CD/DVD

Everyone has seen a Compact Disc, heard music played derived from one of, or used one to store files digitally. Not a lot of people discover how they work though. The CD is often a modern marvel of science that can be a true testament to the tenacity in the human spirit and ingenuity.

Creating a Compact Disc is a more involved process than many individuals realize. The data is recorded onto the disc in microscopic increments which means that during production, even the smallest particles of dust may cause the recordings to be corrupted. The manufacturing process must be very accurate and precise as there is no room for error.

Turning Binary into Sound

The first challenge was developing the disc itself. Optical discs should be in a position to contain huge amounts of data given it takes around a thousand bits to playback one second of music. Fortunately, a million bits with a Compact Disc is about the size of the head of a pin. This made optical discs the effective way to keep your data for later retrieval. Another challenge was inventing a means to read back all in the compressed information about the CD fast enough to learn back sound continuously, which was permitted by integrated circuit technology.

When a whole new audio CD is needed, a glass master must be created first. It is inspected carefully for quality assurance must be flawless master’s what is absolutely needed to manufacture good replicas. Once the glass master is completed, a stamper is created which is loaded into an injection molding machine, the location where the actual replicates are manufactured. Through every step of the manufacturing process, quality and precision have to be solidly maintained on the risk of creating waste.

A Compact Disc plays the sounds last a process of groves organized inside a spiral in the surface with the disc. When the laser from the CD player moves along the spiral, it is going to encounter “pits” and “lands” that can cause the laser to be reflected back at various intensities towards the reader. The computer inside the CD player interprets this data as sound. Using this method eliminates the “fuzz” which you might hear on some older audio recordings, making CD’s one of the most top-quality audio formats around even now.

Alternate Methods

The original formats presented in the Red Book developed by Sony and Philips were eventually discarded by many so that you can produce audio CDs which are in excess of 79.8 minutes and to be able to allow for digital rights management (DRM). Over the years music CDs are becoming for sale in 74, 80, 90, and 99-minute versions. The 80 minute CD (which is actually 79.8 minutes) is currently the standard size. However, the greater music a concise disc hold, the tighter its spiral should be (allowing to get more playback). Not all CD players are prepared for the tighter spirals, particularly the older CD players that existed prior to higher capacity discs hit the industry. Eventually, though, manufacturers updated many and then you are much unlikely to have problems playing 80-minute discs. The 99-minute discs are another story though. Your best bet would be to avoid them.

The consumer is being faced with the most difficult decision with regard to consumer electronics since the days of VHS vs Betamax. A person would spend hard-earned money on one fearing that their choice was to be the one that fades away with time – creating the necessity to buy a new machine and new tapes.

Yes, that same difficult decision between two competing technologies is here with the DVD-A and SACD. Will it be DVD-Audio or the SACD that has a bright future as the primary audio format? What, you never heard of either the DVD-A or SACD? Perhaps you once heard of one, but not the other? Most people aren’t familiar with either format and probably will never be. Yet both have been around for more than a decade now. Yes, I was being sarcastic above – but take a trip over to eBay and do a search for “DVD-Audio” and “SACD” and you will find a number of familiar artists on the unfamiliar formats.

In all likelihood, neither DVD-A nor SACD will ever have much of a following. They have both failed in the consumer market and most people with DVD-A and/or SACD players and discs are audiophiles. Prerecorded SACD music releases rose a bit last year (2010) but are still down quite a bit since their peak years ago. Most SACD releases however are not new music releases but older titles being reissued for the audiophile audience.

It seems that multichannel audio formats are doomed to fail every time. The general public loves stereo, plain and simple – at least when we’re not talking about audio for visual media. Back in the 1970s quadraphonic flopped. Remember the quad 8-tracks? There were also quadraphonic reel-to-reel tapes and even quadraphonic records called Quadradiscs. The newest multichannel failures are DVD-A, SACD, and probably BD-Audio, which means Blu-ray Audio Disc. There is now such a thing.

DVD-Audio

DVD-Audio which is also commonly called DVD-A is a high fidelity digital audio format. Though an extension of the DVD family it does not cover video delivery. DVD Audio first came on the scene at the turn of the millennium and is still in use by a few people today.

