CD and DVD Drive

Compact Disc/Optical Storage Technology It is the electronic recording, storing, and playing back of audio, video, or text, in a digital form on a flat, round plastic storage medium called a disc. Its called optical because the information on the disk is read by a laser in a CD-ROM drive A laser is a device that generates an intense beam of coherent/consistent light. CDs are circular discs that are 4.75 inches (12 cm) in diameter

Types of Compact Disk Technology CD Compact Disk DVD Digital Versatile Disk Blue Ray  CD, DVD and Blue Ray Disks are similar in composition and usage, however they differ in data storage capacity.

Compact Discs (CD) Compact Disc was invented by James Russel in 1965. In 1982 the first CD recording ‘The Visitors’ by ABBA was recorded. A CD stores data or audio which can be played in a regular CD player in your home or car. There are major two types : CD-R (CD Recordable), which are the most popular can be written to only once. The content is permanently stored . CD-RW (CD Rewritable). Rewritable discs can be erased and rewritten to repeatedly. Both can store up to 700 MB of data or 80 min of audio.  CD-RW uses the laser power to melt the data layer so new data can be added

Other Types of CD Technologies CD-ROM Mini CD VCD Enhanced CD

CDROM It describes all pre-recorded CDs that contain music. A recording of the music is burned onto the CD by the vendor and cannot be erased or changed. A CD-ROM recording can be played on any standard CD player and contain 650 MB of storage

Mini CD Its about 3 inches in diameter and hold a maximum of 24 minutes of music or 210 MB of data The most common use of the mini CD format is for single song recording but are also used by businesses for adverts purposes CD-R allows the user to record data or music once some hold as much as 80 minutes of music CD-RW- Can be erased and reused.

Mini CD

Video Compact Disc (VCD) VCD was introduced in 1993 by JVC, Philips, SONY and Matsushita. It is based on the CD-ROM format and is specifically designed to hold MPEG-1 video data and to include interactive capabilities. MPEG is the standards for audio and video compression and transmission.  Although they have been superseded by other media, VCDs continue to be retailed as a low-cost video format.

Digital Versatile/Video Disc (DVD) It is a digital optical disc storage format invented and co-developed by Sony, Philips, Toshiba, and Panasonic in 1995 Its primary function is to store video, but just as easily records other data. Like CDs, DVDs are either recordable or rewritable, but store a tremendous amount of data. . 

DVD Types/Format DVD+R (plus R) and DVD-R (dash R) – These two are the record once formats. DVD+RW and DVD-RW – These are the rewritable formats and can be rewritten over 1000 times. DVD-ROM It is a read only compact disc that can hold a minimum of 4.7 GB enough for a full length digital movie One of the best features of DVD-ROM drives is that they are backward-compatible with CD-ROMs. This means that DVD-ROM players can play old CD-ROMs and video CDs, as well as new DVD-ROMs. DVD-RAM Can be recorded and erased repeatedly but are compatible only with devices that support the DVD- RAM format. Discs can be rewritten 100,000 times It will only play back in a DVD-RAM drive.

Blu-Ray Disk (BD): Blu ray is an optical disc format jointly developed by blu ray disc association, a group of the world’s leading consumer electronics and PC including Apple, LG, HP, Hitachi, Philips, Pioneer etc It is the latest video disc developed to exceed the capacity of the DVD format and it got its name from a blue laser used when recording to and reading a disc. All the other DVD formats utilize a red laser. It enables the storage of extremely large amounts of data and is primarily used for high-definition content and comes in single and dual layer.

DVD Storage Capacity The capacity of a DVD is the maximum amount of data it can store. This depends on the number of layers a disc has and whether or not it can be written to one or both sides. The following are the types of layers: Single sided single layer Double sided single layer Single sided Double layer Double sided double layer

DVD Storage Capacity The original and still very popular is the single-sided, single layer (DVD-5). Data is written to one side only and can hold 4.7 GB of data or 2 hrs. of video. Supported by DVD+/-R and DVD +/-RW formats

DVD Storage Capacity Double-Sided Single Layer (DVD-10): Data can be written to both sides-like a cassette tape. Stores 8.75 GB or about 4.5 hrs of video. Also supported by DVD+/-R and DVD +/-RW. Single-Sided Double Layer (DVD-9): Records to one side but that one side has two layers built into it. Stores 8.5 GB of data or 4 hrs. of video. Supported by DVD+R and DVD-R. They are normally termed DVD+R DL and DVD-R DL. Double-Sided Double Layer (DVD-18): Stores 17 GB of data or over 8 hrs. of video.

DVD Storage Capacity A Blue Ray disc with a single layer store up to 25 GB - that's 2 hrs. of hi-definition content or 13 hrs. of standard video. Dual layer stores 50 GB, which is 4.5 hrs of hi def video or 20 hrs of regular video. 

Disk Drive/Burner/Writer In order to play or record these formats a DVD burner/writer/drive is needed. In addition to a DVD burner, all these formats need some kind of burning software to write DVDs. A burner is a software that enables the copying of music, video, and data unto a DVD. Fortunately, most DVD writers support multiple formats.

Components of a CD Player A Drive Motor  It spins the disc and it is precisely controlled to rotate between 200 and 500 rpm depending on which track is being read. A Laser and a Lens System  It focuses on reading the track. The Tracking System It moves laser assembly so that the laser's beam can follow the spiral track.

How the Drive Works The disc is rotated by a drive system that regulates the speed of rotation so that data is read at the same speed regardless of the laser detector’s position. This means that rotation speed decreases as the laser detector slowly travels from the centre to the periphery of the disc in order to maintain a constant rate of data acquisition A beam is emitted by the laser and directed onto a single track on the disc.

Inside the CD Drive

CD Tracks

Speed of Disc Drive Optical disc drives come in different speeds that measure how fast they write, rewrite, and read data. Listed first is usually the write speed, followed by the rewrite and read speeds. These three rates are written with an "x" separating them (for instance, 32 x 12 x 48) and are based upon the original 1x record speed of the first CD or DVD writers. The first CD writers recorded at 150 KB/s (1 x 150), therefore every rate afterwards is a multiple of that speed. 

Speed of Disc Drive Using the numbers above as an example, lets say a CD drive is advertised as 32 x 12 x 48. The maximum record speed for writing a CD would be 32 times the original rate, in other words, 32 times 150 KB/s. The rewrite speed 12 times 150 KB/s, and the read speed 48 times 150 KB/s

Video Compression It is a reversible conversion (encoding) of video file to take less space than. Software and hardware that can encode and decode are called decoders. Both combined to form a codec. An uncompressed video produces an enormous amount of data

Video Compression Uncompressed video file cause extreme high computational demands for managing the it. Fortunately, digital video is suitable for compression Howeevr the higher the compression ratio, the lower the size and the lower the quality.

Video Compression Forma Joint Photographic Expert Group (JPEG) is the format for compressing still image file especially taken by digital camera Motion Picture Expert Group (MPEG) Standard for encoding and compressing video images. Video and sound on digital storage media (CD-ROM). H.263 Video telephony

END OF LECTURE