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μ-law Algorithm
The μ-law algorithm (sometimes written Mu (letter), mu-law, often typographic approximation, approximated as u-law) is a companding algorithm, primarily used in 8-bit PCM Digital data, digital telecommunication systems in North America and Japan. It is one of two versions of the G.711 standard from ITU-T, the other version being the similar A-law algorithm, A-law. A-law is used in regions where digital telecommunication signals are carried on E-1 circuits, e.g. Europe. Companding algorithms reduce the dynamic range of an audio Signal (electrical engineering), signal. In analog systems, this can increase the signal-to-noise ratio (SNR) achieved during transmission; in the digital domain, it can reduce the quantization error (hence increasing the signal-to-quantization-noise ratio). These SNR increases can be traded instead for reduced Bandwidth (signal processing), bandwidth for equivalent SNR. Algorithm types The μ-law algorithm may be described in an analog form and in a qua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1's Complement
The ones' complement of a binary number is the value obtained by inverting all the bits in the Binary number, binary representation of the number (swapping 0s and 1s). The name "ones' complement" (''note this is Apostrophe#Basic rule (plural nouns), possessive of the plural "ones", not of a singular "one"'') refers to the fact that such an inverted value, if added to the original, would always produce an 'all ones' number (the term "Method of complements, complement" refers to such pairs of mutually additive inverse numbers, here in respect to a non-0 base number). This mathematical operation is primarily of interest in computer science, where it has varying effects depending on how a specific computer represents numbers. A ones' complement system or ones' complement arithmetic is a system in which negative numbers are represented by the inverse of the binary representations of their corresponding positive numbers. In such a system, a number is negated (converted from positive t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java Package
A Java package organizes Java classes into namespaces, providing a unique namespace for each type it contains. Classes in the same package can access each other's package-private and protected members. In general, a package can contain the following kinds of types: classes, interfaces, enumerations, and annotation types. A package allows a developer to group classes (and interfaces) together. These classes will all be related in some way – they might all have to do with a specific application or perform a specific set of tasks. Programmers also typically use packages to organize classes belonging to the same category or providing similar functionality. Using packages In a Java source file, the package that this file's class or classes belong to is specified with the package keyword. This keyword is usually the first keyword in the source file. At most one package declaration can appear in a source file. package java.awt.event; To use a package's classes inside a Java source ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Application Programming Interface
An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build or use such a connection or interface is called an ''API specification''. A computer system that meets this standard is said to ''implement'' or ''expose'' an API. The term API may refer either to the specification or to the implementation. In contrast to a user interface, which connects a computer to a person, an application programming interface connects computers or pieces of software to each other. It is not intended to be used directly by a person (the end user) other than a computer programmer who is incorporating it into the software. An API is often made up of different parts which act as tools or services that are available to the programmer. A program or a programmer that uses one of these parts is said to ''call'' that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SPARCstation 1
The SPARCstation 1 (Sun 4/60, code-named ''Campus'') is the first of the SPARCstation series of SPARC-based computer workstations sold by Sun Microsystems. The design originated in 1987 by a Sun spin-off company, Unisun, which was soon re-acquired. The SPARCstation 1 has a distinctive slim enclosure (a square 3-inch-high "pizza box") and was first sold in April 1989, with Sun's support ending in 1995. Based on a LSI Logic RISC CPU running at 20 MHz, with a Weitek 3170 (or 3172) FPU coprocessor, it was the fourth Sun computer (after the 4/260, 4/110 and 4/280) to use the SPARC architecture and the first of the sun4c architecture. The motherboard offered three SBus slots and had built-in AUI Ethernet, 8 kHz audio, and a 5 MB/s SCSI-1 bus. The basic display ran at 1152×900 in 256 colours, and monitors shipped with the computer were 16 to 19 inch greyscale or colour. Designed for ease of production to compete with high-end PCs or Macs (its principal competitors wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Au File Format
