The Benq 1640's confusing C2 reporting feature

CD, DVD and (Ultra HD) Blu-ray Writers BenQ / Philips Writer
#1

Hi all :slight_smile:

I finally bought a 1640. Excellent drive. :cool:

Some time ago, when searching for the C2 errors reporting ability of the drive, I first came across info that it DID report C2, then across other info that it did NOT. :eek:

At some time, even Nero info tool mentioned it COULD report C2 though in real-world users said it wasnā€™t true.

Now here I am with my 1640 (BSLB), and here are my confusing findings:

  1. The 1640 seems to actually report C2 errors (see image, partial scan of a very bad CD).
  2. Nero InfoTool does NOT mention that the drive reports C2 (see image).
  3. Exact Audio Copy canā€™t retrieve C2 infos from the drive (see image).

:eek: :eek: :eek: :confused: :confused: :confused:

Can someone shed some light on this very confusing matter?? :bow:

#2

Maybe a post form the author of Nero CD-DVD Speed and Nero ToolKit will convince you? Click here.

Plus some other discussions, click here (read the 2nd page as well.)

#3

Thanks Zevia :bow: We can always count on you :flower:

Searching for ā€˜C2ā€™ in the Benq forum was impossible with the search utility (too short expression), so I didnā€™t find Ericā€™s post, post which definitly makes the matter clear once and for all. :cool:

As a sidenote, Iā€™m slightly disappointed that Benq choosed not to implement the ā€˜standardā€™ C2 reporting feature, this makes ripping slower with EAC in secure mode. Iā€™m currently trying to recover about twenty audio CDs. The C2 reporting feature of my Nec 3540A does work in conjuction with EAC, but itā€™s error correction ability is not on par with the Benqā€™s. :frowning:

Bah, you canā€™t always get the best of both worldsā€¦

Thanks again :smiley:

#4

C2 should really be used for truly secure rips anyway.

#5

Yes but if the C2 ā€˜standardā€™ capable drive is a poorer reader (like my NECs), a part of the benefit is lost. If the drive canā€™t retrieve the data and pass it to EAC to start with, the C2 feature is uselessā€¦ see what I mean? More security with successful ripping, but less sucessful rippingā€¦

I think itā€™s time for me either to say ā€˜bye byeā€™ to these heavily damaged audio CDs of mine, or borrow a LiteOn drive to see how it does with them.

#6

The Benq C2 error reporting feature is broken. If your disk is really bad, it will report C2 errors where uncorrectable errors occur. A mildly damaged disk that shows no uncorrectable errors will show no C2 errors on the benq, even though it may have many.

You can test this yourself by getting a CD-R and drawing a thin black line using a marker from the inside of the disk out to the edge, on the data side. If you scan this disk in a liteon CD-burner, you will see a lot of C2 errors, even though it will still be readable. Scan it in a benq drive, and the C2 errors will be unreported.

#7

Yeah, this is covered in the thread Zevia linked to. :slight_smile:

Looks like the Nec 3540A is rather ā€˜accurateā€™ for C2 (I put the quotes as there is no such thing as ā€˜accurateā€™ scanning with our end-user drives :rolleyes: ) so itā€™s not a problem for me. The 1640 is a much better DVD burner and it reports jitter, so itā€™s a great addition here. :cool:

#8

Hey I just noticed Eric Deppe used for his demonstration a disc from the same manufacturer than the one I used for my scan aboveā€¦

Looks like ā€˜Multi Mediaā€™ CDRs are perfect for C2 demonstration purposes :wink: - among the crappiest discs available here :Z

#9

CD-R / CD-ROM: C2 Report supported.

Also, CD-DA: C2 Report Supported.

Butā€¦

When we using CD-DA Extraction (DAE) Mode: C2 Report Not Supported.

#10

what do you mean ā€˜uncorrectableā€™, when the data can be extracted it is correctable. if the benq report a C2 error and the data can be extracted, it is not reporting wrong. also even Eric Deppe says the C2 reporting of the 1640 is reliable, see the link posted by zevia above :slight_smile:

also very important the C2 error is not on the disc, it is the reader reporting a difficulty in correcting at first level and passing to second level. a very good reader will have less C2 reporting than a bad reader.

#11

Good points :iagree:

People (including me sometimes :bigsmile: ) tend to forget that scanning is not examining ā€œerrors on the discā€, but examining how the drive manages to read the disc and what reading error correction it has to resort toā€¦

#12

I actually meant that ā€¦ during a scan, the benq drive reports CU errors instead of C1 uncorrectable errors for the C2 error statistic. Its confusion, but can be seen if you try the test above.

In fact, I will reproduce that test ā€¦ yet again, and post the results

Yep, I also acknowledge that C2 errors are actually not on the disk itself, but are the result of the error correction hardware/firmware.

#13

Ok, here are a few scans that more or less explain what I am saying.

This is an old CD-R that I turned into a CD-R with a lot of C2 errors using a marker.

The first scan show the disk is still completely readable in my liteon 52 speed burn (evil, crazy machine that is when running at 52 speed).

The second scan shows that the disk hardware is using C2 correction very heavily.

The third scan shows the disk is still readable by the benq drive, but there are areas that are generating uncorrectable errors that the drive has to slow down and read again to correct.

The forth scan shows that the benq is only reports a significant number of C2 corrected errors for areas that the benq drive had trouble reading. (in other words, errors that have gotten past C2 error corrector.)

This leads me to conclude the benq reports errors that get past the C2 error corrector as C2 corrected errors, rather then correctly reporting C2 corrected errors.

damage-2.PNG572x672 7.26 KB




#14

Strange discrepancy between your experience and Eric Deppeā€™s statements.
This gets more confusing. Iā€™ll perform some tests here and report.

#15

1 & 2: damaged audio CD.
1 : Benq 1640 scan
2 : Nec 4550 scan
Notice the same C2 ā€˜averageā€™ reporting and the similar count.

3 & 4: good CD with marker spots
1 : Benq 1640 scan
2 : Nec 4550 scan
Numbers are different - the 4550A reports MORE errors. Sidenote: the 4550A C2 feature is compatible with EAC.
Figures are similar.

No conclusions drawn from these tests :doh:

Also see Zeviaā€™s test

1640 marker.png641x524 19.2 KB

4550 marker.png641x524 18.1 KB

4550.png641x524 16.8 KB

#16

I Repeat.

CD-DA Extraction (DAE) Mode: C2 Report NOT Supported.

#17

I got that part, whatā€™s you point ? :confused:

#18

You better read ErikDeppe explanation especially #1. I believe it uses the standard MMC method, same as Nero InfoTool.

#19

:disagree: thatā€™s the whole point, it does notā€¦ :wink:
Oh, you mean DAE uses MMC? If so, sorry :o - I thought you meant the Benq doesā€¦

#20

This is why I shouldnā€™t post when Iā€™m tired. I meant to say that you SHOULDNā€™T use C2 for truly secure rips.