detail information

The specifications of this drive tells us that is should write both DVD-R and DVD+R discs at 4X speed. In this part we will measure the write time for various types of DVD-/+R discs. We do also focus on write quality and media compatibility.

DVD-Writing performance:

In this test we will measure the time for writing to DVD-R and DVD+R discs. We used Nero burning Rom to set up a new UDF/ISO compilation containing 4482Mb of data and started the write process. We used the Disc-At-Once write method.

 
DVD+R

 
DVD-R

Out from these screenshots we could see that the Mediagear wrote the DVD+R in 14 minutes and 40 seconds, and the DVD-R in 14 minutes and 48 seconds. How this compares to other drives may bee seen in the table below:

For DVD+R discs it is average compared to the other writers, but is actually the fastest writer for DVD-R discs. But media compatibility and write quality is even more important than speed so let us take a look at this.

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 the last two months we could 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 reports 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 LDW-411S 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/PO (Parity Inner/Parity Outer) Sum: 8 ECC, reading speed: 4X CLV (Constant Linear Velocity).

But what is a good scan? That is a discussion that we don't think will end soon as different drives reports 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 that only the first layer is scanned.

If you read below you will see that both the pressed DVD-discs is 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 PI errors. In practical use a disc with 1664 PI errors is unreadable.

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

But what are the PO errors that K-Probe reports? Actually the PO errors that K-Probe reports is the Parity Inner uncorrectable errors, meaning errors left after PI correction. Only the ECMA 337 standard describes the Parity Inner uncorrectable errors. So how is a Parity Inner uncorrectable error 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 PI uncorrectable errors since every ECC block is 208 rows long. But the ECMA 337 standard goes further and specifies the max amount of accepted PI uncorrectable errors allowed on a good disc:

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

This is where K-Probe gives us problems as for PI errors it have to be set to a PI/PO sum of 8 ECC blocks to show results that compares to the standard, but for PI uncorrectable errors (Called PO in K-Probe) the PI/PO sum have to be set to a sum of 1 ECC block.

A guideline is to calculate the Parity Inner Uncorrectable errors to 8 ECC sum, which is max 32 (4 x 8) Parity Inner uncorrectable errors, but now we can't be sure if one of the 8 ECC blocks exceeds the specifications. But if the result exceeds 32 PI uncorrectable errors we know that at least one block have more than 4 PI uncorrectable errors.

But what makes a disc unreadable? A PO uncorrectable error will make the disc unreadable, but K-Probe does not display the PO uncorrectable errors.

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 JLMS XJ-HD165H DVD-ROM that seems to be pretty easy affected by the quality of a written disc.

Easier explanation on how to read the test results.

Maybe this got to technical detailed and you are wondering what to look for out of the errors that K-Probe report?

Use this as a guideline for good discs:

PI(Parity Inner): No larger areas on the disc should exceed 280 PI errors, do not worry too much about high single spikes that exceed 280.
PO(Parity Outer): No larger areas on the disc should exceed 32 PO (actually PI uncorrectable) errors, do not worry too much about high single spikes that exceeds 32.

And look at the reading curve, a slight slowdown at the end is probably nothing to worry about, but huge bumps and slowdowns are not good.

And as always; lower is better ;)

DVD+R media compatibility and write quality:

We know Taiyo Yuden as one of the best manufacturers for CD-R discs. And as we could see their DVD+R is just as excellent as their CD-R discs. Our highest recommendations for these discs! The drive set a new record, as this is the lowest amount of errors we have ever seen on a DVD disc!

And then the result went from very good on the previous disc to very bad with these discs. Disappointing as Mitsubishi is a well-known manufacturer and about all other drives we have tested is able to give back good results with these discs. Re-tested with firmware version 0048, with 0048 the result was even slightly worse.

A very disappointing result, we can't recommend these discs with this drive at all. But surprisingly the reading curve shows that the disc is still readable, but with slowdowns of course. We have tried 4 different brands (Ritek, That's Write, Arita and Fortis) with the RICOHJPNR01 code, and we did also re-test with firmware 0048. The result stays the same.

What could we say? The JLMS XJ-HD165H immediately fails to read this discs. This is not too surprising as these discs are of a very low quality so you should stay away from these discs.

Head on to next page and read about DVD-R compatibility and write quality...