Lite-On SHW-1635S review

The specifications of this drive tell us that it should write DVD+R discs at 16x and DVD-R discs at 16X speed. In this part we will measure the write time for various types of DVD+/-R(W) discs. We do also focus on write quality and media compatibility.

DVD-Writing performance:

We will start with taking a look at the writing strategy used and compare it to other drives;

The Lite-On SHW-1635S uses CAV (Constant Angular Velocity) to write at 16x speed. This gives an average speed of 11.96x and a total writing time of 5m:59s. Let us also take a look at writing a DVD-R disc:

As we could see it also uses CAV (Constant Angular Velocity) to write DVD-R at 16x. This gives an average speed of about 11.96x and a writing time of 5 minutes and 56 seconds. We have also included the results from two other drives below.

The BenQ DW1640 uses CAV (Constant Angular Velocity) to write at 16x. This gives an average writing speed of 11.51x and the lowest time we have obtained is 5 minutes and 44 seconds. The drive uses a bit longer time than ideally since it uses running OPC technology when writing (shown as small dips in the transfer curve above).

The LG GSA-5163D uses P-CAV (Partial-Constant Angular Velocity) to write at 16x. The average speed for the LG GSA-5163D is 12.82x and total writing time is 5 minutes and 19 seconds. This is the fastest result we have got with all tested writers so far, and is thus the record to beat for other drives.

Let us see how long of a time it needs to create a disc with Nero. We used Nero Burning Rom to set up a new UDF/ISO compilation containing 4483Mb of data, and started the write process. We used the Disc-At-Once write method.

DVD+R

DVD-R

The DVD+R disc was finished in 6 minutes and 14 seconds, while the DVD-R disc was finished in 6 minutes and 22 seconds; again we are unable to show the usual picture due to the new Nero version.

The Lite-On SHW-1635S is not the fastest drive around, but it’s still below the 6 minute mark in Nero CD-DVD Speed. But let us take a look at the writing quality of this drive, maybe Lite-On have finally gotten it right?

Write quality:

You should first notice that this is not a scientific and professional way to test the discs. But according to our testing done in recent months, we would conclude that there is a clear link between the quality reported when scanning the disc and the playability of the disc in different devices. Also notice that different drives report different amounts of errors. K-Probe was designed to work with Lite-On DVD-Writers. So we recommend using a DVD-Writer from Lite-On, in this test we use a Lite-On SOHW-1693S DVD-Writer, as already said; remember that scans done with a Lite-On DVD-ROM or Lite-On combo drive can’t be compared with the results obtained with a Lite-On DVD-Writer. Also remember that different PI/PO ECC sum settings along with different reading speeds in K-Probe will affect the result, we use these settings;  PI (Parity Inner) set to summarize 8 ECC blocks, PIF (Parity Inner Failures) set to summarize 1 ECC block, reading speed: 4X CLV (Constant Linear Velocity). Setting the PI sum to 8 and the PIF sum to 1 will give a result that we may compare to the standards for DVD+R/RW and DVD-R/RW.

But what is a good scan? That is a discussion that we don’t think will end soon, as different drives report different amount of errors, some players is more picky about media than others, and so on. But as a comparison we present you with a scan from two pressed DVD discs:

This scan shows the results from a pressed DVD-ROM disc (Colin McRae Rally 2005).

This scan shows the result from a pressed DVD-Video disk (Final Destination). Notice the error jump when shifting to the second layer (the error level actually drops from the end of the first layer to the beginning of the second layer).

If you read below you will see that both the pressed DVD-discs are well within the standards.

Download the ECMA 267 Standard for DVD-ROM, the ECMA 337 Standard for DVD+R/RW and the ECMA 338 Standard for DVD-R/RW at http://www.ecma-international.org if you want to look at the standards for yourself. Here is some data from the ECMA standards (same for DVD-ROM, DVD-R/RW and DVD+R/RW):

Random errors:

A row of an ECC Block that has at least 1 byte in error constitutes a PI error. In any 8
consecutive ECC Blocks the total number of PI errors before correction shall not exceed 280.

Here we see what a PI error is defined as a row in an ECC block having 1 byte or more containing errors. And that the sum of PI errors in 8 ECC blocks after each other should not exceed 280 PI errors.

