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Plex (also known as "Plexapp", "Plex Media Center", or "PMC") is a partially open-source freeware media player with a 10-foot user interface, which is available for Intel-based Macintosh computers and computers running Microsoft Windows.^[1] Its source code was initially forked from XBMC Media Center on May 21, 2008; this fork is used today as a front end media player for Plex's back end server component.^[2][3][4]

Plex's front end media player, Plex Media Center, allows the user to manage and playback video, photos, music, and podcasts from a local or remote computer running Plex Media Server. In addition, the integrated Plex Online service provides the user with a growing list of community-driven plugins for online content including Hulu, Netflix, and CNN video.^[4]

Plex began as a freeware hobby project but since 2010 has evolved into a commercial software business that is owned and developed by a single for-profit startup company, (Plex, Inc.). It is a high tech company based in the United States that is responsible for the development of the Plex front-end and back-ends, its client–server model, and all accompanying software under the "Plex" trademark, as well as the exclusive copyright of the closed source software/code parts, both when distributed on its own or when it comes as third-party software component in products by other manufacturers via a strategic partnership.^[5][6][7]

Plex Media Center[link]

Plex Media Center is the front end component of Plex. Forked from XBMC in 2008, Plex Media Center allows users to browse and play local media, as well us utilize plugins and content which are hosted by a Plex Media Server.

Plex supports a wide range of multimedia formats and includes features such as playlists, audio visualizations, slideshows, weather forecasts reporting, and an expanding array of third-party plugins. As a media center, Plex can play most audio and video file formats, as well as display images from many sources, including CD/DVD-ROM drive, USB flash drives, the Internet, and local area network shares. DVD playback is not yet fully integrated and requires the use of helper applications like Apple's DVD Player.^[8]

On the appropriate hardware, Plex is able to decode high-definition video up to 1080p.^[4][9] Older Macintosh computers lack support for hardware video decoding; users need a 2 GHz Intel Core 2 processor to decode the majority of 1080p videos encoded with the H.264 codec. Newer models using Nvidia 9400M/GT320M/GT330M chipsets and Snow Leopard OS 10.6.3 or later benefit from H.264 hardware accelerated video decoding, offloading most of the work to the GPU.^[10]

Plex Media Center can be controlled remotely using an Apple or Harmony remote control, or via mobile apps.^[8]

Plex Media Center is distributed under the GNU General Public License, with source code on GitHub. The founder of Plex, Elan Feingold, was part of the official XBMC development team for a short while, but tensions over direction and philosophy led him to leave the project and create the Plex fork.^[2][3][4]

Audio and video playback[link]

Plex can play files from CD and DVD media using the systems' DVD-ROM drive, from a local hard disk drive, or streaming over SMB/SAMBA/CIFS shares (Windows File-Sharing), ReplayTV DVRs, or UPnP (Universal Plug and Play) and DLNA shares and media servers. Plex is designed to take advantage of an Internet connection if available, using the IMDb to obtain thumbnails and reviews of movies, TheTVDB for TV show thumbnails and metadata, CDDB (via FreeDB) for audio CD track listings, and AMG for album cover images. Plex also includes the option to submit music usage statistics to Last.fm. It also has music and video playlists, slideshows, a karaoke function, and many audio visualizers and screensavers.

Like other XBMC-derived media players, Plex uses FFmpeg and other open source libraries to handle all common multimedia formats. It can decode these in software, using hardware video decoding where available and optionally passing-through AC3/DTS audio directly to an external audio-amplifier/receiver via S/PDIF.

Video playback in detail[link]

The Video Library, one of the Plex metadata databases, is a key feature of Plex. It allows for the automatic organization of your video content by information associated with the video files (movies and recorded TV Shows) themselves. The Library Mode view in Plex allows you to browse your video content by categories such as Genre, Title, Year, Actors and Directors.

Plex video-playback uses a video-player "core" which was originally developed in-house by the XBMC developers as a DVD-player for DVD-Video movies, including the support of DVD-menus. This video-player "core" supports all the FFmpeg codecs, and in addition the MPEG-2 video codec, and the audio codecs DTS and AC3.

