Let's start with the BDXL recording tests. Here we used a BD-R TL (Triple Layer) disc. It is based on the Blu-ray Disc Association's (BDA) BDXL (High Capacity Recordable and Rewritable discs) specifications, which was introduced last year.

The BDXL specification was initially targeted primarily at commercial segments such as broadcasting, medical and document imaging enterprises with significant archiving needs. However, many consumer Blu-ray disc players have been supporting the format, especially those appearing at the Japanese market. The BDXL discs will be available in write-once versions with capacities of 100GB (BD-R TL) and 128GB (BD-R QL) and also in 100GB rewritable versions (BD-RE TL). The discs reach these capacities by incorporating three to four recordable layers.

Currently, TDK / Imation is the sole company that manufactures BD XL recordable discs. The discs feature three recordable layers and are able to hold up to 100GB of data (95.6 GB to be exact). TDK's BD-R TL (Triple Layer) discs are recognized as TDKBLDRNC ( MID.) Here is some information on these discs, as it is reported by Erik Deppe's OptiDrive Control utility:

Currently, Sony, Sharp and Panasonic are also using TDK's discs in an OEM basis and offer them under their brands. Mitsubishi Kangaku Media (MKM), the company better known for its Verbatim brand, will also release its own BD-R TL (100GB) discs sometime in the autumn of this year.

We should notice here that the TDK BD-R TL discs are really expensive and are currently retailing for 4,300 - 5,000 YEN ($52~$60 / €39~€45) , mainly due to limited supply.

BD-RE TL discs are not available in market yet.

The BDXL discs require hardware (players/recorder) that is compatible with the BDXL format and carry the corresponding logo. So previous generation BD players or recorders/burners cannot recognize the discs.

The BDXL format is specified in six format books for both recordable and rewritable discs:

This version was defined in June 2010 and is a multi-layered recordable in BDAV with the speed of 2X and 4X, capable of 100/128GB and usage of UDF2.5/2.6 as file system:

• System Description Blu-ray Disc Recordable Part 1: Basic Format Specifications Ver. 2.0 June, 2010
• System Description Blu-ray Disc Recordable Part 2: File System Specifications Ver. 2.0 June, 2010
• System Description Blu-ray Disc Rewritable Part 3: Audio Visual Basic Specifications Ver.4.01 Sept. 2010 together with System Description Blu-ray Disc Rewritable Format Part 3: Audio Visual Basic Specifications Ver.2.13 Sept. 2010

This version was defined in June 2010 and is a multi-layered rewritable in BDAV with the speed of 2X and 4X, capable of 100GB and usage of UDF2.5 as file system.

• System Description Blu-ray Disc Rewritable Part 1: Basic Format Specifications Ver.3.0 June, 2010
• System Description Blu-ray Disc Rewritable Part 2: File System Specifications Ver.3.0 June, 2010
  
• System Description Blu-ray Disc Rewritable Part 3: Audio Visual Basic Specifications Ver.4.01 Sept. 2010 together with System Description Blu-ray Disc Rewritable Format Part 3: Audio Visual Basic Specifications Ver.2.13 Sept. 2010

Compared to the BD-R DL, the BD-R TL disc features three layers of data (L0, L1 and L2), with a thickness of 100um(L0),75um(L1) and 57um(L2). The thickness of the L0 and the L1 are the same for both BD-R DL, the BD-R TL. However, each layer of the BD-R TL disc holds 33.4GB of data, which is 8.4GB more than what the layers of BD-R SL and DL can hold (25GB). In order to achieve this, the BD-R TL features an increased linear density. It uses shorter marks on the recording layer (112nm for BD-R TL) and also applies the Integrated-Maximum-Likelihood-Sequence-Error-Estimation technology or i-MLSE using PR(1,2,2,2,1) signal quality evaluation index. Other than that, the BDXL discs use the same addressing and modulation method also met with legacy BD-R SL and DL media.

So the main difference with legacy BD-R format are cover layer thickness distribution, capacity per layer, minimum mark length and evaluation index for signal quality. For both TL and QL, the BDA has specified 2X and 4X recording of 72~144Mbps user transfer rate.

