from drive to drive and even between multiple scans of the same disc in the same drive, but in general there's always at least one scanning dip for scans performed at medium or high speeds for both CDs and DVDs.

There have been many theories at CDFreaks about how to fix this by flashing back and forth between different firmwares, but these theories fail when applied to other people's drives.

It looks like it's something we'll have to live with.
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Postby MediumRare on Sat Dec 02, 2006 2:03 pm

That's too bad- I bought this drive just for the scanning. :evil:

The dips in the CD seem to occur at intervals of 32 sec. (wall time) for CAV scans- I can't think of anything useful that that might do. A scan @16x CLV had only 2 dips near the beginning.

I haven't seen dips while doing DVD scans (8x).

I scanned another disc with high C1 levels to see what the jitter does and ran into another problem: above a certain level, the C1 counts seem to be quantized (at least in the graph): they come in multiples of 250.

Since the reported maximum is 765, I think this is an artifact of the CD-Speed display.

Has this been reported before? I normally use KProbe (1.1.29 because it reports a CD ID in the property tab) with my LTR-48246S for CD scans, so I don't have any comparison with CD_speed.

G
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high_C1_with_label_qual_BCIB_max.png
high C1 counts show in multiples of 250
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Postby DrageMester on Sat Dec 02, 2006 4:50 pm

I'd be interested in seeing an Advanced Disc Quality scan of that CD preferrably at the same scanning speed.
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Postby MediumRare on Sat Dec 02, 2006 5:54 pm

DrageMester wrote:I'd be interested in seeing an Advanced Disc Quality scan of that CD preferrably at the same scanning speed.

Here you go. The dips in scanning speed showed up as zeros in the jitter curve during the scan, but only the last one remained (even after maximizing the display.

The count here seem to be normal- no trace of 250 multiples.

Good night!

G
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high_C1_with_label_adqual_BCIB_max.png
advanced quality scan
high_C1_with_label_adqual_BCIB_max.png (18.14 KiB) Viewed 1160 times
high_C1_with_label_adqualsum_BCIB_max.png
summary statistics for advanced quality scan
high_C1_with_label_adqualsum_BCIB_max.png (5.22 KiB) Viewed 1160 times
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Postby Scour on Sat Dec 02, 2006 8:38 pm

Is a Benq DVD-writer good for CD-scans?
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Postby DrageMester on Sat Dec 02, 2006 11:48 pm

Scour wrote:Is a Benq DVD-writer good for CD-scans?

It rather depends on what your requirements are for a "good" scanner, but since the introduction of the Advanced Quality Scan in Nero CD-DVD Speed 4.7.0.0 I think that the BenQ DVD writers (1655, 1650, 1640, 1620) are now among the most useful CD scanners along with Plextor drives. (Not counting commercial scanning equipment).

You should know that e.g. BenQ DVD writers are far more picky than LiteOn CD-RW drives when it comes to scanning CDs, but IMO that's a good thing because LiteOn CD-RW drives are so good readers that you won't necessarily discover even major flaws on a CD.

Unlike other scanning drives, the BenQ DVD writers can report all the six different Exy errors in an Advanced Disc Quality Scan, whereas most other drives usually report only C1=BLER=E11+E21+E31 and C2=E32.

Plextor drives (except rebadges) report C1=BLER=E11+E21+E31 and C2=E22 and CU=E32 in PlexTools and PxScan/PxView.

LiteOn DVD writers are not very useful for CD scanning because they only report C1=E31 and C2=E32, so almost any disc looks really good in a scan.

So don't compare scans made in different drives directly against each other, unless you know that they report errors in the same way and that they are comparable readers.
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Postby Scour on Sun Dec 03, 2006 12:00 am

Thanks DrageMester for ur explanation :)
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