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Sound Server
A sound server is software that manages the use of and access to audio devices (usually a sound card). It commonly runs as a background process. Sound server in an operating system In a Unix-like operating system, a sound server mixes different data streams and sends out a single unified audio to an output device. The mixing is usually done by software, or by hardware if there is a supported sound card. Layers The "sound stack" can be visualized as follows, with programs in the upper layers calling elements in the lower layers: * Applications (e.g. mp3 player, web video) * Sound server (e.g. aRts, ESD, JACK, PulseAudio) * Sound subsystem (described as kernel modules or drivers; e.g. OSS, ALSA) * Operating system kernel (e.g. Linux, Unix) Motivation Sound servers appeared in Unix-like operating systems after limitations in Open Sound System were recognized. OSS is a basic sound interface that was incapable of playing multiple streams simultaneously, dealing with multip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software
Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consists of machine language instructions supported by an individual processor—typically a central processing unit (CPU) or a graphics processing unit (GPU). Machine language consists of groups of binary values signifying processor instructions that change the state of the computer from its preceding state. For example, an instruction may change the value stored in a particular storage location in the computer—an effect that is not directly observable to the user. An instruction may also invoke one of many input or output operations, for example displaying some text on a computer screen; causing state changes which should be visible to the user. The processor executes the instructions in the order they are provided, unless it is instructed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Advanced Linux Sound Architecture
Advanced Linux Sound Architecture (ALSA) is a software framework and part of the Linux kernel that provides an application programming interface (API) for sound card device drivers. Some of the goals of the ALSA project at its inception were automatic configuration of sound-card hardware and graceful handling of multiple sound devices in a system. ALSA is released under GNU General Public License, GPL-2.0-or-later and GNU Lesser General Public License, LGPL-2.1-or-later. On Linux, sound servers, like sndio, PulseAudio, JACK Audio Connection Kit, JACK (low-latency professional-grade audio editing and mixing) and PipeWire, and higher-level APIs (e.g OpenAL, Simple DirectMedia Layer#Subsystems, SDL audio, etc.) work on top of ALSA and its sound card device drivers. ALSA succeeded the older Linux port of the Open Sound System (OSS). History The project to develop ALSA was led by Jaroslav Kysela, and was based on the Linux device driver for the Gravis Ultrasound sound card. It sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Icecast
Icecast is a streaming media project released as free software maintained by the Xiph.Org Foundation. It also refers specifically to the server program which is part of the project. Icecast was created in December 1998/January 1999 by Jack Moffitt and Barath Raghavan to provide an open-source audio streaming server that anyone could modify, use, and tinker with. Version 2, a ground-up rewrite aimed at multi-format support (initially targeting Ogg Vorbis) and scalability, was started in 2001 and released in January 2004. History Icecast was originally developed by Moffitt in 1998 for SMU's radio station. At the time, the station was constantly losing its FCC license and was at the time only able to reach listeners in the same building. Given that all of the dorms throughout campus had Ethernet connectivity, using streaming audio to broadcast was a natural solution, but currently available audio streaming software, such as RealAudio, was too expensive. Moffitt created Icecast, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OpenBSD
OpenBSD is a security-focused, free and open-source, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by forking NetBSD 1.0. According to the website, the OpenBSD project emphasizes "portability, standardization, correctness, proactive security and integrated cryptography." The OpenBSD project maintains portable versions of many subsystems as packages for other operating systems. Because of the project's preferred BSD license, many components are reused in proprietary and corporate-sponsored software projects. The firewall code in Apple's macOS is based on OpenBSD's PF firewall code, Android's Bionic C standard library is based on OpenBSD code, LLVM uses OpenBSD's regular expression library, and Windows 10 uses OpenSSH (OpenBSD Secure Shell) with LibreSSL. The word "open" in the name OpenBSD refers to the availability of the operating system source code on the Internet, although the word "open" in the nam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sndio
sndio is the software layer of the OpenBSD operating system that manages sound cards and MIDI ports. It provides an optional sound server and a documented application programming interface to access either the server or the audio and MIDI hardware in a uniform way. sndio is designed to work for desktop applications, but pays special attention to synchronization mechanisms and reliability required by music applications. Features The audio and MIDI server is the main component of sndio. It aims to fill the gap between programs requirements and the bare hardware as exposed by operating system device drivers. This includes: * perform re-sampling and format conversions; for instance to allow a program that requires 44.1 kHz sample frequency to use a device that supports 48 kHz only. * mix and route the sound of multiple programs; this allows multiple programs to use the audio device concurrently. * split an audio device into sub-devices, for instance allowing one program ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PipeWire