The Au file format is a simple audio file format introduced by Sun Microsystems. The format was common on NeXT systems and on early Web pages. Originally it was headerless, being simply 8-bit mu-law, μ-law-encoded data at an 8000 Hz sample rate. Hardware from other vendors often used sample rates as high as 8192 Hz, often integer multiples of video clock signal frequencies. Newer files have a header that consists of six Signedness, unsigned 32-bit words, an optional information chunk which is always of non-zero size, and then the data (in big endian format). Although the format now supports many digital audio, audio encoding formats, it remains associated with the mu-law, μ-law logarithmic encoding. This encoding was native to the SPARCstation 1 hardware, where SunOS exposed the encoding to application programs through the /dev/audio interface. This encoding and interface became a de facto standard for Unix sound. New format All fields are stored in big-endian format, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distortion
In signal processing, distortion is the alteration of the original shape (or other characteristic) of a signal. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio signal representing sound or a video signal representing images, in an electronic device or communication channel. Distortion is usually unwanted, and so engineers strive to eliminate or minimize it. In some situations, however, distortion may be desirable. For example, in noise reduction systems like the Dolby system, an audio signal is deliberately distorted in ways that emphasize aspects of the signal that are subject to electrical noise, then it is symmetrically "undistorted" after passing through a noisy communication channel, reducing the noise in the received signal. Distortion is also used as a musical effect, particularly with electric guitars. The addition of noise or other outside signals (hum, interference) is not considered di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Channel Coding
In computing, telecommunication, information theory, and coding theory, an error correction code, sometimes error correcting code, (ECC) is used for controlling errors in data over unreliable or noisy communication channels. The central idea is the sender encodes the message with redundant information in the form of an ECC. The redundancy allows the receiver to detect a limited number of errors that may occur anywhere in the message, and often to correct these errors without retransmission. The American mathematician Richard Hamming pioneered this field in the 1940s and invented the first error-correcting code in 1950: the Hamming (7,4) code. ECC contrasts with error detection in that errors that are encountered can be corrected, not simply detected. The advantage is that a system using ECC does not require a reverse channel to request retransmission of data when an error occurs. The downside is that there is a fixed overhead that is added to the message, thereby requiring a h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loudness
In acoustics, loudness is the subjectivity, subjective perception of sound pressure. More formally, it is defined as, "That attribute of auditory sensation in terms of which sounds can be ordered on a scale extending from quiet to loud". The relation of physical attributes of sound to perceived loudness consists of physical, physiological and psychological components. The study of apparent loudness is included in the topic of psychoacoustics and employs methods of psychophysics. In different industries, loudness may have different meanings and different measurement standards. Some definitions, such as LKFS, ITU-R BS.1770 refer to the relative loudness of different segments of electronically reproduced sounds, such as for broadcasting and cinema. Others, such as ISO 532A (Stevens loudness, measured in sones), ISO 532B (Eberhard Zwicker, Zwicker loudness), DIN 45631 and ASA/ANSI S3.4, have a more general scope and are often used to characterize loudness of environmental noise. More ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acoustic Intensity Level
Sound intensity, also known as acoustic intensity, is defined as the power carried by sound waves per unit area in a direction perpendicular to that area. The SI unit of intensity, which includes sound intensity, is the watt per square meter (W/m2). One application is the noise measurement of sound intensity in the air at a listener's location as a sound energy quantity. Sound intensity is not the same physical quantity as sound pressure. Human hearing is sensitive to sound pressure which is related to sound intensity. In consumer audio electronics, the level differences are called "intensity" differences, but sound intensity is a specifically defined quantity and cannot be sensed by a simple microphone. Sound intensity level is a logarithmic expression of sound intensity relative to a reference intensity. Mathematical definition Sound intensity, denoted I, is defined by \mathbf I = p \mathbf v where * ''p'' is the sound pressure; * v is the particle velocity. Both I and v ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
