Crazy LiteOn 1635S Read Transfer benchmarks

I have been burning and testing some media lately, and I have observed that my LiteOn SHW-1635S can be very touchy when doing Read Transfer benchmarks, expecially with DVD+R discs burned on my NEC ND-4551A drive.

When reading some Taiyo Yuden DVD+R discs burned in my NEC 4551, the LiteOn 1635 will slow down or even abort a Read Transfer benchmark at a point on the disc that seems to be the exact location of a re-linking point, i.e. a point where the burning drive stopped and re-started burning due to its Running OPC write strategy. No other drive that I have show any problem with these discs.

The LiteOn 1635 reports PIF spikes with maximum values of approx 5-7 at these re-linking points, but these spikes should in theory have no effect since they are located outside actual data blocks, and my Plextor and NEC drives don’t show these PIF spikes when scanning.

Comments, experiences and opinions are welcome!

Also the reading speed seems to depend on the media used; burning the exact same disc image to a Taiyo Yuden 8x certified T02 disc and to a 16x certified T03 disc produces two theoretically identical discs, except for MID, where the T02 disc is read at 12x and the T03 is read at 16x.

Is anyone else seeing this behaviour, and do you suppose it’s intentional?

Here are three Read Transfer benchmarks performed in the LiteOn 1635 of the same disc that shows the touchyness of the LiteOn.

The fourth image is a Quality Scan of the same disc - note that all PIF spikes above 2 are exactly at the re-linking point seen in the burn graph.

The fifth image is a Quality Scans of the same disc in my NEC 4551 drive which generally shows massive amounts of PIE and PIF but actually likes this disc.

Here are Read transfer scans of the same disc as above in some other drives.

None of the other drives show any problems!

Here are some Read Transfer scans of another disc (T03) showing the same behaviour but at an earlier re-linking point.

First image is a Read Transfer at maximum speed (16x) which is obviously faster than the reading speed for the T02 disc above. The content is exactly the same however.

The second image is a Read Transfer performed at 12x instead of 16x. The transfer completes but it slows down at the exact same point that the first read transfer fails.

Third image is the LiteOn Disc Quality scan of that disc - note that all PIF spikes above 2 are exactly at the re-linking points seen in the burn graph.

Fourth image is a PxScan performed on a Plextor PX-712 drive that shows no problems at the re-linking point at 1.4 GB.

Fifth image is a Read Transfer scan in another drive showing no problem.

More Read Transfer benchmarks of the T03 disc showing no problems.

I thought for liteons it was generally accepted to ignore single spikes of high PIF. as for the transfer test failing, is the dvd readable at all by the liteon?

Yes both discs are readable, but the drive has to slow down to read the discs, and for the T03 disc the LiteOn also has to re-read a few sectors (marked with yellow color as “damaged” by ScanDisc).

See these ScanDisc tests:

[ol]
[li]ScanDisc of T02 disc above[/li][li]ScanDisc of T03 disc above[/li][/ol]

More crazy Read Transfer benchmarks on the LiteOn 1635S drive, this time of a Verbatim 16x DVD+R (MCC 004) burned at 12x on a NEC ND-4551A 1-Z2.

Here are three Read Transfer benchmarks performed in the LiteOn 1635 of the same disc that again shows the touchyness of the LiteOn.

The fourth image is a Quality Scan of the same disc - note that all PIF spikes above 2 are exactly at the re-linking points seen in the burn graph, and one of these is where the LiteOn slows down during Read Transfer in the second benchmark.

The fifth image is a Quality Scans of the same disc in my NEC 4551 drive which generally shows massive amounts of PIE and PIF but actually likes this disc - note that the only PIF spike above 2 is exactly at the re-linking point seen in the burn graph, and this is not where the LiteOn slows down during Read Transfer.

I have only seen one other person reporting something like this odd problem in another thread.

Surely there are more of you out there with a NEC 3550/3551/4550/4551 and a LiteOn 1635 (or other recent LiteOn) who is either seeing the same problem, or not seeing the same problem?

Please post with your own experiences here!<!-- / message --><!-- attachments -->

More Read Transfer scans of the same disc as above in some other drives.

None of the other drives show any problems!

I think that’s about a critical mass of posted images. :rolleyes:

NEC drives have been creating these type of re-link blips for a long time. They do cause read issues in some drives, not in others. Looks to me like your 1635 is the one you should be using for transfer rate tests, as it’s the most picky.

My own 1635 is also very picky, and generally stumbles on any disc when read at 16x, so I have it limited to 12x on all discs. (for ripping purposes). It will read some pretty crappy discs at 12x with no trouble, but try it at 16x and all hell breaks loose. Go figure. Just one more example of WHY we don’t recommend comparing different readers’ tests.

It all hinges on a drive’s error correction scheme. All drives are different in this respect. The 1635 appears to be trying to read at higher speed even after errors are detected, hence the failures. Other drives will re-read at a much lower speed, then speed up again later. High speed reading has it’s drawbacks.

Nothing interesting happened until critical mass was achieved; yours was the first response that commented directly on the slowdowns! :wink:

That really depends on your test philosophy: If you only accept flawless read transfers, then you risk having to throw out all your burns if you use a very picky drive. If OTOH you use the pickiest drive to discover serious problems, and then verify later on other drives, this could be a working strategy.

Also on some other discs the LiteOn is not the pickiest drive, but that dubious honor falls on the NEC 4551 - mainly discs with high jitter.

I really don’t like the transfer slowdowns/failures on the LiteOn 1635 drive, but I’m still leaning towards thinking that it is a problem of the reading drive (LiteOn) and not of the burning drive (NEC). But I admit it is a tough call! :confused:

I think it has to be a combination. I’ve had burns with out of spec PIF (>4) and high jitter/beta yet the Liteon can read it relatively well; it’s only the NEC 3550/4551 burns that my Liteons have problems with. Maybe it’s the way that NEC does relinking? or maybe it’s just a bug in the mediatek chipset… remember they were sued for infringements on their earlier chips.

Which LiteOns do you have that show this problem?

There’s a whole bunch of variables besides how the disc is burned. Even the media type can have a noticable impact on reading tests in a given drive. In one particular reading drive, media/dye type, burn speed, error rates, jitter, etc. etc., etc. If each of those variables changes just a little, you get different reading results. And, different drives will react differently to each of the different variables. You can spend the rest of your life trying to figure it all out and get nowhere. In this case, the re-link blip may be the trigger, but the real problem may be something else that this drive does not like. You’ll never know.

Which is why we are always preaching: Pick a drive for testing and stick to it. All you will get from comparing different drives is a lot of proof that all drives are different.

Here’s a Disc Quality scan of the MCC 004 disc above scanned at 16x, and a KProbe scan at 16x of the same disc. These are also very good scans with only a couple of moderate single PIF spikes.

So the only clue to the LiteOn transfer slowdown is still the single PIF spikes at re-linking points, as the LiteOn obviously have no problem scanning the disc at maximum speed!