Which drives for revelant read transfert rate tests ?

[Slywall_GN]

Hi,

I have decided to post this "problem" on several forums on the web, I apologise for asking everywhere the same thing but I really need to get knowledge.

I would like to ask the important question of the conditions of explicit Read Transfert Rate tests. I mean the specific features that a drive must have to perform such a test with the best revelance for DVD writing quality. As it is a "stress test", I do know that reading speeds must be as fast as possible but the real question here concerns the reading capability of the drive used .

For those who want to test drives writing quality and burned media compatibility. It seems obvious, IMO, that the drive used for TRT tests must not be a real good reader. On one hand, if the drive has a good error correction and succeed in reading everything , It can't be enough sensitive to show, with a RTR test, the real way a disc has been burned, it will show only the big problems, I mean real failure as POF or very high PI values. But is it enough ? On the other hand, if the drive is too picky and too sensitive, will the RTR test be revelant in term of burned media compatibility ?

So here's the questions :

1) How "bad" must a drive be so that RTR test can be considered as revelant ?
2) What about BenQ DW1640, it's this drive that is used in CDRLabs reviews... and the 1650&1655 ?
3) Which other drives could be revelant ?

[Ian]

Here is my reason for choosing the BenQ DW1640 and now the DW1655. First off, I wanted a drive that could read DVD+R and DVD-R media at 16x without a hack. That eliminated Lite-On's drives... which are also very good readers and hardly ever slow down, no matter how crappy a disc. I also considered Plextor's drives but they are a bit too sensitive for my tastes.

In the end, it came down to NEC and BenQ drives. I eventually decided on BenQ because it a) reads DL media at 12x and b) I was already using it for write quality testing.

[Slywall_GN]

Thanks Ian, (for reply and for the reviews you release )

I also considered Plextor's drives but they are a bit too sensitive for my tastes.

I eventually decided on BenQ...

I tend to think that in a drive review RTR have to complete PI scans and give an idea of the compatibility of a particular MID burned in the tested drive . In this way, does your choice also mean that BenQ is more reliable to express this playing compatibility ?

[Ian]

In this way, does your choice also mean that BenQ is more reliable to express this playing compatibility ?

Are you asking if the BenQ is more accurate for PI scans?

[Slywall_GN]

My DW1650 sometimes shows weird behaviour in reporting errors (high values and failures) with some MID burned in other drives (LG for example) so I can't consider it as "accurate" in the stric sense, but it's not the point here.

I'm not asking if the BenQ are more accurate for PI scans, I focus on RTR purpose in the reviews. As RTR give an idea of the actual readability of a disc I wonder if your BenQ choice means that for you Benq drives are (because of the reading speeds and sensitivity) among the more revelant for :
- corroborate PI SCans (not especially BenQ scans but reliable scans)
- give an idea of the overall compatibility of a disc.

The other thing I wanted to know (only considering RTR) was which other drives could also fulfill that job, in your opinion.

[Ian]

The BenQ drives will usually exhibit readability problems if there is a large PI/PIF spike on the disc or fail altogether if there are PO Failures. It's not perfect though. What they seem to be most sensitive to though is jitter. If the jitter rates are high, it can magnify the PI rates and cause more readability problems. Some people don't like this fact, but I think it gives a better overall picture.

[frank1]

Very interesting !
I hope that Digital dolphin, RJW, MediumRare and others ...
are also going to give their opinion about this

[Slywall_GN]

Hi,

What they seem to be most sensitive to though is jitter. If the jitter rates are high, it can magnify the PI rates and cause more readability problems.

Ok, Thanks for this précision. So because of their jitter tolerance, BenQ drives are among the "best" ones for RTR purposes. I saw on cd freaks that when jitter rates exceeds about 12% that causes these high error rates we can see reported by these drives. You said it causes more readability problem. It would be interessting to know the jitter tolerance of the drives in general, we just know that they at least must be able to follow ECMA standards but no more... We have to test it and measure it by ourselves or is there any other way ? Is it a kind of trade secret ?