But what is a row and what is an ECC block? Again we refer to the ECMA standards. We do not copy and paste everything but if interested look in the ECMA standards. A row is 182 bytes long where the last 10 bytes contain PI (Parity Inner) information. An ECC block is 208 rows long where the last 16 rows contain the PO (Parity Outer) information. This gives us a maximum possible PI error amount of 208 errors per block and for 8 blocks after each other this sum is of course 8 times higher giving a maximum possible amount of 1664 PIE-8 errors. In practical use a disc with 1664 PIE-8 errors is unreadable.

According to our tests the specified max PI-8 sum of 280 for good discs seems to be a good guideline, as some readers have problems reading discs when the PI-8 errors is over 300 and most players starts to have problems when the PI-8 error level reaches 600 or more.

But what are the PIF errors that K-Probe reports? They are Parity Inner Failures, meaning errors left after PI correction. Only the ECMA 337 standard describes the Parity Inner Failures. So how is a Parity Inner Failure defined? Here are what ECMA 337 states:

‘If a row of an ECC Block as defined in 13.3 contains more than 5 erroneous bytes, the row is said to be ‘PI-uncorrectable”.”

In theory an ECC block may in the worst case have 208 PIF since every ECC block is 208 rows long. But the ECMA 337 standard goes further and specifies the max amount of accepted PI Failures (uncorrectable errors) allowed on a good disc:

‘- In any ECC Block the number of PI-uncorrectable rows should not exceed 4.”  

This means that when the PIF sum is set to 1 the maximum error value should not exceed 4. The theoretical maximum value for PIF is 208 errors.

But what makes a disc unreadable? A POF (Parity Outer Failure) error will make the disc unreadable, but K-Probe does not display the POF’s.

Notice that there are other aspects such as disc reflectivity, jitter, tracking errors and so on that also will affect the readability of a DVD disc ‘“ but for this we do not have measuring equipment available.

And another note is that we have scanned the discs at 4X CLV speed, by lowering the speed to 2X(DVD-R/RW)/2.4X(DVD+R/RW) or 1X the amount of reported errors may drop on some discs. We scanned at 4X CLV due to lower speeds taking to much time.

To see if there is a connection between the reported amount of errors and readability of the discs we also include the reading curve from a NEC ND-3540A DVD-Writer. A small speed reduction near the end is still accepted on good discs, but serious reading problems or reading failures is a bad sign.

Easier explanation on how to read the test results.

Maybe this got too technical, and you are wondering what to look for in KProbe reports?

Use this as a guideline for good discs:

PI(Parity Inner): No larger areas on the disc should exceed 280 PI-8 errors, do not worry too much about high single spikes that exceed 280.
PIF(Parity Inner Failures): No larger areas on the disc should exceed 4 PIF-1 errors, do not worry too much about high single spikes that exceed 4.

And as always; lower is better ;)

And look at the reading curve; does it look clean with no dips? Then it should be good, a small slowdown near the end is acceptable.

DVD+R media compatibility and write quality:

No problems with this media, the error levels are low and increases just slightly near the end. Recommended media.

There are some more errors on the last half of the disc, but not enough to cause any problems. Also recommended media.

The error level increases noticeably near the end, Lite-On should look into calibrating the drive better for this media as it works with no problems in other drives. The reading curve is still perfect and there will most likely not be problems

This media also works satisfactorily and should not cause any problems.

We could see that the error level increases near the end, but not enough to cause any problems. Keep in mind that this Optodisc media appears to be of better quality than most Optodisc media available on the market.

The first real failure, but we suspect that it may be caused by poor media quality rather than a problem with the Lite-On SHW-1635S drive. Avoid this media.

Unfortunately only supported at 12x, but the result is very good, and we could recommend this media if 12x writing speed is enough for you.

Again the error level is a bit high near the end, but still within the allowed limits. Lite-On probably needs to optimise the drive better for this media.

No problems at all with this media.

No problems with this rather rare media either.

The drive performed very well with the Prodisc media and we have no problems recommending this media.

And Taiyo Yuden works excellent as expected. Highly recommended media.

No noticeable problems with this media, but notice that the media we used for this review is among the better Optodisc media on the market.

A bit high amount of errors at the start of the disc, but overall an acceptable result with this rather low quality media.

A surprisingly good result with this low quality media.

Another surprise, this low quality media also gave pretty good results.

Head on to next page and read about DVD-R compatibility and write quality as well as DVD+/-RW writing quality and speed…