detail information

The specifications of this drive tell us that it should write DVD-R discs at 8x and DVD+R discs at 8X 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 4483Mb of data, and started the write process. We used the Disc-At-Once write method.

DVD+R

DVD-R

Look below for the results.

As we could see the BTC is a pretty slow writer when writing at 8x and for DVD+R it's over 2,5 minutes slower than the fastest drive. It's slightly faster for 8x DVD-R writing, but still very slow compared to most other writers. But speed is not everything, maybe this rather slow writing strategy gives any quality benefits? Read on and 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, PO (Parity Outer) set to summarize 1 ECC block, reading speed: 4X CLV (Constant Linear Velocity). Setting the PI sum to 8 and the PO 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 PI-8 errors. In practical use a disc with 1664 PI-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 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 means that when the PO sum is set to 1 the maximum error value should not exceed 4. The theoretical maximum value for PO errors is 208 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 is using a modified firmware and thus tries to read the discs at full 16x speed. Reading the discs at full 16x speed could almost be considered a 'torture" test and most discs will slow down near the end. Only the best of the best discs will be able to get a perfect reading curve, so our limit for good discs will be: A speed drop at the end is accepted, but the reading speed should not drop below 6x for longer periods (small dips below 6x is accepted).

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.
PO(Parity Outer): No larger areas on the disc should exceed 4 PO-1 (actually PI uncorrectable) 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, some slowdowns is expected with most media, but the reading speed should not drop below 6x for longer periods (small dips below 6x is accepted).

DVD+R media compatibility and write quality:

What can we say? The disc is completely useless of course. Ritek r03 revision has been a bit variable in quality, so let's try a revision 2 disc.

What could we say? The K-Probe result is so smooth, but the reading curve shows such serious issues. One of the times when there is no link between K-Probe result and reading curve. Not recommended.

Disappointing to see such bad results with Verbatim media. BTC should really work on improving the situation here.

Big contrasts? Definitively as the result with this media is absolutely perfect! Highly recommended media.

The disc is at least readable without too much trouble, so you should not get any problems with this media type.

As we could see the result is not good and the disc is unreadable, more improvements needed from BTC.

As we could see the disc is unreadable immediately after the switch to 6x writing speed. Not recommended.

Disappointing to see the drive making trash out of the high quality and expensive Taiyo Yuden DVD+R discs. The JLMS XJ-HD165H did not even try to aim at reading at full 16x speed for a reason or another. More room for improvements BTC!

It seems like the result got better when we came down at 4x speed as the result is very good and we could highly recommend these discs.

The result is very good and we have no problems recommending this media.

Again we got a K-Probe result that look better than we would expect out from looking at the reading curve. This is also high quality media, so it's disappointing to see that the BTC DRW1108IM has such problems.

There is an error spike at the beginning of the disc as usual with this media. But overall there are no serious problems and you should not have any problems using this media.

While the result is ok there is still room for improvements as other writers have showed better results with this media.

To see if rather unknown media types are supported at certified speed we include the following table:

A total of 4 discs were not supported at certified speed, this is a bit more than for most competitors.

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