PipeWire is a server for handling audio, video streams, and hardware on Linux. It was created by Wim Taymans at Red Hat. It handles multimedia routing and pipeline processing. History In 2015, Taymans started work on PipeWire. It was based on ideas from a couple of projects, including one called PulseVideo by William Manley. According to Red Hat's Christian Schaller, it drew many of its ideas from an early PulseVideo prototype by Manley and builds upon some of the code that was merged into GStreamer due to that effort. A goal was to improve handling of video on Linux the same way PulseAudio improved handling of audio. Although a separate project from PulseAudio, Taymans initially considered using the name "PulseVideo" for the new project. By June 2015, the name Pinos was being used after a city where Taymans used to live, Pinos de Alhaurin in Spain. Initially, Pinos only handled video streams. By early 2017, Taymans had started working on integrating audio streams. He wanted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Audio System
Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics * Networks, a graph with attributes studied in network theory ** Scale-free network, a network whose degree distribution follows a power law ** Small-world network, a mathematical graph in which most nodes are not neighbors, but have neighbors in common * Flow network, a directed graph where each edge has a capacity and each edge receives a flow Biology * Biological network, any network that applies to biological systems * Ecological network, a representation of interacting species in an ecosystem * Neural network, a network or circuit of neurons Technology and communication * Artificial neural network, a computing system inspired by animal brains * Broadcast network, radio stations, television stations, or other electronic media outl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daemon (computer Software)
In multitasking computer operating systems, a daemon ( or ) is a computer program that runs as a background process, rather than being under the direct control of an interactive user. Traditionally, the process names of a daemon end with the letter ''d'', for clarification that the process is in fact a daemon, and for differentiation between a daemon and a normal computer program. For example, is a daemon that implements system logging facility, and is a daemon that serves incoming SSH connections. In a Unix environment, the parent process of a daemon is often, but not always, the init process. A daemon is usually created either by a process forking a child process and then immediately exiting, thus causing init to adopt the child process, or by the init process directly launching the daemon. In addition, a daemon launched by forking and exiting typically must perform other operations, such as dissociating the process from any controlling terminal (tty). Such procedures are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix
Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others. Initially intended for use inside the Bell System, AT&T licensed Unix to outside parties in the late 1970s, leading to a variety of both academic and commercial Unix variants from vendors including University of California, Berkeley (Berkeley Software Distribution, BSD), Microsoft (Xenix), Sun Microsystems (SunOS/Solaris (operating system), Solaris), Hewlett-Packard, HP/Hewlett Packard Enterprise, HPE (HP-UX), and IBM (IBM AIX, AIX). In the early 1990s, AT&T sold its rights in Unix to Novell, which then sold the UNIX trademark to The Open Group, an industry consortium founded in 1996. The Open Group allows the use of the mark for certified operating systems that comply with the Single UNIX Specification (SUS). Unix systems are chara ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux
Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which includes the kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name "GNU/Linux" to emphasize the importance of GNU software, causing some controversy. Popular Linux distributions include Debian, Fedora Linux, and Ubuntu, the latter of which itself consists of many different distributions and modifications, including Lubuntu and Xubuntu. Commercial distributions include Red Hat Enterprise Linux and SUSE Linux Enterprise. Desktop Linux distributions include a windowing system such as X11 or Wayland, and a desktop environment such as GNOME or KDE Plasma. Distributions intended for ser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Sound System
The Open Sound System (OSS) is an interface for making and capturing sound in Unix and Unix-like operating systems. It is based on standard Unix devices system calls (i.e. POSIX read, write, ioctl, etc.). The term also sometimes refers to the software in a Unix kernel that provides the OSS interface; it can be thought of as a device driver (or a collection of device drivers) for sound controller hardware. The goal of OSS is to allow the writing of sound-based applications that are agnostic of the underlying sound hardware. OSS was created by Hannu Savolainen and is distributed under four license options, three of which are free software licences, thus making OSS free software. API The API is designed to use the traditional Unix framework of open(), read(), write(), and ioctl(), via special devices. For instance, the default device for sound input and output is /dev/dsp. Examples using the shell: cat /dev/random > /dev/dsp # plays white noise through the speaker cat / ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound Reproduction
Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording. Sound recording is the transcription of invisible vibrations in air onto a storage medium such as a phonograph disc. The process is reversed in sound reproduction, and the variations stored on the medium are transformed back into sound waves. Acoustic analog recording is achieved by a microphone diaphragm that senses changes in atmospheric pressure caused by acoustic sound waves and records them as a mechanical representation of the sound waves on a medium such as a phonograph record (in which a stylus cuts grooves on a record). In magnetic tape recording, the sound waves vibrate the microphone diaphragm and are converted into a varying electric current, which is then converted to a v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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