blu-ray disc (seminar report)

RIT GAYA,GAYA,BIHAR 823001 EMAIL-r [email protected] http://www.rajunitk2k6.sampasite.com/

SEMINAR REPORT

ON

BLU-RAY DISC

By:-Raju kumar,

Director of RIT Gaya,

B.Tech (NIT Kurukshetra)

BLU-RAY DISCThe image of BLU-RAY DISC has really revolutionized the way we stored data in recent past. Now we have the power to think and materialize to store much more amount of data on the same area of a normal DVD.

It is an optical disc storage media format. The name of it has been derived from the violet laser which is used for reading & writing this type of disc. As the wavelength of violet color, more data can be stored on it as compared to DVDs. Double layer Blu-ray disc can store up to 50GB of data while single layer can store the half of it.

This disc has been developed by Blu-ray disc association group of companies

representing electronics, computer hardware and motion pictures.

ORIGIN:- The Sony started two projects namely Ultra density optical and DVR blue, a format of rewritable discs that later became Blu-ray Disc. The first DVR Blue prototypes were exhibited at CRETEC exhibition.

The physical specifications of the disc were completed in 2004.The BD-ROM specifications were finalized in early 2006 and at the request of initial manufacturers like Toshiba, Pioneer, Samsung an interim standard was published.

RELEASE:- The first ever Blu-ray disc were released on June 20, 2006. Initially is used MPEG-2 video compression the same as DVD used. The first movies using 50GB disc were released in October, 2006.The first ever audio-release was made in March, 2008.

COMPETITION FROM HD-DVDHigh-definition (HD) video generally refers to any video system of higher resolution than standard-definition (SD) video, most commonly at display resolutions of 1280×720 (720p)

The DVD forum was deeply split over whether to use more expensive Blue-laser technology or not. However DVD forum’s Steering committee decided in August, 2002 to go with this technology.

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At first, it struggled in market because of relatively cheaper HD-DVD, but the coming of Sony’s Play station-3 changed the fate of BLU-RAY DISC. This game used this disc drive as the primary storage medium. In Jan 2008, Warner Bros. announced that it would release only in Blu-ray disc. After this announcement many other studios of Hollywood followed the same. And the disc got the required marketing. In only the first quarter of 2008,Singulus Technologies got the orders of 21 dual layer disc while only 17 DVD

machines were made in the same period in 1997.

SPECIFICATIONSPHYSICAL SIZE SINGLE LAYER DOUBLE LAYER

12cm, single sided 25GB (23.28GiB) 50GB (46.56GiB)

8cm, single sided 7.8GB (7.26GiB) 15.6GB (14.5GiB)

RECORDING SPEED:-

Drive speed data rate (MB/s) write time for disc (min)

Single layer double layer

1x 4.5 90 180

2x 9 45 90

4x 18 23 45

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MECHANISM

LASER:- It uses blue (rather violet) at a wavelength of 405nm while conventional DVD/CDs use red at a wavelength of 650nm.Thus because of using violet color, it has

been possible to store more data on 12cm.

HARD COATING:- As the data stored on the blu-ray disc is closer to the surface of the disc, thus it was more susceptible to scratches. Thus it was placed in cartridges. But a polymer coating denied the necessity of using cartridges.

RECORDIND/PLAYBACK MECHANISM:-

RECORDABLE BD (BD-R):-

In recording process, an active material in recording layer is Separated into two laminar components, the composition of which are different each other, by irradiating a high power laser beam. BD-R disc is designed that the light reflectivity of the recorded area change to very low level.

In read process, a harmless low-power laser beam scans those recorded marks on a disc and retrieves playback signal by using photo detector.

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REWRITABLE BD (BD-RE):-

The recording layer of the BD-RE discs is made of a material that can change its state from a crystalline phase to an amorphous phase. When discs are produced, the recording surface is in it’s crystalline state (no data). If a part of the material is heated up to its melting point, and then cooled rapidly by irradiating high power and short

pulse laser, the state of the part change from crystalline to amorphous phase. (recording process) In contrast, if the laser power is moderate and flat, the material change to crystalline phase. (erase process) Controlling the laser power in such a manner, actual data are overwritten repeatedly. BD-RE disc is designed that the reflectivity of crystalline part is bright, however, amorphous part is dark. So, low read power laser spot can detect playback signal.