The much higher capacity of a DVD allows them to support considerably more music with no loss of quality or vastly increased quality with large amounts of information being able to fit on a single disc. On top of the increased quality and quantity, the DVD-Audio format also offers additional channels for multi-channel effects. Unlike the CD, DVD-A supports everything from mono to 5.1 channel surround sound. The compact disc, on the other hand, only held stereo recordings. If mono music was to be recorded to CD it would have to be converted to “stereo” by having 2 channels with identical material. Multichannel recordings were not possible.

SACD

Super Audio CD more commonly called SACD was developed by Sony and Philips as a High Fidelity audio format for optical media and can support dual-channel stereo recordings and multichannel surround sound recordings. It has been designated as the scarlet book standard as opposed to the red book standard for the traditional Compact Disc. Sony and Philips introduced it in 1999 and were also the companies that collaborated on the original compact disc standard. The original CD has been superseded and surpassed in capacity, fidelity, dynamic range, and stereo imaging by SACD.

As mentioned above the SACD can record audio in both Stereo and Surround Sound and uses a method called PDM to store the information but can also use PCM (the more common way of storing audio digitally – used for the CD, DAT, digital telephone systems, etc). The discs are dimensionally identical to a standard Compact Disc and have the same density as a DVD. It can also stream data at an uncompressed rate of 5.6 Mbps, with a sampling rate of 2.8224 MHz and at a resolution of 1 bit. That is 4 times faster than the Red Book CD.

What the Format War Means to Consumers

Nothing! At least for most of us.

What does it mean for the consumer when a format war takes place between mutually incompatible technologies or proprietary formats? The competition for the same market space can create a bit of pain and grief for the consumer that picks the losing side. Basically, the only thing a consumer can do is to try doing a little research on their own. See how many companies are backing each player and how much the format seems to be spreading. With regard to DVD-A and SACD though, there are numerous “universal” players that can handle both DVD-A and SACD, as well as other formats such as CD and even BD-Audio.

With the advancement of traditional hard drives and now solid-state drives we probably won’t have to worry too much about lots of new and incompatible audio formats warring with each other in the future. But then again, have you noticed how many digital audio file formats are out there already? At least they’re often somewhat easy to convert to other file formats – even if without an improvement in quality that’s promised by a new file format – a kind of backward compatibility.

Both DVD-Audio and SACD offer a higher level of quality and supersede the familiar Compact Disc. Both formats are able to handle multichannel surround sound recordings and both types of players are backward compatible with CDs. With the emergence of hybrid players that can handle both formats the war turned into more of a glaring contest as both formats stalled, unable to grab any real market share beyond the small community of audiophiles. Consumers have basically been turning to the MP3 and other compressed digital file formats rather than buying all new equipment and physical media like CDs and cassettes.

Today, CDs are such commonplace objects, a lot of us cannot even remember a time when they did not exist. But behind these ordinary-looking discs is a long good reputation for development along with a production process determined by ingenious technology that’s the way in front of its once again time.

Making a CD

The technique of CD creation begins with a single master disc. This original disc is made of glass and is also meant to withstand the pressures of replication. This disc is cleaned with deionized water plus a fine brush, then it’s left to dry before photo resistant chemicals are spread on its surface.

After these procedures, the master disc is placed in a machine that will engrave data onto it. Coatings of nickel and vanadium are applied to get a die.

This die will probably be used to make copies in the master disc.

The plastic CDs are made utilizing a hydraulic press. Polycarbonate plastic granules pass into the preheated press until it liquefies. The plastic might be injected into the die to make a translucent disc. This disc is then left for cooling before plastic hardens.

After the master CD is replicated, a thin coating of aluminum is applied to the copies. This means that the information for the discs might be read. A coat of varnish can also be put on to protect the discs against scratches.

Once the varnish dries, silkscreen engraving might be printed for the surface in the discs. The discs are packaged and provided for the marketplace.

How the CD began

The first music CDs were invented in 1965 when inventor James Russell thought of storing information in a light-sensitive plate instead of the black vinyl hole-punched discs which are used to store music then. His product was patented in 1970 – though the idea was too advanced for his time, also it failed to sell.

However, in the 1970s, Sony and Philips got interested in the idea and bought licenses from Russell. In September 1976, Sony made its first public demonstration from the optical digital audio disc, while Philips first displayed its product on March 8, 1979.

With these electronic giants supporting it, the CD market potential was immediately realized. To accelerate the introduction of a marketable version of the CD, Sony and Philips chose to work together to put the standards with the compact disk and it is played.