The following table shows the main parameters of BD-R, including for both TL of 100GB capacity and QL of
128GB capacity format:

In BDXL, the Inter-Symbol-Interference (ISI) of the readout signal becomes much stronger compared to the prior format that allows just 25GB per layer. Therefore the readout signal processing needs to be improved. Also, the prior signal quality evaluation method using the Limit-Equalizer technology has turned out to be no longer applicable. The Integrated-Maximum-Likelihood –Sequence-Error-Estimation (i-MLSE), which is an alternative signal quality evaluation method for BDXL, was newly developed by Sony and Panasonic and was first presented two years ago. The i-MLSE retains the stability and the precision in such a severe ISI condition of BDXL. The evaluation method of i-MLSE stands on the detection principle of the Viterbi-Algorithm (VA) in the Partial-Response-Maximum-Likelihood (PRML) readout signal processing.

Additionally, some contrivances can be incorporated to achieve the better correlation with the Symbol-Error-Rate (SER). For example, the tendency of error occurrences with the PR(1,2,2,2,1) ML readout in the BDXL is considered. Another feature of i-MLSE is that the mathematical expression is the same as that of Time-Interval-Jitter (TI-Jitter or Jitter, simply), which is the prior signal quality evaluation method.

Consequently, the behavior of i-MLSE is very similar to that of the TI-Jitter. This helps people who evaluate the BDXL discs or systems for the first time to comprehend the meaning of measured values obtained through i-MLSE because the TI-Jitter has been used so long since the era of CDs and is very familiar to them.

Burning a TDK BD-R TL disc

For our burning tests, we used the Pioneer BDR-206MBK v1.3 burner and a TDK BD-R TL disc (TDKBLDRNC (000)). The drive supports 4X CLV (144Mbps) burning and reading for the specific disc. We remind you that the drive is also capable of burning BD-R QL (quad-layer, 128GB) discs at 4x, as well as BD-RE TL discs at 4X. However, such discs are not yet available anywhere in the world.

For the test we created a Blu-ray UDF compilation using Nero's Burning Rom software Ver. 10.2. Most of you should be familiar with the specific software and burning a BD-R TL disc does not make any difference. Here is how the software identified the TDK disc we had inserted into the drive's tray:

As you see, the blank BD-R TL disc offers a capacity of 95.466 MB.

Let's move on the settings before burning data on the disc. Our compilation included multiple data files (95.409 MB).

We chose to burn a non-multisession disc (disc-at-once):

The UDF settings were left to default. The software has selected the UDF 2.5 file system for this burn:

The final step before burning was to set the typical settings related to the recording procedure; finalization of the disc data verification - which we selected in order to check whether our data was burned correctly on the disc - and finally the writing speed. You can chose the 2x or 4x CLV burning speed:

With a simple calculation, our 95.409 MB data compilation will be burned at 4X CLV in approximately 1hr and 30 minutes. We start the burning procedure:

After 1hr 43 minutes and 23 seconds, our disc was ready:

Verifying the recorded data is always important, especially when it comes to burning multiple files on a disc. In our case, Nero's verification process was as slow as writing, since the disc was read at 4X CLV. The verification was successful:

The files on the TDK BD-R TL disc were easily accessible the readable through Windows Explorer.

For your information, the currently available disc testing utilities such as the OptiDrive Control v1.51 or Nero's CD Speed and Disc Speed do not fully support the BD-R TL discs. These tools are very convenient since they are displaying the writing / reading strategy of a burner and they are also offering other tests such as seek / access time for each disc or layer switch time for multi-layered discs. Although the utilities read the disc, they cannot deal with its increased capacity and treated them like BD-R DL media. Of course, we expect the OptiDrive Control software to support the the BD XL discs in a future version. For your reference only and although this test is not accurate (seek times, disc length) , here is a transfer rate (read) test of a TDK BD-R XL disc:

As you can see the software recognized the length of the disc (90:23GB) but it just read some part of it, finishing the reading task relatively quickly. We just show you the graph in order to see the 4X CLV reading strategy of the Pioneer BDR-206 MBK drive.