Digital audio
From The Art and Popular Culture Encyclopedia
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| - | :''[[Twitter]] vs. [[Facebook]]'' | ||
| - | '''Micro-blogging''' is a form of multimedia [[blog]]ging that allows users to send brief text updates or [[micromedia]] such as photos or audio clips and publish them, either to be viewed by anyone or by a restricted group which can be chosen by the user. These messages can be submitted by a variety of means, including [[text messaging]], [[instant messaging]], [[email]], [[digital audio]] or [[World Wide Web|the web]]. Leading social networking websites [[Facebook]], [[MySpace]], [[LinkedIn]], and [[XING]] also have their own micro-blogging feature, better known as '''status updates'''. | ||
| - | The content of a micro-blog differs from a traditional blog in that it is typically smaller in actual size and aggregate file size. A single entry could consist of a single sentence or fragment or an image or a brief, ten second video. But, still, its purpose is similar to that of a traditional blog. Users micro-blog about particular topics that can range from the simple, such as "what one is doing at a given moment," to the thematic, such as "sports cars," to business topics, such as particular products. Many micro-blogs provide short commentary on a person-to-person level, share news about a company's products and services, or provide logs of the events of one's life. | + | '''Digital audio''' uses [[digital signal]]s for [[sound reproduction]]. This includes [[Analog-to-digital converter|analog-to-digital conversion]], [[Digital-to-analog converter|digital-to-analog conversion]], storage, and transmission. In effect, the system commonly referred to as digital is in fact a discrete-time, discrete-level analog of a previous electrical analog. While modern systems can be quite subtle in their methods, the primary usefulness of a digital system is that, due to its discrete (in both time and amplitude) nature, signals can be corrected, once they are digital, without loss, and the digital signal can be reconstituted. The discreteness in both time and amplitude is key to this reconstitution, which is unavailable for a signal in which at least one of time or amplitude is continuous. While the hybrid systems (part discrete, part continuous) exist, they are no longer used for new modern systems. |
| - | == See also == | + | |
| - | * [[Blog]] | + | Digital audio has emerged because of its usefulness in the recording, manipulation, mass-production, and distribution of sound. Modern distribution of music across the internet through on-line stores depends on digital recording and digital [[audio data compression|compression]] [[algorithm]]s. Distribution of audio as data files rather than as physical objects has significantly reduced costs of distribution. |
| - | * [[FriendFeed]] | + | |
| - | * [[Gtalkbots.com]] | + | From the [[wax cylinder]] to the [[compact cassette]], analogue audio music storage and reproduction have been based on the same principles upon which human hearing are based. In an analogue audio system, sounds begin as physical waveforms in the air, are transformed into an electrical representation of the waveform, via a transducer (for example, a microphone), and are stored or transmitted. To be re-created into sound, the process is reversed, through amplification and then conversion back into physical waveforms via a loudspeaker. Although its nature may change, its fundamental wave-like characteristics remain unchanged during its storage, transformation, duplication, and amplification. All analogue audio signals are susceptible to noise and distortion, due to the inherent noise present in electronic circuits. In other words, all distortion and noise in a digital signal are added at capture or processing, and no more is added in repeated copies, unless the entire signal is lost, while analog systems degrade at each step, with each copy, and in some media, with time, temperature, and magnetic or chemical issues. |
| - | * [[Identi.ca]] | + | |
| - | * [[Intent.com]] | + | The digital audio chain begins when an [[analog signal|analogue audio signal]] is first sampled, and then (for PCM, the usual form of digital audio) converted into [[binary numeral system|binary]] signals — ‘on/off’ pulses — which are stored as binary electronic, magnetic, or optical signals, rather than as continuous time, continuous level electronic or electromechanical signals. This signal may then further encoded to combat any errors that might occur in the storage or transmission of the signal, however this encoding is for the purpose of error correction, and is not strictly part of the digital audio process. This "channel coding" is essential to the ability of broadcast or recorded digital system to avoid loss of bit accuracy. The discrete time and level of the binary signal allow a decoder to recreate the analogue signal upon replay. An example of a channel code is [[Eight-to-Fourteen Modulation|Eight to Fourteen Bit Modulation]] as used in the [[Compact Disc Digital Audio|audio Compact Disc]]. |
| - | * [[Jaiku]] | + | |
| - | * [[Juick]] | + | |
| - | * [[OpenMicroBlogging]] | + | |
| - | * [[Ping.fm]] | + | |
| - | * [[Plurk]] | + | |
| - | * [[Present.ly]] | + | |
| - | * [[Seesmic]] | + | |
| - | * [[Sfeed]] | + | |
| - | * [[Sideblog]] | + | |
| - | * [[Thumbcast]] | + | |
| - | * [[Traction TeamPage]] | + | |
| - | * [[Tumblelog]] | + | |
| - | * [[Twitter]] | + | |
| - | * [[Yammer]] | + | |
| {{GFDL}} | {{GFDL}} | ||
Revision as of 19:27, 13 July 2009
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Digital audio uses digital signals for sound reproduction. This includes analog-to-digital conversion, digital-to-analog conversion, storage, and transmission. In effect, the system commonly referred to as digital is in fact a discrete-time, discrete-level analog of a previous electrical analog. While modern systems can be quite subtle in their methods, the primary usefulness of a digital system is that, due to its discrete (in both time and amplitude) nature, signals can be corrected, once they are digital, without loss, and the digital signal can be reconstituted. The discreteness in both time and amplitude is key to this reconstitution, which is unavailable for a signal in which at least one of time or amplitude is continuous. While the hybrid systems (part discrete, part continuous) exist, they are no longer used for new modern systems.
Digital audio has emerged because of its usefulness in the recording, manipulation, mass-production, and distribution of sound. Modern distribution of music across the internet through on-line stores depends on digital recording and digital compression algorithms. Distribution of audio as data files rather than as physical objects has significantly reduced costs of distribution.
From the wax cylinder to the compact cassette, analogue audio music storage and reproduction have been based on the same principles upon which human hearing are based. In an analogue audio system, sounds begin as physical waveforms in the air, are transformed into an electrical representation of the waveform, via a transducer (for example, a microphone), and are stored or transmitted. To be re-created into sound, the process is reversed, through amplification and then conversion back into physical waveforms via a loudspeaker. Although its nature may change, its fundamental wave-like characteristics remain unchanged during its storage, transformation, duplication, and amplification. All analogue audio signals are susceptible to noise and distortion, due to the inherent noise present in electronic circuits. In other words, all distortion and noise in a digital signal are added at capture or processing, and no more is added in repeated copies, unless the entire signal is lost, while analog systems degrade at each step, with each copy, and in some media, with time, temperature, and magnetic or chemical issues.
The digital audio chain begins when an analogue audio signal is first sampled, and then (for PCM, the usual form of digital audio) converted into binary signals — ‘on/off’ pulses — which are stored as binary electronic, magnetic, or optical signals, rather than as continuous time, continuous level electronic or electromechanical signals. This signal may then further encoded to combat any errors that might occur in the storage or transmission of the signal, however this encoding is for the purpose of error correction, and is not strictly part of the digital audio process. This "channel coding" is essential to the ability of broadcast or recorded digital system to avoid loss of bit accuracy. The discrete time and level of the binary signal allow a decoder to recreate the analogue signal upon replay. An example of a channel code is Eight to Fourteen Bit Modulation as used in the audio Compact Disc.