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The recording signal is read by a low-power laser beam and used for playback. The amount of reflected light depends on the crystallization state of the recording film (crystalline or amorphous). The recorded content is played back by detecting the reflected light using an optical sensor.

COMPARISIONThere are a great number of recording density differences between Blu-ray Disc and other formats of optical media such as DVDs or CDs. The disc structure and design are very different. To increase the amount of data to be recorded in the same area, it is necessary to increase the density so that the data can be packed more tightly. Beam spot of Blu-ray

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Disc is much smaller to realize such a tight density.

SOFTWARE USEDThe BD-ROM has some codec compatibilities for both hardware decoders and movie contents. The codec is actually a scheme for efficient compression for audio and video. The players required to support MPEG-2 initially.

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Blu-ray movies have a maximum data transfer rate is 54Mbit/s and a maximum video bit rate of 40Mbit/s while DVDs gave only 36Mbit/s data transfer rate and 29.4Mbit/s video bit rate.

JAVA ENABLED:-The JAVA VIRTUAL MACHINE (JVM) as well as network connectivity have included in some BD devices which allows the update through internet. This Java version is called BD-J.

JAVA VIRTUAL MACHINE

A JVM is a set of computer software programs and data structures which use a virtual machine model for execution of other computer’s program and scripts.

JVM operate on Java bytecode which is normally generated from Java source code. The JVM is a crucial component of JAVA platform. The JVM is distributed along with a set of

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standard class libraries which implement the Java API (Application Programming Interface).

The programs intended to run on any JVM must be compiled into standardized portable binary format in the form of “.class ” files. A program may contain many .class files which are combined together in “.jar” (Java archive) files.

Advanced Access Control System (AACS)The advanced access control system, the successor of Content Scramble System (CSS) ensures the content of disc by applying an algorithm and a key. Great care has been placed to ensure that the content is encrypted along the entire path from disc to the

display device.

ADVANCED ENCRYPTION STANDARD

The SubBytes step, one of the four steps in AES.

In cryptography, the Advanced Encryption Standard (AES), also known as Rijndael, is a block cipher adopted as an encryption standard by the U.S. government.

AES algorithm is one of the most popular algorithms used in symmetric key cryptography. It is a successor of Data Encryption Standard (DES).

AES has a fixed block size of 128 bits, 128/8=16 bytes.AES operates on 4x4 array of bytes, termed the state.

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High-level cipher algorithm

• Key Expansion using Rijndael's key schedule

• Initial Round

o Add Round Key

• Rounds

1. SubBytes—a non-linear substitution step where each byte is replaced with another according to a lookup table.

2. ShiftRows—a transposition step where each row of the state is shifted cyclically a certain number of steps.

3. MixColumns—a mixing operation which operates on the columns of the state, combining the four bytes in each column

4. AddRoundKey—each byte of the state is combined with the round key; each round key is derived from the cipher key using a key schedule.

The SubBytes step:-

In the SubBytes step, each byte in the state is replaced with its entry in a fixed 8-bit lookup table, S; bij = S (aij).

In the SubBytes step, each byte in the array is updated using an 8-bit substitution box, the Rijndael S-box. This operation provides the non-linearity in the cipher. The S-box used is derived from the multiplicative inverse over GF(28), known to have good non-linearity properties. To avoid attacks based on simple algebraic properties, the S-box is constructed by combining the inverse function with an invertible affine transformation. The S-box is also chosen to avoid any fixed points (and so is a derangement), and also any opposite fixed points.

The Shift Row step:-

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In the ShiftRows step, bytes in each row of the state are shifted cyclically to the left. The number of places each byte is shifted differs for each row.

The ShiftRows step operates on the rows of the state; it cyclically shifts the bytes in each row by a certain offset. For AES, the first row is left unchanged. Each byte of the second row is shifted one to the left. Similarly, the third and fourth rows are shifted by offsets of two and three respectively. For the block of size 128 bits and 192 bits the shifting pattern is the same. In this way, each column of the output state of the ShiftRows step is composed of bytes from each column of the input state. (Rijndael variants with a larger block size have slightly different offsets). In the case of the 256-bit block, the first row is unchanged and the shifting for second, third and fourth row is 1 byte, 3 bytes and 4 bytes respectively - although this change only applies for the Rijndael cipher when used with a 256-bit block, which is not used for AES.

