detail information

The specifications of this drive tell us that it should write DVD+R discs at 16x and DVD-R discs at 8X 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 BenQ DW1625 uses CAV (Constant Angular Velocity) to write at 16x speed. This gives an average speed of 11.61x and a total writing time of 5m:56s. Let us also take a look at writing a DVD-R disc:

As we could see it uses P-CAV (Partial-Constant Angular Velocity) to write DVD-R at 8x. this gives an average speed of about 7.74x and a writing time of 8 minutes and 15 seconds.

The BenQ DW1620 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 are 5 minutes and 47 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 8 seconds, while the DVD-R disc was finished in 8 minutes and 21 seconds.

The BenQ DW1625 is about average at 16x DVD+R, but lags behind for DVD-R due to the writing speed of only 8x. But it may show its strengths at media compatibility and writing quality? Let us find out!

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-832S 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 (Baldurs Gate DVD-ROM).

This scan shows the result from a pressed DVD-Video disk (Indiana Jones and the Last Crusade). 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, it would have been strange if there were problems, after all the media is BenQ branded.

There are no problems with this media.

No problems with this media either and the result seems to be almost identical.

The OPC control of the drive limited the writing speed to 4x; we tried two discs from different spindles - but the result were the same. But otherwise the result is good.

The PI error level stays a bit high, but still within the specifications and the reading curve shows no problems. But we would like to see 16x writing speed with these. Yes, we did try two discs, both wrote at 8x speed.

We tried two discs, but it failed during the lead in with both discs. BenQ should look into this problem.

Good writing quality, but it looks like the OPC control of the DW1625 is too sensitive as the writing speed was limited to only 8x. Again, we tried two discs with the same result.

No problem at all with this media.

No problems at all.

No problems with this media, it's also one of the better results we have had with this media.

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

And Taiyo Yuden does of course fine.

One of the best results we have ever had with this media.

Excellent, considering this is very cheap media. The slight speed drop at the end is normal with Optodisc media, probably too low reflectivity or too high jitter at the end.

Good quality and readability.

Low quality media and the results reflect this. There is even a dye issue as we could see 3 dark spots close to the edge. This is probably why it failed to read the disc back.

Another very low quality media type and the results are not good near the end.

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