What is Compact Disc (CD)?

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Compact Disc (CD)

A compact disc (CD) is a portable storage device in the form of small plastic discs that store and retrieve computer data or music using light. It is a digital optical disc storage format co-developed by Philips and Sony. The CD is 4.75 inches (12 cm) in diameter and can hold up to 74 minutes of audio on a disc. The data capacity of CD-ROM is 700 MB.

History of Compact Discs

The following is the history of compact disc −

• 1913 − The Otophone, an early device that used light for both recording and playback of sound signals on a transparent photograph, was first introduced.
• 1966 − James T. Russell, an American inventor, filed a patent application for the first system to record digital media on a photosensitive plate.
• 1970 − James T. Russell was granted a patent for his digital media recording system.
• 1974 − Lou Ottens, the director of the audio division at Philips, initiated a group to create an analog optical audio disc with a 20 cm diameter and sound quality better than that of vinyl records. After the analog format showed unsatisfactory performance, two engineers at Philips suggested a digital format. Heitaro Nakajima, working at Sony, developed a digital PCM adaptor that allowed audio recordings using a Betamax video recorder.
• 1976 − Sony publicly demonstrated an optical digital audio disc.
• 1977 − Sony showed a 30 cm optical digital audio disc capable of playing an hour of digital audio with a 44,100 Hz sampling rate and 16-bit resolution using modified frequency modulation encoding.
• 1978 − Sony demonstrated an optical digital audio disc with a 150-minute playing time, 44,056 Hz sampling rate, 16-bit linear resolution, and cross-interleaved Reed-Solomon coding (CIRC) error correction, similar to the specifications that were later adopted for the compact disc.
• 1979 − Philips and Sony presented their respective technical details for their optical digital audio discs. Philips demonstrated a prototype optical digital audio disc at a press event in Eindhoven, Netherlands.
• 1980 − The Red Book CD-DA standard was published after a year of experimentation and discussions between Philips and Sony.
• 1982 − The compact disc (CD) was released commercially.
• 1983-1984 − Despite costing up to $1,000, over 400,000 CD players were sold in the United States.
• 1988 − In the United States, CD sales surpassed those of vinyl LPs, and Sony and Philips licensed James T. Russell's patents for recording.
• 1992 − CD sales in the United States overtook those of prerecorded music cassette tapes.

Compact Disc Shapes and Diameters

The following are the different sizes of compact discs −

Audio CD Formats and Variants

The Audio CD (CD-DA) is a digital optical disc format developed by Sony and Philips. It stores and plays stereo 16-bit PCM audio at 44.1 kHz.

CD-Text − Adds extra information like album name and artist to the CD.

CD+G − Combines audio with graphics for karaoke use.

Super Audio CD (SACD) − A high-resolution audio format offering better quality than CD-DA.

CD-MIDI − Stores music performance data for electronic instruments.

CD-ROM − Data storage format used for computers.

Video CD (VCD) − A video format using CD storage, designed to store VHS-quality video.

Super Video CD (SVCD) − Higher quality video format than VCD, intended as an alternative to DVD-Video.

Photo CD − Stores scanned photos in high-quality format for use on CD-i players or computers.

CD-i − Interactive multimedia disc for CD-i players.

Enhanced Music CD (CD+) − Combines audio and data tracks for use on CD players and computers.

Vinyl Disc − Hybrid disc with a vinyl layer for analog sound and a CD layer for digital audio.

The Future of Compact Discs

The CD has seen a steady decline in use, particularly during the early 2010s.

Digital formats have overtaken CDs in the music world, which has seen a huge shift away from physical mediums with the rise of streaming audio and digital downloads. While compact disc sales were more profitable for those in the music industry, convenience, and low costs have fewer consumers turning to the physical medium.

When compact discs were initially on the rise, PCs could only store approximately 10 MB of data, which had many turning to the CD for storage. That is no longer the case. With higher-capacity hard drives and online storage options consistently entering the market, compact discs and tape cartridges are no longer the top choice for many consumers.

In 1995, Panasonic, Philips, Sony, and Toshiba created the DVD format as a possible media replacement for compact discs. A DVD has the same dimensions as a CD, but a much higher storage capacity of 4.7 gigabytes (GB). The format is probably most known for video entertainment storage but is also used for software and other digital data. DVDs can be played on a DVD player, as well as in a DVD-ROM on a computer.

In 2003, Blu-ray was introduced as a replacement for DVD. Blu-ray has a capacity of 25 GB, which allows for higher-quality video and audio with higher resolution.

How do I save data to CDs?

Recording data to a CD-R −

• Save Files to T − Drive Save all files you want to record to the computer’s T: drive first.
• Insert Blank CD-R − Insert a blank CD-R into the computer’s "Compact Disc Rewritable" drive.
• Open Roxio CD Creator − Open the Roxio CD Creator program.
• Select Data Disc Option − At the Roxio "Welcome" screen, click the "Data and Backup" tab in the left sidebar, then click "Data Disc."
• Add Data − In the "Data Disc" window, click the "Add Data" button, then "Add Files" (or "Add Folder" to add an entire folder of files).
• Select Files − A window will open showing the files available on your computer. Under "Location," select the T: drive, then select each file or folder you want to save to CD and click "Add."

Note − When saving web pages, save both the .html file and the folder of images associated with it.

• Adjust CD Recording Options − When all files are selected, click "Options" under the "Data Disc" header at the bottom right.
• Under "CD recording options," change the "Type:" to "Disc at once (DAO), Closed." This will ensure your data disc can be read on most other computer CD drives.
• Click "OK" to return to the main window.
• Begin Recording − When ready to record, click the orange button next to "Click the button to continue" in the bottom right of the window to begin recording.