APPENDIX
A Brief History of
Audio Recording
Media Technologies
Audio recording media technologies have been in use for over one hundred years. Following are brief descriptions of some of the most popular recording media and recording technologies that were developed during that time. For our purposes we have placed them into two categories—analog and digital—along a time continuum. (See Figure A.1.)
The Age of Analog
Audio Recording
Because most analog recording technologies and media are based on magnetic tape technology, we can describe the first stage of audio recording as the magnetic tape era. (We should note, however, that some digital recordings are also done on magnetic tape.)
The concept of magnetic storage was developed in 1894 by the Danish telephone engineer Valdemar Poulsen of the Copenhagen Telegraph Company while trying to record telephone messages. In 1898 he patented the first magnetic recording device, known as the telegraphone. At the 1900 Paris Exhibition Fair he recorded the voice of the Emperor Franz Joseph of Austria. This recording is still preserved at the Danish Museum of Science and Technology as the oldest magnetic sound recording.
In 1935, during the Radio Fair in Berlin, the German company AEG Telefunken introduced the magnetophone, the predecessor of today’s magnetic tape recorder. Magnetic tape had been developed and provided by BASF, another German company in 1934. (Before the development of magnetic tape, early recordings were done on metallic drums.) The AEG’s magnetophone made its debut as a recording device on November 19, 1936, with a performance of the London Philharmonic orchestra in Germany. Since then many different sound-recording technologies have been developed, and many different media formats have been introduced into the marketplace. Some of the most important ones are described below.
■ The Reel-to-Reel Format
Originally, this magnetic tape format had no name because it was the only format available in the market. Its name came about as a way to differentiate it from other types of tape media that were introduced in the early 1960s, such as cartridges and cassettes. Reel-to-reel became the standard recording media in professional audio and radio studios until it was supplanted by the development of digital optical disc and hard drive recording technologies. Because of the width of the tape and its frequency response, this technology allowed sound technicians to edit the tape and to record with a high degree of sound fidelity. Reel-to-reel consumer formats were also widely used in the home market throughout the 1960s and 1970s.
■ 8-Track Cartridge
Introduced in 1966, the 8-track cartridge was developed by a consortium that included Ampex (best known as the U.S. company that invented videotape recording in 1956), Lear Jet, and RCA Records. First introduced as a car accessory, it was later marketed as a home system. The 8-track cartridge technology was preceded by a 4-track version introduced in 1956 that disappeared with the introduction of the 8-track format. The 8-track format was notable as the first tape format that was marketed to take advantage of prerecorded material that could be played and listened to while driving. Portability became its greatest asset. Both 4- and 8-track cartridge technologies all but disappeared in the early 1980s and are found today only among collectors and in a few radio stations at which the old analog “cart” machines are still used to play back commercials and music.
FIGURE A.1 Recording Media Time Line
■ Audiocassette
Audiocassettes were introduced in 1963 by Phillips and marketed as a low quality-recording device for voice dictation. Later improvements in the technology, including Dolby’s hiss reduction technology and metal particle tape coatings, and the introduction in 1978 of Sony’s Walkman, a small portable cassette player, made the compact audiocassette the most popular, almost universal, device for listening to prerecorded music. The Walkman also enabled home recording, a practice that was condemned and bitterly fought against by the music industry. Audiocassettes came in several different sizes and formats and were also widely used for purposes other than music listening and recording. Some of those uses, such as interview recording by journalists and classroom lecture recording, mimicked the initial voice dictation use envisioned by Phillips. Cassettes were displaced by the development of the compact disc (CD).
The Age of Digital
Audio Recording
Digital audio, as described in Chapter 5, refers to the digital reconstruction of the physical (analog) audio waveform. The telephone industry pioneered the use of digital recording technology to digitally compress telephone conversations so that more voice data could be handled by the narrow bandwidth of the available telephone lines. Since the early 1980s, when the CD format was first introduced, digital recording technology has been widely used in both the professional and consumer markets.
Digital recording media comes in many different flavors, each supported by a different technology and a different format. Despite differences in technology and media, two very important characteristics of the digital formats are that there is no generation loss (degradation of sound and video quality from copy to copy) in digital transfers and that they provide for fast random access to the recorded material.
■ Compact Disc (CD)
Introduced to the public in 1982 by Sony and Phillips, CDs have become one of the most convenient and most popular ways to store music and information (data) in general.
CD optical technology uses a red laser at a wavelength of 650 to 780 nanometers to read the recorded material. CD audio technology is based on a 44.1-kHz audio sampling rate at 16-bit quantization. Audio CDs are used to play music in cars, portable CD players, and home audio systems. The CD-ROM, which stands for “compact disc–read only memory,” became the leading technology for multimedia use with prerecorded CDs. The CD-R, which stands for “compact disc–recordable,” is used to record music and data in home audio systems and personal computers. Practically every computer nowadays incorporates a CD recorder, popularly known as a CD burner.
CD-R discs can be recorded onto only once. CD-RW (compact disc–rewritable) can be recorded over several times. Most CD devices in computers allow you to listen to audio CDs and to view data CDs. However, you should be aware that there are some issues of physical compatibility because of the optical characteristics of the different types of discs that may prevent one type of disc from being read by all drives or players.
