Concept and development of digital audio

Concept

Digital audio refers to the use of pulse code modulation, digital signals and other technologies to process analog signals, and it is recorded and played back a method. Analog to digital converter is responsible for the transmission of analog audio signals into digital audio signals, and then recorded in the storage carrier after coding, to achieve the recording function. The digital to analog converter converts the digital audio signal into analog audio signal in the storage carrier, so as to realize the function of digital audio playback. Digital audio is mainly divided into five parts: recording, editing, compression, transmission and playing. It has the characteristics of convenient storage, low storage cost, no sound distortion in the process of storage and transmission, and very convenient editing and processing.

History of development

1940s

PCM technology for sound transmission and recording was developed at Bell Laboratories in the 1940s. SIGSALY, an encrypted transmission system based on PCM technology developed by engineers at Bell Laboratories, represents the first digital quantization of speech and the first PCM signal transmission of speech.

1950s~1960s

The rapid development of digital audio originated in the late 1950s and early 1960s. At that time, due to the emergence of transistor digital computers, the audio amplification function was realized, and transistors have a certain contribution to promoting audio industrialization. In 1957, Max VernonMathews, an electrical engineer at Bell LABS, used an IBM 704 computer to digitally record and play back, and named it the Music I, which could record and play back only 17 seconds of sound. In 1959, two MIT students, David Gross and Alan Kotok, added Analog to Digital to Analog (D/A), speakers and microphones to a Lincoln Laboratory TX-0 computer. The sound information was stored on a tape carrier. The recorder was used for speech recording in schools, but it was called an “expensive tape recorder” because of its high cost.

1960s

In the 1960s, the advent of the integrated circuit accelerated the improvement of sound quality, and its cheap and practical advantages also reduced the size of electronic products.

1970s

In 1972, Denon and NHK jointly developed the world’s first PCM recorder, the Denon DN-023R, an 8-channel system with 13-bit resolution and 47.25 kHz sampling rate. It is the common ancestor of all today’s digital music formats. Humanity began to escape the inconveniences of the analog recording era.

In July 1979, SONY released the revolutionary Walkman, the world’s first Walkman product: TPS-L2, marking the birth of the concept of portable music. At first, the Walkman only had the functions of radio, tape playing and recording. It was not large enough to carry and was mostly used by young people.

1980s

In the early 1980s, Philips and SONY introduced the digital Compact Disc, which made digital audio popular with consumers, and by the end of the decade, the compact disc (CD) had overtaken the record. In the early 1980s, SONY, Panasonic and Tokyo Electric Acoustic Company jointly developed the Digital Audio Stationary Head (DASH) format. The DASH format recorder is the brilliant product of the digital tape recorder, and it is also the last large-scale digital tape recorder using open tape. It is mainly used to record high quality music programs or digital master tapes. In addition to the DASH format recorder, Digital Audio Tape (DAT) is also an important name in the history of digital recording. It was developed by SONY Corporation to replace the recording system composed of analog tape recorder and PCM processor. DAT recorders use smaller size digital cassette tapes, mainly for recording studios and record companies.

1990s

In September 1993, Jiang Wanmeng and Sun Yansheng developed the world’s first Video Compact Disc (VCD) player in Hefei, named “Wan Yan”. VCD DVD player is a kind of digital audio and video product which integrates optical, electrical and mechanical technology. It uses MPEG decompression technology and CD technology which can store image and sound in a relatively small disc.

2000s

In September 2002, the world’s first support Windows Media Audio (WMA) encoding function of MP3 birth, it is LG MF-PE520, not only can support WMA music format playback can also support a variety of audio formats.

Your task

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