It took 12 months of trial and error prior to the first commercial disc arrived. The Laserdisc – a 30cm version in the CD to be sure it now – took over as the blueprint for that 12cm cd’s manufacturing process. Philips worked on prolonging the compact disk’s playing time and improve its resistance to scratching. Meanwhile, Sony created a player that would see the discs.

In 1982, Billy Joel’s 52nd Street had become the first album to be sold in CD format. Three years later, Dire Straight’s Brother’s in Arms became the first CD album to sell more than the usual million pieces.

The compact disk then continued beyond its original function of storing and playing high-quality music. It took over as a medium for holding software. As early as 1990, it became possible to write computer data on a compact disc.

Soon, the CDs’ effects on magnetic storage devices such as cassettes and VCDs became felt. Ten years after CDs became rewritable, cassette tapes disappeared from the market industry almost completely.

Today, CD manufacturers are thinking about creating even more scratch-resistant CDs that will hold often more data than our current CDs. With the improving technologies on CD production and CD replication, there is not any telling what this shiny little plastic device has in store for us. But one thing’s for sure: it would be worth expecting.

A Compact Disc is a digital storage medium having an optical disc. While originally developed for audio recording and playback, later it found use as storage for all forms of digital data. Sony was the first brand to openly demonstrate their optical audio disc technology inside the late 1970s. In the eighties, compact discs became commercially accessible, which began the war with audiotape and vinyl. The Compact Disc ultimately emerged the winner of audio formats, only to be replaced themselves by solid-state memory storage devices.

Standards and Formats

Standard sized Compact Discs are 1.2 mm thick using a diameter of 120mm. The original storage capacity of a CD was 680 MB or 74 minutes of audio. Currently, 700 MB of data or about 80 minutes of audio is what one would typically encounter. However, larger sizes are readily available. Also available are smaller Mini CD’s which could vary both in size and playback time, nevertheless the most popular ones are 80 mm in diameter or approximately 3 inches. These hold 24 minutes of audio or 210 MB of internet data.

In 1979, Sony and Philips collaborated on new ways to make CD a more efficient storage and playback device, further refining technology started almost 5yrs previous in Sony’s case. In a sense, it was this team that “invented” the CD as we know it today as one of the world’s most reliable kinds of audio playback. One of the first developments into the future from your coalition was the Red Book, which defined standard specification for your CD format. Among other details, it sets the specific guidelines for playback length, deviations, error rate, modulation, and the like.

Becoming commercially available in 1982, the 1st album being made in huge amounts on compact disk was Billy Joel’s 52nd Street, that has been released simultaneously as Sony’s CD player CDP-101 in October. In subsequent years, CBS music continued to honor the anniversary by releasing several albums on Compact Disc yearly for the same day.

Reception

For audiophiles with the time, the new Compact Disc seemed to be a dream to be realized. It was highly praised because the superior way of playback by classical music connoisseurs have been one of the first groups to really get behind the newest trend. As the 1980s progressed, the price of CD players slowly fell allowing the format to achieve mainstream popularity, especially within the rock and pop categories. By 1989, almost a half-billion CDs were manufactured on a yearly basis.

Data and Video on the CD

While it turned out originally intended as a possible audio format, the Compact Disc found use as a data storage way for computer programs. In June of 1985, the initial CD-ROM was developed for use in computers. A few years of progress later saw the creation of CD-Recordable (originally called CD-WO) and finally CD-RW, allowing consumers to record what they have to want on the discs.

In 1987 the CD-V (Compact Disc – Video) was introduced using laserdisc technology on the CD format to produce moving pictures. The fatal flaw, however, was that there was not really enough room for the necessary video data, and the format quickly fell into decline, disappearing completely by 1991.

Don’t confuse the CD-V with the VCD though. A VCD, or Video Compact Disc, is a more productive video format on CD that was created in 1993. Like audio CDs, a VCD holds either 74 minutes or 80 minutes of video and its particular quality is roughly the same as a VHS tape. Most DVD players are designed for playing VCDs but VCD players were also manufactured and quite popular in certain parts of the world – especially China plus some other Asian countries.

Time continues to march on, however, and the Compact Disc is slowly getting left inside the dust. Since the advent of solid-state MP3 players, large label CD sales have consistently dropped. The CD is still equipped with a location inside the computer world, however as a possible inexpensive approach to store data. Though the road has been long, the tale from the Compact Disc isn’t over yet.