What Is BD-R (Blu-Ray Disc Recordable)?
Summary: This article tells basic information on BD-R, which is a Blu-ray disc that can be written only once.
Table of Contents
BD-R, short for Blu-Ray Disc Recordable, refers to two direct optical disc recording technologies that can be recorded on a Blu-ray-based disc using an optical disc recorder. Users can only write data to BD-R once, while its subcategory – BD-RE (Blu-ray Disc Recordable Erasable) can be recorded and erased multiple times.
Both BD-R and BD-RE are based on Blu-ray technology, so they have much higher storage capacity than the regular compact discs (CDs). Blu-ray technology entered the market around the mid-2000s and has evolved into a standard storage method for high-quality video and audio.
A single-layer disc’s disc capacity is 25 GB, a double-layer disc is 50 GB, a triple-layer is 100 GB, and a quadruple-layer disc is 128 GB (only in BD-R). Blu-ray discs have a minimum write speed of 36 megabits (4.5 MB)/s.
BD-R capacity ranges from 25 GB to 128 GB, while CD-R typically has a capacity of 650 MB to 700 MB, and DVD-R capacity ranges from 4.7 GB to 8.5 GB.
There are four versions of BD-R (Blu-ray Disc Recordable) and five of BD-RE (Blu-ray Disc Recordable Erasable). And each version consists of three parts with a sub-version of each part. Part 1 is Basic Format Specifications, Part 2 is File System Specifications, and Part 3 is Audio Visual Basic Specifications.
BD-R and RE discs contain grooves along with a wobble frequency that positions the reading or writing laser on the disc, rather than pre-pressing/pre-recording/replicated the pits and lands on the disc.
The BD-R has an OPC (Optimum Power Calibrations) / Test Zone for calibrating the speed at which the laser is written before and during writing, and there is also a DCZ, Drive Calibration Zone, at the outside edge of the disc for optional high-speed calibration.
Calibration is necessary to allow slight manufacturing defects, which significantly reduces or eliminates rejected discs and drives, also lowers costs, and avoids potential waste. Different types of recording mechanisms are using in BD-R and BD-RE discs.
HTL (High to Low)
The “Normal” BD-R disc uses a composite material (or a phase-changing alloy in the case of BD-RE) that reduces the reflectivity during recording, i.e., High To Low. Melting materials with very high-power beams converts them into a low-reflective, amorphous state, while low-power heating erases them back to high reflectivity, crystalline state.
In a BD-RE disc, a pair of dielectric Zinc Sulfur-Silicon Dioxide layers surround the data layer. Bonding gasket layers and semi-reflective layers are used for multi-layer discs. Sputtering is used to deposit The recording and dielectric layers.
Each GeSbTe recording layer on the multi-layered BD-RE discs is thinning, so that the first layer, also called L0, is 10 nanometers thick, L1 is 7.5 nanometers thick, L2 is 6nm thick, and so on.
The silver alloy reflective layer behind each recording layer is also gradually thinning so that the L0 silver layer is 10 nanometers thick, and the L1 layer is 9 nanometers thick, the L2 layer is 7 nanometers thick, etc.
The separation layers separating the record layers from each other are also gradually thinning.
BD-R LTH (Low to High)
BD-R LTH is a Blu-ray Disc format with an organic dye recording layer that can only write once. “Low to High” indicates the change in reflectivity from low to high during burning, as opposed to normal Blu-rays, which changes from high to low in reflectivity during writing.
BD-R LTH has an advantage in that it protects manufacturers’ investment in DVD-R/CD-R manufacturing equipment. That’s because it doesn’t require investment in new manufacturing equipment and production lines, which may reduce the disc manufacturing cost. On the contrary, the manufacturer modifies the current device.
BD-R LTH is unusable for old Blu-ray players and recorders. However, upgrading firmware enables the device to access the BD-R LTH.
- In November 2007, Panasonic released a firmware update for DMR-BW200, DMR-BR100, and MR-BW900/BW800/BW700 models.
- In Spring 2008, Pioneer would deliver the first LTH BD drives.
- In March 2008, Sony released an upgrade of the PlayStation 3 firmware, which enabled BD-R LTH reading.
In 2011, the Ministry of Culture and Communication of French launched a study on the suitability of data archives for LTH discs compared to HTL discs. They collected data in this study, which shows that the overall quality of LTH discs was worse than that of HTL discs.
This article briefly introduces the BD-R (Blu-ray Disc Recordable) with its definition, version, and Recording Mechanisms. Enjoy reading!
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