The storage capacity for a CD-ROM is 640 megabytes (MB); for an audio CD it is 740 MB.
■ Digital Audio Tape (DAT)
Introduced by Sony in 1987, DAT is similar in appearance to a regular audiocassette but only half the size. The DAT recording standard does not use data compression. As a result the digital copies are identical to the source from which they were created.
DAT recorders can record audio using four different sampling rates: 32 kHz at 12-bit quantization and 48, 44.1, and 32 kHz at 16-bit quantization. Some special recorders can record at 96 kHz and 24-bit quantization.
All DAT standards use the same type of tape, with the length of the recording depending on the quality of the sampling. For instance, the same tape will allow for a longer duration of recording when sampling media at 32 kHz and 12 bits than when sampling at 48 kHz and 16 bits.
DAT recorders are used principally in the professional and semiprofessional music and video recording fields because of the quality of the sound recordings. In addition rewinding and forwarding the tape are very fast, thus facilitating access to any segment on the DAT tape.
DAT technology uses a recording method that is similar to what is used on video recorders: Rotary heads scan the tape helically and record the tracks of audio information diagonally on the tape.
DAT tapes are also used by the computer industry to store data backups. The storage capacity of a DAT is 1 gigabyte (GB).
■ Minidisc
Introduced by Sony in 1992, minidiscs can be prerecorded or recordable, similar to a CD. Minidisc media come in 60-, 74-, and 80-minute discs and have several recording options: the standard CD-quality mode, also known as SP; MiniDisc Long Play, or LP2, which doubles the recording time of a regular cassette (160 minutes on an 80-minute cassette); and LP4, which allows four times more recording than the conventional SP mode (320 minutes on an 80-minute cassette). The quality of the sound that is reproduced will depend on the recording mode that is used, with SP producing a high-quality, CD-like sound and the LP4 mode producing a medium-quality sound.
Minidiscs are used in home audio systems, in portable devices, for studio recording, and in car systems. In 2004 Sony introduced the Hi-MD format (fully compatible with the MD format), which can store up to 1 GB of music, images, or data and can record up to 45 hours of high-quality music.
■ Hard Disk Recording
Hard disk recording is the process of recording and storing audio on a computer hard disk drive. In the not-so-distant past, hard disk recording was associated with expensive studio equipment that was available only to professional audio engineers. Today, a variety of reasonably priced computer-based software and hardware are available in the consumer market.
In hard disk recording, audio is recorded to a computer hard disk drive via a sound card from an analog source, such as an audiocassette or a microphone, or from a digital source, such as a DAT or a CD. Recording capacity is determined by the size of the hard drive in the computer and the free space available on the drive. Hard disk recording devices are also known as digital audio workstations, which are discussed in Chapter 5.
■ DVD
CD laser technology served as the basis for the development of DVD technologies. Introduced in its first version by Pioneer in 1994, DVD, like CD, is an optical disc storage media system that is used today mostly for high-quality playback of movies. Originally, DVD stood for “digital video disc,” but as its uses diversified to include data and high-definition sound, the name was changed to “digital versatile disc.” DVD drives are backward compatible with CDs, which means that they can read most CD formats. This makes DVD players and recorders likely replacements for CD drives.
Like CDs, DVDs come in several formats. Although most of today’s DVD players can read almost all of the important formats, some compatibility issues remain. The most common DVD formats are as follows.
Pre-recorded DVD-ROM (“DVD read-only memory”) discs are used mostly for multimedia applications and computer games. DVD-ROM discs can be viewed on both computer screens and televisions. DVD-ROM is backward compatible with the CD-ROM format and forward compatible with future recordable (R) and rewritable (RW) DVD formats.
DVD-RAM (“DVD random access memory”) is a rewritable format; it is not compatible with most other DVD drives and players.
DVD-R (“DVD minus recordable”) discs can be recorded onto only once but have a high rate of compatibility with older DVD drives and players.
DVD+R (“DVD plus recordable”) discs have technical standards similar to those of the DVD-R and are partially compatible with it. The plus and minus signs have to do with different sets of technical standards used to record the discs. About half the industry supports one format, and the other half of the industry supports the other format.
DVD-RW (“DVD rewritable”) discs are rewritable, but they have little compatibility with older DVD drives and DVD players.
To protect marketing strategies, most commercial DVDs have a regional coding that makes it impossible to play a particular disc in different regions. There are six regions in the world as follows:
• Region 1: United States, Canada
• Region 2: Europe, Japan, Middle East, South Africa
• Region 3: Southeast Asia, Taiwan
• Region 4: Australia, New Zealand, Central and South America, Mexico, Pacific Islands, Caribbean
• Region 5: Russia, India, Pakistan, part of Africa, North Korea, Mongolia
• Region 6: China
The next generation of DVD technology will most likely see the development of HD-DVD, which stands for “high-definition or high-density DVD.” These systems will use “blu ray” technology (a blue laser with a wavelength as short as 400 nanometers) and will be able to store several more times the amount of information than the current versions are capable of storing.