The primary concern when using optical storage media to
store data, is to ensure that the result will be
a readable disc, over a very long period of time.
Readability then, depends on the reading drive, which is influenced by the
resultant writing quality produced on the disc, which is in turn
directly related to the recorder used for burning
and the optical medium itself.
The Optical Storage industry has defined specific parameters
that reflect the quality of a recorded disc. These
are actual measurements of electric signals that
represent the overall condition of a disc and, when
looked at as a whole, provide a complete picture of the recording quality. These signals provide information about
the physical condition of a disc and the integrity
of the digital data, as they are stored on the disc
and retrieved by the player.
Quality testing has been practiced for decades now,
first for CD and later for DVD media. Currently, with
the High-Definition formats already available on the
market, there is a further and growing need for accurate testing. Moreover, the fact that the next-generation
formats are squeezing even more data onto 12cm
media using various techniques, makes it easy to
understand why measuring the quality of the
recorded data is more complicated when compared to CD and
In the following pages, we present some writing
quality measurements of BD-R (Blu-Ray Recordable)
and BD-RE (Blu-Ray Re-Rewritable) media. The discs
were burned with some of the most popular Blu-Ray recorders for
PCs, currently available on the market. In
cooperation with DaTARIUS, the leader in quality
optimization, measurements and evaluation of optical
storage media, CDRInfo presents a brief explanation
of the basic signals related to the quality of a
Blu-Ray disc, and of course, the first real-life
measurements on sample discs.
In the first pages, we tried to summarize the physical characteristics of the Blu-Ray disc format, the basics of the data encoding and error correction used, as well as an explanation of the basic signals that are essential for the evaluation of the writing quality of a Blu-Ray disc. Moving on, we provide information about the testing procedure, and of course the results.
At this point, we should mention that some discs were measured a second time. After initial measurements, a number of discs produced uncharacteristically poor results and we were keen to find out why. As we have done on similar occasions in the past when testing DVD media, we decided to run a second pass to confirm the results. Before doing the second pass, a random selection of discs was taken and cleaned using air spray and special tissues. The results after this procedure are quite revealing as will be seen in the ensuing pages.