The Mix Columns Step:-

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In the MixColumns step, each column of the state is multiplied with a fixed polynomial c(x).

In the MixColumns step, the four bytes of each column of the state are combined using an invertible linear transformation. The MixColumns function takes four bytes as input and outputs four bytes, where each input byte affects all four output bytes. Together with ShiftRows, MixColumns provides diffusion in the cipher. Each column is treated as a polynomial over GF(28) and is then multiplied modulo x4 + 1 with a fixed polynomial c(x) = 3x3 + x2 + x + 2. The MixColumns step can also be viewed as a multiplication by a particular MDS matrix in Rijndael's finite field.

The Add Round Key Step:-

In the AddRoundKey step, each byte of the state is combined with a byte of the round sub key using the XOR operation (⊕).

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In the AddRoundKey step, the sub key is combined with the state. For each round, a sub key is derived from the main key using Rijndael's key schedule; each sub key is the same size as the state. The subkey is added by combining each byte of the state with the corresponding byte of the sub key using bitwise XOR.

Self Protecting Digital ContentSelf Protecting Digital Content (SPDC), is a copy protection architecture which allows restriction of access to, and copying of, the next generation of optical discs and streaming/downloadable content.

Designed by Cryptography Research, Inc. of San Francisco, SPDC executes code from the encrypted content on the DVD player, enabling the content providers to change DRM systems in case an existing system is compromised. It adds functionality to make the system "dynamic", as opposed to "static" systems in which the system and keys for encryption and decryption do not change, thus enabling one compromised key to decode all content released using that encryption system. "Dynamic" systems attempt to make future content released immune to existing methods of circumvention.

FILE SYSTEMS

UNIVERSAL DISC FORMAT:-The UDF is a format specification of a file system for storing files on an optical media. It is considered to be the replacement of ISO 9660 file format and widely used for (re)writable optical media.

Initially, UDF was mainly found on optical media. Thus most operating system needed different software for reading UDF file system.

Nowadays almost all operating systems support at least reading this file system and some of they support writing as well.

A UDF file system is normally mastered by authoring software in a batch process, and written to disc in a single pass. But when packet writing to rewriteable media, such as CD-RW, UDF allows files to be created, deleted and changed on-disc just as a general-purpose filesystem would on removable media like floppy disks and flash drives.

FILENAME LENGTH LIMITATIONS

The name of the files can be of 255 charecters. The first byte is reserved for the compression ID, thus leaving 254 charecters for the file name.

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TYPES OF UDF:-

Plain:-This format can be used on any kind of disk that requires random read and write access like hard disks. Since this is the basic file format so any OS or file format driver that claims to support UDF will support this format as well.

Vat :-To enable CD-R to be used virtually like a hard disk, whereby the user can add and modify files on a CD-R at will (so-called "drive letter access" on Windows), OSTA added the VAT type to the UDF standard. The Vat is an additional structure on the optical disc that helps remapping when the files on the disc have been modified.

Spared (RW):-In this type sectors can be rewritten at random. The optical media can be erased any time. However, it is important to understand that sectors of -RW media may "wear out" after a while, meaning that their data becomes unreliable, through having been rewritten too often.

LATEST DEVELOPMENTS

Quad layer disc of 100 GB has been developed with modified optics. Hitachi stated that such a disc could be used to store 7 hours of 32 Mbit/s video (HDTV). In January 2007, Hitachi showcased a 100 GB

IT IS COMMENDABLE THAT THE ADVANCEMENT IN TECHNOLOGY HAS MADE IT POSSIBLE WHICH WERE THOUGHT IMPOSSIBLE FEW YEARS BACK.

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REFERENCESWIKIPEDIA,THE FREE ENCYCLOPEDIA-

en.wikipedia.org.

SEMINAR TOPICS-www.seminartopics.org.

www.pcworld.com

www.homemediamagazine.com

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