Audio playback in detail[link]

The Music Library, one of the Plex metadata databases, is another key feature of Plex. It allows for the automatic organization of your music collection by information stored in your music file ID meta tags, like title, artist, album, genre and popularity.

For audio playback, Plex includes the audio-player called PAPlayer (Psycho-Acoustic Audio Player) which was originally developed in-house by the XBMC developers. Some of this audio-player core's most notable features are on-the-fly audio frequency resampling, gapless playback, crossfading, ReplayGain, cue sheet and Ogg Chapter support. PAPlayer handles a very large variety of audio file-formats.

Digital picture/image display in detail[link]

Plex handles all common digital picture/image formats with the options of panning/zooming and slideshow with "Ken Burns Effect", with the use of CxImage open source library code.

Plex Media Server[link]

Plex's back end component, Plex Media Server, is closed source software. Introduced in 2009, Plex Media Server is used to host the content and plugins that are then streamed to Plex Media Center and Plex mobile app clients, either on the same machine, the same local area network, or over the Internet. In addition to the platforms supported by the front end, the server is also available for Linux. Plex Media Server can be configured to index content in any directory on the machine it's run on, as well as automatically acquiring iTunes, iPhoto, and Aperture content. Content may be transcoded by the server before it's streamed in order to reduce bandwidth requirements, or for compatibility with the device being streamed to.

Plex Media Server allows extensibility through the addition of plug-ins. Many of these plug-ins are available through the built-in Plex Online digital distribution service. This service can be used directly within Plex Media Center's GUI.^[4][11][12]

Mobile software[link]

Plex mobile apps exist for Windows Phone, iOS and Android. Compatible with devices running a minimum of Windows Phone 7.5, iOS 4.1 or Android 1.6, the apps allow remote controlling the Plex media center on a computer. They also feature browsing and streaming content directly to the device from a Plex server, using transcoding when necessary, as well as from various online content "channels". Both support MyPlex for remote access (over the Internet) to Plex servers. Unlike the desktop versions of Plex, these apps are not freeware. ^[13][14][15]

Third-party applications are also available on both platforms for remote controlling Plex.

Programming and developing[link]

Plex Media Center is primarily programmed in C++, and makes use of the SDL (Simple DirectMedia Layer) framework with an OpenGL renderer. Some of the third-party libraries that Plex depends on are written in the C, but are used with a C++ wrapper and loaded as shared libraries when used inside Plex.

Plugins for Plex Media Server[link]

While Plex Media Server is close source, developers can make plugins for its proprietary plugin architecture using Python and XML. They can then submit these plugins to Plex Online.^[11][12]

Many plug-ins for Plex Media Server leverage WebKit to display video from online sources using the same Flash and Silverlight players that the sources provide for web browsers. ^[4]

Skins, skinning, and the skinning-engine[link]

Since Plex Media Center is based on XBMC Media Center it shares its flexible GUI toolkit and robust framework. With themes based on a standard XML base, theme-skinning and personal customization are very accessible. Users can create their own skin (or simply modify an existing skin) and share it with others via third-party public websites for XBMC skin trading.

Plex currently uses a modified version of the "MediaStream" skin as its default skin, a skin that was originally designed by Team Razorfish for XBMC.^[16]

Legality[link]

Copyright[link]

Plex media center software is licensed under the GNU General Public License (GPL) by the developers, meaning they allow anybody to redistribute the Plex media player source code under the conditions of that GPL license. Plex Media Server, the proprietary back-end server that all plugins for Plex are dependent on, is however closed source.

Patents[link]

For most popular video and audio codecs, Plex includes native support through free and open source software libraries, such as LAME, faad, faac, libmpeg2, and libavcodec (from the FFmpeg project). Since these source code libraries are released under free and open source licenses they are legally redistributable. However, some of these compression methods algorithms, such as the popular MP3 format, are in many countries protected by software patents. Absent a license, this could possibly make it illegal in certain countries to distribute compiled versions of Plex which includes support for these formats.

Web Scraping[link]

Plex has the built-in optional function to automatically download meta data information and artwork online through its scrapers (i.e. web scraping sites like IMDb, TheMovieDB, TheTVDB, freedb, Allmusic etc.).

Other[link]

Plex also includes libdvdcss in order to support playback of DVD-Video movies encrypted using the CSS (Content Scramble System) encryption scheme. The distribution of executable versions of Plex containing this code could possibly fall afoul of the Digital Millennium Copyright Act in the U.S. and the EU Copyright Directive in European Union member countries which have incorporated it into national law, this has however, not been proven to be lawful in any court for an open source project before.

See also[link]

• List of other software video players

References[link]

External links[link]

• Official website
• Narrated Video of Plex features and functionality

Look up -plex in Wiktionary, the free dictionary.

PLEX or Plex may refer to:

• PLEX (programming language), a programming language used by Ericsson for their AXE telephone exchange
• Plex (software), media center software including a media server, and desktop and mobile clients
• Prairie Lindy Exchange, an acronym used in various lindy exchanges in central North America
• Googolplex, a large number, which has given rise to "n-plex" notation in the names of large numbers
• Googleplex, corporate headquarters complex of Google, Inc.
• Light Water Reactor Sustainability Program or Plant Life Extension of nuclear power plants

Entertainment[link]

• Plex, a magic robot character in the children's television show Yo Gabba Gabba!
• Plex soldiers, characters in the computer game Star Wars: Empire at War
• Com Plex, a 2000 album by The Helio Sequence
• Megaplex, a large theatre with many screens
• Supaplex, a computer game
• 30 Days Concord Pilot License Extension (PLEX), an item in EVE Online MMORPG game that adds 30 days of game time
• Plex (video game developer), developer of video games Ruin Arm and Shōnin yo Taishi wo Idake!!

Technology[link]

• Plex, a brand name of North State Communications
• Plex Systems, a software company that develops Plex Online
• Parallel Sysplex, a cluster of IBM mainframes
• Steinberg Plex, Virtual Studio Technology software

This disambiguation page lists articles associated with the same title. If an internal link led you here, you may wish to change the link to point directly to the intended article.

Computer software, or just software, is a collection of computer programs and related data that provides the instructions for telling a computer what to do and how to do it. Software refers to one or more computer programs and data held in the storage of the computer for some purposes. In other words, software is a set of programs, procedures, algorithms and its documentation concerned with the operation of a data processing system. Program software performs the function of the program it implements, either by directly providing instructions to the computer hardware or by serving as input to another piece of software. The term was coined to contrast to the old term hardware (meaning physical devices). In contrast to hardware, software "cannot be touched".^[1] Software is also sometimes used in a more narrow sense, meaning application software only. Sometimes the term includes data that has not traditionally been associated with computers, such as film, tapes, and records.^[2]

Computer software is so called to distinguish it from computer hardware, which encompasses the physical interconnections and devices required to store and execute (or run) the software. At the lowest level, executable code consists of machine language instructions specific to an individual processor. A machine language consists of groups of binary values signifying processor instructions that change the state of the computer from its preceding state. Programs are an ordered sequence of instructions for changing the state of the computer in a particular sequence. It is usually written in high-level programming languages that are easier and more efficient for humans to use (closer to natural language) than machine language. High-level languages are compiled or interpreted into machine language object code. Software may also be written in an assembly language, essentially, a mnemonic representation of a machine language using a natural language alphabet. Assembly language must be assembled into object code via an assembler.

History[link]

This section may need to be rewritten entirely to comply with Wikipedia's quality standards. You can help. The discussion page may contain suggestions. (January 2012)

The first theory about software was proposed by Alan Turing in his 1935 essay Computable numbers with an application to the Entscheidungsproblem (Decision problem).^[3] The term "software" was first used in print by John W. Tukey in 1958.^[4] Colloquially, the term is often used to mean application software. In computer science and software engineering, software is all information processed by computer system, programs and data.^[4] The academic fields studying software are computer science and software engineering.

The history of computer software is most often traced back to the first software bug in 1946^{[citation needed]}. As more and more programs enter the realm of firmware, and the hardware itself becomes smaller, cheaper and faster as predicted by Moore's law, elements of computing first considered to be software, join the ranks of hardware. Most hardware companies today have more software programmers on the payroll than hardware designers^{[citation needed]}, since software tools have automated many tasks of Printed circuit board engineers. Just like the Auto industry, the Software industry has grown from a few visionaries operating out of their garage with prototypes. Steve Jobs and Bill Gates were the Henry Ford and Louis Chevrolet of their times^{[citation needed]}, who capitalized on ideas already commonly known before they started in the business. In the case of Software development, this moment is generally agreed to be the publication in the 1980s of the specifications for the IBM Personal Computer published by IBM employee Philip Don Estridge. Today his move would be seen as a type of crowd-sourcing.

Until that time, software was bundled with the hardware by Original equipment manufacturers (OEMs) such as Data General, Digital Equipment and IBM^{[citation needed]}. When a customer bought a minicomputer, at that time the smallest computer on the market, the computer did not come with Pre-installed software, but needed to be installed by engineers employed by the OEM. Computer hardware companies not only bundled their software, they also placed demands on the location of the hardware in a refrigerated space called a computer room. Most companies had their software on the books for 0 dollars, unable to claim it as an asset (this is similar to financing of popular music in those days). When Data General introduced the Data General Nova, a company called Digidyne wanted to use its RDOS operating system on its own hardware clone. Data General refused to license their software (which was hard to do, since it was on the books as a free asset), and claimed their "bundling rights". The Supreme Court set a precedent called Digidyne v. Data General in 1985. The Supreme Court let a 9th circuit decision stand, and Data General was eventually forced into licensing the Operating System software because it was ruled that restricting the license to only DG hardware was an illegal tying arrangement.^[5] Soon after, IBM 'published' its DOS source for free,^{[citation needed]} and Microsoft was born. Unable to sustain the loss from lawyer's fees, Data General ended up being taken over by EMC Corporation. The Supreme Court decision made it possible to value software, and also purchase Software patents. The move by IBM was almost a protest at the time. Few in the industry believed that anyone would profit from it other than IBM (through free publicity). Microsoft and Apple were able to thus cash in on 'soft' products. It is hard to imagine today that people once felt that software was worthless without a machine. There are many successful companies today that sell only software products, though there are still many common software licensing problems due to the complexity of designs and poor documentation, leading to patent trolls.

With open software specifications and the possibility of software licensing, new opportunities arose for software tools that then became the de facto standard, such as DOS for operating systems, but also various proprietary word processing and spreadsheet programs. In a similar growth pattern, proprietary development methods became standard Software development methodology.

Types of software[link]

A layer structure showing where the operating system software and application software are situated while running on a typical desktop computer

Software includes all the various forms and roles that digitally stored data may have and play in a computer (or similar system), regardless of whether the data is used as code for a CPU, or other interpreter, or whether it represents other kinds of information. Software thus encompasses a wide array of products that may be developed using different techniques such as ordinary programming languages, scripting languages, microcode, or an FPGA configuration.

The types of software include web pages developed in languages and frameworks like HTML, PHP, Perl, JSP, ASP.NET, XML, and desktop applications like OpenOffice.org, Microsoft Word developed in languages like C, C++, Objective-C, Java, C#, or Smalltalk. Application software usually runs on an underlying software operating systems such as Linux or Microsoft Windows. Software (or firmware) is also used in video games and for the configurable parts of the logic systems of automobiles, televisions, and other consumer electronics.

Practical computer systems divide software systems into three major classes^{[citation needed]}: system software, programming software and application software, although the distinction is arbitrary, and often blurred.

System software[link]

System software is computer software designed to operate the computer hardware to provide basic functionality and to provide a platform for running application software.^[6][7] System software includes device drivers, operating systems, servers, utilities, and window systems.

System software is responsible for managing a variety of independent hardware components, so that they can work together harmoniously. Its purpose is to unburden the application software programmer from the often complex details of the particular computer being used, including such accessories as communications devices, printers, device readers, displays and keyboards, and also to partition the computer's resources such as memory and processor time in a safe and stable manner.

Programming software[link]

Programming software include tools in the form of programs or applications that software developers use to create, debug, maintain, or otherwise support other programs and applications. The term usually refers to relatively simple programs such as compilers, debuggers, interpreters, linkers, and text editors, that can be combined together to accomplish a task, much as one might use multiple hand tools to fix a physical object. Programming tools are intended to assist a programmer in writing computer programs, and they may be combined in an integrated development environment (IDE) to more easily manage all of these functions.

Application software[link]

Application software is developed to perform in any task that benefits from computation. It is a set of programs that allows the computer to perform a specific data processing job for the user. It is a broad category, and encompasses software of many kinds, including the internet browser being used to display this page. This category includes:

• Business software
• Computer-aided design
• Databases
• Decision-making software
• Educational software
• Image editing
• Industrial automation
• Mathematical software
• Medical software
• Molecular modeling software
• Quantum chemistry and solid state physics software
• Simulation software
• Spreadsheets
• Telecommunications (i.e., the Internet and everything that flows on it)
• Video editing software
• Video games
• Word processing

Software topics[link]

Architecture[link]

Users often see things differently than programmers. People who use modern general purpose computers (as opposed to embedded systems, analog computers and supercomputers) usually see three layers of software performing a variety of tasks: platform, application, and user software.

• Platform software: Platform includes the firmware, device drivers, an operating system, and typically a graphical user interface which, in total, allow a user to interact with the computer and its peripherals (associated equipment). Platform software often comes bundled with the computer. On a PC you will usually have the ability to change the platform software.
• Application software: Application software or Applications are what most people think of when they think of software. Typical examples include office suites and video games. Application software is often purchased separately from computer hardware. Sometimes applications are bundled with the computer, but that does not change the fact that they run as independent applications. Applications are usually independent programs from the operating system, though they are often tailored for specific platforms. Most users think of compilers, databases, and other "system software" as applications.
• User-written software: End-user development tailors systems to meet users' specific needs. User software include spreadsheet templates and word processor templates. Even email filters are a kind of user software. Users create this software themselves and often overlook how important it is. Depending on how competently the user-written software has been integrated into default application packages, many users may not be aware of the distinction between the original packages, and what has been added by co-workers.

Documentation[link]

Most software has software documentation so that the end user can understand the program, what it does, and how to use it. Without clear documentation, software can be hard to use—especially if it is very specialized and relatively complex like Photoshop or AutoCAD.

Developer documentation may also exist, either with the code as comments and/or as separate files, detailing how the programs works and can be modified.

Library[link]

An executable is almost always not sufficiently complete for direct execution. Software libraries include collections of functions and functionality that may be embedded in other applications. Operating systems include many standard Software libraries, and applications are often distributed with their own libraries.

Standard[link]

Since software can be designed using many different programming languages and in many different operating systems and operating environments, software standard is needed so that different software can understand and exchange information between each other. For instance, an email sent from a Microsoft Outlook should be readable from Yahoo! Mail and vice versa.

Execution[link]

Computer software has to be "loaded" into the computer's storage (such as the hard drive or memory). Once the software has loaded, the computer is able to execute the software. This involves passing instructions from the application software, through the system software, to the hardware which ultimately receives the instruction as machine code. Each instruction causes the computer to carry out an operation – moving data, carrying out a computation, or altering the control flow of instructions.

Data movement is typically from one place in memory to another. Sometimes it involves moving data between memory and registers which enable high-speed data access in the CPU. Moving data, especially large amounts of it, can be costly. So, this is sometimes avoided by using "pointers" to data instead. Computations include simple operations such as incrementing the value of a variable data element. More complex computations may involve many operations and data elements together.

Quality and reliability[link]

Software quality is very important, especially for commercial and system software like Microsoft Office, Microsoft Windows and Linux. If software is faulty (buggy), it can delete a person's work, crash the computer and do other unexpected things. Faults and errors are called "bugs." Many bugs are discovered and eliminated (debugged) through software testing. However, software testing rarely – if ever – eliminates every bug; some programmers say that "every program has at least one more bug" (Lubarsky's Law). All major software companies, such as Microsoft, Novell and Sun Microsystems, have their own software testing departments with the specific goal of just testing. Software can be tested through unit testing, regression testing and other methods, which are done manually, or most commonly, automatically, since the amount of code to be tested can be quite large. For instance, NASA has extremely rigorous software testing procedures for many operating systems and communication functions. Many NASA based operations interact and identify each other through command programs called software. This enables many people who work at NASA to check and evaluate functional systems overall. Programs containing command software enable hardware engineering and system operations to function much easier together.

License[link]

The software's license gives the user the right to use the software in the licensed environment. Some software comes with the license when purchased off the shelf, or an OEM license when bundled with hardware. Other software comes with a free software license, granting the recipient the rights to modify and redistribute the software. Software can also be in the form of freeware or shareware.

Patents[link]

Software can be patented in some but not all countries; however, software patents can be controversial in the software industry with many people holding different views about it. The controversy over software patents is about specific algorithms or techniques that the software contains, which may not be duplicated by others and considered intellectual property and copyright infringement depending on the severity.

Design and implementation[link]

Design and implementation of software varies depending on the complexity of the software. For instance, design and creation of Microsoft Word software will take much more time than designing and developing Microsoft Notepad because of the difference in functionalities in each one.

Software is usually designed and created (coded/written/programmed) in integrated development environments (IDE) like Eclipse, Emacs and Microsoft Visual Studio that can simplify the process and compile the program. As noted in different section, software is usually created on top of existing software and the application programming interface (API) that the underlying software provides like GTK+, JavaBeans or Swing. Libraries (APIs) are categorized for different purposes. For instance, JavaBeans library is used for designing enterprise applications, Windows Forms library is used for designing graphical user interface (GUI) applications like Microsoft Word, and Windows Communication Foundation is used for designing web services. Underlying computer programming concepts like quicksort, hashtable, array, and binary tree can be useful to creating software. When a program is designed, it relies on the API. For instance, if a user is designing a Microsoft Windows desktop application, he/she might use the .NET Windows Forms library to design the desktop application and call its APIs like Form1.Close() and Form1.Show()^[8] to close or open the application and write the additional operations him/herself that it need to have. Without these APIs, the programmer needs to write these APIs him/herself. Companies like Sun Microsystems, Novell, and Microsoft provide their own APIs so that many applications are written using their software libraries that usually have numerous APIs in them.

Computer software has special economic characteristics that make its design, creation, and distribution different from most other economic goods.^{[specify][9][10]}

A person who creates software is called a programmer, software engineer, software developer, or code monkey, terms that all have a similar meaning.

Industry and organizations[link]

A great variety of software companies and programmers in the world comprise a software industry. Software can be quite a profitable industry: Bill Gates, the founder of Microsoft was the richest person in the world in 2009 largely by selling the Microsoft Windows and Microsoft Office software products. The same goes for Larry Ellison, largely through his Oracle database software. Through time the software industry has become increasingly specialized.

Non-profit software organizations include the Free Software Foundation, GNU Project and Mozilla Foundation. Software standard organizations like the W3C, IETF develop software standards so that most software can interoperate through standards such as XML, HTML, HTTP or FTP.

Other well-known large software companies include Novell, SAP, Symantec, Adobe Systems, and Corel, while small companies often provide innovation.

See also[link]

	Software portal
	Free software portal

• List of software
• Personal computer hardware

References[link]

External links[link]

Wikimedia Commons has media related to: Software

Look up software in Wiktionary, the free dictionary.

• Software Wikia