The DVD±RW formats have become very popular, mostly because they offer a convenient way to transport large amounts of information from one PC to another, on a single disc at low cost in comparison to other media such as USB flash disks which as yet don't offer the same capacities. Rewritable discs also allow for experimenting when creating master discs for duplication. In this case, the same RW disc can be used again and again, something that is not possible with ±R media where a new disc would be required each time. Moreover most standalone CD/DVD recorder owners choose the rewritable formats because they can author/edit their movies on the same disc, even after recording has finished, as with VR mode for example.

The cost of rewritable media is higher in comparison to plain recordable media. And there have been quite a few occassions where we have been asked by our readers "how many times can I rewrite on my RW" or "how is the writing quality affected after several burnings". For this reason we decided to run some basic tests, rewriting CD and DVD RW media "a lot of times" while at the same time measuring the writing quality.

We wrote our own utility which is capable of writing one file or several files/directories over and over again on the same disc, performing either a quick, full format, or a combination of both between rewrites of a continuous batch of burnings, in order to find out when RW media begins to degrade and at what point it will become useless. We set our utility to perform continuous cycles of single burnings with a quick erase between each burn. After a specific number of burnings (1, 5, 10, 50 and 100), we took quality measurements with Plextools and CDSpeed. The recording project for the CD-RW was an audio file of 650MB capacity and for the DVDRW a movie file of 4.21GB capacity.

Our first goal was to burn and reburn all the media until they were no longer writeable. However, after the first tests we did, we decided to perform only up to 100 burns since the time needed, especially for the DVDRW formats was too much. According to Verbatim, their RW media can perform up to 1000 burns while other media at least 500. If we try to estimate that a full DVDRW burn needs approximately 14 minutes, then the time for the whole project would take months to complete (each DVD RW disc would need around 230 hours at 1000 burns, each 14 minutes long).

The ID codes of the media we used for our tests are presented in the following tables:

For our tests, Pioneer had kindly supplied us with 10 DVR-108 burners. We would like to add that each disc needed over 24 hours of continuous recording and none of the Pioneer drives reported any problems during the tests which revealed the reliability of the Pioneer drives, even under such gruelling conditions.

In the two cases of 6X DVD-RW media from Traxadata and Mitsubishi Chemicals, we used the Pioneer DVD-109instead of the DVD-108, due to its 6X supported writing speed for the DVD-RW format.

- DVD Writing Quality Measurements Method

In order to test the writing quality and readability of the burned media after the 1st, 5th, 10th, 50th and 100th burns, we used two readers with two software applications:

• The LiteON SOHD-167T with patched firmware being able to read DVD5 up to 16X CAV and DVD9 up to 10X CAV. For the transfer rate tests we used Nero CDSpeed.
• The Plextor PX-712A with the latest available firmware ( v1.05). For scanning the disc, we used PlexTools at 2X CLV reading speed, BURST mode, with middle accuracy.

In general, a "perfect" disc should have a smooth reading curve, very low PIE/POE and zero (0) POF error rates. Most times however, even though a disc has very low PIE/POE error rates, the reading curve may not be smooth containing dropoffs. Due to the fact that we oversped the reading capabilities of the LiteON SOHD-167T, such drops are expected, especially near the outer area of the disc.

The measurements in the following pages should be taken not as the absolute criteria of the burning quality, but as an indication level.

- CD Writing Quality Measurements Method

For checking the writing quality of the CD media, we used the Plextools C1/C2 Test. The reader was once again Plextor PX-712A

- Testing software

1. Nero CD-DVD Speed v3.75
2. PlexTools v2.20

More information about our test PC is included in the table below: